PZT-based piezoelectric ceramic material with large electrostrictive strain and high Curie temperature in low electric field and preparation method of PZT-based piezoelectric ceramic material

Abstract

The invention relates to a PZT-based piezoelectric ceramic material with large electrostrictive strain and high Curie temperature in a low electric field and a preparation method thereof. The chemical composition of the PZT-based piezoelectric ceramic material is Pb1-2n-1.5 xLaxSrnBan (ZryTi1-y) O3-zwt% Sn, wherein x is more than or equal to 0.004 and less than or equal to 0.007, y is more than or equal to 0.52 and less than or equal to 0.6, z is more than or equal to 0.3 and less than or equal to 0.7, and n is more than or equal to 0.01 and less than or equal to 0.04. The preparation method of the PZT-based piezoelectric ceramic material comprises the following steps: (1) preparing materials; (2) calcining; (3) granulating; and (4) removing plastic and sintering.

Description

Technical Field

[0001] The invention belongs to the field of aerospace actuators, and in particular relates to a PZT-based piezoelectric ceramic material with large electro-induced strain and high Curie temperature and a preparation method thereof. Background Art

[0002] Piezoelectric actuators have the characteristics of small size, fast response, and large output torque. They are widely used in modern high-tech fields such as aerospace, nuclear energy, and petrochemicals. As the core component of piezoelectric actuators, piezoelectric ceramic materials use the inverse piezoelectric effect to generate proportional strain values ​​under electric field loading to achieve precision driving. With the rapid development of electronic information technology, aerospace, and defense industries, higher requirements are placed on the performance of driver piezoelectric ceramics in high-tech applications. Piezoelectric ceramics are required to have better strain characteristics. Their large strain characteristics can achieve larger strains under lower driving electric field strengths. Drivers used in these fields, especially aerospace, usually need to work in a wide temperature range (room temperature-high temperature). As the Curie temperature increases, the performance of piezoelectric ceramics will significantly decrease, which seriously limits the application of piezoelectric actuators.

[0003] For aerospace service environments, piezoelectric ceramics should not only have high piezoelectric coefficients and large strain characteristics under low electric fields, but also have high Curie temperature. Summary of the invention

[0004] In order to solve the above problems, the present invention aims to provide a PZT-based piezoelectric ceramic material having both large electro-induced strain under low electric field and high Curie temperature and a preparation method thereof. The ceramic of this component has both high Curie temperature and large electro-induced strain, and also has good temperature stability of strain performance, and is expected to be applied in the field of aerospace actuators.

[0005] On the one hand, the present invention provides a PZT-based piezoelectric ceramic material having both large electro-induced strain under low electric field and high Curie temperature. The chemical composition of the PZT-based piezoelectric ceramic material is: Pb 1-2n-1.5x La x Sr n Ba n (Zr y Ti 1-y )O3-zwt%Sn, where 0.004≤x≤0.007, 0.52≤y≤0.6, 0.3≤z≤0.7, 0.01≤n≤0.04. 1-2n-1.5x La x Sr n Ba n (Zr y Ti 1-y) On the basis of the O3 system, zwt% SnO2 is added; when x, y, z, and n exceed the above ranges, the piezoelectric properties and strain value of the PZT-based piezoelectric ceramic material will decrease, and the Curie temperature will decrease.

[0006] The present invention designs Pb 1-2n-1.5x La x Sr n Ba n (Zr y Ti 1-y )O3-zwt%Sn (PLSBZT-zwt%Sn) components, to obtain a PZT-based piezoelectric ceramic material with high Curie temperature and large strain, which is expected to be used in the field of aerospace drives. 1-2n-1.5x La x Sr n Ba n (Zr y Ti 1-y )O3 is used as the matrix material, and La is doped into the matrix material to improve the piezoelectric properties of the material and increase the strain. This is because La is a "soft" dopant. After La element enters the solid solution, it will replace the position of Pb. After the trivalent ion La replaces the divalent ion Pb, lead vacancies will be generated, the lattice will be distorted, and the electric domain wall movement will be easier. Under the action of a small electric field, the domain wall can move, thereby improving the piezoelectric properties of the material. Doping with Sn element helps the formation of the perovskite structure and further increases its strain performance under a low electric field. After Sn element enters the unit cell, it will replace the position of Zr or Ti in the unit cell structure, causing the crystal lattice distortion, while the grain size of the material will be relatively reduced, the domain size will be refined, and it will be more conducive to the reversal of the domain. Under the combined effect of the above two factors, the performance of the PZT-based piezoelectric ceramic material system of the present invention has been significantly improved.

