JP6965028B2 - Piezoelectric materials, piezoelectric elements, liquid discharge heads, liquid discharge devices, vibration wave motors, optical equipment, vibration devices, dust removers, imaging devices and electronic devices - Google Patents

Description

The present invention relates to a piezoelectric material, and more particularly to a lead-free piezoelectric material. The present invention also relates to a piezoelectric element, a liquid discharge head, a liquid discharge device, a vibration wave motor, an optical device, a vibration device, a dust removing device, an imaging device, and an electronic device using the piezoelectric material.

_ABO-3 type perovskite type metal oxides such as lead-containing lead zirconate titanate (hereinafter referred to as "PZT") are typical piezoelectric materials, and various piezoelectric materials such as actuators, oscillators, sensors and filters are used. Used in the device. However, since PZT contains lead as an A-site element, the lead component in the discarded piezoelectric material may dissolve into the soil and harm the ecosystem, and the impact on the environment is regarded as a problem.

Therefore, various piezoelectric materials using lead-free perovskite-type metal oxides have been studied.

For example, barium titanate is known as a lead-free piezoelectric material for perovskite-type metal oxides. However, the piezoelectric properties of the piezoelectric material using barium titanate, particularly the piezoelectric constant and the mechanical quality coefficient, are not sufficient as compared with PZT, which has been a problem.

In Patent Document 1, oxygen vacancies are formed and a ferroelectric domain is pinned by adding Mn, Fe, or Cu to a material in which a part of the A site of barium titanate is replaced with Ca. Discloses a piezoelectric material with improved mechanical quality coefficient.

Japanese Patent No. 5217997

However, if the amount of additives such as Mn added is increased, the piezoelectric constant decreases and the dielectric loss increases. Therefore, the piezoelectric characteristics can be improved by this method, and particularly a high piezoelectric constant and a high mechanical quality coefficient can be achieved at the same time. Was limited. For example, it has been difficult to achieve both a _{piezoelectric constant d 31} ≥ 100 pm / V and a mechanical quality coefficient Q _m ≥ 2000 in a room temperature environment.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a piezoelectric material having a small environmental load and a high piezoelectric constant and a high mechanical quality coefficient.

Another object of the present invention is to provide a piezoelectric element, a liquid discharge head, a liquid discharge device, a vibration wave motor, an optical device, a vibration device, a dust removing device, an imaging device, and an electronic device using the piezoelectric material.

The piezoelectric material of the present invention for solving the above problems is a perovskite-type piezoelectric material containing a metal oxide represented by the following general formula (1), Bi, and Mn, and the content of Bi. Is 0.1 mol% or more and 0.5 mol% or less with respect to 1 mol of the metal oxide, and the Mn content is 0.3 mol% or more and 1.5 mol with respect to 1 mol of the metal oxide. % Or less, and X-rays when the distances of 12 types of Bi-O bonds starting from Bi at the position of 12 coordination with respect to O in the perovskite unit cell are L _{1 to} L _{12 in order of increasing length.} length of the Bi-O bonds by measuring absorption fine _structure, meets the _{(L 4 -L 5) / L} 5 ≧ 0.05 and (L8-L9) /L9≧0.05,
The Mn content is higher than the Bi content .
General formula (1)
(Ba _1-x M1 _x ) (Ti _1-y M2 _y ) O ₃
(However, 0 ≦ x ≦ 0.2, 0 ≦ y ≦ 0.1, M1 and M2 are different metal elements having a sum of +6 valences, and are selected from elements other than Ba, Ti, Bi, and Mn. )

According to the present invention, it is possible to provide a piezoelectric material having a small environmental load because lead is not used and having both a high piezoelectric constant and a high mechanical quality coefficient.

Further, according to the present invention, it is possible to provide a piezoelectric element, a liquid discharge head, a liquid discharge device, a vibration wave motor, an optical device, a vibration device, a dust removing device, an imaging device, and an electronic device using the piezoelectric material. ..

It is a schematic diagram which shows the positional relationship between the Bi atom introduced into the crystal lattice which comprises the piezoelectric material of this invention, and a series of atoms coordinated with the surroundings. It is the schematic which shows one Embodiment of the structure of the piezoelectric element of this invention. (A) It is sectional drawing which shows one Embodiment of the structure of the laminated piezoelectric element (two-layer laminated structure) of this invention. (B) It is sectional drawing which shows one Embodiment of the structure of the laminated piezoelectric element (9-layer laminated structure) of this invention. It is an overall schematic which shows one Embodiment of the structure of the liquid discharge head of this invention. It is the schematic which shows one Embodiment of the structure of the liquid discharge device of this invention. It is the schematic which shows one Embodiment of the structure of the liquid discharge device of this invention. (A) It is a schematic diagram which shows one Embodiment of the structure of the ultrasonic motor (single plate structure) of this invention. (B) It is a schematic diagram which shows one Embodiment of the structure of the ultrasonic motor (laminated structure) of this invention. It is the schematic which shows one Embodiment of the structure of the optical device of this invention. It is the schematic which shows one Embodiment of the structure when the vibration device of this invention is a dust removal device. (A) It is a schematic diagram which shows an example (7th order vibration mode) of the vibration principle of the dust removal apparatus of this invention. (B) It is a schematic diagram which shows an example (the sixth vibration mode) of the vibration principle of the dust removal apparatus of this invention. It is the schematic which shows one Embodiment of the structure of the image pickup apparatus of this invention. It is the schematic which shows one Embodiment of the structure of the image pickup apparatus of this invention. It is the schematic which shows one Embodiment of the structure of the electronic device of this invention. It is an X-ray diffraction chart of the piezoelectric material of Example 2 of this invention. It is a figure which shows the lattice constant and the lattice volume of the piezoelectric material of Examples 1 to 6 and Comparative Examples 1 to 5 of this invention. It is a schematic diagram which shows the crystal lattice and atomic coordinates of the piezoelectric material of Examples 1 to 5 and Comparative Examples 1 and 2 of this invention, the figure which shows the spontaneous polarization value calculated from the atomic coordinates, and the figure which shows the atomic displacement parameter. .. It is a figure which shows the XANES spectrum, EXAFS vibration spectrum, and the radial structure function obtained by _{the Bi-L 3} XAFS measurement of the piezoelectric material and the reference substance of Examples 1 to 4 and Comparative Example 2 of this invention. It is a figure which shows the radius structure function obtained by the Ba-K XAFS measurement of the piezoelectric material of Examples 1 to 4 and Comparative Examples 1, 2 and 4 of this invention. It is a figure which shows the XANES spectrum, EXAFS vibration spectrum, and the radial structure function obtained by Mn-K XAFS measurement of the piezoelectric material and the reference substance of Examples 1 to 4 and Comparative Example 4 of this invention. It is a figure which shows an example of the temperature dependence of the magnetic susceptibility of the piezoelectric material of this invention, and is the figure which shows the Bi / Mn content ratio dependence of the Mn valence in the piezoelectric material evaluated from the temperature dependence of the magnetic susceptibility. It is a figure which shows the temperature dependence of the relative permittivity and the dielectric loss of the piezoelectric material of Examples 1 to 5 and Comparative Examples 1 to 4 of this invention. It is a figure which shows _{the Curie temperature T c} and the tetragonal-orthorhombic phase transition temperature _Tot of the piezoelectric material of Examples 1 to 6 and Comparative Examples 1 to 5 of this invention. It is a figure which shows the polarization-electric field (PE) property of the piezoelectric material of Examples 2, 4 and 5, and Comparative Examples 1 and 3 of this invention.

Hereinafter, modes for carrying out the present invention will be described.
The piezoelectric material of the present invention is a perovskite-type piezoelectric material having a main component containing a metal oxide represented by the following general formula (1), a first subcomponent composed of Bi, and a second subcomponent composed of Mn. The Bi content is 0.1 mol% or more and 0.5 mol% or less with respect to 1 mol of the metal oxide, and the Mn content is 0 with respect to 1 mol of the metal oxide. . The distances of 12 types of Bi-O bonds starting from Bi, which are 3 mol% or more and 1.5 mol% or less and are in the position of 12 coordination with respect to O in the perovskite unit cell, are L ₁ to longest. When L ₁₂ , the distance of the Bi—O bond measured by measuring the X-ray absorption microstructure is (L _4- L ₅ ) / L ₅ ≧ 0.05 and (L _8- L ₉ ) / L ₉ ≧. 0.05 meet the,
The Mn content is higher than the Bi content .
General formula (1)
(Ba _1-x M1 _x ) (Ti _1-y M2 _y ) O ₃
(However, 0 ≦ x ≦ 0.2, 0 ≦ y ≦ 0.1, M1 and M2 are different metal elements having a sum of +6 valences, and are selected from elements other than Ba, Ti, Bi, and Mn. )

(Perovskite type structure)
A metal oxide having a perovskite-type structure (also referred to as a perovskite-type structure) is generally represented by the chemical formula of _{ABO 3.} In a metal oxide having a perovskite-type structure, elements A and B (referred to as elements A and B, respectively) occupy specific positions in a unit cell called A site and B site in the form of ions, respectively. For example, in the case of a cubic unit cell, when element A is the apex of the cube, element B is located at the center of the body, and element O occupies the face-centered position of the cube as an anion of oxygen. When the unit lattice is distorted in the [001], [011], or [111] directions of the cubic unit lattice, it becomes a crystal lattice having a perovskite-type structure of tetragonal, orthorhombic, and rhombohedral crystals, respectively. In _{the crystal lattice of the perovskite type structure represented by these chemical formulas of ABO 3,} the element in the first vicinity of the element A is the element O, and 12 elements of O are coordinated around the element A. The second nearest element of the A element is the B element, and eight B elements are coordinated around the A element. On the other hand, the element in the first proximity of the element B is also the element O, six O elements are coordinated around the element B, and the element in the second proximity of the element B is the element A, which is the element B. Eight A elements are coordinated around it.

The above general formula (1) is a chemical formula of a metal oxide having a perovskite structure, in which (Ba _1-x M1 _x ) corresponds to element A and (Ti _1-y M2 _y ) corresponds to element B. When x = 0 and y = 0, the general formula (1) becomes BaTIO ₃ , which means barium titanate. It is known that barium titanate BaTiO ₃ has a tetragonal perovskite structure, Ba occupies the A site at the oxygen 12 coordination position, and Ti occupies the B site at the oxygen 6 coordination position. There is. That is, the Ba atom forms a Ba—O bond with the 12 O atoms around it, and the Ti atom forms a Ti—O bond with the 6 O atoms around it. The metal element M1 can be located at the A site by substituting a part of Ba. However, the permissible substitution ratio is 20% or less of the total A-site element, in other words, the range of x is 0 or more and 0.2 or less with _{respect to the A element (Ba 1-x} M1 _x). Similarly, M2 can be located at the B site by substituting a part of Ti, and the substitution ratio is 10% or less of the total B site element, in other words, the A element (Ti _1-y M2 _y ). On the other hand, the range of y is 0 or more and 0.1 or less. If M1 and M2 are substituted in excess of 20% of the A-site element and 10% of the B-site element, respectively, they _{greatly deviate from the properties of BaTiO 3} and the desired piezoelectric properties cannot be obtained. For example, characteristic deterioration may occur due to a decrease in the piezoelectric constant or a decrease in the Curie temperature due to a large amount of substitution.

The metal elements M1 and M2 are selected from elements other than Ba and Ti. Further, Bi and Mn, which are the first and second subcomponents described later, are also not included in the options of M1 and M2. Similar to the combination of Ba and Ti, M1 and M2 are selected from a combination in which the sum of the valence of M1 and the valence of M2 is +6 valence. The combination may be M1 with +1 valence and M2 with +5 valence, M1 with +3 valence and M2 with +3 valence. In particular, like the combination of Ba and Ti, the combination of M1 with +2 valence and M2 with +4 valence is desirable. .. Of these, a combination in which M1 is at least one of +2 valent Sr and Ca and M2 is at least one of +4 valent Hf, Sn and Zr is particularly desirable.

However, some Ba and M1 may be located at the B site. Similarly, some Ti and M2 may be located at the A site.

In the general formula (1), the molar ratio of the element B site to the element O is 1: 3, but even if the ratio of the element amounts is slightly different, the metal oxide contains a perovskite-type structure as the main phase. For example, it is included in the scope of the present invention.

The piezoelectric material of the metal oxide having the perovskite structure represented by the general formula (1) generally _{exhibits a high piezoelectric constant (for example, d 31} piezoelectric constant). However, the mechanical quality coefficient Q _m did not reach the desired value, and the piezoelectric performance was insufficient. Therefore, the piezoelectric material represented by the above general formula (1), was added a second subcomponent consisting of a first subcomponent and a Mn consisting Bi, new to both high piezoelectric constant and high mechanical quality factor Q _m We came up with the idea of piezoelectric materials.

(Piezoelectric constant and mechanical quality coefficient)
The piezoelectric constant referred to here is a quantity indicating the degree of displacement (extension, contraction, displacement) of the piezoelectric material when a voltage is applied to the piezoelectric material. For example, the d ₃₁ piezoelectric constant is the voltage with respect to the contraction (extension) displacement in the direction orthogonal to the polarization direction when a voltage is applied in the macropolarization direction (usually the direction in which the voltage is applied during the polarization process) of the piezoelectric material. Proportional coefficient, that is, the amount of displacement per unit voltage. Conversely, it can also be defined as the amount of charge induced when stress is applied to the material. Further, the mechanical quality coefficient referred to here is a coefficient representing an elastic loss due to vibration when a piezoelectric material is evaluated as a vibrator. The higher the mechanical quality factor, the less energy is lost during vibration. The piezoelectric constant and mechanical quality coefficient of the piezoelectric material are calculated based on the Japan Electronics and Information Technology Industries Association standard (JEITA EM-4501) from the measurement results of the resonance frequency and the antiresonance frequency obtained by using a commercially available impedance analyzer. Can be obtained by. Hereinafter, this method is referred to as a resonance-antiresonance method. The piezoelectric constant can also be obtained by directly measuring the amount of displacement when a voltage is applied or the amount of electric charge induced when a stress is applied.

(Effect of Bi's lone pair of electrons)
The valence of Bi can be +3 or +5 in the oxide, but the +3 valence Bi is characterized by the presence of a 6s lone pair of electrons. It is known that the existence of this lone pair of electrons can cause steric hindrance to the coordination environment between Bi and the atoms existing around it. That is, in a situation where Bi is surrounded by the same kind of elements, Bi often does not exist at a centrally symmetric position but exists at a biased position. Therefore, compounds containing +3 valent Bi as a main component (particularly metal oxides) often have a distorted crystal structure instead of having a highly symmetric crystal structure such as cubic crystals. A typical example is BiFeO _3, which is a perovskite-type structure that is originally a cubic crystal or a crystal structure close to it, but has a rhombohedral crystal perovskite-type structure that is greatly distorted in the [111] direction in cubic notation at a wide temperature. It is known to take in the range. Due to the nature of this Bi isolated electron pair, when a small amount of Bi is added to a compound (particularly a metal oxide) that does not contain Bi as a main component and a part of the main component element is replaced, Bi replaces the original main component element. However, it can exist at a position shifted from the original atomic position. This causes a bias in the coordination environment with the atoms around Bi, and local electric polarization occurs around Bi. When the main component compound is a ferroelectric substance having spontaneous polarization, the local electric polarization around Bi and the spontaneous polarization of the ferroelectric substance interact with each other, and in particular, the local electric polarization enhances the macroscopic spontaneous polarization. By acting as such, the polarization state of the ferroelectric substance becomes stable.

Barium titanate BaTIO ₃ is a ferroelectric substance having a square perovskite-type structure slightly distorted in the c-axis direction, and is a piezoelectric material exhibiting piezoelectricity due to its spontaneous polarization. Such a ferroelectric material is used as a piezoelectric material after exhibiting its piezoelectricity and improving the piezoelectric constant by subjecting it to a treatment (polarization treatment) in which the polarization directions are aligned by applying a high voltage. NS. When the piezoelectric material subjected to the polarization treatment is used as the piezoelectric element, the voltage for driving the piezoelectric element is sufficiently lower than the voltage applied during the polarization treatment. There is almost no change. Looking at the polarization state of the piezoelectric element microscopically, the inside of the piezoelectric material is composed of domains (divisions) having different polarization directions, and each of them exists adjacent to each other with a domain wall (division wall) in between. In the case of tetragonal BaTiO ₃ , domains having orthogonal polarization directions (90 ° domains) or domains with antiparallel polarization directions (180 ° domains) exist adjacent to each other. The magnitude of macro-polarization is the spatial average of the polarization of each domain, and the fact that the macro-polarization does not change due to the drive of the piezoelectric element means that the distribution of domains and the magnitude of polarization within each domain change. It means that it is not. However, the domain wall can move slightly by applying the drive voltage, and when the drive voltage is an AC voltage, the domain wall vibrates. The vibration of this domain wall causes elastic loss, resulting in a decrease in the mechanical quality coefficient of the piezoelectric material. One method of obtaining a high mechanical quality coefficient is to provide a mechanism for suppressing the movement (vibration) of the domain wall due to voltage application by making the domain wall difficult to move. Since the movement of the domain wall is based on the reversal (or rotation) of the micro-spontaneous polarization of the lattice near the domain wall, one of the means for suppressing the movement of the domain wall prevents the reversal of the micro-spontaneous polarization. A stable polarization that can be achieved is to be installed near the domain wall. Since the above-mentioned local electric polarization around Bi is caused by the deviation of the Bi atom position from the centrally symmetric position due to the lone electron pair, it cannot be easily inverted or rotated by applying a voltage. Therefore, if this _{can be introduced in the vicinity of the domain wall of the piezoelectric material containing BaTiO 3} as a main component, the movement of the domain wall due to the application of the driving voltage can be suppressed. In addition, this local electric polarization _{interacts with the spontaneous polarization of the piezoelectric material containing BaTiO 3} as a main component existing in the neighboring lattice, and stabilizes the surrounding polarization state, that is, makes it difficult to move, so that a further domain wall is further formed. It is expected that movement will be suppressed. As a result, an improvement in the mechanical quality coefficient can be realized. Based on this mechanism, the piezoelectric material of the present invention has been obtained.

