JPH0751460B2 - Piezoelectric composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric ceramic composition.
The present invention relates to a piezoelectric ceramic composition suitable for a voltage-driven piezoelectric displacement element that requires highly precise position control together with large mechanical displacement.

[Prior Art] In recent years, a voltage-driven piezoelectric displacement element (hereinafter referred to as a displacement element) that converts electric energy into mechanical energy by utilizing the electric strain effect of a piezoelectric ceramic as a drive source of a new method replacing the electromagnetic method The practical application of has been promoted in various fields such as minute position control devices. As this type of displacement element, for example, as shown in FIG. 2, one having a bimorph structure in which piezoelectric elastic plates 2 and 2'having electrodes attached to both sides of a metal elastic plate 1 are bonded together is used. Are known. When a DC or AC voltage is applied to this displacement element, the mechanical displacement dS ₁ or d due to the electrostriction effect (in this case, the piezoelectric lateral effect) is generated.
S ₂ occurs. Although this mechanical displacement depends on the application or the mechanism when it is mounted, it is generally desirable that it is as large as possible in terms of the function as a displacement element. − It is desirable that the displacement hysteresis is as small as possible. For example, regarding mechanical displacement, a piezoelectric device composition having a larger electrostrictive effect is considered to be advantageous. [Problems to be Solved by the Invention] Conventionally, a piezoelectric device composition of this type is, for example, a relatively piezoelectric constant. Large d ₃₁ Pb (Ni _1/3 Nb _2/3 ) O ₃ −PbrO ₃ −Pb
There are three-component systems such as TiO ₃ . However, with the conventional composition, although mechanical displacement can be obtained to some extent, the voltage-displacement hysteresis is large and the use as a displacement element is limited to a very narrow range. Therefore, there has been a demand for a piezoelectric ceramic material which can provide a larger mechanical displacement and has a smaller voltage-displacement hysteresis as a displacement element in order to be applied to a wide range of applications.

Therefore, the technical problem of the present invention is to sufficiently meet such requirements, and a piezoelectric ceramic composition which has a large electrostriction effect by voltage application and a small hysteresis, and which can be applied to a wide range of applications as a displacement element is provided. To provide.

[Means for Solving the Problems] The piezoelectric ceramic composition of the present invention has a general formula: Pb [Ni _1/3 Nb _2/3 ) _A (Zn _1/3 Nb _2/3 ) _B (Sb _1/2 Nb _{1 / 2} ) _C Zr _D Ti _E ] O ₃ (where A + B + C + D + E = 1) 0.300 ≦ A ≦ 0.550, 0.005 ≦ B ≦ 0.100, 0.002 ≦ C ≦ 0.050, 0.070 ≦ D ≦ 0.288, 0.230 ≦ E ≦ 0.405 , 0.02 to 0.5% by weight of at least one selected from NiO and Bi ₂ O ₃ as auxiliary components, and 0.005 to MnO of 0.005 to
It is characterized by containing 0.15% by weight.

In the present invention, 0.300> A, A> 0.550, B> 0.100, C> 0.05
0, 0.700> D, D> 0.288, 0.230> E, E> 0.405 and at least one selected from the sub-components NiO and Bi ₂ O _3.
The composition containing more than 0.5% by weight of MnO and more than 0.15% by weight of MnO has reduced electrostriction and mechanical displacement.
Not desirable as the target displacement element, and 0.005>
B, 0.002> C and a composition containing at least one selected from NiO and Bi ₂ O _{3 of} less than 0.02% by weight do not show a significant effect of improving electrostriction and mechanical displacement. MnO
If it is less than 0.005% by weight, no significant improvement effect on the hysteresis is recognized, so it was excluded from the scope of the present invention.

[Examples] Examples of the present invention will be described in detail below in comparison with reference examples.

PbO, NiO, Nb ₂ O ₅ , Zn with a chemical purity of 99% or more as a starting material
O, Sb ₂ O ₃ , ZrO ₂ , TiO ₂ and selected subcomponents are selected from Table 1 ~
The composition was precisely weighed so as to have the composition shown in Table 5. Next, these raw materials were mixed in a ball mill, dried, and calcined at 850 ° C. Then, an appropriate amount of an organic binder was added to the powder obtained by crushing with a ball mill to granulate, followed by pressure molding at a pressure of 1 ton / cm ² and firing at a temperature of 1200 to 1250 ° C for several hours. After cutting the obtained sintered body into a predetermined shape and polishing,
An electrode was applied, and a direct current electric field of 35 to 50 kV / cm was applied for 30 minutes in silicone oil at a temperature of 60 to 100 ° C, and polarization was applied to activate the voltage. Next, after obtaining various voltage constants by a predetermined measuring method, further polishing is performed to confirm the substantial effect, and rectangular piezoelectric elements of two types of shapes, namely, length 10 mm, width 2 mm, Thickness 1mm, length 35m
We obtained m, width 10 mm, and thickness 0.15 mm. A DC voltage of 500 V was applied to the shape of these two types of voltage elements in the same direction as the polarization direction, and the amount of electric strain (contraction strain) generated at that time was measured and evaluated by the Δl / l value (Δl ... Shrinkage, l ... element length),
On the other hand, the piezoelectric element of one shape was sandwiched from both sides with a metallic elastic plate to prepare a bimorph type displacement element as shown in FIG. 2, and mechanical displacement and hysteresis were investigated.

