JP6932966B2 - Piezoelectric element and piezoelectric element application device - Google Patents

Description

The present invention relates to piezoelectric elements and piezoelectric element application devices.

Generally, a piezoelectric element has a piezoelectric layer having electromechanical conversion characteristics and two electrodes sandwiching the piezoelectric layer. In recent years, the development of devices using such piezoelectric elements as drive sources (piezoelectric element application devices) has been actively carried out. As one of the piezoelectric element application devices, a liquid injection head represented by an inkjet recording head, a MEMS element represented by a piezoelectric MEMS element, an ultrasonic measuring device represented by an ultrasonic sensor, a piezoelectric actuator device, etc. There is.

As a material (piezoelectric material) for the piezoelectric layer of the piezoelectric element, for example, sodium potassium niobate ((K, Na) NbO ₃ , hereinafter referred to as “KNN”) has been proposed. Since KNN exhibits relatively high piezoelectric properties, it is considered to be a promising candidate for lead-free piezoelectric materials. In a piezoelectric body made of polycrystalline KNN, attempts have been made to improve durability (see, for example, Patent Document 1) and the amount of displacement by orienting the piezoelectric material in a predetermined plane orientation.

_{In addition, polycrystalline nickel lanthanate (LaNiO 3} , hereinafter referred to as "LNO") is used as a buffer layer (also referred to as an orientation control layer _{), and strontium titanate (Nb: SrTIO 3} ) doped with niobium (Nb) is used. Attempts have been made to orient KNN, which is a piezoelectric material, in a predetermined plane orientation by using the single crystal substrate of (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2012-124233 Japanese Patent No. 5716799

However, LNO tends to diffuse into the piezoelectric body during firing at a high temperature, and tends to cause a change in the composition of the piezoelectric body. Further, when the dielectric constant of the buffer layer made of LNO is low, various problems such as difficulty in applying a voltage to the piezoelectric layer may occur. On the other hand, Nb: SrTiO ₃ single crystal substrate, it is difficult practical in terms of cost.

It should be noted that such a problem exists not only in the piezoelectric element mounted on the liquid injection head represented by the inkjet recording head but also in the piezoelectric element used in other piezoelectric element application devices.

The present invention has been made in view of such circumstances, and is a piezoelectric element and a piezoelectric element application having a piezoelectric layer containing a perovskite-type composite oxide which is preferentially oriented to the (100) plane and has excellent crystallinity. The purpose is to provide a device.

An aspect of the present invention for solving the above problems is a perovskite-type composite oxide sandwiched between a first electrode, a second electrode, the first electrode and the second electrode, and _{represented by the general formula ABO 3.} A piezoelectric element having a piezoelectric layer which is a laminate of a plurality of piezoelectric films containing the above crystals, and is a first piezoelectric body formed directly above the first electrode among the plurality of piezoelectric films. The film is preferentially oriented on the (100) plane and has a piezobskite-type composite oxide containing potassium, sodium and niobium, and the amount of sodium contained in the A site of the piezobskite-type composite oxide is larger than the amount of potassium. It is in a piezoelectric element characterized by.
In such an embodiment, it is possible to obtain a piezoelectric element having a piezoelectric layer containing a perovskite-type composite oxide which is preferentially oriented on the (100) plane and has excellent crystallinity.

Here, in the piezoelectric element, the composition ratio of potassium (K) and sodium (Na) contained in the A site of the perovskite-type composite oxide of the first piezoelectric film is represented by the following formula (1). It is preferable to have a relationship with each other.
0.5 <Na / (Na + K) ≤ 0.9 ... (1)
According to this, it is possible to obtain a piezoelectric element having a piezoelectric layer containing a perovskite-type composite oxide which is preferentially oriented toward the (100) plane and has excellent crystallinity.

Further, in the piezoelectric element, the first piezoelectric film has a relationship in which the molar ratio (A / B) of A sites to B sites of the perovskite-type composite oxide is represented by the following formula (2). Is preferable.
0.8 <A / B ≦ 1.4 ・ ・ ・ (2)
According to this, it is possible to obtain a piezoelectric element having a piezoelectric layer containing a perovskite-type composite oxide which is preferentially oriented toward the (100) plane and has excellent crystallinity.

Further, in the piezoelectric element, in the first piezoelectric film, the half width of the peak derived from the (100) plane in the crystal of the perovskite type composite oxide measured by the X-ray diffraction method is 0.55 ° or less. It is preferable to have.
According to this, it is possible to obtain a piezoelectric element having a piezoelectric layer containing a perovskite type composite oxide having excellent displacement characteristics.

Another aspect of the present invention is a piezoelectric element application device, which comprises any one of the above piezoelectric elements.
In such an embodiment, it is possible to provide a piezoelectric element application device in which the piezoelectric / dielectric characteristics are stable and toughness against external stress (mechanical characteristics) is realized.

The perspective view which shows the schematic structure of the inkjet recording apparatus. An exploded perspective view showing a schematic configuration of an inkjet recording head. The plan view which shows the schematic structure of the inkjet recording head. FIG. 3 is a cross-sectional view taken along the line AA'in FIG. FIG. 4 is an enlarged cross-sectional view taken along the line BB'in FIG. FIG. 2 is a cross-sectional view illustrating a manufacturing example of an inkjet recording head. FIG. 2 is a cross-sectional view illustrating a manufacturing example of an inkjet recording head. FIG. 2 is a cross-sectional view illustrating a manufacturing example of an inkjet recording head. FIG. 2 is a cross-sectional view illustrating a manufacturing example of an inkjet recording head. FIG. 2 is a cross-sectional view illustrating a manufacturing example of an inkjet recording head. FIG. 2 is a cross-sectional view illustrating a manufacturing example of an inkjet recording head. FIG. 2 is a cross-sectional view illustrating a manufacturing example of an inkjet recording head. The graph which shows the relationship between Na ratio, half width and intensity of samples 1-9. The graph which shows the relationship between the A site ratio, the full width at half maximum and the intensity of samples 10 to 15. The graph which shows the relationship between the A site ratio, the full width at half maximum and the intensity of samples 16-21.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows one aspect of the present invention, and can be arbitrarily changed without departing from the gist of the present invention. In each drawing, those having the same reference numerals indicate the same members, and the description thereof is omitted as appropriate. Further, X, Y and Z represent three spatial axes orthogonal to each other. In the present specification, the directions along these axes are defined as the first direction X (X direction), the second direction Y (Y direction), and the third direction Z (Z direction), respectively, and the arrows in each figure. The direction in which the head is headed will be described as the positive (+) direction, and the direction opposite to the arrow will be described as the negative (-) direction. The X direction and the Y direction represent the in-plane direction of the plate, the layer and the film, and the Z direction represents the thickness direction or the stacking direction of the plate, the layer and the film.

Further, the components shown in each drawing, that is, the shape and size of each part, the thickness of the plate, the layer and the film, the relative positional relationship, the repeating unit, etc. are exaggerated in explaining the present invention. May be. Further, the term "above" in the present specification does not limit the positional relationship of the components to be "immediately above". For example, the expressions "first electrode on the substrate" and "piezoelectric layer on the first electrode" have other configurations between the substrate and the first electrode and between the first electrode and the piezoelectric layer. Do not exclude those that contain elements.