When a small amount _{of Bi is added to a metal oxide containing BaTiO 3} as a main component, most of Bi replaces Ba site (A site) with +3 valence from the comparison of the ionic radii of each element. The valence and site of Bi can be identified by the measurement of X-ray absorption fine structure (XAFS). In particular, among the XAFS spectra, the valence can be evaluated by comparing the X-ray absorption near edge structure (XANES) spectrum with the measurement data of the reference substance having a known valence and structure. Although it is possible to estimate the site where Bi exists from the comparative analysis of the XANES spectrum with the reference substance, the extended X-ray absorption fine structure (EXAFS) located on the higher energy side of the XAFS region of the XAFS spectrum. By analyzing (structure), the site where Bi exists can be identified, and further, information on the coordination environment around Bi, especially the bond distance with the coordination atom and its number (coordination number) can be obtained. Can be done. It is desirable to measure the XAFS using high-intensity X-rays, and it is desirable to measure it in a synchrotron radiation facility such as SPring-8. In addition, in order to confirm the change in the average structure (for example, lattice constant) of the crystal lattice due to the addition and compare it with the change in the local structure obtained by XAFS, powder X-ray diffraction measurement may be performed in parallel. desirable. At this time, it is desirable to measure using short-wavelength X-rays, and similarly, it is desirable to measure at a synchrotron radiation facility such as SPring-8.

Since _{Ba of BaTIO 3} is located at the A site of the perovskite type structure, 12 O atoms, which are the first neighboring atoms, are coordinated around the Ba atom. The Ba atom surrounded by 12 O atoms is located almost in the center. However, since BaTIO ₃ is a tetragonal ferroelectric substance that is slightly distorted in the c-axis direction and has broken central symmetry, the position of the Ba atom is slightly deviated from the center of the 12 O atoms. However, the deviation from the center is expressed in terms of, for example, the Ba-O bond distance, and the difference between the longest Ba-O bond distance and the shortest Ba-O bond distance is less than 5% of the shortest Ba-O bond distance. It is a little.

(Bi shift)
When the Ba site (A site) of BaTIO ₃ is replaced by Bi, Bi starts from a centrally symmetric position surrounded by 12 surrounding O atoms as shown in FIG. 1 due to the steric hindrance caused by the above-mentioned lone electron pair. It will exist in a position that is greatly deviated. Due to the deviation of the Bi position from the centrally symmetric position, local electric polarization occurs around the Bi. In order for this local electric polarization to interact with macroscopic spontaneous polarization and to further stabilize the polarization state of the entire piezoelectric material, the local electric polarization around Bi is approximately larger than a certain level in the c-axis direction. Must have For that purpose, Bi needs to exist at a centrally symmetric position surrounded by 12 O atoms, that is, a position relatively largely deviated in the c-axis direction from the symmetric position of the unit cell. Since BaTIO ₃ is a tetragonal crystal slightly distorted in the c-axis direction and the direction of spontaneous polarization is also in the c-axis direction, it is presumed that the deviation of the Bi position from the centrally symmetric position is in the c-axis direction or a direction close to it. can.

(Bi-O bond length)
When 12 types of Bi-O bond distances are _{expressed as L 1 to} L _{12 in} order from the longest one, as shown in FIG. 1, L _{1 to} L _{4 having} a long bond distance and L _{9 to} L _{12 having a short bond distance} , and intermediate can be classified into three groups of _L 5 ~L ₈ bond lengths, so that the relatively large difference is generated between the _{L 4} and _L 5, _{L 8} and _{L 9.} Condition at this _time, L 1 group of ~L ₄ is _L 5 ~L ₈ than 5% or more distance is long, similarly groups _L 5 ~L ₈ is that more than 5% or more long distance Group _L 9 _{~L 12} If so, local electric polarization that only stabilizes macroelectric polarization will occur around Bi. _Preferably, L 1 group of ~L ₄ is _L 5 ~L ₈ than 10% or more distance is long, similarly _L 5 groups ~L ₈ is provided that more than 10% or more long distance Group _L 9 _{~L 12} Is. More preferably, the L _{5 to} L ₈ groups are 20% or more longer than the _{L 9 to} L _{12 groups.} Difference in distance of the group of the group and _L 5 ~L ₈ of _L 1 ~L ₄ conversely is less than _5%, the difference in distance of the group of the group and _L 9 _{~L 12} of L 5 ~L ₈ 5% If it is less than, local electric polarization that stabilizes macroscopic electric polarization is not generated around Bi, the effect of suppressing the movement of the domain wall cannot be obtained, and as a result, sufficient mechanicalness is obtained at room temperature. The quality coefficient cannot be obtained. Expressing these conditions as an expression,
(L _4- L ₅ ) / L ₅ ≥ 0.05 and (L _8- L ₉ ) / L ₉ ≥ 0.05 (2)
It is preferable that (L _4- L ₅ ) / L ₅ ≥ 0.10 and (L _8- L ₉ ) / L ₉ ≥ 0.10 (2').
More preferably, (L _4- L ₅ ) / L ₅ ≥ 0.10 and (L _8- L ₉ ) / L ₉ ≥ 0.20 (2 ″).
Is. _However, the distance of the group of L 1 the distance of a group of ~L ₄ is longer than 50% than the distance of the group of _L 5 ~L _8, or _L distance Group 5 ~L ₈ is _L 9 _{~L 12} If it becomes longer than 100%, it is considered that the perovskite type structure can no longer be maintained. Expressing this condition as an expression,
(L _4- L ₅ ) / L ₅ ≤ 0.50 and (L _8- L ₉ ) / L ₉ ≤ 1.00 (2 "")
Will be.
Further, even under the condition that the longest Bi-O bond length L ₁ is 25% or more longer than the shortest bond length L ₁₂ , local electric polarization that stabilizes macroscopic spontaneous polarization occurs around Bi. It becomes a condition of that. Preferably, L ₁ is 35% or more longer than _{L 12.} On the contrary, when _{the difference between the distances of L 1} and L ₁₂ is less than 25%, the local electric polarization that stabilizes the macro electric polarization is not generated around Bi, and the domain wall moves. The suppressive effect cannot be obtained, and as a result, a sufficient mechanical quality coefficient cannot be obtained at room temperature.
Expressing this condition as an expression,
(L _1- L ₁₂ ) / L ₁₂ ≧ 0.25 (3)
It is preferable that (L _{1 −} L ₁₂ ) / L ₁₂ ≧ 0.35 (3 ′).
Will be. However, when the difference between _{L 1} and _{L 12} is more than 200%, it is no longer considered to be impossible to maintain a perovskite structure. Expressing this condition as an expression,
(L _{1 −} L ₁₂ ) / L ₁₂ ≦ 2.00 (3 ″)
Will be.
Twelve types of Bi-O bond lengths L _{1 to} L ₁₂ can be obtained by acquiring the XAFS spectrum of Bi and fitting the radial structure function obtained from the EXAFS analysis. The fitting process _{may be performed using 12 L 1 to} L 12 as unknown parameters, but when Bi is biased in the c-axis direction, the bond distance is long L _{1 to} L ₄ , and the bond distance is short. Sufficiently reliable results can be obtained by performing the fitting assuming three bond lengths of L _{9 to} L _{12 and L 5 to} L _{8 having an intermediate bond distance.}

(Bi-Ti bond length)
Similarly, as shown in FIG. 1, it can be seen that due to the bias of the Bi atom position, the position is relatively large from the center position surrounded by the eight Ti atoms that are the second neighbors. That is, the condition for defining the occurrence of local electric polarization around Bi can also be defined by the Bi-Ti bond length. If the eight types of Bi-Ti bond distances starting from Bi located at the position of eight coordinates with respect to Ti are _{expressed as D 1 to} D _{8 in} order from the longest bond length, the bond lengths D _{1 to} D ₄ and the bond lengths are long. It can be divided into two groups with short D _{5 to} D ₈ , and there will be a relatively large difference between _{D 4} and D _5. At this time, if the distances of the groups _{D 1 to} D _{4 are 5% or more longer than those of D 5 to} D ₈ , local electric polarization sufficient to stabilize macro electric polarization occurs around Bi. It will be. Preferably, the group _{D 1 to} D ₄ is 10% or more longer than _{D 5 to} D _8. If the difference between the distance of the group of the group and D ₅ to D ₈ of D ₁ to D ₄ in reverse is less than 5%, to generate a localized electric polarization of only stabilizing the macro electric polarization in Bi ambient As a result, the effect of suppressing the movement of the domain wall cannot be obtained, and as a result, a sufficient mechanical quality coefficient cannot be obtained at room temperature. Expressing these conditions as an expression,
(D _4- D ₅ ) / D ₅ ≧ 0.05 (4)
It is preferable that (D _4- D ₅ ) / D ₅ ≧ 0.10 (4').
Will be. However, when the distance of the group of D ₁ to D ₄ is longer than 40% than the distance of the group of D ₅ to D _8, considered no longer able to maintain a perovskite structure. Expressing this condition as an expression,
(D _4- D ₅ ) / D ₅ ≤ 0.40 (4 ″)
Will be.

(Ba-O bond length)
In this way, a locally distorted structure is realized around the Bi atom that is slightly added and substituted at the position of the Ba atom, but the circumference of Ba, which is the main component element that originally exists, is formed by the addition of Bi. There is almost no effect, and local distortion hardly occurs around Ba. That is, when the strain around Ba is expressed by the Ba-O bond distance, the difference between the longest Ba-O bond distance and the shortest Ba-O bond distance is the shortest Ba-O, as in the case without Bi addition described above. It remains so small that it is less than 5% of the bond distance. That is, the distribution of the Ba—O bond length is within the range of less than ± 5%. In _{the case of BaTiO 3} , the difference between the longest Ba-O bond distance and the shortest Ba-O bond distance remains so small that it is less than 3% of the shortest Ba-O bond distance, and thus Ba is more preferable. The distribution of −O bond lengths is within ± 3%.

(Bio content)
Piezoelectric materials containing BaTiO ₃ as a main component are often used in the form of sintered bodies (ceramics). At this time, the particle size of the piezoelectric ceramics is preferably in the range of 500 nm to 10 μm from the viewpoint of piezoelectric characteristics and mechanical strength. When the domain structure of such piezoelectric ceramics is observed with an optical microscope or an electron microscope, the domain wall of the grain having a particle size of less than 1 μm crosses the inside of the grain from one end to the other, and the particle size exceeds 1 μm. In some grains, the domain wall crosses from one end to the other, and in some grains, the domain wall is divided into two or several pieces. Generally, the length of the domain wall is about 500 nm. It is known to be more than that. BaTiO ₃ was added to slightly Bi metal oxide piezoelectric material represented by the general formula (1) as a main component, when introducing local electrical polarization around Bi, general formula as a main component BaTiO ₃ Since the lattice constant of the metal oxide of (1) is about 0.4 nm, if Bi can be introduced into one of the 1000 lattices of the metal oxide crystal of the general formula (1), the domain wall in the grain can be introduced. At least one local electrical polarization can be placed in a row of grids along. That is, if the content of Bi, which is the first subcomponent contained in the metal oxide of the general formula (1), is 0.1 mol% or more with respect to 1 mol of the metal oxide of the general formula (1). At least one Bi can be introduced into each row of the crystal lattice along the domain wall, and at the same time, local electric polarization around the Bi can be introduced. As a result, the polarization state near the domain wall is stabilized, that is, the domain wall is difficult to move (vibrate), and the mechanical quality coefficient is improved. However, when Bi is _{introduced into a metal oxide containing BaTiO 3} as a main component, it is difficult to uniformly distribute Bi in the metal oxide. Due to the addition of a certain amount of Bi or insufficient mixing of the raw material powder to which Bi has been added, Bi is unevenly distributed in the metal oxide, exhibiting characteristics such as an irregular dielectric called a relaxer, or Bi. Insulation is deteriorated due to insufficient generation of local electric polarization around Bi due to the atomic position being unevenly biased in an unspecified direction without showing a bias in a specific direction, or due to grain boundary precipitation of Bi. And so on, and there is a problem that the original properties of the material are not exhibited. In the case of the metal oxide represented by the general formula (1), the upper limit of the Bi content for uniform distribution of Bi is 0.5 mol% with respect to 1 mol of the metal oxide of the general formula (1). .. It should be noted that even if the Bi content is 0.5 mol% or less with respect to 1 mol of the metal oxide of the general formula (1), the Bi raw material powder and the metal oxide of the general formula (1) It is necessary to sufficiently mix the raw material powders of the above and then bake. Otherwise, Bi will be a metal oxide with non-uniform distribution or grain boundary precipitation, and the desired material properties will not be obtained.

(Confirmation of uniform distribution of Bi)
The following methods can be used as a means for confirming that the added Bi is uniformly distributed.
The first method is to confirm by an electron microscope having an analytical function that there are no different phases or precipitates having different Bi contents.
The second method is to confirm by X-ray diffraction that there is no specific diffraction peak depending on the presence or absence of Bi addition or the amount of addition.
The third method is that the radial structure function obtained from the EXAFS analysis can be fitted by a structural model that assumes that Bi is uniformly present in the EXAFS analysis, for example, a single coordination structure model. To confirm.
The fourth method is to measure the temperature dependence of the permittivity, and the Curie temperature T _c and the phase transition temperature _Tot change systematically depending on the amount of Bi added, and the permittivity at the time of the phase transition. The steepness of the change is to confirm that it is not affected by the addition of Bi.
The fifth method is to obtain the frequency-dependent spectrum of impedance and confirm the uniformity by analyzing the spectrum using a model assuming series and parallel connections of the capacitance component and the resistance component. At that time, even an aggregate of uniform particles may exhibit different resistance components inside the particles and at the grain boundaries. This is due to the fact that the potential barrier at the grain boundaries changes depending on the bonding conditions between the grains, and is distinguished from the one caused by Bi precipitation at the grain boundaries. As long as it is not caused by Bi precipitation at the grain boundaries, the volume components do not differ significantly between the inside of the grains and the grain boundaries.
Using these methods, the uniform distribution of Bi can be confirmed. In addition, other reasonable methods may be used.

(Mn content)
As described above, by containing 0.1 mol% or more and 0.5 mol% of Bi with respect to 1 mol of the metal oxide of the general formula (1), a material in which the domain wall does not easily move can be realized. Does not function as a piezoelectric material. This is because if Bi is introduced into the A site of the metal oxide of the general formula (1), +3 valent Bi is contained in the A site which is usually +2 valence, which is equivalent to doping the donor, that is, Bi. By introducing the above, conduction electrons are generated and the insulating property is deteriorated. With a piezoelectric material having poor insulating properties, it becomes difficult to apply a high voltage in the polarization treatment, macropolarization cannot be sufficiently aligned, and there arises a problem that desired piezoelectric characteristics cannot be obtained. Further, since the dielectric loss tangent increases due to the deterioration of the insulating property, there arises a problem that the electrical loss when the drive voltage is applied, that is, the generation of Joule heat becomes large. In order to solve the problem, it is necessary to introduce an acceptor that compensates for the Bi donor, and Mn is desirable as an acceptor for that purpose. When a _{small amount of Mn is added to BaTiO 3} and calcined, Mn usually replaces a part of Ti and is present at the B site. The valence of Mn at that time is usually +4, and even if Ti, which is +4, is replaced, the electrical neutrality is maintained. When a donor is introduced into this Mn-added BaTiO ₃ , for example, when +3 valent Bi is introduced into the A site, Mn can stably take +3 valence and +2 valence in addition to +4 valence. A part of Mn becomes a +3 or +2 valent acceptor so as to satisfy the electrical neutrality condition depending on the amount of the donor. Therefore, unlike the case where Bi is introduced alone, conduction electrons are not generated, and the insulating property is maintained in good condition. Therefore, even if Bi is added, the expected piezoelectric characteristics can be obtained without deteriorating the insulating property, and the electrical loss during operation can be kept small. The amount of Mn added may be the same as that of Bi in order to compensate for the Bi donor, but even if Mn is added alone, the characteristics do not deteriorate if the amount is small, but rather the insulation property is improved and the piezoelectric performance (especially). Since the effect of improving the mechanical quality coefficient) is recognized, it is desirable to introduce more than the amount of Bi added. However, if a large amount of Mn is introduced, the insulation characteristics deteriorate due to the formation of conduction holes by the Mn acceptor or the precipitation of conductive by-products containing Mn as a main component. Therefore, when Bi is added in the range of 0.1 mol% to 0.5 mol% with respect to the general formula (1), Mn is 0.3 mol% or more with respect to the general formula (1). It is desirable to add in the range of 5 mol%.