The mechanical displacement is determined by the displacement dS ₃₀ that occurs at the tip when one end is fixed and the other end is free when a DC voltage of 30 V is applied as shown in Fig. 1, while the hysteresis is the displacement dS at a voltage of 30 V.
_It was calculated from the residual displacement dS ₀ generated when the voltage was returned to 0 and _{30 by the} following formula.

Hysteresis = (dS ₀ / dS ₃₀ ) x 100 [%] Tables 1 to 5
The table shows an example of the results.

Incidentally, in Tables 1 to 5, sample numbers marked with * correspond to the piezoelectric ceramic composition of the present invention.

As is clear from Tables 1 to 5, the samples made of the piezoelectric ceramic composition of the present invention have a larger voltage distortion amount and a larger mechanical displacement than the reference examples of the respective composition groups, and the voltage- It is obvious that the displacement hysteresis is extremely small and it has suitable characteristics as a displacement element. Incidentally, the same effect as long as NiO by-component, Bi ₂ O ₃ added in a total content be co-added is in the range of 0.02 to 0.5 wt% is obtained At a present invention.

[Effects of the Invention] As described above, the present invention provides Pb [Ni _1/3 Nb _2/3 ) _A (Zn _1/3 Nb _2/3 ) _B
(Sb _1/2 Nb _1/2 ) _C Zr _D Ti _E ] O as the basic composition, A, B, C,
Set D and E in appropriate ranges, and use NiO and B as auxiliary components.
One kind of iO ₂ O ₃ and MnO are simultaneously added and contained in a proper range. Especially, Pb (Zn _1/3 Nb _2/3 ) O ₃ , Pb- in the basic composition is contained.
Due to the interaction between the (Sb _1/2 Nb _1/2 ) O ₃ component and the accessory component, a lower hysteresis was realized along with a larger amount of electric strain and mechanical displacement that could not be achieved with conventional compositions.

The piezoelectric ceramic composition of the present invention can be expected to be applied to the following uses.

(1) Since the voltage-displacement hysteresis is small together with the occurrence of a large mechanical displacement, it can be widely applied to a new displacement element field that requires highly accurate position control and the like.

(2) Since a large mechanical displacement is generated, it is possible to reduce the size and weight and drive at a low voltage, and it can be applied to the field of displacement elements that match the energy saving era.

(3) It can be applied to a displacement element that requires a large mechanical displacement at a relatively low voltage.

(4) It can be applied to a displacement element that requires a large mechanical displacement by adopting a one-sided driving method (applying only a DC voltage in the same direction as the polarization direction of the piezoelectric element).

In this case, the magnitude of the applied voltage can be freely selected according to the application.

(5) Since it has a relatively high piezoelectric constant (for example, piezoelectric d constant), it can be applied to various piezoelectric products that require a high voltage constant. In the embodiment of the present invention,
The amount of electrostriction, mechanical displacement and voltage-displacement hysteresis associated with the piezoelectric lateral effect have been explained with reference to a bimorph type piezoelectric displacement element, but the longitudinal effect of the piezoelectric is also investigated using the same composition, and its improvement effect is confirmed. Therefore, it is sufficiently applicable to, for example, a laminated piezoelectric displacement element.

As described above in detail, the piezoelectric ceramic composition of the present invention is suitable for a displacement element that can be used in a wide range of applications, and is extremely valuable in industry.

[Brief description of drawings]

FIG. 1 is a graph showing a measurement standard in an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a conventional bimorph type piezoelectric displacement element. In the figure, 1 ... Metal elastic plate, 2, 2 '... Piezoelectric ceramic plate.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C04B 35/00 J

Claims (1)

[Claims] 1. _A compound represented by the general formula Pb [Ni _1/3 Nb _2/3 ) _A (Zn _1/3 Nb _2/3 ) _B (Sb _1/2 Nb _1/2 ) _C Zr _D Ti _E ] O ₃ . (However, A + B + C + D + E = 1) 0.300 ≦ A ≦ 0.550, 0.005 ≦ B ≦ 0.100, 0.002 ≦ C ≦ 0.050, 0.070 ≦ D ≦ 0.288, 0.230 ≦ E ≦ 0.405 , 0.02 to 0.5% by weight of at least one selected from Bi ₂ O ₃ and 0.005 of MnO.
A piezoelectric ceramic composition characterized by containing 0.1 to 0.15% by weight.