[0007] Preferably, 0.53≤y≤0.55, 0.5≤z≤0.55. When y and z are within this range, the strain performance and Curie temperature of the material are both high.

[0008] Preferably, the Curie temperature of the PZT-based piezoelectric ceramic material is at least 250° C., preferably 255-270° C.; the strain value of the PZT-based piezoelectric ceramic material under an electric field of 2 kV / mm is at least 0.16%, preferably 0.197%-0.203%.

[0009] On the other hand, the present invention also provides a method for preparing a PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature, comprising: (1) weighing and mixing a Pb source, a Zr source, a Ti source, a Sr source, a Ba source, a La source and a Sn source according to the chemical composition ratio of the PZT-based piezoelectric ceramic material to obtain a raw material powder; (2) calcining the raw material powder to obtain a synthetic powder; (3) mixing the synthetic powder with a binder and granulating the mixture, and then forming the mixture to obtain a ceramic green body; (4) The ceramic green body is subjected to plastic disassembly and sintering to obtain the PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature.

[0010] Preferably, the Pb source is Pb3O4 powder; the Zr source is ZrO2 powder; the Ti source is TiO2 powder; the Sr source is SrCO3 powder; the Ba source is BaCO3 powder; the La source is La2O3 powder; and the Sn source is SnO2 powder.

[0011] Preferably, in step (2), the calcination temperature is 800-900°C, the time is 2-4 hours, and the heating rate is 1.5-3°C / min.

[0012] Preferably, in step (3), the binder is at least one of polyvinyl alcohol (PVA) and polyvinyl butyral (PVB); and the amount of the binder added is 5-7% of the mass of the synthetic powder.

[0013] Preferably, the temperature of the plastic removal is 700-800° C., and the time is 2-3 hours.

[0014] Preferably, in step (4), the sintering temperature is 1280-1300° C., the time is 2-4 hours, and the heating rate is 1.5-3° C. / min.

[0015] Beneficial effects:

[0016] The PZT-based piezoelectric ceramic material obtained by the present invention uses PZT as the base material and adds La 3+ , while doping Sn 4+ , which improves the piezoelectric properties of the material. The strain value under an electric field of 2kV / mm can reach more than 0.18%, its Curie temperature is above 250°C, and its relative dielectric constant value is low, which can make the driver have a faster response speed.

[0017] In the present invention, a piezoelectric ceramic material having a Curie temperature higher than 250° C. and large strain characteristics under a low electric field is prepared by a conventional solid phase method, and is suitable for use as an aerospace piezoelectric stack driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The PZT-based piezoelectric ceramic materials prepared in Examples 1-4 and the undoped Pb prepared in Comparative Example 1 1-2n- 1.5x La x Sr nBa n (Zr y Ti 1-y ) Dielectric temperature spectrum of O3 piezoelectric ceramic material; where a is undoped Pb 1-2n-1.5x La x Sr n Ba n (Zr y Ti 1-y ) O3 piezoelectric ceramic material, b is the piezoelectric ceramic material prepared in Example 1, c is the piezoelectric ceramic material prepared in Example 2, d is the piezoelectric ceramic material prepared in Example 3, and e is the piezoelectric ceramic material prepared in Example 4; Figure 2 The lead-free piezoelectric ceramic materials prepared in Examples 1-4 and the undoped Pb prepared in Comparative Example 1 1-2n- 1.5x La x Sr n Ba n (Zr y Ti 1-y )O3 piezoelectric ceramic material under 2kV / mm electric field unipolar electrostrain curve, where a is undoped Pb 1-2n-1.5x La x Sr n Ba n (Zr y Ti 1-y )O3 piezoelectric ceramic material, b is the piezoelectric ceramic material prepared in Example 1, c is the piezoelectric ceramic material prepared in Example 2, d is the piezoelectric ceramic material prepared in Example 3, and e is the piezoelectric ceramic material prepared in Example 4. DETAILED DESCRIPTION