The valence and site of Mn can be specified by XAFS measurement as in Bi. In particular, the valence can be evaluated by comparing the XANES spectrum with the measurement data of the reference substance having a known valence and structure. Further, by analyzing EXAFS, the site where Mn exists can be identified, and further, information on the coordination environment around Mn, particularly the bond distance with the coordination atom and its number (coordination number) can be obtained. be able to. Further, the valence of a trace amount of Mn atoms uniformly present in a non-magnetic (diamagnetic) substance such as _{BaTiO 3 can be evaluated more accurately by measuring the temperature dependence of the magnetic susceptibility.}

(Confirmation of uniform distribution of Mn)
As a means for confirming that the added Mn is uniformly distributed, the above-mentioned method for confirming the uniform distribution of Bi can be similarly used. In addition, in the case of Mn, a method of confirming that the temperature dependence of the magnetic susceptibility follows the Curie-Weiss law can also be used. When Mn is partially present at a high concentration due to precipitation or the like, an abnormality due to a magnetically ordered phase transition of Mn may be observed at a low magnetic susceptibility. Moreover, even if there is no obvious abnormality, the temperature dependence of the magnetic susceptibility deviates from the Curie-Weiss law. Since the temperature dependence of the magnetic susceptibility behaves according to the Curie-Weiss law only when Mn is present uniformly and dilutely, Mn is examined by examining the change in the temperature-dependent behavior of the magnetic susceptibility depending on the amount of Mn added. The uniform distribution of can be confirmed.

For the measurement of the contents of Bi, which is the first subcomponent, and Mn, which is the second subcomponent, ICP (Inductively Coupled Plasma) emission spectroscopy, ICP mass analysis, X-ray fluorescence analysis (XRF), Atomic absorption spectrometry and the like can be used. In the present invention, the "sub-component" is contained in the piezoelectric material and corresponds to an adjusting component related to various properties of the piezoelectric material such as a mechanical quality coefficient. A very small amount of elemental components that do not substantially affect the characteristics of the piezoelectric material correspond to impurities and do not correspond to sub-components.

In the present invention, it is assumed that the first subcomponent Bi and the second subcomponent Mn are located at the A site and the B site of the perovskite type structure, respectively, but some Bi are the B site and the B site, respectively. It is also permissible for some Mn to be located at the A site.

The piezoelectric material of the present invention contains a perovskite-type metal oxide as a main phase from the viewpoint of insulating properties. The "main phase" is a case where the peak having the strongest diffraction intensity is caused by the perovskite-type metal oxide structure when powder X-ray diffraction of the piezoelectric material is performed. Whether or not the perovskite-type metal oxide is the main phase is determined by, for example, in X-ray diffraction, the maximum diffraction intensity derived from the perovskite-type metal oxide is 100 times or more the maximum diffraction intensity derived from the impurity phase. It can be judged by whether or not. It is preferable that it is composed of only a perovskite type metal oxide because it has the highest insulating property. More preferably, it is a "single phase" in which crystals having a perovskite-type metal oxide structure occupy almost all.

The form of the piezoelectric material according to the present invention is not limited, and any form such as ceramics, powder, single crystal, film, slurry, etc. may be used, but ceramics or a film is preferable.
In the present specification, the term "ceramics" refers to a so-called polycrystal, which is a metal oxide as a basic component and is an agglomerate (also referred to as a bulk body) of crystal particles hardened by heat treatment. In addition, "ceramics" include those processed after sintering.
As used herein, the term "membrane" refers to an aggregate structure provided in close contact with a flat plate so as to cover a surface of a substrate. The thickness of the film measured in the direction perpendicular to the installation surface is 10 μm or less, and the number of stacked crystal grains in the vertical direction is 20 or less as the film in the present invention.

The means for measuring the composition of the piezoelectric material according to the present invention is not particularly limited. Examples of such means include X-ray fluorescence analysis, ICP emission spectroscopic analysis, atomic absorption spectroscopy and the like. By either means, the weight ratio and composition ratio of each element contained in the piezoelectric material can be calculated.

(Measurement of phase transition temperature _Tot and Curie temperature _Tc)
T _ot and T _c can be determined by measuring the capacitance with an impedance analyzer (for example, 4194A manufactured by Keysight Technologies (formerly Agilent Technologies)) while changing the temperature of the sample (piezoelectric material). The capacitance obtained by the measurement can be converted into a dielectric constant. At the same time, the temperature dependence of the dielectric loss tangent can also be measured and obtained with an impedance analyzer. _Tot is the temperature at which the crystal system changes from tetragonal to orthorhombic.

Samples were measured permittivity while cooling to -60 ° C. from 25 ° C., the value obtained by differentiating the dielectric constant sample temperature can be determined T _ot by determining the temperature at which the maximum.

T _c is the Curie temperature, which is the temperature at which the dielectric constant becomes maximum in the vicinity of the phase transition temperature from the ferroelectric phase (square crystal phase) to the normal dielectric phase (cubic crystal phase). It can be determined by measuring the dielectric constant while heating the sample and finding the temperature at which the value of the dielectric constant becomes maximum.

The crystal system can be evaluated by X-ray diffraction, electron diffraction, Raman scattering, or the like.

(Manufacturing method of piezoelectric material)
The method for producing the piezoelectric material according to the present invention is not particularly limited, but a typical method for producing the piezoelectric material will be described below.

(Raw material for piezoelectric material)
When producing ceramic-like piezoelectric materials (piezoelectric ceramics), it is possible to adopt a general method of sintering solid powders such as oxides, carbonates, nitrates, and oxalates containing constituent elements under normal pressure. can.

The raw material is composed of metal compounds such as Ba compound, Ti compound, Mn compound, Bi compound, Ca compound, Sr compound, Zr compound, Hf compound and Sn compound. Among these, when a perovskite type metal oxide is used for all of the Ba compound, Ti compound, Ca compound, Sr compound, Zr compound, Hf compound, and Sn compound and mixed, the effect of refining the crystal grains after sintering can be obtained. Therefore, it is preferable because the occurrence of cracks and chipping during processing of the piezoelectric material and the piezoelectric element can be further suppressed.

Examples of the Ba compound that can be used include barium oxide, barium carbonate, barium oxalate, barium acetate, barium nitrate, perovskite-type barium titanate, perovskite-type barium titanate, and perovskite-type barium titanate.

Examples of Ti compounds that can be used include titanium oxide, perovskite-type barium titanate, perovskite-type barium titanate, and perovskite-type calcium titanate.

Examples of the Mn compound that can be used include manganese carbonate, manganese monoxide, manganese dioxide, trimanganese tetraoxide, manganese acetate and the like.

Examples of the Bi compound that can be used include bismuth oxide and perovskite-type bismuth iron acid.

Examples of Ca compounds that can be used include calcium oxide, calcium carbonate, calcium oxalate, calcium acetate, perovskite-type calcium titanate, and perovskite-type calcium zirconate.

Examples of Sr compounds that can be used include strontium oxide, strontium carbonate, strontium oxalate, strontium acetate, perovskite-type strontium titanate, and perovskite-type strontium titanate.

Examples of Zr compounds that can be used include zirconium oxide, perovskite-type barium zirconate, perovskite-type barium zirconate titanate, and perovskite-type calcium zirconate.

Examples of the Hf compound that can be used include hafnium oxide, perovskite-type barium hafniumate, and perovskite-type calcium hafniumate.

Examples of Sn compounds that can be used include tin oxide, perovskite-type barium tinate, perovskite-type barium titanate, and perovskite-type calcium tinate.

(Mixing of raw material powder)
A method of mixing a raw material powder of piezoelectric ceramics according to the present invention is not particularly limited, greater force than mixing method used in the production of conventional BaTiO ₃ based piezoelectric ceramics, mixed well by particular methods plus shear stress Is desirable. The most desirable method is a mixing method using a planetary ball mill. Put the raw material powder weighed to the desired composition in a zirconia, alumina or metal pot together with a zirconia or alumina ball with a diameter of 0.5 mm to 10 mm, and put it at about 100 to 900 rpm. Mixing is performed by rotating and revolving at the speed of. At this time, a dry mixing method in which only the raw material powder and the balls are put in a pot and mixed may be used, or a wet mixing method in which a liquid such as ethanol or water is put in and mixed at the same time may be used. By mixing the raw material powders in this way, the Bi raw material is well mixed with other raw materials, and subsequent firing can obtain a metal oxide in which Bi is uniformly distributed. When the raw material powder to which Bi is added is insufficiently mixed, Bi is unevenly distributed in the metal oxide, exhibiting characteristics like an irregular dielectric called a relaxer, or having a specific Bi atomic position. There is a possibility that problems such as insufficient generation of local electric polarization around Bi may occur due to the uneven bias in an unspecified direction without showing a bias in the direction.

(Granulated powder and molded product)
The method for granulating the raw material powder of the piezoelectric ceramics according to the present invention is not particularly limited. Examples of binders that can be used for granulation include PVA (polyvinyl alcohol), PVB (polyvinyl butyral), and acrylic resins. The amount of the binder to be added is from 1 part by weight with respect to 100 parts by weight of the total of the raw material powders such as Ba compound, Ti compound, Mn compound, Bi compound, Ca compound, Sr compound, Zr compound, Hf compound and Sn compound. 10 parts by weight is preferable, and 2 to 5 parts by weight is more preferable from the viewpoint of increasing the density of the molded product.

As a granulation method, a mixed powder obtained by mechanically mixing raw materials such as Ba compound, Ti compound, Mn compound, Bi compound, Ca compound, Sr compound, Zr compound, Hf compound and Sn compound may be granulated. Alternatively, these compounds may be calcined at about 800 to 1300 ° C. and then granulated. The most preferable granulation method is a spray-drying method from the viewpoint that the particle size of the granulated powder can be made more uniform.

The method for producing the piezoelectric ceramic molded product according to the present invention is not particularly limited. A molded product is a solid material produced from a raw material powder, a granulated powder, or a slurry. As means for producing the molded body, uniaxial pressure processing, cold hydrostatic pressure processing, warm hydrostatic pressure processing, casting molding and extrusion molding and the like can be used.

(Sintered body)
The method for sintering piezoelectric ceramics according to the present invention is not particularly limited. Examples of sintering methods include sintering with an electric furnace, sintering with a gas furnace, energization heating method, microwave sintering method, millimeter wave sintering method, HIP (hot isostatic pressing), etc. Can be mentioned. Sintering in an electric furnace and a gas furnace may be a continuous furnace or a batch furnace.

The sintering temperature of the piezoelectric ceramics in the sintering method is not particularly limited. The sintering temperature is preferably a temperature at which each compound reacts and sufficiently crystal grows. The preferred sintering temperature is 1100 ° C. or higher and 1400 ° C. or lower, and more preferably 1100 ° C. or higher and 1380 ° C. or lower, from the viewpoint of setting the particle size of the piezoelectric ceramics in the range of 500 nm to 10 μm. Piezoelectric ceramics sintered in the above temperature range show good piezoelectric performance.

In order to reproducibly stabilize the characteristics of the piezoelectric ceramics obtained by the sintering treatment, it is preferable to keep the sintering temperature constant within the above range and perform the sintering treatment for 2 hours or more and 24 hours or less.

A sintering method such as a two-step sintering method may be used, but a method without a sudden temperature change is preferable in consideration of productivity.

After polishing the piezoelectric ceramics, it is preferable to heat-treat the piezoelectric ceramics at a temperature of 1000 ° C. or higher. When mechanically polished, residual stress is generated inside the piezoelectric ceramics, but by heat treatment at 1000 ° C. or higher, the residual stress is relaxed and the piezoelectric characteristics of the piezoelectric ceramics are further improved. Further, by heat-treating at a temperature of 1000 ° C. or higher, there is also an effect of removing raw material powder such as barium carbonate precipitated at the grain boundary portion. The time of the heat treatment at a temperature of 1000 ° C. or higher is not particularly limited, but 1 hour or longer is preferable.

When the piezoelectric material of the present invention is obtained as a film formed on a substrate, the thickness of the piezoelectric material is preferably 200 nm or more and 10 μm or less, more preferably 300 nm or more and 3 μm or less. This is because a sufficient electromechanical conversion function as a piezoelectric element can be obtained by setting the film thickness of the piezoelectric material to 200 nm or more and 10 μm or less.

The method for forming the film is not particularly limited. For example, chemical solution deposition method (CSD method), sol-gel method, metalorganic chemical vapor deposition method (MOCVD method), sputtering method, pulsed laser deposition method (PLD method), hydrothermal synthesis method, aerosol deposition method (AD). Law) and so on. Of these, the most preferable laminating method is a chemical solution deposition method or a sputtering method. The chemical solution deposition method or the sputtering method can easily increase the film formation area.

The substrate used for the piezoelectric material of the present invention is preferably a single crystal substrate cut and polished on the (001) plane or the (110) plane. By using a single crystal substrate cut and polished on a specific crystal plane, the piezoelectric material film provided on the surface of the substrate can also be strongly oriented in the same direction.

(Piezoelectric element)
The piezoelectric element using the piezoelectric material of the present invention will be described below.
FIG. 2 is a schematic view showing an embodiment of the configuration of the piezoelectric element of the present invention. The piezoelectric element according to the present invention has at least a first electrode 1, a piezoelectric material portion 2 provided on the first electrode and containing a piezoelectric material, and a second electrode 3 provided on the piezoelectric material portion. It is a piezoelectric element, and the piezoelectric material portion 2 is the piezoelectric material of the present invention.

The piezoelectric material according to the present invention can be evaluated for its piezoelectric characteristics by forming a piezoelectric element having at least a first electrode and a second electrode.

The first electrode and the second electrode are made of a conductive layer having a thickness of about 5 nm to 10 μm. The material is not particularly limited as long as it is usually used for a piezoelectric element. For example, metals such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, Cu and compounds thereof can be mentioned. The first electrode and the second electrode may be one of these, a mixture or alloy of two or more, or a laminate of two or more of them. It may be. Further, the first electrode and the second electrode may be made of different materials.

The method for producing the first electrode and the second electrode is not limited, and the first electrode and the second electrode may be formed by baking a metal paste, or may be formed by sputtering, vapor deposition, or the like. Further, both the first electrode and the second electrode may be patterned and used in a desired shape.

(Polarization treatment)
It is more preferable that the piezoelectric element has polarization axes aligned in a certain direction. When the polarization axes are aligned in a certain direction, the piezoelectric constant of the piezoelectric element becomes large.

The polarization method of the piezoelectric element is not particularly limited. The polarization treatment may be carried out in the atmosphere or in silicone oil.

The temperature for polarization is preferably 60 ° C. to 150 ° C., but the optimum conditions differ slightly depending on the composition of the piezoelectric material constituting the piezoelectric element.

The electric field applied for the polarization treatment is preferably 600 V / mm to 2.0 kV / mm.

(Measurement of piezoelectric constant and mechanical quality coefficient)
The piezoelectric constant and the mechanical quality coefficient of the piezoelectric element are calculated based on the electronic information technology industry association standard (JEITA EM-4501) from the measurement results of the resonance frequency and the antiresonance frequency obtained by using a commercially available impedance analyzer. Can be obtained by. Hereinafter, this method is referred to as a resonance-antiresonance method.

(Laminated piezoelectric element)
Next, a laminated piezoelectric element using the piezoelectric material of the present invention will be described.
The laminated piezoelectric element according to the present invention has a configuration in which at least one internal electrode is provided in the piezoelectric material portion, and includes a piezoelectric material layer made of the piezoelectric material constituting the piezoelectric material portion and at least one layered internal electrode. Is a piezoelectric element having a laminated structure in which is alternately laminated, and the piezoelectric material layer is made of the piezoelectric material of the present invention.

3 (a) and 3 (b) are schematic cross-sectional views showing an embodiment of the configuration of the laminated piezoelectric element of the present invention. The laminated piezoelectric element shown in FIG. 3A is composed of a piezoelectric material layer 54 and an electrode including an internal electrode 55, and is a laminated piezoelectric element in which a piezoelectric material layer and layered electrodes are alternately laminated. The piezoelectric material layer 54 is made of the piezoelectric material of the present invention. The electrode may include an external electrode such as a first electrode 51 or a second electrode 53 in addition to the internal electrode 55.

FIG. 3A shows the present invention in which two layers of piezoelectric material layers 54 and one layer of internal electrodes 55 are alternately laminated, and the laminated structure is sandwiched between the first electrode 51 and the second electrode 53. The configuration of the laminated piezoelectric element is shown. The laminated piezoelectric element of the present invention is not limited to the configuration shown in FIG. 3A, and the number of piezoelectric material layers and internal electrodes may be increased as shown in FIG. 3B described below. , The number of layers is not limited.

In the laminated piezoelectric element of FIG. 3B, 9 layers of piezoelectric material layers 504 and 8 layers of internal electrodes 505 (in the illustrated example, 4 layers of internal electrodes 505a and 4 layers of internal electrodes 505b) are alternately arranged. The laminated structure is laminated, and the laminated structure is sandwiched between the first electrode 501 and the second electrode 503. Further, the laminated piezoelectric element of FIG. 3B has an external electrode 506a and an external electrode 506b for short-circuiting the alternately formed internal electrodes. Specifically, in the embodiment shown in FIG. 3B, the four-layer internal electrode 505a is short-circuited by the external electrode 506a, and the four-layer internal electrode 505b is short-circuited by the external electrode 506b.