(Embodiment 1)
(Liquid injection device)
First, an inkjet recording device, which is an example of a liquid injection device, will be described with reference to the drawings.
FIG. 1 is a perspective view showing a schematic configuration of an inkjet recording device. As shown in the figure, in the inkjet recording device (recording device) I, the inkjet recording head unit (head unit) II is detachably provided on the cartridges 2A and 2B. The cartridges 2A and 2B form an ink supply means. The head unit II has a plurality of inkjet recording heads (recording heads) 1 (see FIG. 2 and the like), and is mounted on the carriage 3. The carriage 3 is provided on the carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction. The head unit II and the carriage 3 are configured to be capable of ejecting, for example, a black ink composition and a color ink composition, respectively.

Then, the driving force of the drive motor 6 is transmitted to the carriage 3 via a plurality of gears and a timing belt 7 (not shown), and the carriage 3 equipped with the head unit II is moved along the carriage shaft 5. ing. On the other hand, the apparatus main body 4 is provided with a transport roller 8 as a transport means, and the recording sheet S, which is a recording medium such as paper, is transported by the transport roller 8. The transporting means for transporting the recording sheet S is not limited to the transport roller, and may be a belt, a drum, or the like.

A piezoelectric element 300 (see FIG. 2 and the like) is used as a piezoelectric actuator device in the recording head 1. By using the piezoelectric element 300, it is possible to avoid deterioration of various characteristics (durability, ink ejection characteristics, etc.) in the recording device I.

(Liquid injection head)
Next, the recording head 1, which is an example of the liquid injection head mounted on the liquid injection device, will be described with reference to the drawings. FIG. 2 is an exploded perspective view showing a schematic configuration of an inkjet recording head. FIG. 3 is a plan view showing a schematic configuration of an inkjet recording head. FIG. 4 is a cross-sectional view taken along the line AA'of FIG. Note that FIGS. 2 to 4 show a part of the configuration of the recording head 1, and are omitted as appropriate.

As shown in the figure, the flow path forming substrate (substrate) 10 is made of, for example, a silicon (Si) single crystal substrate. The material of the substrate 10 is not limited to Si, and may be SOI (Silicon On Insulator), glass, or the like.

The substrate 10 is formed with a pressure generating chamber 12 partitioned by a plurality of partition walls 11. The pressure generating chambers 12 are arranged side by side along the direction (+ X direction) in which a plurality of nozzle openings 21 for ejecting ink of the same color are provided.

An ink supply path 13 and a communication passage 14 are formed on one end side (+ Y direction side) of the pressure generating chamber 12 in the substrate 10. The ink supply path 13 is configured so that the area of the opening on the one end side of the pressure generating chamber 12 is small. Further, the communication passage 14 has substantially the same width as the pressure generating chamber 12 in the + X direction. A communication portion 15 is formed on the outside (+ Y direction side) of the communication passage 14. The communication portion 15 forms a part of the manifold 100. The manifold 100 serves as a common ink chamber for each pressure generating chamber 12. As described above, the substrate 10 is formed with a liquid flow path including the pressure generation chamber 12, the ink supply path 13, the communication passage 14, and the communication portion 15.

For example, a nozzle plate 20 made of SUS is joined on one surface (the surface on the −Z direction side) of the substrate 10. Nozzle openings 21 are arranged side by side in the nozzle plate 20 along the + X direction. The nozzle opening 21 communicates with each pressure generating chamber 12. The nozzle plate 20 can be bonded to the substrate 10 with an adhesive, a heat welding film, or the like.

A diaphragm 50 is formed on the other surface (the surface on the + Z direction side) of the substrate 10. The diaphragm 50 is composed of, for example, an elastic film 51 formed on the substrate 10 and an insulator film 52 formed on the elastic film 51. The elastic membrane 51 is made of, for example, silicon dioxide (SiO ₂ ), and the insulator membrane 52 is made of, for example, zirconium oxide (ZrO ₂ ). The elastic membrane 51 does not have to be a separate member from the substrate 10. A part of the substrate 10 may be thinly processed and used as the elastic film 51. The elastic film 51 is _{not limited to SiO 2,} and may be a film using, for example, aluminum oxide (Al ₂ O ₃ ), tantalum oxide (V) (Ta ₂ O ₅ ), silicon nitride (SiN), or the like.

A piezoelectric element 300 including a first electrode 60, a piezoelectric layer 70, and a second electrode 80 is formed on the insulator film 52 via an adhesion layer 56. For the adhesion layer 56, for example, titanium oxide (TiO _X ), titanium (Ti), SiN or the like is used, and has a function of improving the adhesion between the piezoelectric layer 70 and the diaphragm 50. The adhesion layer 56 can be omitted.

In the process of forming the piezoelectric layer 70, which will be described later, when the piezoelectric material constituting the piezoelectric layer 70 contains an alkali metal such as potassium (K) or sodium (Na), it may diffuse into the first electrode 60. be. Therefore, by providing the insulator film 52 between the first electrode 60 and the substrate 10, the insulator film 52 functions as a stopper, and the arrival of the alkali metal on the substrate 10 can be suppressed.

The first electrode 60 is provided for each pressure generating chamber 12. That is, the first electrode 60 is configured as an independent electrode for each pressure generating chamber 12. The first electrode 60 is formed with a width narrower than the width of the pressure generating chamber 12 in the ± X direction. Further, the first electrode 60 is formed with a width wider than that of the pressure generating chamber 12 in the ± Y direction. That is, both ends of the first electrode 60 are formed to the outside of the region facing the pressure generating chamber 12 on the diaphragm 50 in the ± Y direction. A lead electrode 90 is connected to one end side of the first electrode 60 (the side opposite to the communication passage 14).

The piezoelectric layer 70 is provided between the first electrode 60 and the second electrode 80. The piezoelectric layer 70 is formed to have a width wider than the width of the first electrode 60 in the ± X direction. Further, the piezoelectric layer 70 is formed in a width wider than the length of the pressure generating chamber 12 in the ± Y direction in the ± Y direction. The end portion of the piezoelectric layer 70 on the ink supply path 13 side (+ Y direction side) is formed to the outside of the end portion on the + Y direction side of the first electrode 60. That is, the end portion of the first electrode 60 on the + Y direction side is covered with the piezoelectric layer 70. On the other hand, the end portion of the piezoelectric layer 70 on the lead electrode 90 side (−Y direction side) is inside (+ Y direction side) of the end portion of the first electrode 60 on the −Y direction side. That is, the end portion of the first electrode 60 on the −Y direction side is not covered by the piezoelectric layer 70. The piezoelectric layer 70 is a thin-film piezoelectric body having a predetermined thickness, which will be described later.

The second electrode 80 is continuously provided on the piezoelectric layer 70 and the diaphragm 50 in the + X direction. That is, the second electrode 80 is configured as a common electrode common to the plurality of piezoelectric layers 70. In the present embodiment, the first electrode 60 constitutes an individual electrode provided independently corresponding to the pressure generating chamber 12, and the second electrode 80 is continuously provided in the parallel direction of the pressure generating chamber 12. Although the common electrodes are formed, the first electrode 60 may form a common electrode and the second electrode 80 may form an individual electrode.