[0019] To further explain the content, features and practical effects of the present invention, the present invention is described in detail below in conjunction with the embodiments. It should be pointed out that the modification method of the design of the present invention is not limited to these specific implementation methods. Without departing from the spirit and connotation of the design of the present invention, the equivalent replacement and modification made by those skilled in the art on the basis of reading the content of the present invention are also within the scope of the present invention.

[0020] In the present invention, the chemical composition of the PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature is: Pb 1-2n-1.5x La x Sr n Ba n (Zr y Ti 1-y)O3-zwt%Sn(PLSBZT-zwt%Sn). Among them, 0.004≤x≤0.007, 0.52≤y≤0.6, 0.3≤z≤0.7, 0.01≤n≤0.04.

[0021] The PZT-based piezoelectric ceramic material of the present invention realizes significant improvement of material strain performance and Curie temperature under low electric field, the strain value under 2kV / mm electric field can reach more than 0.18%, and the Curie temperature is above 250°C.

[0022] The doping of Sn element in the present invention causes lattice distortion in the crystal and changes the domain morphology and size of the material to a certain extent. The dual effects of lattice distortion and domain improve the strain performance of the system under low electric field.

[0023] The PLSBZT-0.55wt% Sn piezoelectric ceramic material has both high Curie temperature and large strain characteristics, wherein the Curie temperature is greater than 259.5° C., and the monopolar strain value under an electric field of 2 kV / mm can reach 0.203%.

[0024] Preferably, 0.53≤y≤0.55, 0.5≤z≤0.55. Wherein, y is the molar content of zirconium element. When 0.53≤y≤0.55, the material component is near the MPB (metamorphic phase boundary) two-phase coexistence zone. z is the weight ratio of Sn content to the PLSBZT basic system. When 0.5≤z≤0.55, the grain size of the material is relatively smaller, and the domain size is also smaller and easier to flip. If the z value is too large, the grain size will increase relatively, which will significantly reduce the material performance.

[0025] In the present invention, the PZT-based piezoelectric ceramic material is prepared by steps of batching, mixing, calcining, molding, plastic removal, sintering, etc. The following is an exemplary description of a method for preparing a PZT-based piezoelectric ceramic material having large electrostrain under low electric field and high Curie temperature provided by the present invention.

[0026] Pb3O4, ZrO2, TiO2, SrCO3, BaCO3, La2O3 and SnO2 powders are used as raw materials, and synthetic powders are obtained after mixing and calcining.

[0027] In an optional embodiment, wet ball milling is used for mixing, and the parameters of the wet ball milling include: the ball milling solvent is deionized water, the grinding balls are zirconia balls, the grinding balls are zirconia balls, the mass ratio of raw material: zirconia balls: deionized water is (0.5-1): (1.5-3): (0.5-1), and the ball milling time is 4-6 hours; preferably, the mass ratio of raw material: zirconia balls: deionized water is 1:3:1, and the ball milling time is 4 hours.

[0028] In an optional embodiment, the ball-milled powder is dried, pressed into blocks, and then calcined at a temperature of 800 to 900° C., for 2 to 4 hours, and at a heating rate of 1.5 to 3° C. / min.

[0029] In an optional embodiment, the calcined powder is finely ground by wet ball milling, and the parameters of the fine grinding include: the ball milling solvent is deionized water, the grinding balls are zirconia balls, the mass ratio of raw material: zirconia balls: deionized water is (0.5-1): (1.5-3): (0.5-1), and the ball milling time is 6-8 hours; preferably, the grinding balls are zirconia balls, the mass ratio of raw material: zirconia balls: deionized water is 1:3:1, and the ball milling time is 6 hours.