The sizes and shapes of the internal electrodes 55 and 505 and the external electrodes 506a and 506b do not necessarily have to be the same as those of the piezoelectric material layers 54 and 504, and may be divided into a plurality of layers.

The internal electrodes 55 and 505, the external electrodes 506a and 506b, and the first electrodes 51 and 501 and the second electrodes 53 and 503 are made of a conductive layer having a thickness of about 5 nm to 10 μm.

The material used for these electrodes is not particularly limited, and may be any material usually used for piezoelectric elements. For example, metals such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, Cu and compounds thereof can be mentioned. The internal electrodes 55 and 505 and the external electrodes 506a and 506b may be composed of one of them, a mixture or alloy of two or more of them, or a stack of two or more of them. It may be a thing. Further, the plurality of electrodes may be made of different materials.

From the viewpoint that the electrode material is inexpensive, the internal electrodes 55 and 505 preferably contain at least one of Ni and Cu. When at least one of Ni and Cu is used for the internal electrodes 55 and 505, the laminated piezoelectric element of the present invention is preferably fired in a reducing atmosphere.

Further, in the laminated piezoelectric element of the present invention, the internal electrode contains Ag and Pd, and the weight ratio m1 / m2 of the Ag content weight m1 and the Pd content weight m2 is 0.25 ≦ m1 / m2 ≦ 4. It is preferably 0. If the weight ratio m1 / m2 is less than 0.25, the sintering temperature of the internal electrodes may increase, which is not desirable. On the other hand, if the weight ratio m1 / m2 is larger than 4.0, the internal electrodes become island-shaped and may become non-uniform in the plane, which is not desirable. The weight ratio m1 / m2 is more preferably 0.3 ≦ m1 / m2 ≦ 3.0.

As shown in FIG. 3B, the plurality of electrodes including the internal electrode 505 may be short-circuited with each other for the purpose of aligning the phases of the drive voltages. For example, the internal electrode 505a and the first electrode 501 may be short-circuited by the external electrode 506a. The internal electrode 505b and the second electrode 503 may be short-circuited by the external electrode 506b. Further, the internal electrodes 505a and the internal electrodes 505b may be arranged alternately. Furthermore, the form of short circuit between the electrodes is not limited. An electrode or wiring for short-circuiting may be provided on the side surface of the laminated piezoelectric element, or a through hole penetrating the piezoelectric material layer 504 may be provided, and a conductive material may be provided inside the through hole to short-circuit the electrodes.

(Liquid discharge head)
The liquid discharge head according to the present invention is characterized by having a liquid chamber provided with a vibrating portion in which the piezoelectric element of the present invention is arranged and a discharge port communicating with the liquid chamber. The liquid discharged by the liquid discharge head of the present invention is not particularly limited as long as it is a fluid, and water-based liquids such as water, ink, and fuel and non-water-based liquids can be discharged.

FIG. 4 is a schematic view showing an embodiment of the configuration of the liquid discharge head of the present invention. The liquid discharge head of the present invention is a liquid discharge head having the piezoelectric element 101 of the present invention. The piezoelectric element 101 is a piezoelectric element having at least a first electrode 1011 and a piezoelectric material 1012, and a second electrode 1013. The piezoelectric material 1012 is patterned as needed, as shown in FIG.

The liquid discharge head shown in FIG. 4 includes a discharge port 105, an individual liquid chamber 102, a communication hole 106 connecting the individual liquid chamber 102 and the discharge port 105, a liquid chamber partition wall 104, a common liquid chamber 107, a diaphragm 103, and a piezoelectric element 101. Has. Although the piezoelectric element 101 has a rectangular shape in FIG. 4, the shape may be other than a rectangle such as an ellipse, a circle, or a parallelogram. Generally, the piezoelectric material 1012 has a shape that follows the shape of the individual liquid chamber 102.

The liquid chamber in the present embodiment is composed of a diaphragm 103 which is a vibrating part in which the piezoelectric element 101 is arranged, a liquid chamber partition wall 104, and a bottom surface in which a communication hole 106 is formed, and is an individual liquid. Ink that is a liquid can be stored in the chamber 102. However, the present invention is not limited to such a configuration.

In FIG. 4, the first electrode 1011 is used as the lower electrode, and the second electrode 1013 is used as the upper electrode. However, the arrangement of the first electrode 1011 and the second electrode 1013 is not limited to this. For example, the first electrode 1011 may be used as a lower electrode or as an upper electrode. Similarly, the second electrode 1013 may be used as the upper electrode or the lower electrode. Further, a buffer layer may be present between the diaphragm 103 and the lower electrode.

In the liquid discharge head, the diaphragm 103 fluctuates up and down due to expansion and contraction of the piezoelectric material 1012, and applies pressure to the liquid in the individual liquid chamber 102. As a result, the liquid is discharged from the discharge port 105. The liquid discharge head of the present invention can be used for printer applications and manufacturing of electronic devices.

The size of the discharge port 105 is preferably a circle-equivalent diameter of 5 μm or more and 40 μm or less. The shape of the discharge port 105 may be circular, star-shaped, square-shaped, or triangular-shaped.

(Liquid discharge device)
Next, the liquid discharge device of the present invention will be described. The liquid discharge device of the present invention includes a mounting portion on which the transferred body is placed, and the liquid discharge head that discharges the liquid to the transferred body.

As an example of the liquid discharge device of the present invention, the inkjet recording device shown in FIGS. 5 and 6 can be mentioned. FIG. 6 shows a state in which the exteriors 882-885 and 887 of the liquid discharge device (inkjet recording device) 881 shown in FIG. 5 are removed. The inkjet recording device 881 has an automatic feeding unit 897 that automatically feeds the recording paper as a transfer target into the device main body 896. Further, a transport unit 899 that guides the recording paper sent from the automatic feeding unit 897 to a predetermined recording position and guides the recording paper from the recording position to the discharge port 898, and a recording unit 891 that records on the recording paper conveyed to the recording position. It has a recovery unit 890 that performs recovery processing on the recording unit 891. The recording unit 891 is provided with a carriage 892 that houses the liquid discharge head of the present invention and is reciprocally transferred on the rail. Here, the transport unit 899 as the mounting unit is a position where the recording paper as the transfer target is transported and placed at a predetermined recording position, and the recording unit 891 records the recording paper on the recording paper at the mounting location. Is done.

In such an inkjet recording device, the carriage 892 is transferred on a rail by an electric signal transmitted from a computer, and the piezoelectric material is displaced when a driving voltage is applied to an electrode that sandwiches the piezoelectric material. Due to the displacement of the piezoelectric material, the individual liquid chamber 102 is pressurized via the diaphragm 103 as shown in FIG. 4, and ink is discharged from the discharge port 105 to perform printing. In the liquid discharge device of the present invention, the liquid can be uniformly discharged at a high speed, and the device can be miniaturized.

Although the above example has been exemplified as a printer, the liquid discharge device of the present invention is used as a printing device such as an inkjet recording device such as a facsimile, a multifunction device, and a copier, an industrial liquid discharge device, and a drawing device for an object. can do. In addition, the user can select the desired transfer material according to the application. It should be noted that the liquid discharge head may be configured to move relative to the transferred body mounted on the stage as the mounting portion.

(Vibration wave motor)
The vibration wave motor according to the present invention is characterized by having a vibrating body in which the piezoelectric element is arranged and a moving body in contact with the vibrating body.

7 (a) and 7 (b) are schematic views showing the configuration of an ultrasonic motor according to an embodiment of the vibration wave motor of the present invention.

An ultrasonic motor in which the piezoelectric element of the present invention is made of a single plate is shown in FIG. 7 (a). Such an ultrasonic motor is integrally provided with the vibrator 201 (vibrating body), the rotor 202 (moving body) which is in contact with the sliding surface of the vibrator 201 by the pressure applied by a pressure spring (not shown), and the rotor 202. It has the output shaft 203. The vibrator 201 is composed of a metal elastic ring 2011, a piezoelectric element 2012 of the present invention, and an organic adhesive 2013 (epoxy-based, cyanoacrylate-based, etc.) that adheres the piezoelectric element 2012 to the elastic ring 2011. The piezoelectric element 2012 of the present invention is composed of a piezoelectric material sandwiched between a first electrode and a second electrode (not shown).

When a two-phase alternating voltage having a phase different by an odd multiple of π / 2 is applied to the piezoelectric element of the present invention, a bending traveling wave is generated in the vibrator 201, and each point on the sliding surface of the vibrator 201 makes an elliptical motion. do. When the rotor 202 is in pressure contact with the sliding surface of the vibrator 201, the rotor 202 receives a frictional force from the vibrator 201 and rotates in the direction opposite to the bending traveling wave. The driven body (not shown) is joined to the output shaft 203 and is driven by the rotational force of the rotor 202.

When a voltage is applied to the piezoelectric material, the piezoelectric material expands and contracts due to the piezoelectric lateral effect. When an elastic body such as metal is bonded to the piezoelectric element, the elastic body is bent by the expansion and contraction of the piezoelectric material. The types of ultrasonic motors described here make use of this principle.

Next, an ultrasonic motor including a piezoelectric element having a laminated structure is illustrated in FIG. 7 (b). The vibrator 204 is composed of a laminated piezoelectric element 2042 sandwiched between tubular metal elastic bodies 2041. The laminated piezoelectric element 2042 is an element composed of a plurality of laminated piezoelectric materials (not shown), and has a first electrode and a second electrode on the outer surface of the laminate and an inner electrode on the inner surface of the laminate. The metal elastic body 2041 is fastened by bolts, sandwiches and fixes the laminated piezoelectric element 2042, and becomes a vibrator 204 together with the laminated piezoelectric element 2042. Of course, the laminated piezoelectric element 2042 is not limited to the laminated piezoelectric element, and a single-layer type piezoelectric element may be used.

By applying alternating voltages having different phases to the laminated piezoelectric element 2042, the vibrator 204 excites two vibrations orthogonal to each other. These two vibrations are combined to form a circular vibration for driving the tip of the oscillator 204. A constricted peripheral groove is formed in the upper part of the vibrator 204 to increase the displacement of the vibration for driving. The rotor 205 is in pressure contact with the vibrator 204 by a pressurizing spring 206 to obtain a frictional force for driving. The rotor 205 is rotatably supported by bearings.

(Optical equipment)
Next, the optical device of the present invention will be described. The optical device of the present invention is an optical device having a drive unit, and the drive unit includes the vibration wave motor.

FIG. 8 is an exploded perspective view of an interchangeable lens barrel of a single-lens reflex camera, which is an example of a preferred embodiment of the optical device of the present invention. In the interchangeable lens barrel of FIG. 8, when the ultrasonic motor 725 is rotationally driven with respect to the fixed cylinder 712 by a control unit (not shown), the joining member 729 is in frictional contact with the roller 722, so that the roller 722 is moved. It rotates around the center of the shaft 720f extending radially from the rotation transmission ring 720. When the roller 722 rotates about the axis 720f, the rotation transmission ring 720 rotates about the optical axis as a result (autofocus operation).
The rotational force is transmitted to the cam ring 715 rotatably fitted on the inner circumference of the straight guide cylinder 713 via a focus key (not shown). When the cam ring 715 is rotated around the optical axis, the rear group lens barrel 716 whose rotation is restricted by the cam roller of the rear lens barrel 716 provided so as to fit in the cam groove of the cam ring 715 changes the cam of the cam ring 715. Advance and retreat along the groove. As a result, the focus lens 702 held in the rear lens barrel 716 is driven, and the focus operation is performed.
The interchangeable lens barrel shown in FIG. 8 is provided with a manual focus ring 724 that is fitted to the fixed cylinder 712 via a low friction sheet (washer member) 733 in order to perform a manual focus operation. There is.

Here, as the optical device of the present invention, the interchangeable lens barrel of a single-lens reflex camera has been described. However, regardless of the type of camera such as a compact camera, an electronic still camera, a portable information terminal with a camera, etc. It can be applied to optical instruments that have.

(Vibration device and dust remover)
Vibration devices used for transporting and removing particles, powders, and droplets are widely used in electronic devices and the like. Hereinafter, the vibration device using the piezoelectric element of the present invention will be described.

The vibrating device according to the present invention is characterized by having a vibrating body including a diaphragm on which the piezoelectric element of the present invention is arranged. The vibrating device of the present invention can be suitably used, for example, as a vibrating part of a dust removing device, and can effectively remove dust adhering to the surface of the diaphragm.

FIG. 9 is a schematic view showing a vibrating body 310 of the vibrating device of the present invention. The vibrating body 310 is composed of a plate-shaped piezoelectric element 330 and a vibrating plate 320. The piezoelectric element 330 may be the piezoelectric element of the present invention described above.

The material of the diaphragm 320 is not limited, but when the vibrating body 310 is used for an optical device, a translucent material or a light reflecting material can be used as the diaphragm 320. When a translucent material or a light-reflecting material is used as a diaphragm, the translucent portion or the light-reflecting portion of the diaphragm is the target of dust removal.

As shown in FIG. 9, the piezoelectric element 330 is composed of a piezoelectric material 331, a first electrode 332, and a second electrode 333, and the first electrode 332 and the second electrode 333 face the plate surface of the piezoelectric material 331. Is arranged. The piezoelectric element 330 may be the laminated piezoelectric element of the present invention. In that case, the piezoelectric material 331 has an alternating structure of the piezoelectric material layer and the internal electrode, and the internal electrodes are alternately short-circuited with the first electrode 332 or the second electrode 333, so that the phase is different for each layer of the piezoelectric material. A drive waveform can be given.

As shown in FIG. 9, the piezoelectric element 330 and the diaphragm 320 are fixed to the plate surface of the diaphragm 320 on the surface of the first electrode 332 of the piezoelectric element 330. Then, by driving the piezoelectric element 330, stress is generated between the piezoelectric element 330 and the diaphragm 320, and out-of-plane vibration is generated in the diaphragm 320.

By using the vibrating device of the present invention having the vibrating body 310 as the vibrating part of the dust removing device, foreign matter such as dust adhering to the surface of the vibrating plate 320 due to the out-of-plane vibration of the vibrating plate 320 can be effectively removed. Can be done. The out-of-plane vibration means elastic vibration that displaces the diaphragm in the optical axis direction, that is, in the thickness direction of the diaphragm.

10 (a) and 10 (b) are schematic views showing the vibration principle of the vibrating body 310. FIG. 10A shows a state in which an alternating voltage having the same phase is applied to the pair of left and right piezoelectric elements 330 to generate out-of-plane vibration in the diaphragm 320. The polarization direction of the piezoelectric material constituting the pair of left and right piezoelectric elements 330 is the same as the thickness direction of the piezoelectric elements 330. The vibrating body 310 shown in FIG. 10A is driven in the seventh vibration mode. FIG. 10B shows a state in which out-of-plane vibration is generated in the diaphragm 320 by applying an alternating voltage having opposite phases 180 ° opposite to the pair of left and right piezoelectric elements 330. The vibrating body 310 shown in FIG. 10B is driven in the sixth vibration mode. In the dust removing device using the vibrating device of the present invention having such a vibrating body 310 for the vibrating portion, dust adhering to the surface of the diaphragm can be effectively removed by properly using at least two vibration modes.

(Imaging device)
Next, the image pickup apparatus of the present invention will be described. The imaging device of the present invention is an imaging device having an imaging unit including the dust removing device and an imaging element unit that receives light, and the diaphragm included in the dust removing device is on the light receiving surface side of the imaging element unit. It is characterized by being arranged in.

11 and 12 are views showing a digital single-lens reflex camera which is an example of a preferred embodiment of the image pickup apparatus of the present invention. FIG. 11 is a front perspective view of the camera body 601 as viewed from the subject side, showing a state in which the photographing lens unit is removed. FIG. 12 is an exploded perspective view showing a schematic configuration inside the camera for explaining the peripheral structure of the image pickup unit 400 provided with the dust removing device of the present invention.

A mirror box 605 for guiding a shooting light flux passing through a shooting lens is provided in the camera body 601 shown in FIG. 11, and a main mirror (quick return mirror) 606 is arranged in the mirror box 605. The main mirror 606 is held at an angle of 45 ° with respect to the shooting optical axis in order to guide the shooting light flux in the direction of the pentadha mirror (not shown), and in order to guide the shooting light flux in the direction of the image sensor (not shown). It can be held in a position retracted from the shooting light flux.

In FIG. 12, a mirror box 605 and a shutter unit 200 are arranged in order from the subject side on the subject side of the main body chassis 300 which is the skeleton of the camera body. Further, an imaging unit 400 is arranged on the photographer side of the main body chassis 300. The image pickup unit 400 is composed of the dust removing device of the present invention and an image pickup device unit. The diaphragm of the dust removing device is arranged on the light receiving surface side on the same axis as the light receiving surface of the image sensor unit. The image pickup unit 400 is installed on the mounting surface of the mount portion 602 (FIG. 11) as a reference to which the photographing lens unit is attached, and the image pickup surface of the image pickup element unit is parallel to the image pickup lens unit at a predetermined distance. It is adjusted so that.

Here, the digital single-lens reflex camera has been described as the image pickup apparatus of the present invention, but for example, a camera with an interchangeable shooting lens unit such as a mirrorless digital single-lens camera without a mirror box 605 may be used. In addition, among electronic and electrical equipment equipped with various image pickup devices or image pickup devices such as video cameras with interchangeable shooting lens units and copiers, facsimiles, scanners, etc., devices that require removal of dust adhering to the surface of optical components in particular. It can also be applied to.

