1. The modified lead titanate-based high-temperature piezoelectric ceramic is characterized in that the chemical composition of the modified lead titanate-based high-temperature piezoelectric ceramic is 0.365BiScO₃-0.635Bi_xPb_1-3x/2Ti_0.99Zn_0.01O₃X represents the mole percentage of Bi, and x is more than or equal to 0 and less than or equal to 0.03; preferably, 0 < x.ltoreq.0.03.

2. The lead titanate-based high-temperature piezoelectric ceramic according to claim 1, wherein the modified lead titanate-based high-temperature piezoelectric ceramic has a room-temperature piezoelectric coefficient of 300 to 550pC/N, a Curie temperature of 300 to 500 ℃, a strain of 0.2 to 0.4%, and a remanent polarization of 40 to 50 μ C/cm²Depolarization temperature 350-450 ℃.

3. The preparation method of the modified lead titanate-based high-temperature piezoelectric ceramic according to claim 1 or 2, wherein the preparation method comprises: according to the chemical composition of modified lead titanate-based high-temperature piezoelectric ceramics, Bi is used₂O₃、Sc₂O₃、PbO、TiO₂And ZnO are used as raw materials, the raw materials are weighed according to the corresponding stoichiometric ratio and mixed, and the mixture is subjected to heat preservation and synthesis at the temperature of 600-900 ℃ for 2-4 hours to obtain ceramic powder; and sintering the ceramic powder at 1100-1200 ℃ for 1-3 hours to obtain the modified lead titanate-based high-temperature piezoelectric ceramic.

4. The method according to claim 3, wherein the ceramic powder has a particle size of 1 to 2 μm.

5. A preparation method according to claim 3 or 4, characterized in that the mixing manner is wet ball milling mixing, wherein the raw materials: ball milling medium: the mass ratio of water is 1: (1.2-1.8): (0.5-0.9) and the mixing time is 2-6 hours.

6. The production method according to any one of claims 3 to 5, characterized by further comprising: adding a binder into the ceramic powder for granulation before sintering, performing press molding and plastic removal to obtain a ceramic green body, and then sintering the ceramic green body; preferably, the addition amount of the binder is 4-8 wt.% of the ceramic powder; more preferably, the binder is polyvinyl alcohol.

7. The preparation method according to claim 6, wherein the plastic removal condition is heating to 600-800 ℃ at a heating rate of not more than 2 ℃/min and keeping the temperature for less than 3 hours.

8. The production method according to any one of claims 3 to 7, characterized by further comprising: and carrying out silver printing, drying and silver firing treatment on the modified lead titanate-based high-temperature piezoelectric ceramic, and then applying an electrode for polarization.

9. The preparation method according to claim 8, wherein the silver firing condition is that the temperature is maintained at 700-800 ℃ for less than 60 minutes; the polarization condition is that the polarization is carried out for 15-30 minutes at the temperature of 100-140 ℃ at 4-6 kV/mm.

10. The preparation method according to any one of claims 6 to 9, wherein the ceramic powder is subjected to fine grinding by wet ball milling and then dried before being granulated by adding a binder, wherein the ratio of the ceramic powder: ball milling medium: the mass ratio of water is 1: (1.2-1.8): (0.5-0.9) and the fine grinding time is 4-8 hours.

Background

The piezoelectric ceramic can couple electric energy and mechanical energy, is one of key functional materials in numerous components and parts, and is widely applied to the fields of electronic communication, medical equipment, aerospace and the like. The piezoelectric materials are divided into piezoelectric single crystals, piezoelectric ceramics, piezoelectric polymers and piezoelectric composite materials, wherein the piezoelectric ceramics occupy most market shares and have very wide prospects due to low cost, excellent piezoelectric performance, rich component adjustability and simple preparation process.

With the development of industry and science and technology, high-precision drivers, detection transducers and other piezoelectric devices working in high-temperature severe environments are needed in the fields of oil exploration, aerospace, automobiles and the like, so that the lead zirconate titanate ceramics with the use temperature below 300 ℃ cannot meet the high-temperature use requirements. BiScO with Curie temperature about 100 ℃ higher than that of lead zirconate titanate₃-PbTiO₃(BS-PT) high-temperature piezoelectric ceramics become the most competitive piezoelectric material with the use temperature of 200-400 ℃.