In the present embodiment, the diaphragm 50 and the first electrode 60 are displaced by the displacement of the piezoelectric layer 70 having the electromechanical conversion characteristic. That is, the diaphragm 50 and the first electrode 60 substantially have a function as a diaphragm. However, in reality, since the second electrode 80 is also displaced due to the displacement of the piezoelectric layer 70, the region in which the vibrating plate 50, the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are sequentially laminated is formed. It functions as a movable part (also referred to as a vibrating part) of the piezoelectric element 300.

In the present embodiment, either the elastic film 51 or the insulator film 52 may be omitted to function as a diaphragm, or the elastic film 51 and the insulator film 52 may be omitted to omit the first electrode 60. Only may function as a diaphragm. When the first electrode 60 is provided directly on the substrate 10, it is preferable to protect the first electrode 60 with an insulating protective film or the like so that the ink does not come into contact with the first electrode 60.

A protective substrate 30 is bonded to the substrate 10 (diaphragm 50) on which the piezoelectric element 300 is formed by an adhesive 35. The protective substrate 30 has a manifold portion 32. The manifold portion 32 constitutes at least a part of the manifold 100. The manifold portion 32 of the present embodiment penetrates the protective substrate 30 in the thickness direction (Z direction), and is further formed in the width direction (+ X direction) of the pressure generating chamber 12. The manifold portion 32 communicates with the communication portion 15 of the substrate 10. With these configurations, a manifold 100 which is a common ink chamber of each pressure generating chamber 12 is configured.

The protective substrate 30 is formed with a piezoelectric element holding portion 31 in a region including the piezoelectric element 300. The piezoelectric element holding portion 31 has a space that does not hinder the movement of the piezoelectric element 300. This space may or may not be sealed. The protective substrate 30 is provided with a through hole 33 that penetrates the protective substrate 30 in the thickness direction (Z direction). The end of the lead electrode 90 is exposed in the through hole 33.

Examples of the material of the protective substrate 30 include Si, SOI, glass, ceramics, metal, resin, etc., but it is more preferable that the protective substrate 30 is made of a material having substantially the same coefficient of thermal expansion as the substrate 10. In this embodiment, it is formed by using Si which is the same material as the substrate 10.

A drive circuit 120 that functions as a signal processing unit is fixed on the protective substrate 30. As the drive circuit 120, for example, a circuit board or a semiconductor integrated circuit (IC: Integrated Circuit) can be used. The drive circuit 120 and the lead electrode 90 are electrically connected via a connection wiring 121 made of a conductive wire such as a bonding wire through which the through hole 33 is inserted. The drive circuit 120 can be electrically connected to the printer controller 200 (see FIG. 1). Such a drive circuit 120 functions as a control means for the piezoelectric actuator device (piezoelectric element 300).

Further, a compliance substrate 40 composed of a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. The sealing film 41 is made of a material having low rigidity, and the fixing plate 42 can be made of a hard material such as metal. The region of the fixing plate 42 facing the manifold 100 is an opening 43 completely removed in the thickness direction (Z direction). One surface of the manifold 100 (the surface on the + Z direction side) is sealed only with the flexible sealing film 41.

Such a recording head 1 ejects ink droplets by the following operation. First, ink is taken in from an ink introduction port connected to an external ink supply means (not shown), and the inside is filled with ink from the manifold 100 to the nozzle opening 21. Then, according to the recorded signal from the drive circuit 120, a voltage is applied between the first electrode 60 and the second electrode 80 corresponding to the pressure generating chamber 12, and the piezoelectric element 300 is flexed and deformed. As a result, the pressure in each pressure generating chamber 12 increases, and ink droplets are ejected from the nozzle opening 21.

(Piezoelectric actuator device)
Next, the configuration of the piezoelectric element 300 used as the piezoelectric actuator device of the recording head 1 will be described with reference to the drawings.
FIG. 5 is an enlarged cross-sectional view taken along the line BB'of FIG. As shown in the figure, in the piezoelectric element 300, a vibrating plate 50 composed of an elastic film 51 and an insulator film 52 is formed on a substrate 10 on which a pressure generating chamber 12 partitioned by a plurality of partition walls 11 is formed. On top of this, the adhesion layer 56, the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are sequentially laminated, and a movable portion is formed by these.

The piezoelectric layer 70 is a laminate composed of a plurality of piezoelectric films 74 (see FIG. 8), and the piezoelectric material constituting the piezoelectric layer 70 is a perovskite type structure (ABO ₃ type) _{represented by the general formula ABO 3.} It contains a composite oxide having a perovskite structure (perovskite type composite oxide). Of the plurality of piezoelectric films 74, the first piezoelectric film 74a formed directly above the first electrode 60 is preferentially oriented toward the (100) plane. In addition, it contains crystals of a perovskite-type composite oxide containing potassium (K), sodium (Na) and niobium (Nb), and the amount of Na contained in the A site of the _{ABO type 3 perovskite structure is larger than the amount of K.} It is formed to be.

The KNN-based composite oxide constituting the first piezoelectric film 74a is formed so that the amount of Na contained in the A site of _{the ABO type 3 perovskite structure is larger than the amount of K.} Specifically, it is preferable that the composition ratios of K and Na contained in the A site have a relationship represented by the following formula (3). In the following equation (3), X satisfies 0.5 <X ≦ 0.9.
(K _X , Na _1-X ) NbO ₃ ... (3)
In the above formula (3), it is preferable that the composition ratio of K and Na contained in the A site of the KNN composite oxide has a relationship represented by the following formula (1).
0.5 <Na / (Na + K) ≤ 0.9 ... (1)

That is, the content of Na is more than 50 mol% and 90 mol% or less with respect to the total amount of metal elements constituting A site (in other words, the content of K is the total amount of metal elements constituting A site. On the other hand, it is preferably 10 mol% or more and less than 50 mol%). According to this, it is possible to obtain a piezoelectric layer 70 containing a composite oxide having a composition that is preferentially oriented on the (100) plane and has excellent crystallinity and has a composition advantageous for piezoelectric properties.

The piezoelectric material constituting the first piezoelectric film 74a may be any KNN-based composite oxide, and is not limited to the composition represented by the above formula (3). For example, the A site and B site of potassium niobate sodium may contain other metal elements (additives). Examples of such additives include manganese (Mn), lithium (Li), barium (Ba), calcium (Ca), strontium (Sr), zirconium (Zr), titanium (Ti), bismuth (Bi), Examples thereof include tantalum (Ta), antimony (Sb), iron (Fe), cobalt (Co), silver (Ag), magnesium (Mg), zinc (Zn), copper (Cu) and the like.

One or more additives of this type may be contained. Generally, the amount of the additive is 20% or less, preferably 15% or less, more preferably 10% or less, based on the total amount of the main component elements. By using the additive, it becomes easy to improve various properties and diversify the composition and function, but it is preferable that KNN is present in an amount of 80% or more from the viewpoint of exhibiting the properties derived from KNN. Even in the case of a composite oxide containing these other elements, it is preferable that the _{composite oxide has an ABO type 3 perovskite structure.}

The alkali metals (K and Na) at the A site in the first piezoelectric film 74a may be added in excess to the composition of stoichiometry. Further, the alkali metal of A site may be insufficient for the composition of stoichiometry. Therefore, the KNN-based composite oxide contained in the first piezoelectric film 74a can also be represented by the following formula (4). In the following equation (4), X satisfies 0.5 <X ≦ 0.9.
(K _αX , Na _{α (1-X)} ) NbO ₃ ... (4)

In the above formula (4), α represents the amount of K and Na that may be added in excess or the amount of K and Na that may be insufficient. When the amounts of K and Na are excessive, 1.0 <α. When the amounts of K and Na are insufficient, α <1.0. For example, if α = 1.1, it means that 110 mol% of K and Na are contained when the amount of K and Na in the composition of stoichiometry is 100 mol%. If α = 0.9, it means that 90 mol% of K and Na are contained when the amount of K and Na in the composition of stoichiometry is 100 mol%. When the alkali metal of A site is neither excessive nor insufficient with respect to the composition of stoichiometry, α = 1. From the viewpoint of orientation and crystallinity, 0.8 <α ≦ 1.4 is preferable.