(Piezoelectric audio parts / electronic devices)
Next, the piezoelectric acoustic component and the electronic device of the present invention will be described. The piezoelectric acoustic component of the present invention includes the piezoelectric element of the present invention.
Further, the electronic device of the present invention is characterized by including the piezoelectric element of the present invention. Piezoelectric acoustic components include speakers, buzzers, microphones, and surface acoustic wave (SAW) elements.

FIG. 13 is an overall perspective view of the main body 931 of the digital camera, which is an example of the embodiment of the electronic device of the present invention, as viewed from the front.

An optical device 901, a microphone 914, a strobe light emitting unit 909, and an auxiliary light unit 916 are arranged on the front surface of the main body 931. Since the microphone 914 is built in the main body, it is shown by a broken line. A hole for picking up sound from the outside is provided in front of the microphone 914 (front side of the main body 931).

A power button 933, a speaker 912, a zoom lever 932, and a release button 908 for executing a focusing operation are arranged on the upper surface of the main body 931. The speaker 912 is incorporated inside the main body 931 and is shown by a broken line. A hole for transmitting sound to the outside is provided in front of the speaker 912 (upper surface side of the main body 931).

The piezoelectric acoustic component provided with the piezoelectric element of the present invention is used for at least one of the microphone 914 and the speaker 912.

Here, the digital camera has been described as the electronic device of the present invention, but the electronic device of the present invention is also applied to an electronic device having various piezoelectric acoustic components such as a voice reproduction device, a voice recording device, a mobile phone, and an information terminal. be able to.

As described above, the piezoelectric element of the present invention is suitably used for a liquid discharge head, a liquid discharge device, a vibration wave motor, an optical device, a vibration device, a dust removing device, an imaging device, and an electronic device.

By using the piezoelectric element of the present invention, it is possible to provide a liquid discharge head having a nozzle density and a discharge rate equal to or higher than those in the case of using a piezoelectric element containing lead.

By using the liquid discharge head of the present invention, it is possible to provide a liquid discharge device having a discharge speed and discharge accuracy equal to or higher than those in the case of using a piezoelectric element containing lead with good yield.

By using the piezoelectric element of the present invention, it is possible to provide a vibration wave motor having a driving force equal to or higher than that when the piezoelectric element containing lead is used and durability.

By using the vibration wave motor of the present invention, it is possible to provide an optical device having durability and operating accuracy equal to or higher than those in the case of using a piezoelectric element containing lead.

By using the piezoelectric element of the present invention, it is possible to provide a vibration device having a vibration capacity and durability equal to or higher than those in the case of using a piezoelectric element containing lead.

By using the vibrating device of the present invention, it is possible to provide a dust removing device having dust removing efficiency and durability equal to or higher than those in the case of using a piezoelectric element containing lead.

By using the dust removing device of the present invention, it is possible to provide an imaging device having a dust removing function equal to or higher than that when a piezoelectric element containing lead is used.

By using the piezoelectric acoustic component provided with the piezoelectric element of the present invention, it is possible to provide an electronic device having soundability equal to or higher than that when the piezoelectric element containing lead is used.

The piezoelectric material of the present invention can be used for piezoelectric devices such as ultrasonic vibrators, piezoelectric actuators, piezoelectric sensors, strong dielectric memories, and power generation devices, in addition to liquid discharge heads and motors.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

(Examples 1 to 6 and Comparative Examples 1 to 5)
(Manufacturing process)
In the general formula _{(1) (Ba 1-x} M1 x) (Ti 1-y M2 y) metal oxide represented by _{O 3,} the composition of x = 0 and y = 0 not added metal elements M1, M2, i.e. A piezoelectric material was prepared by adding Bi, which is a first sub-component, and Mn, which is a second sub-component, to BaTiO _3. First, as Examples 1 to 5, the Mn content was 0.5 mol% and the Bi content was 0.1 mol%, 0.2 mol%, 0.3 mol%, and 0.4 mol, respectively, with respect to _{BaTiO 3.} %, 0.5 mol% of metal oxide piezoelectric material was produced. In order to make it easy to understand the amount of the additive, the material names of Examples 1 to 5 will be referred to as "BaTIO ₃ : Mn: Bi (x%)". Here, "x%" indicates the above-mentioned Bi content (mol%). BaTiO ₃ materials as a comparative example 1 Bi also Mn not be added as well, without the addition of Mn relative to BaTiO ₃ as Comparative Example 2, Bi only 0.4 mol% added material (material name "BaTiO _3: Bi ( 0.4%) "), as Comparative examples 3 and 4, without the addition of Bi with respect to BaTiO _3, Mn only, 0.3 mol% and 0.5 mol% added material (material name" BaTiO ₃ : Mn (0.3%) ”and“ BaTIO ₃ : Mn (0.5%) ”) were prepared. In addition, for the purpose of confirming the effect _{of Bi, a material in which half and the total amount of Bi of BaTiO 3} : Mn: Bi (0.5%) was replaced with La having the same +3 valence and the same ionic radius was carried out. It was prepared as Example 6 (material name “BaTIO ₃ : Mn :( Bi, La)”) and Comparative Example 5 (material name “BaTIO ₃ : Mn: La”). The manufacturing procedure is shown below.

Barium titanate powder (average particle size 100 nm, purity 99.99% or more), bismuth oxide (Bi ₂ O ₃ ) powder (average particle size 1 μm, purity 99.999% or more), manganese dioxide (MnO ₂ ) powder (average) The particle size (particle size: 1 μm, purity: 99.99% or more) was weighed so that Ba, Ti, Mn, and Bi had a desired ratio. These powders are placed in a zirconia planetary ball mill pot, and a zirconia ball (a mixture of approximately the same amount of 1 mm and 3 mm in diameter) having the same bulk (volume) as the weighed raw material powder, and the raw material powder and balls Further dipping ethanol was added into the pot, a resin packing was sandwiched between the pot and the lid, and the lid was closed. A pot is installed in the planetary ball mill device, and the pot and lid are firmly held down by the holding tool attached to the device so that powder and ethanol do not overflow from the gap between the pot and the lid during operation, and then every 500 revolutions. The material was revolved for 12 hours and mixed well while applying a strong shear stress to the raw material powder.

After the mixing by the planetary ball mill was completed, the contents in the pot were taken out and the zirconia balls were removed from the pot to obtain a mixed raw material powder dispersed in ethanol. PVB (Polyvinyl butyral), which is 3 parts by weight based on 100 parts by weight of the total weight of the raw material powder, is added thereto as a binder after being dissolved in ethanol, and the ethanol is volatilized while stirring and mixing to make the binder into the mixed raw material powder. Was attached to prepare a granulated powder. This granulation step can also be obtained by adhering PVA (Polyvinyl alcohol), which is 3 parts by weight based on 100 parts by weight of the raw material powder, to the surface of the mixed powder as a binder using a spray dryer device. The results were the same.

Next, the obtained granulated powder was filled in a mold, and a molding pressure of 200 MPa was applied using a press molding machine to prepare a disk-shaped molded product. The obtained compact was placed in a variable-atmosphere electric furnace, first heated at 600 ° C. in an atmospheric atmosphere and held, then further heated to 1350 ° C. and held for 4 hours. The temperature was lowered by allowing it to cool. Through the above steps, a disk-shaped sintered body (polycrystalline ceramics) was obtained. This sintered body was used as the piezoelectric material of the present invention.

The Bi content and Mn content in the obtained material were evaluated by ICP emission spectroscopic analysis and ICP mass spectrometry. The results are as shown in Table 1, and the materials having Bi and Mn contents almost as planned were obtained.

(X-ray diffraction)
A part of the obtained material was pulverized into a fine powder, and then X-ray diffraction measurement was performed. Using a bending magnet synchrotron radiation X-ray light source, X-rays monochromatic to a wavelength of 0.39984 Å or 0.39987 Å were used, and measurements were taken at room temperature in 2θ angle steps of 0.01 ° by the device sheller method. When the X-ray diffraction charts obtained were analyzed, reliable analysis results were obtained by assuming a single tetragonal perovskite crystal structure for all materials, so the main phase was single. It was found to have a tetragonal perovskite crystal structure. In addition, it was confirmed that only a very small amount of phases other than the main phase existed. As a representative, FIG. 14 _{shows an X-ray diffraction chart of BaTIO 3} : Mn: Bi (0.2%) (Example 2). FIG. 14A is a powder X-ray diffraction chart of a powder sample mixed _{with a CeO 2} standard sample whose crystal structure and lattice constant are known for the purpose of precisely determining the lattice constant. Lattice constants a and c, atomic displacement parameters B and coordinates z, reliability parameters (R _wp , S, R _B , R) obtained by Rietveld analysis of the measurement data mixed with the CeO _{2 standard sample. The results of F} ) and the mixing ratio (Fraction) are shown in Table 2. From this analysis, the lattice constants a and c of each material were determined. FIG. 14B is a powder X-ray diffraction chart measured without mixing the _{CeO 2 standard sample.} By using this measurement data and the values of the lattice constants a and c precisely determined by the previous analysis as fixed values and performing Rietveld analysis again, Ba site, Ti site, and two types of oxygen sites (O1 and O2) ) Atomic displacement parameter B and coordinates z were determined. The results are shown in Table 3.

The evaluation results of the lattice constants a and c shown in Table 2 in FIGS. 15 (a) and 15 (c) show the lattice constant ratio c / a and the Bi content of the lattice volume obtained from the evaluation results in FIGS. 15 (b) and 15 (d). Shows dependencies. From FIGS. 15 (a) and 15 (b), _{in the material containing both Bi and Mn in BaTiO 3} , the lattice constant a tends to decrease as the amount of Bi added increases, while the lattice constant c increases. It was found that the lattice constant ratio c / a increased. It is present in a position offset of Bi atoms causes a local electric polarization in the c-axis direction as the polarization axis of BaTiO ₃ which is a strong dielectric, square Akirakoto by enhancing spontaneous polarization of BaTiO ₃ It can be inferred that this is due to the enhanced anisotropy. On the other hand, FIGS. 15 (c) and 15 (d) show the results of the material in which part or all of Bi was replaced with La, but the changes in the lattice constants a and c and the lattice constant ratio c / a were +3 valence ( It can be seen that the La + Bi) content is constant but depends on the Bi content. That is, the increase in tetragonal anisotropy is not due to any effect due to + trivalent donor doping (for example, the Jahn-Teller effect due to the change of Mn to + trivalent), but Bi plays a role in exerting that effect. confirmed. That is, it is considered that this is the effect of the generation of local electric polarization by the isolated electron pair of Bi.

FIG. 16A is a schematic diagram illustrating the atomic coordinates z shown in Tables 2 and 3. The Rietveld analysis in Tables 2 and 3 fixed the Ba site and expressed the relative positional deviation of the Ti site and the two types of O sites (O1 and O2) as their respective coordinates z. Assuming that the charges at the Ba site, Ti site, O1 and O2 sites are point charges, the magnitude of spontaneous polarization can be evaluated from the value of the coordinate z. FIG. 16B shows the Bi content dependence of the magnitude of spontaneous polarization Ps of each material evaluated using the z value in Table 3. As shown in FIG. 15, the tetragonal anisotropy is remarkably enhanced by the increase in Bi, but the magnitude of spontaneous polarization does not change much by the increase in the amount of Bi, and the spontaneous polarization by Bi is remarkably enhanced. The effect could not be recognized numerically. FIG. 16C shows the Bi content dependence of the atomic displacement parameter B shown in Table 3. It is easy to understand that the value of the atomic displacement parameter B of the Ba site increases due to the increase of Bi existing at the biased position, that is, the distribution of the atomic position becomes large. On the other hand, it is interesting that the value of the atomic displacement parameter B of the Ti site also increases as the Bi content increases. That is, it seems that Bi also disturbs the atomic position of the Ti site. This is because the local electric polarization around Bi _{may have some influence on Ti, which is originally the main player in the spontaneous polarization generation of BaTiO 3} , which contributes to the stabilization of macroscopic polarization. You might also say that.

(XAFS)
The surface of a part of the obtained sintered body of the piezoelectric material was polished and used for fluorescence XAFS measurement. _{L 3} K absorption XAFS absorption XAFS and Mn of Bi contained in the piezoelectric material of the present invention, the fluorescence is highly sensitive measurement (fluorescence XAFS), that measured using a synchrotron radiation X-rays of high intensity desirable. Fluorescence method _{of Bi-L 3 XAFS of BaTiO 3} : Mn: Bi (0.1 to 0.4%) material of Examples 1 to 4 and _{BaTiO 3} : Bi (0.4%) material of Comparative Example 2. Measured by. Using the bending magnet synchrotron radiation X-ray as a light source, X-rays monochromaticized from 13.1 keV to 14.3 keV by the Si (311) surface are irradiated while sweeping the X-ray energy at an angle of 45 ° from the sample surface, and the sample is irradiated. at an angle of 45 ° in the opposite direction from the surface, i.e., by using a 19-element Ge semiconductor detector arranged at an angle of the incident X-ray and 90 ° via the sample surface, detecting the Bi-L ₃ fluorescence emitted from the sample The fluorescence XAFS measurement was performed by the above. The fluorescent X-ray intensity measured by the semiconductor detector was normalized by the incident X-ray intensity monitored at the same time to obtain a measurement spectrum. _{As standard samples, BaBiO 3} is located at the B site of the perovskite structure with +4 valence on average _{, BiFeO 3} is located at the A site of the perovskite structure with +3 valence of Bi, and Bi is also +3 valent and has a perovskite structure. _Bi-L 3 XAFS measurements 0.67BiFeO ₃ -0.33BaTiO ₃ solid solution located at the a site were also performed. FIG. 17A shows an enlarged view (XANES spectrum) near the absorption edge _{of the Bi-L 3} XAFS spectrum of the above material and the standard sample. _{BaTiO 3: Mn: Bi-L} 3 XANES spectra of Bi (0.1 to 0.4%) material it can be seen that is also different from the spectral shape absorption edge energy as compared with _Bi-L 3 XANES spectrum of BaBiO ₃ .. On the other hand, when compared with _Bi-L 3 XANES spectra of BiFeO ₃ and 0.67BiFeO ₃ -0.33BaTiO ₃ solid solution, even spectral structure absorption edge energy is also similar. From this, it _{can be seen that Bi in the BaTiO 3} : Mn: Bi (0.1 to 0.4%) material is located at the A site with a +3 valence.

The EXAFS spectrum obtained by extracting the vibration structure of the XAFS spectrum having the _{Bi-L 3 absorption edge energy or more of the BaTiO 3} : Mn: Bi (0.1 to _{0.4%) material and the BaTiO 3} : Bi (0.4%) material. It is shown in FIG. 17 (b). The Fourier transform of this is the radial structure function shown in FIG. 17 (c). Here, the peak at r = 1.8 Å is the peak caused by the Bi—O bond, and the peak near r = 3.0 Å is the peak caused by the Bi—Ti bond. By analyzing these peak structures by fitting, it is possible to obtain information on the bond lengths and coordination numbers of the Bi-O bond and the Bi-Ti bond. _{FIG. 17 (c) shows the Bi radial structure function of the BaTiO 3} : Mn: Bi (0.4%) material and the curve reproduced by the fitting, as represented by the lower middle part of the figure. It can be seen that the two match very well.

FIG. 17 (c) Coordination environment (Bi-O bond length, Bi-Ti bond length, Bi-) around Bi of _{BaTIO 3} : Mn: Bi (0.4%) material obtained from the fitting curve in the lower middle of the figure. The Ba bond length and the coordination number of each) are shown in Table 4. The 12-coordinated Bi-O bond was well fitted in a model with 4 bonds each at 3 different bond lengths. For example, if fitting is performed assuming two types of bond distances, no matter what bond length and each coordination number are assumed, a fitting result with a low reliability parameter R like the result in Table 4 cannot be obtained. (The smaller the value of the reliability parameter R, the higher the fitting reliability). Also, regarding the Bi-Ti bond, good fitting results could be obtained with a model having four bonds each at two types of bond distances. It is possible to further divide and fit four bond groups for both Bi-O and Bi-Ti, but the fitting results are not particularly improved compared to the results in Table 4, and each of them is not particularly improved. There was not much change in bond lengths within the four groups. In a Bi-coordination environment with four Bi-O bonds with three bond lengths and four Bi-Ti bonds with two bond lengths, the Bi atom is c at the A site of the square perovskite structure. It is suggested that the position is biased in the axial direction. When _{the distance of Bi-O bond of BaTiO 3} : Mn: Bi (0.4%) material is set from L _{1 to L 12 in the} order of longest, L ₁ = L ₂ = L ₃ = L ₄ = 3.045 Å, L ₅ = L ₆ = L ₇ = L ₈ = 2.738 Å, L ₉ = L ₁₀ = L ₁₁ = L ₁₂ = 2.254 Å, and (L _4- L ₅ ) / L ₅ = 0.11, (L _{8-L 5)} L ₉ ) / L ₉ = 0.21 and (L _1- L ₁₂ ) / L ₁₂ = 0.35. When the distance of Bi-Ti bond is changed _{from D 1} to D _{8 in the} order of longest, D ₁ = D ₂ = D ₃ = D ₄ = 3.698 Å, D ₅ = D ₆ = D ₇ = D ₈ = 3.295 Å. Then, (D _4- D ₅ ) / D ₅ = 0.12. This means that Bi is relatively largely shifted in the c-axis direction from the A-site position of the perovskite-type structure. FIG. 1 illustrates the Bi position of the perovskite type structure so as to meet this condition. Here, Ti of the B site is placed at each grid point and Bi is placed near the center of the grid. However, when the Bi arrangement is adjusted so as to satisfy the bond length (coordination environment) in Table 4, FIG. As shown in, it can be seen that the lattice is relatively largely biased in the c-axis direction from the center position. Table 4 also to BaTiO _3: Bi shows a coordination environment around Bi obtained by fitting Bi radial structure function (0.4%) _{material, BaTiO 3: Mn: Bi (} 0.4%) It can be seen that the environment is almost the same as the coordination environment of. In addition, _{almost the same results were obtained with the BaTiO 3} : Mn: Bi (0.1 to 0.3%) material.