[0030] The synthetic powder is mixed with a binder to form granules, and then pressed and molded to obtain a ceramic green body.

[0031] In an optional embodiment, the binder is at least one of polyvinyl alcohol (PVA) and polyvinyl butyral (PVB); the amount of the binder added is 5-7% of the mass of the synthetic powder.

[0032] The pressure of the compression molding is 1.4-3 MPa.

[0033] The temperature of the plastic removal is 700-800° C., and the time is 2-3 hours.

[0034] The ceramic green body is sintered to obtain the PZT-based piezoelectric ceramic material. In order to reduce the volatilization of the Pb element, during the sintering process, the ceramic green body is covered with a powder having the same chemical composition as the PZT-based piezoelectric ceramic material, and the crucible is covered with a lid, and the PZT-based piezoelectric ceramic material is sintered to obtain the PZT-based piezoelectric ceramic material.

[0035] In an optional embodiment, the sintering temperature is 1280-1300°C, the time is 2-4 hours, and the heating rate is 1.5-3°C / minute. If the sintering temperature is too high, it will cause serious lead loss and over-burning, and if the temperature is too low, the ceramic sintering is not dense.

[0036] The obtained PZT-based piezoelectric ceramic material is prepared into a piezoelectric element by silver printing, silver burning and polarization treatment on the PZT-based piezoelectric ceramic material.

[0037] In an optional embodiment, the obtained PZT-based piezoelectric ceramic material is processed into a thin sheet of a desired size, cleaned, dried, screen-printed with silver paste, dried again, and finally subjected to silver burning treatment. The temperature of the silver burning treatment is 650-750°C, the time is 30-60 minutes, and the heating rate is 2-5°C / min. The polarization conditions can be 120±5°C, 2-4kV voltage, and polarization for 15-20min.

[0038] The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0039] Example 1

[0040] The chemical composition of the PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature in this embodiment 1 is (Pb 0.931 La 0.006 Sr 0.03 Ba 0.03 (Zr 0.535 Ti 0.465 )O3-zwt%Sn, where z=0.4.

[0041] The method for preparing the PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature in this embodiment 1 comprises:

[0042] (1) Pb3O4, ZrO2, TiO2, SrCO3, BaCO3, La2O3 SnO2 were weighed as raw materials according to the stoichiometric ratio, and mixed by wet ball milling, and the raw materials: zirconium oxide balls: deionized water were mixed in a mass ratio of 1:3:1, and the components were evenly mixed by ball milling for 4 hours. After drying, the mixture was passed through a 40-mesh sieve and then pressed into a block, and the temperature was raised to 850°C at a heating rate of 2°C / min for calcination, and the mixture was kept at this temperature for 2 hours to obtain a synthetic powder.

[0043] (2) The obtained synthetic powder is crushed, ground, and sieved, and the powder is further finely ground by wet ball milling. The powder is finely ground for 6 hours according to the mass ratio of raw materials: zirconium oxide balls: deionized water = 1:3:1, and the finely ground ceramic powder is dried. Then, a PVA binder is added for granulation. The amount of the binder added is 6% of the mass of the synthetic powder. The ceramic blank is pressed under a pressure of 1.5 MPa to obtain a flaky ceramic blank. The ceramic blank is heated to 700°C and kept warm for 2 hours for plastic removal.

[0044] (3) The ceramic green body after plasticizing is placed in a crucible. In order to reduce the volatilization of the Pb element, the green body is covered with a ceramic powder having the same composition as that in step (1). The crucible is covered with a lid, and the temperature is increased to 1280°C at a heating rate of 2°C / min to sinter the green body. The temperature is kept for 2 hours, and the green body is cooled in the furnace to obtain a sheet-like PZT-based piezoelectric ceramic material.