In other words, in the formula (4), the molar ratio (A / B) of the A site (K + Na) to the B site (Nb) of the KNN-based composite oxide has a relationship represented by the following formula (2). Is preferable.
0.8 <A / B ≦ 1.4 ・ ・ ・ (2)

Piezoelectric materials also include materials having a composition in which some of the elements are missing, materials having a composition in which some of the elements are in excess, and materials having a composition in which some of the elements are replaced with other elements. .. As long as the basic characteristics of the piezoelectric layer 70 do not change, a material deviating from the composition of stoichiometry due to deficiency or excess, or a material in which a part of an element is replaced with another element is also a piezoelectric material according to the present embodiment. Included in the material.

As used herein, "K, composite oxides of ABO ₃ type perovskite structure containing Na and Nb," A, K, is not limited only to the composite oxide ABO ₃ type perovskite structure containing Na and Nb. That is, this composite oxide is a composite oxide having an ABO _{type 3} perovskite structure containing K, Na and Nb (for example, the KNN-based composite oxide exemplified above) and another composite oxide having _{an ABO type 3 perovskite structure.} Includes piezoelectric materials represented as mixed crystals containing substances.

Other composite oxides are not particularly limited, but are preferably lead-free piezoelectric materials containing no Pb from the viewpoint of reducing the environmental load. For example, bismuth iron acid containing bismuth (Bi) and iron (Fe) (bismuth iron acid (Fe)). BFO) -based composite oxide, bismuth iron acid containing Bi, barium (Ba), Fe and Ti-Bismuth titanate (BF-BT) -based composite oxide, iron containing Bi, Fe, Mn, Ba and Ti A perovskite-type composite oxide such as a bismuth bismuth-valium titanate (BFM-BT) -based composite oxide can be used. The other composite oxide may be a lead-free piezoelectric material that does not contain Pb and Bi depending on the intended use. According to these, the piezoelectric element 300 has excellent biocompatibility and has a small environmental load.

Other composite oxides include lead zirconate titanate (PZT) containing Pb, zirconate (Zr) and Ti, and metal oxides such as niobium oxide, nickel oxide and magnesium oxide added to this PZT. Etc. can be used, such as lead titanate (PbTiO ₃ ), lead zirconate (PbZrO ₃ ), lead lanthanate titanate ((Pb, La), TiO ₃ ), lead lanthanate titanate titanate ((Pb, La)). (Zr, Ti) O ₃ ), lead zirconate titanate magnesiumniobate (Pb (Zr, Ti) (Mg, Nb) O ₃ ) and the like can be used.

The first piezoelectric film 74a constituting the piezoelectric layer 70 contains the above-mentioned KNN-based composite oxide. Specifically, the first piezoelectric film 74a is heat-treated by removing unnecessary substances such as a solvent from the KNN crystal (precursor solution of KNN-based composite oxide) preferentially oriented to the crystal plane of (100) by crystallization. It is a KNN film composed of (crystallized by).

In the present specification, the preferential orientation means that 50% or more, preferably 80% or more of the crystals are oriented to a predetermined crystal plane. For example, "priority oriented to the (100) plane" means that all the crystals of the piezoelectric layer 70 are oriented to the (100) plane, and more than half of the crystals (50% or more, preferably 80%). The above) includes the case where the plane (100) is oriented.

Further, the first piezoelectric film 74a in which the KNN crystal is preferentially oriented with respect to the (100) plane is a half of the peak derived from the (100) plane in the crystal of the perovskite type composite oxide measured by the X-ray diffraction method. The price range is 0.55 ° or less. According to this, it is possible to obtain the piezoelectric element 300 having the piezoelectric layer 70 containing the perovskite type composite oxide having excellent displacement characteristics.

Generally, when controlling the orientation of the piezoelectric crystals constituting the piezoelectric layer, the orientation control layer (also referred to as a buffer layer) is located between the first electrode and the piezoelectric layer, for example, on the adhesion layer. It is preferable to provide. By providing the orientation control layer, the piezoelectric material constituting the piezoelectric layer can be preferentially oriented in a predetermined plane orientation, for example, the (100) plane.

On the other hand, when a KNN film in which the KNN crystal is not preferentially oriented with respect to the (100) plane is used as the buffer layer, or depending on the manufacturing method of the KNN film, random orientation, or the (110) plane or the (111) plane may be used. In some cases, it is preferentially oriented in the plane orientation of.

However, in the present embodiment, the amount of Na and the amount of K contained in the A site of the KNN-based composite oxide contained in the first piezoelectric film 74a among the plurality of piezoelectric films 74 constituting the piezoelectric layer 70 are set as described above. By defining it as the formula (1), it becomes a KNN-based composite oxide that is preferentially oriented to the (100) plane and has excellent crystallinity (the orientation is good), and has a composition advantageous for piezoelectric characteristics. A piezoelectric layer 70 containing the composite oxide having the same can be obtained. That is, as long as the amount of Na and the amount of K contained in the A site of the KNN-based composite oxide are specified as in the above formula (1), the buffer layer is formed when the piezoelectric layer 70 is formed by the KNN-based composite oxide. It does not have to be provided.

Further, a KNN-based composite oxide is used as the piezoelectric material constituting the first piezoelectric film 74a, and a perovskite-type composite other than the KNN-based composite oxide is used as the piezoelectric material constituting the plurality of piezoelectric film 74 formed on the upper layer thereof. Oxides can also be used. The perovskite-type composite oxide other than the KNN-based composite oxide may be the lead-free piezoelectric material or the lead-based piezoelectric material described above. In this case, the first piezoelectric film 74a using the KNN-based composite oxide in which the amount of Na and the amount of K contained in the A site are defined as in the above formula (1) functions as a buffer layer. This makes it possible to form a plurality of piezoelectric films 74 containing a perovskite-type composite oxide having excellent crystal orientation and regularity.

Further, by using the first piezoelectric film 74a in which the amount of Na and the amount of K are defined as in the above formula (1) as the orientation control layer, it is easy to preferentially orient the planes (110) and (111), for example. Even if a plurality of layers of the piezoelectric film 74 containing the piezoelectric material are formed to obtain the piezoelectric layer 70, the plane orientation of the crystal is likely to be preferentially oriented in the (100) direction. For example, by using this first piezoelectric film 74a as an orientation control layer, it is difficult to preferentially orient the crystal plane of (100) without this orientation control layer, such as potassium niobate (KNbO ₃ ) and titanoic acid. Bismuth sodium ((Bi _0.5 , Na _0.5 ) TiO ₃ ), bismuth iron acid (BiFeO ₃ ) and the like can be oriented.
The piezoelectric layer 70, which is excellent in crystal orientation and crystallinity, has an advantage that various properties can be easily improved as compared with a piezoelectric layer which is randomly oriented or preferentially oriented to another crystal plane.