In order to investigate the coordination environment around Ba, which is the main component element of the obtained piezoelectric material, Ba-K XAFS measurement was also performed. Since Ba is a main component element and is present in a high concentration in the material, the effect of self-absorption is large in the fluorescence method and the spectrum is distorted. Therefore, a part of the material was crushed into powder, mixed and diluted with boron nitride powder so as to have a concentration suitable for measurement, a tablet-shaped sample was prepared, and XAFS measurement was performed by a permeation method. EXAFS vibration was extracted from the obtained spectrum, and the Ba radial structure function obtained by the Fourier transform was shown in FIG. It can be seen that all of them have almost the same peak shape regardless of the contents of Bi and Mn added to BaTiO _3. When _{the Ba radial structure function of the BaTiO 3} : Mn: Bi (0.4%) material was analyzed by fitting, the Ba-O bond length was 2.867 Å for the longest one and 2.810 Å for the shortest one. .. That is, the distribution of 12 Ba—O bond lengths is included in the range of 2% at most. Almost the same results were obtained with other materials, and the distribution of Ba—O bond lengths was within the range of less than 5% at the maximum. From this, it can be seen that the above-mentioned Bi—O coordination environment is greatly biased.

Similar to Bi, Mn-K XAFS measurement, which is an additive element in the piezoelectric material, was carried out by the fluorescence method. At the same time, XAFS measurements of _{SrMnO 3} and LaMnO ₃ were also performed as valence standards for +4-valent and +3-valent Mn located at the B site of the perovskite-type structure. Was added only Mn in FIG. 19 (a), and the Mn-K XANES spectra of BaTiO ₃ to the Mn and Bi were simultaneously added, was shown with XANES spectra of SrMnO ₃ and LaMnO ₃ is the valence of Mn standards. Comparing _{the XANES spectra of SrMnO 3} and LaMnO ₃ , it can be seen that the Mn-K absorption edge shifts to the low energy side as Mn changes from +4 valence to +3 valence. Similarly, it can be seen that the Mn absorption end is slightly shifted to the low energy side as Bi increases from 0% to 0.4% in the BaTiO _{3: Mn: Bi material. That is, it can be understood that the valence of Mn in the BaTiO 3} : Mn: Bi material changes from +4 valence to +3 valence due to the increase in Bi content. However, since the shapes of SrMnO ₃ and LaMnO ₃ are different from those of the XANES spectra, it is difficult to quantitatively evaluate the valence by comparing them.

The EXAFS spectrum obtained by extracting the vibration structure of the XAFS spectrum _{equal to or higher than the Mn-K absorption edge energy of the BaTiO 3} : Mn: Bi (0.1 to 0.4%) material and the BaTiO _{3: Mn (0.5%) material is shown.} It is shown in 19 (b). The radial structure function obtained by Fourier transforming this is shown in FIG. 19 (c). When the Mn radial structure function was analyzed by fitting, Mn-O was assumed to have 6 coordinations as shown in the example of _{BaTiO 3} : Mn: Bi (0.2%) in the lower middle of FIG. 19 (c). Good fitting results were obtained. In addition, it was confirmed that Mn is located at the B site of the perovskite type structure because the fitting was not successful in the 12 coordination.

(Mn valence evaluation based on temperature dependence of magnetic susceptibility)
Temperature dependence measurements of the magnetic susceptibility of these materials were performed for the purpose of evaluating the valence of Mn in the BaTIO ₃ : Mn material and the BaTIO _{3: Mn: Bi material.} BaTIO ₃ and BaTIO ₃ : Bi are non-magnetic (diamagnetic), and among the BaTIO ₃ : Mn and BaTIO ₃ : Mn: Bi materials, only Mn is an element exhibiting magnetism. Moreover, since Mn is contained in an insulating material having a low concentration and almost no conduction electrons, the magnetic interaction between Mn atoms is weak, and the temperature dependence of the magnetic susceptibility caused by Mn is curie to a low temperature. -It is expected to show paramagnetism according to Weiss's law. The valence of Mn can be evaluated by analyzing the temperature-dependent behavior of the magnetic susceptibility. The magnetic susceptibility χ of a material in which temperature-independent diamagnetism and paramagnetism according to the Curie-Weiss law coexist is χ = C / (T−θ _p ) + χ _c (where C is C) as the Curie-Weiss law including a constant term. The Curie constant, T is the temperature, θ _p is the paramagnetic Curie temperature, and χ _c is the diamagnetic susceptibility without temperature dependence, that is, the constant term). The temperature dependence of the magnetic susceptibility was measured by applying a magnetic field of 100 Oe in a temperature range of 2K to 300K using a superconducting quantum interfering element (SQUID) magnetometer. The material to be measured was powdered, filled with about 200 g of gelatin capsules, and set in a SQUID magnetometer for measurement. FIG. 20A shows, as an example of the measurement results, _{the measured value of the temperature dependence of the magnetic susceptibility of the BaTiO 3} : Mn (0.3%) material and its fitting curve (left axis: 2K to 70K). The measured value fits better to the fitting curve, and the reverse magnetic susceptibility (χ-χ _c ) ^-1 minus the constant term shown on the right axis in the figure becomes a straight line, so the temperature dependence of the magnetic susceptibility. Can be understood to follow the Curie-Weiss law above. In addition, the inset in the figure shows the measured value of the temperature dependence of the magnetic susceptibility from 2K to 300K (room temperature) and its fitting curve, and it is confirmed that the Mn valence does not change from room temperature to 2K. can. Table 5 shows each parameter (Curie constant C and Mn valence converted from it, diamagnetic susceptibility χ _c , paramagnetic Curie temperature θ _p and reliability parameter R ^{2) obtained from the temperature dependence of the magnetic susceptibility of each material.} It was shown to. It can be seen that the Mn valence is close to +4 valence in the material not containing Bi, and approaches +3 valence as the Bi content increases. FIG. 20 (b) shows the changes in the Mn valence arranged by the Bi / Mn ratio in the material. The straight line in the figure is the Mn in the model in which the corresponding amount of the +4 valent Mn located at the B site changes to the acceptor +3 valent Mn in order to compensate for the +3 valent Bi donor replaced by the A site. The Bi / Mn ratio dependence of the valence is shown. Since the Mn valence evaluated from the temperature dependence of the magnetic susceptibility behaves in approximately the same manner as the straight line of the above model, Mn is valenceed so as to satisfy the electrical neutrality condition of the material when Bi is added. It was confirmed that it was changed.

(Dielectric property)
A part of the sintered body of these piezoelectric materials was polished on both the front and back surfaces, and then gold electrodes having a thickness of 400 nm were formed on both the front and back surfaces by a DC sputtering method. A layer made of titanium having a thickness of 30 nm was formed as an adhesion layer between the electrode and the piezoelectric material. This piezoelectric material with electrodes was cut to produce a strip-shaped element having a size of 10 mm × 2.5 mm × 0.5 mm. The temperature dependence of dielectric constant and dielectric loss, as well as polarization-electric field (PE) characteristics at room temperature, were measured using this device.

The temperature dependence of the measured dielectric constant in the range of −70 ° C. to + 160 ° C. is shown in FIG. 21 (a). In all the materials, a large abnormality in the dielectric constant corresponding to the _{Curie temperature T c} was observed in the vicinity of + 120 ° C to + 130 ° C. In addition, a dielectric anomaly corresponding to _Tot was observed in the vicinity of -40 ° C to + 20 ° C. An enlarged view of the temperature dependence of the permittivity _{near T c} is shown in FIG. 21 (b), and _{an enlarged view of the vicinity of Tot} is shown in FIG. 21 (c). From these results, T _c and _Tot in the temperature lowering process were read and plotted by the amount of Bi added in the material, which are shown in FIGS. 22 (a) and 22 (b). BaTiO ₃ : Excluding the Bi material, _{it can be seen that as the Bi content increases, T c} increases and _Tot decreases, that is, the temperature region of the tetragonal crystal expands. This is due to the increase in tetragonal anisotropy due to the increase in Bi content shown in FIG. 15, and the deviation of the Bi position in the c-axis direction shown in FIG. 17 and the resulting local electric polarization around Bi. It can be regarded as being closely related to.

FIG. 21D shows the temperature dependence of the dielectric loss. _{In BaTIO 3} without addition of Bi and Mn, the value of the dielectric loss is about 0.02 or more, showing a relatively high dielectric loss. In BaTIO ₃ : Bi (0.4%) in which only Bi was added to BaTIO _{3 , the dielectric loss exceeded 1 at a temperature of T c} or less, and it is considered that the insulation property was significantly deteriorated by the addition of Bi. This is consistent with the above-mentioned behavior that + 3-valent Bi replaces a part of + 2-valent barium to generate conduction electrons as a donor. BaTiO ₃ BaTiO addition of both Bi and Mn in _3: Mn: In Bi material showed no increase in the dielectric loss, it can be seen that lower than BaTiO ₃ additive-free rather. It is understood that this is because, as explained in FIG. 20 (b), a part of Mn changes from +4 valence to +3 valence to compensate the +3 valent Bi donor and suppress the generation of conduction electrons. can.

FIG. 23 shows _{the polarization-electric field (P-) of BaTIO 3} material, BaTIO ₃ : Mn (0.3%) material, and BaTIO ₃ : Mn: Bi (0.2%, 0.4%, 0.5%) material. E) Shows a hysteresis curve. _{In the BaTiO 3} : Mn: Bi material to which both Bi and Mn are added, the width of hysteresis is wider than that of the material without Bi addition, that is, the coercive electric field (polarization reversal electric field) is large. In addition, it can be seen that the coercive electric field increases as the Bi content increases. This suggests that the addition of Bi makes it difficult for the macropolarization to be reversed. _{We also tried to measure the PE characteristics of the BaTiO 3} : Bi (0.4%) material to which Mn was not added, but the insulation breakdown occurred due to the application of voltage during the measurement, and the measurement could not be performed. This is a result that is consistent with the deterioration of the insulating property due to the addition of only Bi shown in FIG. 21 (d).

(Manufacturing of piezoelectric element)
Similar to the sample for measuring the dielectric property, a part of the piezoelectric material sintered body was polished on both the front and back surfaces, and then gold electrodes having a thickness of 400 nm were formed on both the front and back surfaces by the DC sputtering method. A layer made of titanium having a thickness of 30 nm was formed as an adhesion layer between the electrode and the piezoelectric material. This piezoelectric material with electrodes was cut to produce a strip-shaped element having a size of 10 mm × 2.5 mm × 0.5 mm. This element was placed on a hot plate having a surface temperature of 100 ° C. to 140 ° C., and an electric field of 1.0 kV / mm was applied between both electrodes for 30 minutes for polarization treatment. In this way, a piezoelectric element in which the piezoelectric material in the portion sandwiched between the electrodes has residual polarization perpendicular to the electrode surface was obtained. _{The BaTiO 3} : Bi (0.4%) material (Comparative Example 2) to which only Bi was added suffered dielectric breakdown due to the application of a voltage during the polarization treatment, and the polarization treatment could not be performed, so that the piezoelectric element could be manufactured. There wasn't.

(Measurement of piezoelectric constant and mechanical quality coefficient)
_{The piezoelectric constant d 31} at room temperature (25 ° C.) and the mechanical quality coefficient Qm at room temperature of the obtained piezoelectric element were evaluated. Of these, Table 6 shows the results of Example 4 and Comparative Example 2 (polarization treatment cannot be performed and measurement is not possible) and Comparative Examples 3 to 4. The piezoelectric constant d ₃₁ was obtained by the resonance-antiresonance method at room temperature (25 ° C.). The mechanical quality coefficient Qm is a value obtained at the same time as the piezoelectric constant by the resonance-antiresonance method.

_{The piezoelectric constants d 31} of Examples 4, and Examples 1 to 3 and Example 5 are as large as 100 pm / V or more, and the mechanical quality coefficient Qm is 2000 or more, which is a resonance type piezoelectric device. A value suitable for practical use was shown. This is because both the amount of Bi and the amount of Mn are appropriate, and Bi is uniformly distributed by sufficiently mixing the raw material powder, and as a result, Bi exists at a position biased in the c-axis direction from the position symmetrical with respect to the center of the A site. It is probable that it was done.

(Examples 7 to 8 and Comparative Examples 6 to 7)
(Manufacturing process)
In the general formula _{(1) (Ba 1-x} M1 x) (Ti 1-y M2 y) metal oxide represented by _{O 3,} the composition of x = 0 and y = 0 not added metal elements M1, M2, i.e. A piezoelectric material was prepared by adding Bi, which is a first sub-component, and Mn, which is a second sub-component, to BaTIO _3. 0.1 mol% and the Mn content of 0.3 mol% of Bi content against the BaTiO ₃ as Example 7, 0.5 mol% and Mn containing Bi content against the BaTiO ₃ as Example 8 The amount is 1.5 mol%, and as Comparative Example 6 and Comparative Example 7, the Bi content is 1.0 mol% and the Mn content is 0.5 mol% and 2.0 mol%, respectively, with respect to _{BaTiO 3.} A metal oxide piezoelectric material was prepared.

Barium titanate powder (average particle size 100 nm, purity 99.99% or more), bismuth oxide (Bi ₂ O ₃ ) powder (average particle size 1 μm, purity 99.999% or more), manganese dioxide (MnO ₂ ) powder (average) The particle size (particle size: 1 μm, purity: 99.99% or more) was weighed so that Ba, Ti, Mn, and Bi had a desired ratio. These powders are placed in a zirconia planetary ball mill pot, and a zirconia ball (a mixture of approximately the same amount of 1 mm and 3 mm in diameter) having the same bulk (volume) as the weighed raw material powder, and the raw material powder and balls Further dipping ethanol was added into the pot, a resin packing was sandwiched between the pot and the lid, and the lid was closed. A pot is installed in the planetary ball mill device, and the pot and lid are firmly held down by the holding tool attached to the device so that powder and ethanol do not overflow from the gap between the pot and the lid during operation, and then every 500 revolutions. The material was revolved for 12 hours and mixed well while applying a strong shear stress to the raw material powder.

After the mixing by the planetary ball mill was completed, the contents in the pot were taken out and the zirconia balls were removed from the pot to obtain a mixed raw material powder dispersed in ethanol. PVB (Polyvinyl butyral), which is 3 parts by weight based on 100 parts by weight of the total weight of the raw material powder, is added thereto as a binder after being dissolved in ethanol, and the ethanol is volatilized while stirring and mixing to make the binder into the mixed raw material powder. Was attached to prepare a granulated powder. This granulation step can also be obtained by adhering PVA (Polyvinyl alcohol), which is 3 parts by weight based on 100 parts by weight of the raw material powder, to the surface of the mixed powder as a binder using a spray dryer device. The results were the same.

Next, the obtained granulated powder was filled in a mold, and a molding pressure of 200 MPa was applied using a press molding machine to prepare a disk-shaped molded product. The obtained compact was placed in a variable-atmosphere electric furnace, first heated at 600 ° C. in an atmospheric atmosphere and held, then further heated to 1350 ° C. and held for 4 hours. The temperature was lowered by allowing it to cool. Through the above steps, a disk-shaped sintered body (polycrystalline ceramics) was obtained. This sintered body was used as a piezoelectric material.

The Bi content and Mn content in the obtained material were evaluated by ICP emission spectroscopic analysis and ICP mass spectrometry. The results are as shown in Table 6, and the materials having Bi and Mn contents almost as planned were obtained.

(X-ray diffraction)
A part of the obtained material was pulverized into a fine powder, and then X-ray diffraction measurement was performed. Using a bending magnet synchrotron radiation X-ray light source, X-rays monochromatic to a wavelength of 0.39984 Å or 0.39987 Å were used, and measurements were taken at room temperature in 2θ angle steps of 0.01 ° by the device sheller method. When the X-ray diffraction charts obtained were analyzed, reliable analysis results were obtained by assuming a single tetragonal perovskite crystal structure for all materials, so the main phase was single. It was found to have a tetragonal perovskite crystal structure. In addition, it was confirmed that only a very small amount of phases other than the main phase existed.

(XAFS)
Some of the sintered body of the obtained piezoelectric material was used in the Bi-L ₃ fluorescence XAFS measurement by polishing the surface. The measurement was carried out using the same method as in Examples 1 to 4. The EXAFS vibration spectrum was extracted from the obtained Bi-L ₃ XAFS spectrum, and this was Fourier transformed to obtain a Bi radial structure function. This peak structure was analyzed by fitting to obtain information on the coordination environment around Bi. (L _4- L ₅ ) / L ₅ , (L _8- L ₉ ) / L ₉ , (L _1- L ₁₂ ) / L ₁₂ when the distance of the Bi-O bond is _{from L 1} to L _{12 in order of increasing length.} The values of (D _4- D ₅ ) / D ₅ when the distances of the Bi-Ti bond are set _{from D 1} to D _{8 in} descending order are shown in Table 6.