The method mainly reduces the material cost and regulates and controls the performance of the BS-PT high-temperature piezoelectric ceramic by means of a preparation process, single element doping, solid solution new elements and the like. The piezoelectric coefficient of the nano-scale BS-PT ceramic prepared by the two-step sintering method is improved to 520pC/N (J.Am.Ceram.Soc.2008; 91: 121-; replacing Sc with Nb (JAm Ceram Soc, 2007; 90:477- & lt482 >), Fe (Appl Phys Lett, 2005; 87:242901.), Co (Appl Phys Lett 2008; 92: 142905.); in BiScO₃-PbTiO₃Solid solution of Pb (In)_1/3Nb_2/3)O₃(Acta Mater 2019；181:238-248)、Bi(Mn_1/2Zr_1/2)O₃(JEur Ceram Soc,2020；40:3003-3010.)、PbZrO₃(ceramic int.2018; 44:6817-6822.) has a piezoelectric coefficient of more than 300pC/N and a Curie temperature of 130-317 ℃; BiScO disclosed in Chinese patent CN103936412A₃-xPbTiO₃-0.05Pb(Sn_1/3Nb_2/3)O₃The piezoelectric ceramic has high Curie temperature (400-420 ℃) and piezoelectric coefficient (370-560 pC/N) at the same time, but the remanent polarization is 30-42 mu C/cm²(Adv.Funct.Mater.2019；29:1807920)。

It is considered that the piezoelectric coefficient is influenced by intrinsic factors (crystal structure change) and extrinsic factors (ferroelectric domain motion, domain wall movement, etc.), the remanent polarization is mainly influenced by phase change due to lattice distortion, space charge change due to oxygen vacancies, etc., and the curie temperature is influenced by tolerance factors, phase structure, dislocations, etc. The mutual balance and interaction between these influencing factors makes it difficult to maximize all three simultaneously in ceramics of the same composition. However, the piezoelectric ceramics can be subjected to the comprehensive action of multi-field coupling such as temperature, electric field, force field and the like in the actual service process, and the performance advantage of only a single aspect is far from sufficient. Therefore, the search for high-temperature piezoelectric ceramics having excellent overall performance is an urgent problem to be solved.

Disclosure of Invention

Aiming at the condition that the Curie temperature and the comprehensive electrical property of the conventional piezoelectric ceramic cannot meet specific indexes at the same time, the invention provides the modified lead titanate-based high-temperature piezoelectric ceramic with high piezoelectric coefficient, high Curie temperature, high remanent polarization and high depolarization temperature and the preparation method thereof.

In a first aspect, the invention provides a modified lead titanate-based high-temperature piezoelectric ceramic. The chemical composition of the modified lead titanate-based high-temperature piezoelectric ceramic is 0.365BiScO₃-0.635Bi_xPb_1-3x/2Ti_0.99Zn_0.01O₃(BS-BPZT), x represents the molar percentage of Bi, and x is more than or equal to 0 and less than or equal to 0.03. The lead titanate-based high-temperature piezoelectric ceramic takes BS-PT ceramic which is in a partial three-side phase and is near a Morphotropic Phase Boundary (MPB) as a substrate, and adopts an A, B-site co-doping strategy to enhance the performance adjustability: the Zn with ferroelectric activity and capable of enhancing the tetragonal phase of the ceramic replaces the titanium at the B site in an oxygen octahedron in a perovskite structure, the Bi with the tetragonal phase replaces the Pb at the A site in the lead titanate with high price, so that a homomorphic phase boundary with the coexistence of the trigonal phase and the tetragonal phase is obtained, and the piezoelectric, ferroelectric and dielectric properties are improved. In addition, the microstructure is regulated by regulating the Bi content, so that the piezoelectricity of the piezoelectric ceramic with the lead titanate-based perovskite structure is effectively improved, the ferroelectricity of the piezoelectric ceramic is synergistically optimized, and a new thought is provided for the application of the piezoelectric ceramic with the lead titanate-based perovskite structure in a high-temperature piezoelectric sensor.

Wherein, x is controlled below 0.03, and the structure and the performance of the controllable ceramic can be adjusted by only adjusting the substitution amount of Bi, so as to meet the requirements (high piezoelectric coefficient, high Curie temperature and better ferroelectricity) of the high-temperature piezoelectric sensor on the ceramic material. If the value of x is more than 0.03, the phase structure of the ceramic completely deviates from MPB, so that the performance (such as piezoelectric coefficient) of the material is greatly reduced, which is contrary to the aim of improving the performance of the ceramic.