In the piezoelectric element 300, the thickness of the elastic film 51 is 0.1 μm or more and 2.0 μm or less, the thickness of the insulator film 52 is 0.01 μm or more and 1.0 μm or less, and the thickness of the adhesion layer 56 is 0.005 μm. The thickness of the first electrode 60 is 0.01 μm or more and 1.0 μm or less, the thickness of the piezoelectric layer 70 is 0.1 μm or more and 3.0 μm or less, and the thickness of the second electrode 80 is 0.1 μm or less. Is preferably 0.01 μm or more and 1.0 μm or less. When the first piezoelectric film 74a is formed as the buffer layer, the thickness of the buffer layer is set to 0.20 μm or less, preferably 0.01 μm or more and 0.10 μm or less. The thickness of each element listed here is an example, and can be changed without changing the gist of the present invention.

The materials of the first electrode 60 and the second electrode 80 may be any electrode material that does not oxidize when forming the piezoelectric element 300 and can maintain conductivity. Such materials include, for example, metal materials such as platinum (Pt), iridium (Ir), gold (Au), aluminum (Al), copper (Cu), Ti, silver (Ag), stainless steel; iridium oxide. _(IrO X), indium tin oxide (ITO), fluorine-doped tin oxide-based conductive material such as tin oxide (FTO), zinc oxide-based conductive material such as gallium-doped zinc oxide (GZO), strontium ruthenate (SrRuO _3), Oxide conductive materials such as lanthanum nickate (LaNiO ₃ ) and element-doped strontium ruthenate; conductive polymers and the like can be mentioned. As the electrode material, any of the above materials may be used alone, or a laminate in which a plurality of materials are laminated may be used. The electrode material of the first electrode 60 and the electrode material of the second electrode 80 may be the same or different.

(Manufacturing method of piezoelectric element)
Next, an example of the manufacturing method of the piezoelectric element 300 will be described together with the manufacturing method of the recording head 1 with reference to the drawings. 6 to 12 are cross-sectional views illustrating a manufacturing example of an inkjet recording head.

First, as shown in FIG. 6, a Si single crystal substrate is prepared as the substrate 10. Next, the substrate 10 is thermally oxidized to form an elastic film 51 made _{of SiO 2 on its surface.} Further, a zirconium film is formed on the elastic film 51 by a sputtering method, a vapor deposition method, or the like, and the zirconium film is thermally oxidized to obtain an insulator film 52 _{made of ZrO 2.} In this way, the diaphragm 50 composed of the elastic film 51 and the insulator film 52 is formed on the substrate 10. Next, the adhesion layer 56 made of _{TiO X} is formed on the insulator film 52. The adhesion layer 56 can be formed by a sputtering method, thermal oxidation of a Ti film, or the like. Next, the first electrode 60 made of Pt is formed on the close contact layer 56. The first electrode 60 can be appropriately selected depending on the electrode material, for example, vapor deposition such as sputtering method, vacuum vapor deposition method (PVD method), laser ablation method, liquid phase deposition such as spin coating method, etc. Can be formed by

Next, as shown in FIG. 7, a resist (not shown) having a predetermined shape is formed on the first electrode 60 as a mask, and the adhesion layer 56 and the first electrode 60 are simultaneously patterned. The patterning of the adhesion layer 56 and the first electrode 60 can be performed by, for example, dry etching such as reactive ion etching (RIE) or ion milling, or wet etching using an etching solution. The shape of the close contact layer 56 and the first electrode 60 in patterning is not particularly limited.

Next, as shown in FIG. 8, a first piezoelectric film 74a is formed on the first electrode 60, and a plurality of piezoelectric films 74 are formed on the first piezoelectric film 74a. The piezoelectric layer 70 is composed of a first piezoelectric film 74a and a plurality of layers of piezoelectric film 74. The piezoelectric layer 70 can be formed, for example, by a chemical solution method (wet method) in which a solution containing a metal complex (precursor solution) is applied, dried, and then calcined at a high temperature to obtain a metal oxide. In addition, it can also be formed by a laser ablation method, a sputtering method, a pulse laser deposition method (PLD method), a CVD (Chemical Vapor Deposition) method, an aerosol deposition method, or the like. In the present embodiment, the wet method (liquid phase method) is used from the viewpoint of orienting the plane orientation of the piezoelectric layer 70 in the (100) direction.

Here, the wet method (liquid phase method) is a method of forming a film by a chemical solution method such as a MOD method or a sol-gel method, and is a concept distinguished from a gas phase method such as a sputtering method. In the present embodiment, the vapor phase method may be used as long as the piezoelectric layer 70 having a plane orientation oriented in the (100) direction can be formed.

For example, the piezoelectric layer 70 formed by the wet method (liquid phase method) will be described in detail later, but is a step of applying a precursor solution to form a precursor film (coating step) and drying the precursor film. The first formed by a series of steps from a step (drying step), a step of heating and degreasing the dried precursor film (degreasing step), and a step of firing the degreased precursor film (firing step). It has a piezoelectric film 74a and a plurality of layers of piezoelectric film 74. That is, the piezoelectric layer 70 is formed by repeating a series of steps from the coating step to the firing step a plurality of times. In the series of steps described above, the firing step may be carried out after repeating the steps from the coating step to the degreasing step a plurality of times.

The layer or film formed by the wet method has an interface. Evidence of coating or firing remains on the layer or film formed by the wet method, and such evidence is used for observing the cross section or analyzing the concentration distribution of elements in the layer (or in the film). This makes it a identifiable interface. Strictly speaking, the interface means the boundary between layers or films, but here, it means the vicinity of the boundary between layers or films. When the cross section of the layer or film formed by the wet method is observed with an electron microscope or the like, such an interface is a darker part than others or a color more than others near the boundary with the adjacent layer or film. Is confirmed as a thin part. In addition, when analyzing the element concentration distribution, such an interface is confirmed as a part where the element concentration is higher than others or a part where the element concentration is lower than others near the boundary with the adjacent layer or film. Will be done. The piezoelectric layer 70 is formed by repeating a series of steps from the coating step to the firing step a plurality of times, or by repeating the firing step after repeating the coating step to the degreasing step a plurality of times (the first piezoelectric layer 70). Since it is composed of the film 74a and the piezoelectric film 74 having a plurality of layers), it has a plurality of interfaces corresponding to the first piezoelectric film 74a and each piezoelectric film 74.

An example of a specific procedure when the piezoelectric layer 70 is formed by a wet method is as follows. First, each of the MOD solution and the sol containing the metal complex is prepared, and the precursor solution for forming the piezoelectric layer 70 is prepared (adjustment step). Then, the precursor solution of the piezoelectric layer 70 is applied onto the patterned first electrode 60 by a spin coating method or the like to form a precursor film (coating step). Next, the precursor membrane is heated to a predetermined temperature, for example, 130 ° C. to 250 ° C. and dried for a certain period of time (drying step), and the dried precursor membrane is further heated to a predetermined temperature, for example, 300 ° C. to 450 ° C. It is degreased by holding it for a certain period of time (defatting step). Further, the degreased precursor film is heated to a higher temperature, for example, 500 ° C. to 800 ° C. and held at this temperature for a certain period of time to crystallize and form the first piezoelectric film 74a (calcination step). After forming the first piezoelectric film 74a, the coating step, the drying step, the degreasing step, and the firing step are repeated a plurality of times to form the first piezoelectric film 74a and the plurality of layers of the piezoelectric film 74. The piezoelectric layer 70 is formed.