In order to investigate the coordination environment around Ba, which is the main component element of the obtained piezoelectric material, Ba-K XAFS measurement was also performed. After a part of the sintered body of the piezoelectric material was powdered, it was mixed and diluted with boron nitride powder so as to have a concentration suitable for measurement to prepare a tablet-shaped sample, and XAFS measurement was performed by a permeation method. EXAFS vibration was extracted from the obtained spectrum, and the Ba radial structure function obtained by the Fourier transform was analyzed by fitting. The distribution of the obtained Ba—O bond length is shown in Table 6.

(Manufacturing of piezoelectric element)
A part of the sintered body was polished on both the front and back surfaces, and then gold electrodes having a thickness of 400 nm were formed on both the front and back surfaces by a DC sputtering method. A layer made of titanium having a thickness of 30 nm was formed as an adhesion layer between the electrode and the piezoelectric material. This piezoelectric material with electrodes was cut to produce a strip-shaped element having a size of 10 mm × 2.5 mm × 0.5 mm. This element was placed on a hot plate having a surface temperature of 100 ° C. to 140 ° C., and an electric field of 1.0 kV / mm was applied between both electrodes for 30 minutes for polarization treatment. In this way, a piezoelectric element in which the piezoelectric material in the portion sandwiched between the electrodes has residual polarization perpendicular to the electrode surface was obtained.

(Measurement of piezoelectric constant and mechanical quality coefficient)
_{The piezoelectric constant d 31} at room temperature (25 ° C.) and the mechanical quality coefficient Qm at room temperature of the obtained piezoelectric element were evaluated. These results are shown in Table 6. The piezoelectric constant d ₃₁ was obtained by the resonance-antiresonance method at room temperature (25 ° C.). The mechanical quality coefficient Qm is a value obtained at the same time as the piezoelectric constant by the resonance-antiresonance method.

_{The piezoelectric constants d 31} of Examples 7 and 8 were both as large as 100 pm / V or more, and the mechanical quality coefficient Qm was 2000 or more, which were values suitable for the practicality of the resonance type piezoelectric device. This is because both the amount of Bi and the amount of Mn are appropriate, and Bi is uniformly distributed by sufficiently mixing the raw material powder, and as a result, Bi exists at a position biased in the c-axis direction from the position symmetrical with respect to the center of the A site. It is probable that it was done.

(Comparative Example 8)
(Manufacturing process)
In the general formula _{(1) (Ba 1-x} M1 x) (Ti 1-y M2 y) metal oxide represented by _{O 3,} the composition of x = 0 and y = 0 not added metal elements M1, M2, i.e. A piezoelectric material obtained by adding 0.4 mol% of Bi, which is the first sub-component, and 0.5 mol% of Mn, which is the second sub-component, to BaTiO _{3 was prepared by using a method different from that of Example 4.}

Barium titanate powder (average particle size 100 nm, purity 99.99% or more), bismuth oxide (Bi ₂ O ₃ ) powder (average particle size 1 μm, purity 99.999% or more), manganese dioxide (MnO ₂ ) powder (average) The particle size (particle size: 1 μm, purity: 99.99% or more) was weighed so that Ba, Ti, Mn, and Bi had a desired ratio. These powders were placed in an agate mortar (mortar) having a diameter of 15 cm, and the mixture was stirred and mixed for about 10 minutes using an agate pestle.

After the stirring and mixing is completed, PVB (Polyvinyl butyral), which is 3 parts by weight based on 100 parts by weight of the raw material powder as a binder, is added to the raw material powder in the agitator after being dissolved in ethanol, and further added to the milk stick. Ethanol was volatilized while stirring and mixing with the above to prepare a granulated powder.

Next, the obtained granulated powder was filled in a mold, and a molding pressure of 200 MPa was applied using a press molding machine to prepare a disk-shaped molded product. The obtained compact was placed in a variable-atmosphere electric furnace, first heated at 600 ° C. in an atmospheric atmosphere and held, then further heated to 1250 ° C. and held for 8 hours. The temperature was lowered by allowing it to cool. Through the above steps, a disk-shaped sintered body (polycrystalline ceramics) was obtained. This sintered body was used as a piezoelectric material.

The Bi content and Mn content in the obtained material were evaluated by ICP emission spectroscopic analysis and ICP mass spectrometry. The results are as shown in Table 6, and the materials having Bi and Mn contents almost as planned were obtained.

(XAFS)
Some of the sintered body of the obtained piezoelectric material was used in the Bi-L ₃ fluorescence XAFS measurement by polishing the surface. The measurement was carried out using the same method as in Examples 1 to 4. The EXAFS vibration spectrum was extracted from the obtained Bi-L ₃ XAFS spectrum, and this was Fourier transformed to obtain a Bi radial structure function. This peak structure was analyzed by fitting to obtain information on the coordination environment around Bi. (L _4- L ₅ ) / L ₅ , (L _8- L ₉ ) / L ₉ , (L _1- L ₁₂ ) / L ₁₂ when the distance of the Bi-O bond is _{from L 1} to L _{12 in order of increasing length.} The values of (D _4- D ₅ ) / D ₅ when the distances of the Bi-Ti bond are set _{from D 1} to D _{8 in} descending order are shown in Table 6. This result suggests that there is almost no bias in the Bi position. It is presumed that this is due to the fact that the Bi raw materials are not sufficiently mixed in the manufacturing process.

In order to investigate the coordination environment around Ba, which is the main component element of the obtained piezoelectric material, Ba-K XAFS measurement was also performed. After a part of the sintered body of the piezoelectric material was powdered, it was mixed and diluted with boron nitride powder so as to have a concentration suitable for measurement to prepare a tablet-shaped sample, and XAFS measurement was performed by a permeation method. EXAFS vibration was extracted from the obtained spectrum, and the Ba radial structure function obtained by the Fourier transform was analyzed by fitting. The distribution of the obtained Ba—O bond length is shown in Table 6.

(Manufacturing of piezoelectric element)
A part of the sintered body was polished on both the front and back surfaces, and then gold electrodes having a thickness of 400 nm were formed on both the front and back surfaces by a DC sputtering method. A layer made of titanium having a thickness of 30 nm was formed as an adhesion layer between the electrode and the piezoelectric material. This piezoelectric material with electrodes was cut to produce a strip-shaped element having a size of 10 mm × 2.5 mm × 0.5 mm. This element was placed on a hot plate having a surface temperature of 100 ° C. to 140 ° C., and an electric field of 1.0 kV / mm was applied between both electrodes for 30 minutes for polarization treatment. In this way, a piezoelectric element in which the piezoelectric material in the portion sandwiched between the electrodes has residual polarization perpendicular to the electrode surface was obtained.

(Measurement of piezoelectric constant and mechanical quality coefficient)
_{The piezoelectric constant d 31} at room temperature (25 ° C.) and the mechanical quality coefficient Qm at room temperature of the obtained piezoelectric element were evaluated. These results are shown in Table 6. The piezoelectric constant d ₃₁ was obtained by the resonance-antiresonance method at room temperature (25 ° C.). The mechanical quality coefficient Qm is a value obtained at the same time as the piezoelectric constant by the resonance-antiresonance method.

The piezoelectric constant d ₃₁ of Comparative Example 8 was as small as about 20 pm / V, and the mechanical quality coefficient Qm was only about 120. Although the amount of Bi and the amount of Mn are appropriate, the amount of Bi is insufficiently mixed, so that Bi does not dissolve well in the crystal and exists at a biased position at the A site of the perovskite type structure. It is thought that the cause was not done.

(Examples 9 to 12 and Comparative Example 9)
(Manufacturing process)
In the general formula _{(1) (Ba 1-x} M1 x) (Ti 1-y M2 y) metal oxide represented by _{O 3,} was added Zr or Hf or Sn in the metal element M1 is Ca or Sr, M2 x A piezoelectric material was prepared by adding Bi, which is a first sub-component, and Mn, which is a second sub-component, to a metal oxide having a composition of = 0.2 and y = 0.1. In Example 9, M1 was Ca and M2 was Zr, and the composition was such that the Bi content was 0.5 mol% and the Mn content was 0.3 mol% with respect to the metal oxide of the general formula (1). In Example 10, M1 was Ca and M2 was Hf, and the composition was obtained by adding 0.4 mol% of Bi content and 0.5 mol% of Mn content to the metal oxide of the general formula (1). In Example 11, M1 was Sr and M2 was Zr, and the composition was obtained by adding 0.4 mol% of Bi content and 0.5 mol% of Mn content to the metal oxide of the general formula (1). In Example 12, M1 was Sr and M2 was Sn, and the composition was obtained by adding 0.1 mol% of Bi content and 1.5 mol% of Mn content to the metal oxide of the general formula (1). Further, in Comparative Example 9, in the metal oxide represented by the general formula (1), M1 was defined as Ca and the composition was x = 0.1, M2 was not added (that is, y = 0), and Bi was not added. The composition was adjusted so that only Mn had a content of 0.6 mol%. These metal oxide piezoelectric materials were produced.

Barium titanate powder (average particle size 100 nm, purity 99.99% or more), calcium titanate powder (average particle size 300 nm, purity 99.99% or more), barium titanate powder (average particle size 300 nm, purity 99.99%) % Or more), barium titanate powder (average particle size 300 nm, purity 99.99% or more), barium titanate powder (average particle size 300 nm, purity 99.99% or more), barium titanate powder (average particle size 300 nm, Purity 99.99% or more), bismuth oxide (Bi ₂ O ₃ ) powder (average particle size 1 μm, purity 99.999% or more), manganese dioxide (MnO ₂ ) powder (average particle size 1 μm, purity 99.99% or more) ) Was weighed so that Ba, Ca, Sr, Ti, Zr, Hf, Sn, Mn, and Bi had a desired ratio. These powders are placed in a zirconia planetary ball mill pot, and a zirconia ball (a mixture of approximately the same amount of 1 mm and 3 mm in diameter) having the same bulk (volume) as the weighed raw material powder, and the raw material powder and balls Further dipping ethanol was added into the pot, a resin packing was sandwiched between the pot and the lid, and the lid was closed. A pot is installed in the planetary ball mill device, and the pot and lid are firmly held down by the holding tool attached to the device so that powder and ethanol do not overflow from the gap between the pot and the lid during operation, and then every 500 revolutions. The material was revolved for 12 hours and mixed well while applying a strong shear stress to the raw material powder.

After the mixing by the planetary ball mill was completed, the contents in the pot were taken out and the zirconia balls were removed from the pot to obtain a mixed raw material powder dispersed in ethanol. PVB (Polyvinyl butyral), which is 3 parts by weight based on 100 parts by weight of the total weight of the raw material powder, is added thereto as a binder after being dissolved in ethanol, and the ethanol is volatilized while stirring and mixing to make the binder into the mixed raw material powder. Was attached to prepare a granulated powder. This granulation step can also be obtained by adhering PVA (Polyvinyl alcohol), which is 3 parts by weight based on 100 parts by weight of the raw material powder, to the surface of the mixed powder as a binder using a spray dryer device. The results were the same.

Next, the obtained granulated powder was filled in a mold, and a molding pressure of 200 MPa was applied using a press molding machine to prepare a disk-shaped molded product. The obtained compact was placed in a variable-atmosphere electric furnace, first heated at 600 ° C. in an atmospheric atmosphere and held, then further heated to 1350 ° C. and held for 4 hours. The temperature was lowered by allowing it to cool. Through the above steps, a disk-shaped sintered body (polycrystalline ceramics) was obtained. This sintered body was used as a piezoelectric material.

The Bi content and Mn content in the obtained material were evaluated by ICP emission spectroscopic analysis and ICP mass spectrometry. The results are as shown in Table 6, and the materials having Bi and Mn contents almost as planned were obtained.

(X-ray diffraction)
A part of the obtained material was pulverized into a fine powder, and then X-ray diffraction measurement was performed. Using a bending magnet synchrotron radiation X-ray light source, X-rays monochromatic to a wavelength of 0.39984 Å or 0.39987 Å were used, and measurements were taken at room temperature in 2θ angle steps of 0.01 ° by the device sheller method. When the X-ray diffraction charts obtained were analyzed, reliable analysis results were obtained by assuming a single tetragonal perovskite crystal structure for all materials, so the main phase was single. It was found to have a tetragonal perovskite crystal structure. In addition, it was confirmed that only a very small amount of phases other than the main phase existed.

(XAFS)
Some of the sintered body of the obtained piezoelectric material was used in the Bi-L ₃ fluorescence XAFS measurement by polishing the surface. The measurement was carried out using the same method as in Examples 1 to 4. The EXAFS vibration spectrum was extracted from the obtained Bi-L ₃ XAFS spectrum, and this was Fourier transformed to obtain a Bi radial structure function. This peak structure was analyzed by fitting to obtain information on the coordination environment around Bi. (L _4- L ₅ ) / L ₅ , (L _8- L ₉ ) / L ₉ , (L _1- L ₁₂ ) / L ₁₂ when the distance of the Bi-O bond is _{from L 1} to L _{12 in order of increasing length.} The values of (D _4- D ₅ ) / D ₅ when the distances of the Bi-Ti bond are set _{from D 1} to D _{8 in} descending order are shown in Table 6.

In order to investigate the coordination environment around Ba, which is the main component element of the obtained piezoelectric material, Ba-K XAFS measurement was also performed. After a part of the sintered body of the piezoelectric material was powdered, it was mixed and diluted with boron nitride powder so as to have a concentration suitable for measurement to prepare a tablet-shaped sample, and XAFS measurement was performed by a permeation method. EXAFS vibration was extracted from the obtained spectrum, and the Ba radial structure function obtained by the Fourier transform was analyzed by fitting. The distribution of the obtained Ba—O bond length is shown in Table 6.

(Manufacturing of piezoelectric element)
A part of the sintered body was polished on both the front and back surfaces, and then gold electrodes having a thickness of 400 nm were formed on both the front and back surfaces by a DC sputtering method. A layer made of titanium having a thickness of 30 nm was formed as an adhesion layer between the electrode and the piezoelectric material. This piezoelectric material with electrodes was cut to produce a strip-shaped element having a size of 10 mm × 2.5 mm × 0.5 mm. This element was placed on a hot plate having a surface temperature of 100 ° C. to 140 ° C., and an electric field of 1.0 kV / mm was applied between both electrodes for 30 minutes for polarization treatment. In this way, a piezoelectric element in which the piezoelectric material in the portion sandwiched between the electrodes has residual polarization perpendicular to the electrode surface was obtained.

(Measurement of piezoelectric constant and mechanical quality coefficient)
_{The piezoelectric constant d 31} at room temperature (25 ° C.) and the mechanical quality coefficient Qm at room temperature of the obtained piezoelectric element were evaluated. These results are shown in Table 6. The piezoelectric constant d ₃₁ was obtained by the resonance-antiresonance method at room temperature (25 ° C.). The mechanical quality coefficient Qm is a value obtained at the same time as the piezoelectric constant by the resonance-antiresonance method.

_{The piezoelectric constants d 31} of Examples 9 to 12 were all as large as 100 pm / V or more, and the mechanical quality coefficient Qm was 2000 or more, which were values suitable for the practicality of the resonance type piezoelectric device. This is because M1 which is an A-site substitution element and M2 which is a B-site substitution element are accurately selected, and appropriate amounts are substituted for each, and both Bi amount and Mn amount are appropriate amounts. It is considered that Bi was uniformly distributed by sufficiently mixing the raw material powders, and as a result, Bi was present at a position biased in the c-axis direction from the position symmetrical with respect to the center of the A site.

(Comparative Example 10)
(Manufacturing process)
In the general formula _{(1) (Ba 1-x} M1 x) (Ti 1-y M2 y) metal oxide represented by _{O 3,} the composition of x = 0 and y = 0 not added metal elements M1, M2, i.e. A piezoelectric material in which 15 mol% of Bi, which is the first subcomponent, and 15 mol% of Fe, instead of Mn, which is the second subcomponent, was added to BaTiO _{3 was prepared by using a method different from that of Example 4.}

Barium titanate powder (average particle size 100 nm, purity 99.99% or more), bismuth oxide (Bi ₂ O ₃ ) powder (average particle size 1 μm, purity 99.999% or more), iron oxide (Fe ₂ O ₃ ) powder (Average particle size 1 μm, purity 99.99% or more) was weighed so that Ba, Ti, Fe, and Bi had a desired ratio. These powders are placed in a zirconia planetary ball mill pot, and a zirconia ball (a mixture of approximately the same amount of 1 mm and 3 mm in diameter) having the same bulk (volume) as the weighed raw material powder, and the raw material powder and balls Further dipping ethanol was added into the pot, a resin packing was sandwiched between the pot and the lid, and the lid was closed. A pot is installed in the planetary ball mill device, and the pot and lid are firmly held down by the holding tool attached to the device so that powder and ethanol do not overflow from the gap between the pot and the lid during operation, and then every 500 revolutions. The material was revolved for 12 hours and mixed well while applying a strong shear stress to the raw material powder.