Compared with a ternary solid solution system, the method can more accurately control the replacement and substitution of atoms by utilizing binary composition design, and can obtain the high-temperature piezoelectric ceramic with high Curie temperature, high piezoelectric coefficient, high remanent polarization and high depolarization temperature by only constructing a homomorphic phase boundary through double-ion substitution.

Preferably, the room temperature piezoelectric coefficient of the modified lead titanate-based high-temperature piezoelectric ceramic is 300-550 pC/N, the Curie temperature is 300-500 ℃, the strain is 0.2-0.4%, and the remanent polarization is 40-50 mu C/cm²Depolarization temperature 350-450 ℃.

In a second aspect, the present invention provides a method for preparing the modified lead titanate-based high-temperature piezoelectric ceramic. The preparation method comprises the following steps: according to the chemical composition of modified lead titanate-based high-temperature piezoelectric ceramics, Bi is used₂O₃、Sc₂O₃、PbO、TiO₂And ZnO are used as raw materials, the raw materials are weighed according to the corresponding stoichiometric ratio and mixed, and the mixture is subjected to heat preservation and synthesis at the temperature of 600-900 ℃ for 2-4 hours to obtain ceramic powder; and sintering the ceramic powder at 1100-1200 ℃ for 1-3 hours to obtain the modified lead titanate-based high-temperature piezoelectric ceramic. The preparation method adopts solid-phase reaction to prepare A, B co-doped lead titanate-based perovskite structure piezoelectric ceramic.

Preferably, the particle size of the ceramic powder is 1 to 2 μm.

Preferably, the mixing mode is wet ball milling mixing, wherein the raw materials: ball milling medium: the mass ratio of water is 1: (1.2-1.8): (0.5-0.9) and the mixing time is 2-6 hours. In some embodiments, the ball milling media are agate balls.

Preferably, the preparation method further comprises: adding a binder into the ceramic powder for granulation before sintering, performing press molding and plastic removal to obtain a ceramic green body, and then sintering the ceramic green body; preferably, the addition amount of the binder is 4-8 wt.% of the ceramic powder; more preferably, the binder is polyvinyl alcohol.

Preferably, the plastic removing condition is that the temperature is raised to 600-800 ℃ at a temperature rise rate of not higher than 2 ℃/min and is kept for less than 3 hours.

Preferably, the preparation method further comprises: and carrying out silver printing, drying and silver firing treatment on the modified lead titanate-based high-temperature piezoelectric ceramic, and then applying an electrode for polarization.

Preferably, the silver firing condition is that the temperature is kept at 700-800 ℃ for less than 60 minutes; the polarization condition is that the polarization is carried out for 15-30 minutes at the temperature of 100-140 ℃ at 4-6 kV/mm.

Preferably, the ceramic powder is subjected to fine grinding by wet ball milling before being added with a binder for granulation, and then is dried, wherein the ceramic powder: ball milling medium: the mass ratio of water is 1: (1.2-1.8): (0.5-0.9) and the fine grinding time is 4-8 hours.

Drawings

In FIG. 1, (A), (B), (C) and (D) are respectively piezoelectric ceramics 0.365BiScO₃-0.635Bi_xPb_{1-3x/ 2}Ti_0.99Zn_0.01O₃(x ═ 0, 0.01, 0.02, 0.03) by scanning electron microscopy;

in FIG. 2, (A) is a piezoelectric ceramic 0.365BiScO₃-0.635Bi_xPb_1-3x/2Ti_0.99Zn_0.01O₃An X-ray diffraction pattern of (0, 0.01, 0.02, 0.03), (B) is a partial enlarged view of (a);

FIG. 3 shows a piezoelectric ceramic 0.365BiScO₃-0.635Bi_xPb_1-3x/2Ti_0.99Zn_0.01O₃A piezoelectric coefficient curve of (x ═ 0, 0.01, 0.02, 0.03);

FIG. 4 shows a piezoelectric ceramic 0.365BiScO₃-0.635Bi_xPb_1-3x/2Ti_0.99Zn_0.01O₃(x is 0, 0.01, 0.02, 0.03) as the annealing temperature increases.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative of, and not restrictive on, the present invention. The following percentages are by mass unless otherwise specified.