In each of the above-mentioned precursor solutions, a metal complex capable of forming a perovskite-type composite oxide by firing is dissolved or dispersed in an organic solvent, respectively. That is, the precursor solution of the piezoelectric layer 70 contains a predetermined element (K, Na and Nb in the first piezoelectric film 74a) as the central metal of the metal complex. At this time, a metal complex containing an element other than the predetermined element may be further mixed in the precursor solution of the piezoelectric layer 70.

As the metal complex containing the above-mentioned predetermined element, for example, an alkoxide, an organic acid salt, a β-diketone complex or the like can be used. In each of the above-mentioned precursor solutions, the mixing ratio of these metal complexes may be such that the predetermined elements contained in the perovskite-type composite oxide have a desired molar ratio.

For example, in the KNN-based composite oxide contained in the first piezoelectric film 74a, examples of the metal complex containing K include potassium 2-ethylhexanoate, potassium acetate and the like. Examples of the metal complex containing Na include sodium 2-ethylhexanoate, sodium acetate and the like. Examples of the metal complex containing Nb include niobium 2-ethylhexanoate and pentaethoxyniobium. When Mn is added as an additive, examples of the metal complex containing Mn include manganese 2-ethylhexanoate. At this time, two or more kinds of metal complexes may be used in combination. For example, potassium 2-ethylhexanoate and potassium acetate may be used in combination as the metal complex containing K.

Examples of the organic solvent used for preparing the precursor solution include propanol, butanol, pentanol, hexanol, octanol, ethylene glycol, propylene glycol, octane, decane, cyclohexane, xylene, toluene, tetrahydrofuran, acetic acid, octyl acid, 2 Examples thereof include -n-butoxyethanol, n-octane and the like, or a mixed solvent thereof.

The precursor solution may contain an additive that stabilizes the dispersion of each metal complex. Examples of such an additive include 2-ethylhexanoic acid and diethanolamine.
Examples of the heating device used in the drying step, the degreasing step, and the firing step include an RTA (Rapid Thermal Annealing) device that heats by irradiation with an infrared lamp, a hot plate, and the like.

Next, as shown in FIG. 9, the piezoelectric layer 70 is patterned. Patterning can be performed by dry etching such as reactive ion etching or ion milling, or wet etching using an etching solution. The shape of the piezoelectric layer 70 in patterning is not particularly limited. Then, the second electrode 80 is formed on the patterned piezoelectric layer 70. The second electrode 80 can be formed by the same method as that of the first electrode 60.

Before and after forming the second electrode 80 on the piezoelectric layer 70, reheating treatment (post-annealing) may be performed in a temperature range of 600 ° C. to 800 ° C., if necessary. By performing post-annealing in this way, a good interface between the adhesion layer 56 and the first electrode 60, the first electrode 60 and the piezoelectric layer 70, and the piezoelectric layer 70 and the second electrode 80 is formed, respectively. And the crystallinity of the piezoelectric layer 70 can be improved.

In the present embodiment, the piezoelectric material of the first piezoelectric film 74a contains an alkali metal (K or Na). The alkali metal tends to diffuse into the first electrode 60 in the above firing step. If the alkali metal passes through the first electrode 60 and reaches the substrate 10, it will react with the substrate 10. However, in the present embodiment, the _{insulator film 52 made of the above ZrO 2} functions as a stopper for K and Na. Therefore, it is possible to prevent the alkali metal from reaching the substrate 10 which is a Si substrate.

Next, although not shown, the lead electrode 90 is formed and patterned into a predetermined shape (see FIG. 4).
Next, as shown in FIG. 10, on the piezoelectric element 300 side of the wafer for the flow path forming substrate (not shown), a wafer for a protective substrate (not shown) which is a silicon wafer and becomes a plurality of protective substrates 30 is attached to the adhesive 35 (FIG. 4). After joining through (see), the wafer for the flow path forming substrate is thinned to a predetermined thickness.

Next, as shown in FIG. 11, a mask film 53 is newly formed on the wafer for the flow path forming substrate, and the mask film 53 is patterned into a predetermined shape. Then, as shown in FIG. 12, the pressure corresponding to the piezoelectric element 300 is obtained by anisotropically etching (wet etching) the wafer for the flow path forming substrate via the mask film 53 using an alkaline solution such as KOH. The generation chamber 12, the ink supply path 13, the communication passage 14, the communication portion 15, and the like (see FIG. 4) are formed.

After that, the unnecessary portion of the outer peripheral edge portion of the flow path forming substrate wafer and the protective substrate wafer is removed by cutting, for example, by dicing or the like. Then, the nozzle plate 20 having the nozzle opening 21 formed on the surface of the flow path forming substrate wafer opposite to the protective substrate wafer is joined, and the compliance substrate 40 is joined to the protective substrate wafer to join the flow path. By dividing the wafer for forming substrate and the like into a substrate 10 and the like having one chip size as shown in FIG. 2, the inkjet recording head (recording head 1) of the present embodiment is obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to the following examples.
(Manufacturing of sample 1)
_{First, a SiO 2} film (elastic film 51) was formed on the surface of the 6-inch (100) -plane Si single crystal substrate (substrate 10) by thermal oxidation. The Zr film is formed on the elastic film 51 is deposited by sputtering, Zr film by thermal oxidation, the vibration plate 50 which forms the ZrO ₂ film (insulator film 52) made of an elastic film 51 and the insulating film 52 Was formed. Next, a Ti layer was formed on the insulator film 52 by a sputtering method, and the Ti layer was thermally oxidized to form a TiO _X layer (adhesion layer 56). Next, a Pt electrode film was formed on the adhesion layer 56 while heating at 450 ° C. by a sputtering method. Next, a predetermined photoresist pattern was prepared on the Pt electrode film, and the Pt electrode film and the adhesion layer 56 were patterned into a predetermined shape by ion milling to form a Pt electrode (first electrode 60).

Next, a precursor solution consisting of potassium 2-ethylhexanoate, sodium 2-ethylhexanoate and niobium 2-ethylhexanoate was prepared. By using this precursor solution, the KNN layer (piezoelectric layer 70) made of the KNN-based composite oxide described later has a composition ratio of K and Na in the first KNN film (first piezoelectric film 74a). And the composition ratio of K and Na of the second layer KNN film (piezoelectric film 74) are the compositions shown in Sample 1 of Table 1 below (K _0.8 , Na _0.2 ) NbO. _{It was 3} , and the A site ratio (A / B) was 1.

Next, the prepared precursor solution was applied by a spin coating method at 1500 rpm to 3000 rpm on a substrate 10 (hereinafter, simply referred to as “substrate 10”) on which the first electrode 60 was formed (application step). Next, the substrate 10 was placed on a hot plate and dried at 180 ° C. (drying step). Next, the substrate 10 was degreased on a hot plate at 380 ° C. (degreasing step). Next, a heat treatment was performed at 600 ° C. for 3 minutes using an RTA apparatus (firing step). Then, the first piezoelectric film 74a was formed.