After the mixing by the planetary ball mill was completed, the contents in the pot were taken out and the zirconia balls were removed from the pot to obtain a mixed raw material powder dispersed in ethanol. PVB (Polyvinyl butyral), which is 3 parts by weight based on 100 parts by weight of the total weight of the raw material powder, is added thereto as a binder after being dissolved in ethanol, and the ethanol is volatilized while stirring and mixing to make the binder into the mixed raw material powder. Was attached to prepare a granulated powder.

Next, the obtained granulated powder was filled in a mold, and a molding pressure of 200 MPa was applied using a press molding machine to prepare a disk-shaped molded product. The obtained compact was placed in a variable-atmosphere electric furnace, first heated at 600 ° C. in an atmospheric atmosphere and held, then further heated to 1250 ° C. and held for 8 hours. The temperature was lowered by allowing it to cool. Through the above steps, a disk-shaped sintered body (polycrystalline ceramics) was obtained. This sintered body was used as a piezoelectric material. The Bi content and Fe content in the obtained material were evaluated by fluorescent X-ray analysis. The results are as shown in Table 6, and the materials having Bi and Fe contents almost as planned were obtained.

(XAFS)
Some of the sintered body of the obtained piezoelectric material was used in the Bi-L ₃ fluorescence XAFS measurement by polishing the surface. The measurement was carried out using the same method as in Examples 1 to 4. The EXAFS vibration spectrum was extracted from the obtained Bi-L ₃ XAFS spectrum, and this was Fourier transformed to obtain a Bi radial structure function. This peak structure was analyzed by fitting to obtain information on the coordination environment around Bi. (L _4- L ₅ ) / L ₅ , (L _8- L ₉ ) / L ₉ , (L _1- L ₁₂ ) / L ₁₂ when the distance of the Bi-O bond is _{from L 1} to L _{12 in order of increasing length.} The values of (D _4- D ₅ ) / D ₅ when the distances of the Bi-Ti bond are set _{from D 1} to D _{8 in} descending order are shown in Table 6.

In order to investigate the coordination environment around Ba, which is the main component element of the obtained piezoelectric material, Ba-K XAFS measurement was also performed. After a part of the sintered body of the piezoelectric material was powdered, it was mixed and diluted with boron nitride powder so as to have a concentration suitable for measurement to prepare a tablet-shaped sample, and XAFS measurement was performed by a permeation method. EXAFS vibration was extracted from the obtained spectrum, and the Ba radial structure function obtained by the Fourier transform was analyzed by fitting. The distribution of the obtained Ba—O bond length is shown in Table 6.

(Manufacturing of piezoelectric element)
A part of the sintered body was polished on both the front and back surfaces, and then gold electrodes having a thickness of 400 nm were formed on both the front and back surfaces by a DC sputtering method. A layer made of titanium having a thickness of 30 nm was formed as an adhesion layer between the electrode and the piezoelectric material. This piezoelectric material with electrodes was cut to produce a strip-shaped element having a size of 10 mm × 2.5 mm × 0.5 mm. This element was placed on a hot plate having a surface temperature of 100 ° C. to 140 ° C., and an electric field of 1.0 kV / mm was applied between both electrodes for 30 minutes for polarization treatment. In this way, a piezoelectric element in which the piezoelectric material in the portion sandwiched between the electrodes has residual polarization perpendicular to the electrode surface was obtained.

(Measurement of piezoelectric constant and mechanical quality coefficient)
_{The piezoelectric constant d 31} at room temperature (25 ° C.) and the mechanical quality coefficient Qm at room temperature of the obtained piezoelectric element were evaluated. These results are shown in Table 6. The piezoelectric constant d ₃₁ was obtained by the resonance-antiresonance method at room temperature (25 ° C.). The mechanical quality coefficient Qm is a value obtained at the same time as the piezoelectric constant by the resonance-antiresonance method.

The piezoelectric constant d ₃₁ of Comparative Example 10 was relatively large, about 100 pm / V, but the mechanical quality coefficient Qm was only about 30. From the results of Bi-L ₃ EXAFS analysis, although the Bi atom exists at a biased position at the A site of the perovskite type structure, a heterogeneous structure is formed due to the large amount of Bi and Fe. It is considered that the cause is that it exhibits properties like a relaxer, which is a heterogeneous ferroelectric substance.

(Confirmation of uniform distribution of added Bi and Mn)
For the purpose of confirming the uniform distribution of added Bi and Mn, electron microscope observation, X-ray diffraction, EXAFS analysis, temperature dependence of permittivity, and frequency dependence of impedance with respect to Examples 1 to 6 and Comparative Examples 1 to 5 Was measured. From electron microscopic observation, no heterogeneous phase due to the precipitation of Bi and Mn was confirmed. From X-ray diffraction, the appearance of specific diffraction peaks due to the addition of Bi and Mn was not observed. In EXAFS analysis, the radial distribution function could be fitted by a single coordination structure model. Regarding the temperature dependence of _{the permittivity, it was confirmed that the Curie temperature T c} and the phase transition temperature _Tot changed systematically, and the steepness of the change in the permittivity at the time of the phase transition did not change depending on the additive. Except for Comparative Example 2, the frequency-dependent spectrum of impedance shows a monotonous positive correlation between the imaginary part and the real part of impedance in the measurement frequency range (100 Hz to 10 MHz), and the capacitance is uniform both inside and at the grain boundaries. -It was confirmed that it showed a resistance component. In Comparative Example 2, a curve was drawn in which the imaginary part had two maximums with respect to the real part of the impedance, and the result suggesting the difference in the components inside the grain and at the grain boundary was obtained, but only the resistance component was different. Since the volume components were similar between the inside of the grains and the grain boundaries, it was confirmed that it was not due to the precipitation of additives.
In addition, the temperature dependence of the magnetic susceptibility was measured for Examples 1 to 6 and Comparative Examples 3 and 4. It was confirmed that all the measurement results were highly reliable and followed the Curie-Weiss law.
From these facts, it was confirmed that the added Bi and Mn were uniformly distributed in the substance without precipitation or heterophasic formation.

(Manufacturing and evaluation of laminated piezoelectric elements)
Next, the laminated piezoelectric element of the present invention was produced.

(Example 13)
Barium titanate powder (average particle size 100 nm, purity 99.99% or more), bismuth oxide (Bi ₂ O ₃ ) powder (average particle size 1 μm, purity 99.999% or more), manganese dioxide (MnO ₂ ) powder (average) The particle size (particle size: 1 μm, purity: 99.99% or more) was weighed so as to have the composition shown in Example 4 of Table 6.

These powders are placed in a zirconia planetary ball mill pot, and a zirconia ball (a mixture of approximately the same amount of 1 mm and 3 mm in diameter) having the same bulk (volume) as the weighed raw material powder, and the raw material powder and balls Further dipping ethanol was added into the pot, a resin packing was sandwiched between the pot and the lid, and the lid was closed. A pot is installed in the planetary ball mill device, and the pot and lid are firmly held down by the holding tool attached to the device so that powder and ethanol do not overflow from the gap between the pot and the lid during operation, and then every 500 revolutions. The spinning was carried out for 12 hours, and the raw material powder was mixed well while applying a strong shear stress.

PVB (polyvinyl butyral) was added to the obtained mixed powder and mixed, and then a sheet was formed by a doctor blade method to obtain a green sheet having a thickness of 50 μm. The conductive paste for the internal electrode was printed on the obtained green sheet. As the conductive paste, an Ag60% −Pd40% alloy paste was used. Nine green sheets coated with the conductive paste were laminated, and the laminated body was fired at 1200 ° C. for 5 hours to obtain a sintered body.

Next, after cutting the sintered body to a size of 10 mm × 2.5 mm, the side surfaces thereof are polished, and a pair of external electrodes (first electrode and second electrode) that alternately short-circuit the internal electrodes are sputtered with Au. To produce a laminated piezoelectric element as shown in FIG. 3 (b). When the internal electrodes of the obtained laminated piezoelectric element were observed, Ag-Pd, which is an electrode material, was formed alternately with the piezoelectric material.

Further, the sample was subjected to a polarization treatment prior to the evaluation of the piezoelectric performance. Specifically, the sample was heated to 100 ° C. in an oil bath, an electric field of 1 kV / mm was applied between the first electrode and the second electrode for 30 minutes, and the sample was cooled to room temperature with the electric field applied.

When the piezoelectric performance of the obtained laminated piezoelectric element was evaluated, it was found that it had sufficient insulating properties and had good piezoelectric characteristics equivalent to those of the piezoelectric material of Example 4. In addition, the same piezoelectric characteristics could be obtained for the laminated piezoelectric element manufactured in the same process except that Ni and Cu were used for the internal electrodes and sintered in a low oxygen atmosphere.

(Example 14)
A green sheet having a thickness of 50 μm was obtained by the same method as in Example 13. A conductive paste for internal electrodes was printed on the green sheet. Ni paste was used as the conductive paste. Nine green sheets coated with the conductive paste were laminated, and the laminate was thermocompression bonded.

The thermocompression-bonded laminate was fired in a tube furnace. Baking is performed in the atmosphere up to 300 ° C., and after debindering, the atmosphere is _{switched to a reducing atmosphere (H 2} : N ₂ = 2: 98, oxygen concentration 2 × ^10-6 Pa), and the temperature is 1200 ° C. for 5 hours. Retained. In the temperature lowering process, the oxygen concentration was switched from 1000 ° C. or lower to 30 Pa and cooled to room temperature.

The sintered body thus obtained is cut into a size of 10 mm × 2.5 mm, and the side surfaces thereof are polished to alternately short-circuit the internal electrodes (first electrode and second electrode). ) Was formed by Au sputtering to produce a laminated piezoelectric element as shown in FIG. 3 (b). When the internal electrodes of the obtained laminated piezoelectric element were observed, Ni, which is an electrode material, was formed alternately with the piezoelectric material layer.

Next, the obtained laminated piezoelectric element was subjected to polarization treatment by applying an electric field of 1 kV / mm for 30 minutes in an oil bath maintained at 100 ° C. When the piezoelectric characteristics of the obtained laminated piezoelectric element were evaluated, it was possible to obtain sufficient piezoelectric characteristics and good piezoelectric characteristics equivalent to those of the piezoelectric element of Example 4.

(Example 15)
Using the piezoelectric element of Example 4, the liquid discharge head shown in FIG. 4 was produced. It was confirmed that the ink was ejected following the input electric signal.

(Example 16)
Using the liquid discharge head of Example 15, the liquid discharge device shown in FIG. 5 was manufactured. Ink ejection following the input electrical signal was confirmed on the recording medium (recording paper).

(Example 17)
Using the piezoelectric element of Example 4, the ultrasonic motor shown in FIG. 7 (a) was manufactured. It was confirmed that the chipping of the outer peripheral portion during machining was suppressed, and the rotation of the motor in response to the application of the alternating voltage was confirmed.

(Example 18)
Using the ultrasonic motor of Example 17, the optical instrument shown in FIG. 8 was manufactured. It was confirmed that the autofocus operation was performed according to the application of the alternating voltage.

(Example 19)
Using the piezoelectric element of Example 4, a dust removing device provided with the vibrating body shown in FIG. 9 was produced. When plastic beads were sprayed and an alternating voltage was applied, a good dust removal rate was confirmed.

(Example 20)
Using the dust removing device of Example 19, the imaging device shown in FIG. 11 was produced. When it was operated, dust on the surface of the imaging unit was satisfactorily removed, and an image without dust defects was obtained.

(Example 21)
The liquid discharge head shown in FIG. 4 was manufactured using the laminated piezoelectric element of Example 13. It was confirmed that the ink was ejected following the input electric signal.

(Example 22)
Using the liquid discharge head of Example 21, the liquid discharge device shown in FIG. 5 was manufactured. Ink ejection following the input electrical signal was confirmed on the recording medium (recording paper).

(Example 23)
Using the laminated piezoelectric element of Example 13, the ultrasonic motor shown in FIG. 7 (b) was manufactured. It was confirmed that the motor rotated according to the application of the alternating voltage.

(Example 24)
Using the ultrasonic motor of Example 23, the optical instrument shown in FIG. 8 was manufactured. It was confirmed that the autofocus operation was performed according to the application of the alternating voltage.

(Example 25)
Using the laminated piezoelectric element of Example 13, a dust removing device provided with the vibrating body shown in FIG. 9 was produced. When plastic beads were sprayed and an alternating voltage was applied, a good dust removal rate was confirmed.

(Example 26)
Using the dust removing device of Example 25, the imaging device shown in FIG. 11 was produced. When it was operated, dust on the surface of the imaging unit was satisfactorily removed, and an image without dust defects was obtained.

(Example 27)
The electronic device shown in FIG. 13 was manufactured using the laminated piezoelectric element of Example 13. It was confirmed that the speaker operated according to the application of the alternating voltage.

The piezoelectric material of the present invention exhibits good piezoelectric performance even at a high environmental temperature. Further, since the piezoelectric material of the present invention does not contain lead, the load on the environment is small. Therefore, the piezoelectric material of the present invention can be used without problems in equipment that uses a large amount of piezoelectric material, such as a liquid discharge head, a vibration wave motor, and a dust removing device.

The present invention provides a piezoelectric material that does not contain lead, has a small environmental load, and has both good piezoelectric performance and workability (the occurrence of cracks, chipping, etc. during processing is suppressed). Therefore, the piezoelectric material of the present invention can be used without problems in devices that use a large amount of piezoelectric material, such as a liquid discharge head, a liquid discharge device, a vibration wave motor, and a dust removing device.

1 First electrode 2 Piezoelectric material part 3 Second electrode

Claims (18)

A piezoelectric material having a perovskite-type structure containing a metal oxide represented by the following general formula (1), Bi, and Mn.
The Bi content is 0.1 mol% or more and 0.5 mol% or less with respect to 1 mol of the metal oxide.
The Mn content is 0.3 mol% or more and 1.5 mol% or less with respect to 1 mol of the metal oxide.
Measurement of X-ray absorption fine structure when the distances of 12 types of Bi-O bonds starting from Bi at the position of 12 coordination with respect to O in the perovskite unit cell are set to L _{1 to} L _{12 in order of increasing length.} length of the Bi-O bonds by _is to satisfy _{(L 4 -L 5) / L} 5 ≧ 0.05 and _{(L 8 -L 9) / L} 9 ≧ 0.05,
A piezoelectric material characterized in that the content of Mn is larger than the content of Bi.
General formula (1)
(Ba _1-x M1 _x ) (Ti _1-y M2 _y ) O ₃
(However, 0 ≦ x ≦ 0.2, 0 ≦ y ≦ 0.1, M1 and M2 are different metal elements having a sum of +6 valences, and are selected from elements other than Ba, Ti, Bi, and Mn. ) The piezoelectric material according to claim 1, wherein the L ₁ and the L ₁₂ satisfy the relationship of (L _{1 −} L ₁₂ ) / L _{12 ≧ 0.25.} Wherein there crystal system tetragonal piezoelectric material, according to claim 1, characterized in that Bi at the position of 12 coordination of the perovskite unit cell is shifted to the c-axis direction from the symmetry of the unit cells or 2. The piezoelectric material according to 2. When the distances of eight types of Bi-Ti bonds starting from Bi at the position of eight coordination with respect to Ti in the perovskite unit cell are set to D _{1 to} D _{8 in} order of increasing length, the X-ray absorption fine structure The piezoelectric material according to any one of claims 1 to 3 , wherein the distance of the Bi-Ti bond as measured _{satisfies (D 4-} D ₅ ) / D _{5> 0.05.} The distribution of the perovskite unit O Ba-O bond distance starting from the Ba at position 12 coordinated with respect to the lattice of claims 1 to 4, characterized in that in the range of less than ± 5% The piezoelectric material according to any one item. The piezoelectric material according to any one of claims 1 to 5 , wherein the M1 is at least one of Sr and Ca. The piezoelectric material according to any one of claims 1 to 6 , wherein M2 is at least one of Hf, Sn and Zr. A piezoelectric element having a first electrode, a piezoelectric material portion, and a second electrode, and the piezoelectric material constituting the piezoelectric material portion is the piezoelectric material according to any one of claims 1 to 7. Piezoelectric element characterized by. The piezoelectric element according to claim 8 , further comprising a laminated structure in which the piezoelectric material portion and the electrodes are alternately laminated. A liquid discharge head having a liquid chamber provided with a vibrating portion in which the piezoelectric element according to claim 8 or 9 is arranged and a discharge port communicating with the liquid chamber. A liquid discharge device including a mounting portion of a transfer target and the liquid discharge head according to claim 10. A vibration wave motor comprising a vibrating body provided with the piezoelectric element according to claim 8 or 9 and a moving body in contact with the vibrating body. An optical device having a drive unit, wherein the drive unit includes the vibration wave motor according to claim 12. A vibrating device comprising a vibrating body including a diaphragm provided with the piezoelectric element according to claim 8 or 9. A dust removing device having a vibrating portion, wherein the vibrating portion includes the vibrating device according to claim 14. An image pickup apparatus comprising the dust removal apparatus according to claim 15 and an image pickup element unit that receives light, wherein a vibrating plate of the dust removal apparatus is arranged on the light receiving surface side of the image pickup element unit. An image sensor characterized by being present. A piezoelectric acoustic component comprising the piezoelectric element according to claim 8 or 9. An electronic device comprising the piezoelectric element according to claim 8 or 9.

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