The Curie temperature and the comprehensive electrical property of the conventional piezoelectric ceramic material cannot meet the requirements of a high-temperature piezoelectric sensor at the same time, so that an innovative composition design is provided, the morphotropic phase boundary is regulated and controlled by A, B bit codoping, the piezoelectricity of the piezoelectric ceramic with the lead-based perovskite structure is effectively improved while the high Curie temperature is ensured, the ferroelectricity and depolarization behavior are synergistically optimized, and a new idea is provided for the application of the piezoelectric ceramic with the lead-based perovskite structure in the high-temperature piezoelectric sensor. Specifically, the composition of the modified lead titanate-based high-temperature piezoelectric ceramic (also called as "lead-based perovskite high-temperature piezoelectric ceramic") is 0.365BiScO₃-0.635Bi_xPb_1-3x/2Ti_0.99Zn_0.01O₃Wherein x is more than or equal to 0 and less than or equal to 0.03. In some technical schemes, x is more than 0 and less than or equal to 0.03. More preferably 0.01. ltoreq. x.ltoreq.0.03.

In the lead-based perovskite high-temperature piezoelectric ceramic, a BS-PT component which is in a trigonal phase and is near MPB is selected as a matrix, meanwhile, the performance adjustability is enhanced by adopting an A, B-site co-doping strategy, Zn which has high ferroelectric activity and enhances the tetragonal phase of the ceramic is used for replacing B-site titanium in an oxygen octahedron in a perovskite structure, Bi which has high valence and enhances the trigonal phase is used for replacing A-site Pb in lead titanate, so that a quasi-homomorphic phase boundary in which the trigonal phase and the tetragonal phase coexist is obtained, and the piezoelectric, ferroelectric and dielectric properties are improved.

Compared with BS-PT, the invention introduces Zn²⁺The ferroelectric activity of the material is better than that of Sc and Ti, and larger displacement of B site ions can be generated. Zn²⁺The hybridization of the 4s and 4p orbitals and the 2p orbitals of O plays a role in promoting the displacement of A-site ions and B-site ions, in addition, the 3s, 3p and 3d orbitals of B-site Zn ions are all in a full state, and the repulsive force of the orbitals and O also increases the displacement of Zn and OThe presence of a strong tetragonal phase is stabilized. These complex and strong hybridization effects result in ceramics with strong tetragonal distortion. And, Bi³⁺Substitution for Pb²⁺Belonging to donor doping, producing Pb²⁺Vacancies promote the motion of domain walls, and the ceramic sample is easy to be mono-domain. Bi³⁺Exists for 6s²Lone pair electrons, the presence of which can distort the perovskite to some extent, Bi³⁺The hybridization of the 6s orbital and the 2p orbital of O increases the bond energy of the A-O bond, and not only can maintain higher Curie temperature, but also improves the ferroelectric property. In addition, Bi with the characteristics of the trigonal phase is adopted to inhibit the distortion of the tetragonal phase, so that a homomorphic phase boundary where trigonal and tetragonal coexist is obtained. The method is simple and easy to implement, only Zn element is additionally introduced and is used as a binary solid solution component, the main purpose is to replace B site, the hybridization degree of A and O is enhanced, and the depolarization temperature and the ferroelectric property of the ceramic are improved.

The high-temperature piezoelectric ceramic material is prepared by adopting the components and regulating the morphotropic phase boundary, so that the piezoelectric coefficient of the high-temperature piezoelectric ceramic is improved, the higher Curie temperature (300-500 ℃) is ensured, the requirements of high-temperature piezoelectric ceramic components on the high-temperature piezoelectric ceramic material are met, a powerful propulsion effect is realized for the application of the high-temperature piezoelectric ceramic material in the high-temperature field, and the high-temperature piezoelectric ceramic material is expected to be used for high-temperature piezoelectric devices with the use temperature of 200-400 ℃. In some examples, the piezoelectric coefficient of the high-temperature piezoelectric ceramic is 380 to 530pC/N (preferably 490 to 530pC/N), the Curie temperature is 300 to 500 ℃, the strain is 0.2 to 0.4%, and the remanent polarization is 40 to 50 mu C/cm²Depolarization temperature 350-450 ℃. This and undoped BiScO₃-PbTiO₃(T_C＝430℃，d₃₃＝350pC/N，P_r＝39μC/cm²) Compared with the prior art, the comprehensive performance of the material is obviously improved. In the composition debugging process, the invention tries to carry out ceramic modification through solid solution of a third element construction phase boundary, and the obtained system is BiScO₃-PbTiO₃-Bi(Sn_1/3Nb_2/3)O₃But its piezoelectric coefficient (38)0 to 460pC/N), Curie temperature (340 to 440 ℃) and depolarization temperature (200 to 270 ℃), which are lower than those of the invention.