Next, one layer of the piezoelectric film 74 is formed by performing such a coating step to a firing step once, and a KNN layer (piezoelectric layer) having a thickness of 160 nm composed of a total of two piezoelectric films is formed. 70) was formed, and this was used as sample 1.

(Manufacturing of samples 2-9)
The piezoelectric layer 70 was formed in the same manner as in Sample 1 except that the precursor solution was adjusted so that the composition of the KNN-based composite oxide constituting the piezoelectric layer 70 was as shown in Table 1 below. Samples 2 to 9 were used, respectively. In sample 8, the piezoelectric layer 70 is composed of an NN layer made of _{NaNbO 3} (NN), and in sample 9, the piezoelectric layer 70 is made up of a KN layer made of _{KNbO 3 (KN).}

(Manufacturing of samples 10 to 15)
Samples 10 to 15 in which the Na ratio of sample 5 (Na / (Na + K) = 0.6) having the highest intensity was fixed and the A site ratio (A / B) was changed were prepared. In samples 10 to 15, A> 1 when the amount of K and Na is excessive, and A <1 when the amount of K and Na is insufficient. The piezoelectric layer 70 was formed in the same manner as in Sample 1 except that the precursor solution was adjusted so that the composition of the KNN-based composite oxide constituting the piezoelectric layer 70 was as shown in Table 2 below. Samples 10 to 15 were used, respectively.

(Manufacturing of samples 16 to 21)
The Na ratio of sample 6 (Na / (Na + K) = 0.8) was fixed to prepare samples 16 to 21 in which the A site ratio (A / B) was changed. The piezoelectric layer 70 was formed in the same manner as in Sample 1 except that the precursor solution was adjusted so that the composition of the KNN-based composite oxide constituting the piezoelectric layer 70 was as shown in Table 3 below. Samples 16 to 21 were used, respectively.

(Manufacturing of sample 22)
The KNN-based composite oxide constituting the piezoelectric layer 70 has a composition ratio of K, Na and Mn of the first piezoelectric film 74a and a composition ratio of K, Na and Mn of the second piezoelectric film 74. There is a composition as shown in table _{4 (K 0.4, Na 0.6)} (Nb 0.995 Mn 0.005) except that by adjusting the precursor solution to a _{O 3} sample The piezoelectric layer 70 was formed in the same manner as in 1, and used as sample 22.

(Manufacturing of sample 23)
The composition ratio of K and Na in the first piezoelectric film 74a in the KNN-based composite oxide constituting the piezoelectric layer 70 is as shown in Table 4 below (K _0.4 , Na _0.6 ). Piezoelectricity is the same as in sample 1 except that the precursor solution is adjusted to NbO _{3 and the precursor solution for NaNbO 3} (NN) is prepared to form the second layer piezoelectric film 74. A body layer 70 was formed and used as sample 23.

(Manufacturing of sample 24)
The composition ratio of K and Na in the first piezoelectric film 74a in the KNN-based composite oxide constituting the piezoelectric layer 70 is as shown in Table 4 below (K _0.4 , Na _0.6 ). The _{precursor solution is adjusted to NbO 3,} and the precursor solution for (Bi _0.5 , Na _0.5 ) TiO ₃ (BNT) is further prepared to form the second layer piezoelectric film 74. The piezoelectric layer 70 was formed in the same manner as in Sample 1 except for the above, and used as Sample 24.

(Manufacturing of sample 25)
The composition ratio of K and Na in the first piezoelectric film 74a in the KNN-based composite oxide constituting the piezoelectric layer 70 is as shown in Table 4 below (K _0.4 , Na _0.6 ). Piezoelectricity is the same as in sample 1 except that the precursor solution is adjusted to NbO _{3 and the precursor solution for BiFeO 3} (BF) is prepared to form the second layer piezoelectric film 74. A body layer 70 was formed and used as a sample 25.

(XRD measurement)
For samples 1 to 25, the X-ray diffraction pattern of the piezoelectric layer 70 was measured at room temperature by the X-ray diffraction (XRD) method using "D8 Discovery" manufactured by Bruker AXS Co., Ltd. I went there. In this measurement, the radiation source was CuKα, the X-ray collimator was 0.1 mmφ, and the detector was a two-dimensional detector (GADDS). The tube voltage and tube current at the time of measurement were set to 50 kV and 100 mA, respectively. The measurement conditions were ω as 10, 2θ as 35, and the integration time as 120 seconds. Using the two-dimensional measurement results obtained here as a one-dimensional diffraction pattern with an integration range of 2θ = 20 to 50 and χ = -95 to -85, the diffraction intensity (peak intensity) (Counts) and full width at half maximum (°) are calculated. bottom.

Generally, in the X-ray diffraction pattern of the KNN layer (piezoelectric layer 70), a peak derived from the (100) plane is observed in the vicinity of 2θ of 22.5 °, and a peak derived from the (110) plane is observed in the vicinity of 32.0 °. Will be done. In Samples 1 to 7, Samples 11 to 15, and Samples 17 to 25, a peak was observed in the vicinity of 22.5 ° for 2θ, and no peak was observed in the vicinity of 32.0 °. As a result, it was found that the piezoelectric layers 70 of Samples 1 to 7, Samples 11 to 15, and Samples 17 to 25 were preferentially oriented toward the (100) plane. In addition, the intensity (Counts) and full width at half maximum (°) of the peak derived from the (100) plane of each sample were calculated and shown in Tables 1 to 4. Since no peak derived from the (100) plane was observed in Samples 8 to 10 and Sample 16, the intensity became 0 and the full width at half maximum could not be calculated.

Further, based on Tables 1 to 3, the relationship between the composition ratio, the full width at half maximum and the peak intensity in each sample was graphed. FIG. 13 is a graph showing the relationship between the Na ratio, the full width at half maximum and the intensity of samples 1 to 9, and FIG. 14 is a graph showing the relationship between the A site ratio, the full width at half maximum and the intensity of samples 10 to 15. FIG. 15 is a graph showing the relationship between the A-site ratio, the full width at half maximum and the intensity of the samples 16 to 21.

As shown in Tables 1 to 4 and FIGS. 13 to 15, the composition ratio of potassium and sodium contained in the A site of the KNN-based composite oxide constituting the first piezoelectric film 74a is 0.5 <Na / (Na + K). ) ≤ 0.9, it was confirmed that the samples 4 to 7 had a large peak intensity (Counts) derived from the (100) plane and a half width (°) of 0.55 ° or less. rice field. That is, by adjusting the composition ratio of potassium and sodium of the KNN-based composite oxide constituting the piezoelectric layer 70 and the molar ratio (A / B) of A-site to B-site within a predetermined range, KNN-based composite oxidation It has been clarified that the piezoelectric layer 70, in which the material is preferentially oriented to the (100) plane and has excellent crystallinity, can be obtained.

In addition to the above, Samples 11 to 15 and Samples 17 to 17 in which the molar ratio (A / B) of the A site to the B site of the KNN-based composite oxide is in the range of 0.8 <A / B ≦ 1.4. 21, sample 22 containing 10 mol% or less of Mn as an additive, and samples 23 to 25 in which the second layer piezoelectric film 74 is a perovskite-type composite oxide other than the KNN-based composite oxide are also various. It was confirmed that the composite oxide was excellent in orientation and crystallinity.