The invention also discloses a preparation process of the lead-based perovskite high-temperature piezoelectric ceramic, which specifically comprises the steps of material preparation, material mixing, synthesis, fine grinding, molding, plastic discharge, sintering and the like.

In some examples, the preparation method of the perovskite structure high-temperature piezoelectric ceramic material may include the following steps:

step (a) of weighing Bi in a stoichiometric ratio₂O₃、PbO、Sc₂O₃ZnO and TiO₂Wet planetary ball milling and synthesizing the powder to obtain 0.365BiScO₃-0.635Bi_xPb_1-3x/2Ti_0.99Zn_0.01O₃Ceramic powder.

In the wet planetary ball mill, the raw materials are as follows: ball milling medium: water 1: (1.2-1.8): (0.5-0.9) and mixing for 2-6 hours. The ball milling media may be agate balls. And the synthesis condition is that the synthesis is carried out for 2 to 4 hours at the temperature of 600 to 900 ℃. Preferably, the temperature is raised to 700-900 ℃ at a temperature rise rate of not higher than 2 ℃/min, the temperature is kept for 1-3 hours, and the mixture is cooled to room temperature along with the furnace and then taken out to obtain the composition. In some examples, the particle size of the composition (i.e., ceramic powder) is 1 to 2 μm.

After the synthesis, the compound can be subjected to secondary planetary ball milling and drying. According to the composition: ball milling medium: water 1: (1.2-1.8): (0.5-0.9) for 4-8 hours. The ball milling media may be agate balls. And drying at 100-150 ℃ after secondary planetary ball milling.

And (b) adding a binder into the ceramic powder for granulation, aging, performing compression molding, and then heating and removing plastic to obtain a ceramic blank. In some examples, the binder may be polyvinyl alcohol (PVA). The addition amount of the binder can be 4-8 wt% of the ceramic powder. In addition, the plastic discharge condition can be as follows: heating to 600-800 ℃ at a heating rate of not higher than 2 ℃/min, and keeping the temperature for less than 3 hours.

And (c) putting the ceramic blank into a (small) high-temperature furnace, covering the ceramic blank with powder of the corresponding components of the ceramic powder obtained in the step (a) in order to reduce the volatilization of lead oxide and bismuth oxide at high temperature, and sintering according to certain conditions to obtain the ceramic plate. The sintering condition can be that the temperature is raised to 1000-1200 ℃ at the temperature rise rate of not higher than 2 ℃/min, the temperature is kept for 1-3 hours, and the sintering is cooled to the room temperature along with the furnace.

And (d) processing the sintered ceramic wafer into a required size, ultrasonically cleaning, screen-printing silver, drying, burning the silver, and then performing electrode polarization to obtain the high-temperature piezoelectric ceramic material. The silver firing condition can be 700-800 ℃ for less than 60 minutes. In addition, the polarization condition can be 100-140 ℃, 4-6 kV/mm, and the polarization time can be 15-30 minutes.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.

Examples 1 to 4

1. Prepared by adopting a solid-phase sintering method (0.365 BiScO)₃-0.635Bi_xPb_1-3x/2Ti_0.99Zn_0.01O₃High temperature piezoelectric ceramics. Wherein x (molar ratio of Bi) is 0 to 0.03. With Bi₂O₃、PbO、TiO₂ZnO and Sc₂O₃The powder is taken as a raw material, is weighed according to a stoichiometric ratio, is mixed by a wet ball milling method, and comprises the following steps: grinding medium: water 1: 1.5: the mixture was mixed at a mass ratio of 0.7 for 4 hours to mix them uniformly. Drying the mixed raw materials at 120 ℃, sieving the dried raw materials by a 40-mesh sieve, forming the raw materials under the pressure of 3MPa, heating the raw materials to 850 ℃ at the heating rate of 2 ℃/min, and preserving the heat for 2 hours to synthesize the required ceramic powder.

2. Grinding the ceramic powder synthesized in the step 1, sieving the powder by a 40-mesh sieve, and finely grinding the powder by a wet ball grinding method, wherein the ceramic powder comprises the following components in percentage by weight: grinding medium: water 1: 1.5: 0.6 for 6 hours to obtain powder with the grain diameter of 1-3 mu m. Drying the obtained powder, adding 6 wt.% of PVA binder, granulating, molding under the pressure of 5MPa, aging for 24 hours, sieving with a 40-mesh sieve, pressing into a wafer with the diameter of 13mm under the pressure of 1.3MPa, heating to 750 ℃ in a low-temperature furnace, preserving heat for 60 minutes, and removing plastic to obtain a plain blank body.

3. And burying the ceramic blank in a closed alumina crucible filled with ceramic powder with the same composition, putting the ceramic blank into a high-temperature furnace, heating to a target temperature of 1080-1180 ℃ at a heating rate of 2 ℃/min, preserving heat for 2 hours, cooling to room temperature along with the furnace, and taking out to obtain the required ceramic chip.

4. Processing the obtained ceramic wafer to the thickness of 0.5mm, ultrasonically cleaning, drying, brushing silver on the two sides of a silk screen, heating to 750 ℃ at the heating rate of 2 ℃/min, preserving the temperature for 10 minutes, burning the silver, and then polarizing the electrode for 20 minutes at the temperature of 120 ℃ at 4-6 kV/mm to obtain the high-temperature piezoelectric ceramic with the perovskite structure.

In examples 1 to 4, x is 0, 0.01, 0.02 or 0.03, respectively.

The polarized ceramics were tested: curie temperature T_cTesting according to GB/T3389.3; analyzing the phase structure of the piezoelectric ceramic by using an X-ray diffractometer model RAX-10 of Rigaku corporation in Japan; quasi-static d of type ZJ-3A produced by the acoustics of Chinese academy of sciences₃₃Tester for measuring d of piezoelectric ceramic at room temperature₃₃Measuring 10 samples with the test frequency of 100Hz, and taking an average value; the piezoelectric ceramics were tested for hysteresis loop using a ferroelectric Analyzer TF Analyzer 2000 manufactured by AIxACCT, Germany. The results of various performance tests of the high-temperature piezoelectric ceramic of the invention are shown in Table 1.

TABLE 1 Performance test Table for piezoceramic materials

As can be seen from Table 1, d₃₃，P_rWith increasing value of xThe curie temperature gradually decreased with increasing x, increasing and decreasing, and the optimum value was obtained in example 3(x is 0.02), i.e., in the vicinity of MPB; t is_cThe value of (A) shows a linear decrease with an increase in the amount of solid solution, and a higher value (T) is maintained at 0.02 x_c＝407℃)。

Fig. 1 is a cross-sectional profile of the high-temperature piezoelectric ceramic (x ═ 0, 0.01, 0.02, 0.03) according to the present invention. As seen from figure 1, the ceramic section has fewer pores, obvious liquid phase sintering traces can be seen at the grain boundary of each component, and the compactness is improved. As x increases, the average grain size of the ceramic gradually decreases from 11.5 μm to 2.3 μm. The ceramic fracture surface gradually changes from along-grain fracture to transgranular fracture, which is mainly caused by the gradual increase of the bonding force at the grain boundary.

Fig. 2 is an X-ray spectrum of the high-temperature piezoelectric ceramic (X ═ 0, 0.01, 0.02, 0.03) of the present invention. As seen from fig. 2, the piezoelectric ceramic exhibits a single perovskite structure, and no significant second phase appears. In addition, when x is 0, the ceramic shows a typical tetragonal phase, which indicates that the introduction of Zn increases the distance between B-site ions and O ions, resulting in an increase in the tetragonal phase. With the increasing x value, the (002) and (200) peaks near 45 ° gradually become two-in-one. This shows that the substitution of Bi ions causes a serious lattice structure mismatch phenomenon, and a significant change occurs from a tetragonal phase to a tetragonal phase in the perovskite structure, so that the tetragonal phase and the tetragonal phase coexist near a certain solid solution amount (x ═ 0.02), that is, a Morphotropic Phase Boundary (MPB).

Fig. 3 shows the piezoelectric coefficients at room temperature of the high-temperature piezoelectric ceramic of the present invention (x is 0, 0.01, 0.02, 0.03). Along with the increase of the solid solution amount, the piezoelectric coefficient is firstly increased and then reduced, the piezoelectric coefficient near MPB can reach 495pC/N, and the piezoelectric coefficient has very important significance for improving the sensitivity of the sensor.

Fig. 4 is a graph showing the change of the piezoelectric coefficient with the increase of the annealing temperature in the high-temperature piezoelectric ceramic of the present invention (x is 0, 0.01, 0.02, 0.03). As can be seen from the figure, the ceramic depolarization temperatures for all components are between 350-450 ℃. The method has great promotion effect on the high-temperature application of the high-temperature piezoelectric ceramic.