Although not shown in Examples, a first piezoelectric film 74a is formed as in Samples 4 to 7, Samples 11 to 15 and Samples 17 to 25, and a plurality of piezoelectric films 74 are formed on the upper layer thereof. Therefore, even if the thickness of the piezoelectric layer 70 is set to, for example, 0.1 μm or more and 3.0 μm or less, the excellent orientation and crystallinity of various composite oxides can be maintained.

On the other hand, in Samples 1 to 3, Samples 8 to 10 and Sample 16 which do not meet the above conditions, the piezoelectric layer 70 in which the KNN-based composite oxide is not preferentially oriented on the (100) plane, or the regularity (orientation) of the crystals thereof. The piezoelectric layer 70 was inferior in orientation).

(Other embodiments)
In the above embodiment, the liquid injection head mounted on the liquid injection device has been described as an example of the piezoelectric element application device, but the scope of application of the present invention is not limited to this. Further, although the inkjet recording head has been described as an example of the liquid injection head, the present invention can of course be applied to a liquid injection head that injects a liquid other than ink. Examples of the liquid injection head for injecting a liquid other than ink include a color material injection head used for manufacturing a color filter such as a liquid crystal display, and an organic EL material injection used for forming a light emitting layer and a charge transport layer of an organic EL display. Head, electrode material injection head that forms an electrode pattern by drawing the electrode pre-drive body solution, curing material injection head that performs three-dimensional arbitrary modeling (3D printing) by repeating material injection and material curing by light or heat Examples thereof include a piezoelectric material injection head that forms an arbitrary piezoelectric element pattern by drawing a piezoelectric material precursor solution and heat treatment, a bioorganic substance injection head used for manufacturing a biochip, and the like.

Since the piezoelectric element and the piezoelectric element application device of the present invention have high piezoelectric characteristics, they can be suitably used for piezoelectric actuators. Specific examples of the piezoelectric actuator device include an ultrasonic transmitter, an ultrasonic motor, a vibration dust removing device, a piezoelectric transformer, a piezoelectric speaker, a piezoelectric pump, a temperature-electric converter, and a pressure-electric converter. ..

Since the piezoelectric element and the piezoelectric element application device of the present invention have high piezoelectric performance, they can be suitably used for piezoelectric sensor elements. Specific sensor elements include, for example, an ultrasonic detector (ultrasonic sensor), an angular velocity sensor (gyro sensor), an acceleration sensor, a vibration sensor, a tilt sensor, a pressure sensor, a collision sensor, a human sensor, an infrared sensor, and terahertz. Examples include sensors, heat detection sensors (heat sensitive sensors), charcoal sensors, piezoelectric sensors, and the like. In addition, it may be applied to a filter such as a filter for blocking harmful rays such as infrared rays, an optical filter using a photonic crystal effect by forming quantum dots, and an optical filter using light interference of a thin film.

In an ultrasonic measuring device equipped with an ultrasonic sensor, for example, at least the piezoelectric element of the present invention, the ultrasonic waves transmitted by the piezoelectric element of the present invention, and the ultrasonic waves received by the piezoelectric element of the present invention. An ultrasonic measuring device can also be configured by providing a control means for measuring a detection target using a signal based on one of them. Such an ultrasonic measuring device is based on the time from the time when the ultrasonic wave is transmitted to the time when the transmitted ultrasonic wave is reflected by the measurement object and receives the echo signal returned. A piezoelectric element may be used as an element for generating ultrasonic waves or an element for detecting an echo signal, which obtains information on a position, a shape, a speed, and the like. As such an ultrasonic wave generating element or an echo signal detecting element, it is possible to provide an ultrasonic wave measuring device having excellent displacement characteristics.

Since the piezoelectric element and the piezoelectric element application device of the present invention have high ferroelectricity, they can be suitably used for ferroelectric elements. Specific examples of the ferroelectric element include a ferroelectric memory (FeRAM), a ferroelectric transistor (FeFET), a ferroelectric arithmetic circuit (FeLogic), and a ferroelectric capacitor.

Since the piezoelectric element and the piezoelectric element application device of the present invention can control the domain domain by voltage, they can be suitably used for voltage-controlled optical elements. Specific examples of the optical element include a wavelength converter, an optical waveguide, an optical path modulator, a refractive index control element, an electronic shutter mechanism, and the like.

Since the piezoelectric element and the piezoelectric element application device of the present invention exhibit good pyroelectric characteristics, they can be suitably used for pyroelectric elements, and are also applied to robots and the like using the above-mentioned various motors as drive sources. can do.

I ... Recording device, II ... Head unit, S ... Recording sheet, 1 ... Recording head, 2A, 2B ... Cartridge, 3 ... Carriage, 4 ... Device body, 5 ... Carriage shaft, 6 ... Drive motor, 7 ... Timing belt, 8 ... Conveying roller, 10 ... Substrate, 11 ... Partition, 12 ... Pressure generating chamber, 13 ... Ink supply path, 14 ... Communication passage, 15 ... Communication part, 20 ... Nozzle plate, 21 ... Nozzle opening, 30 ... Protective substrate, 31 ... Piezoelectric element holding part, 32 ... Manifold part, 33 ... Through hole, 35 ... Adhesive, 40 ... Compliance substrate, 41 ... Sealing film, 42 ... Fixing plate, 43 ... Opening, 50 ... Vibrating plate, 51 ... Elastic film, 52 ... Insulator film, 53 ... Mask film, 56 ... Adhesive layer, 60 ... First electrode, 70 ... Piezoelectric layer, 74 ... Piezoelectric film, 74a ... First piezoelectric film, 80 ... Second Electrode, 90 ... Lead electrode, 100 ... Manifold, 120 ... Drive circuit, 121 ... Connection wiring, 200 ... Printer controller, 300 ... Piezoelectric element

Claims (5)

With the first electrode
With the second electrode
A piezoelectric element sandwiched between the first electrode and the second electrode and having a piezoelectric layer which is a laminate of a plurality of piezoelectric films containing crystals of a perovskite-type composite oxide represented by the general formula ABO3. And
Of the plurality of piezoelectric films, the first piezoelectric film formed immediately above the first electrode is (1).
00) It has a perovskite-type composite oxide that is preferentially oriented to the plane and contains potassium, sodium, and niobium, and the amount of sodium contained in the A site of the perovskite-type composite oxide is larger than the amount of potassium.
Of the plurality of piezoelectric films, the second piezoelectric film formed on the first piezoelectric film is (
100) Perovskite type that is preferentially oriented to the surface and contains bismuth, sodium, and titanium.
A piezoelectric element having a composite oxide. The first piezoelectric film is characterized in that the composition ratio of potassium (K) and sodium (Na) contained in the A site of the perovskite-type composite oxide has a relationship represented by the following formula (1). The piezoelectric element according to claim 1.
0.5 <Na / (Na + K) ≤ 0.9 ... (1) Claim 1 is characterized in that the first piezoelectric film has a relationship in which the molar ratio (A / B) of A sites to B sites of the perovskite-type composite oxide is represented by the following formula (2). Alternatively, the piezoelectric element according to claim 2.
0.8 <A / B ≦ 1.4 ・ ・ ・ (2) The first piezoelectric film is characterized in that the half-value width of the peak derived from the (100) plane in the crystal of the perovskite type composite oxide measured by the X-ray diffractometry is 0.55 ° or less. The piezoelectric element according to any one of items 1 to 3. A piezoelectric element application device comprising the piezoelectric element according to any one of claims 1 to 4.

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