[0045] The sintered ceramic sheet was ground to a thickness of 0.5-1 mm, cleaned, dried, screen-printed with silver paste, dried again, and heated to 750° C. at a heating rate of 2° C. / min for silver sintering, and kept warm for 30 minutes to obtain a piezoelectric ceramic element.

[0046] The piezoelectric ceramic element prepared in Example 1 was polarized at 120±5°C, 2-4 kV, and 15 min. The piezoelectric and dielectric properties of the polarized piezoelectric ceramic element were tested. The results are shown in Table 1. Figure 1 and Figure 2 .

[0047] Example 2

[0048] The chemical composition of the PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature in this embodiment 2 is Pb 0.931 La 0.006 Sr 0.03 Ba 0.03 (Zr 0.535 Ti 0.465 )O3-zwt%Sn, wherein z=0.5. The preparation method of the piezoelectric ceramic material is as described in Example 1.

[0049] The piezoelectric ceramic element prepared in Example 2 was polarized at 120±5°C, 2-4 kV, and 15 min. The piezoelectric and dielectric properties of the polarized piezoelectric ceramic element were tested. The results are shown in Table 1. Figure 1 and Figure 2 The dielectric temperature spectrum and unipolar electrostrain curve of the piezoelectric ceramic material prepared in Example 2 are shown in Figures 2 and 3 respectively. Figure 1 and 2 shown.

[0050] Example 3

[0051] The chemical composition of the PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature in this embodiment 3 is Pb 0.931 La 0.006 Sr 0.03 Ba 0.03 (Zr 0.535 Ti 0.465 )O3-zwt%Sn, wherein z=0.55. The preparation method of the piezoelectric ceramic material is as described in Example 1.

[0052] The piezoelectric ceramic element prepared in Example 3 was polarized at 120±5°C, 2-4 kV voltage, and 15 min. The piezoelectric and dielectric properties of the polarized piezoelectric ceramic element were tested. The results are shown in Table 1. Figure 1 and Figure 2 .

[0053] Example 4

[0054] The chemical composition of the PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature in this embodiment 4 is Pb 0.931 La 0.006 Sr 0.03 Ba 0.03 (Zr 0.535 Ti 0.465 )O3-zwt%Sn, wherein z=0.6. The preparation method of the piezoelectric ceramic material is as described in Example 1.

[0055] The piezoelectric ceramic element prepared in Example 4 was polarized at 120±5°C, 2-4 kV voltage, and 15 min. The piezoelectric and dielectric properties of the polarized piezoelectric ceramic element were tested. The results are shown in Table 1. Figure 1 and Figure 2 .

[0056] Comparative Example 1

[0057] The chemical composition of the piezoelectric ceramic material of this comparative example 1 is Pb 0.931 La 0.006 Sr 0.03 Ba 0.03 (Zr 0.535 Ti 0.465 )O3 wherein z = 0. The preparation method of the piezoelectric ceramic material is as described in Example 1.

[0058] The piezoelectric ceramic element prepared in Comparative Example 1 was polarized at 120±5°C, 2-4 kV voltage, and 15 min. The piezoelectric and dielectric properties of the polarized piezoelectric ceramic element were tested. The results are shown in Table 1. Figure 1 and Figure 2 .

[0059] Table 1 lists the piezoelectric and dielectric properties of the polarized PZT-based piezoelectric ceramic materials prepared in Examples 1-4 and Comparative Example 1, respectively. 33 、T c And the electrostrain can be directly measured by the experimental instrument, ε r It can be calculated from the room temperature capacitance and the sample thickness and area, k p and Q m can be calculated from the resonant and anti-resonant frequencies).

[0060] Table 1:

[0061] From Table 1, we can see that the piezoelectric coefficient, strain, and dielectric constant ε of the material r and the electromechanical coupling coefficient kp As the doping amount of Sn element increases, it first increases and then decreases. When the doping amount of Sn element increases to 0.6wt%, the overall performance is lower than the optimal state (Sn doping amount is 0.55wt%), but it is still higher than the piezoelectric ceramic material without Sn element doping (Comparative Example 1). As the doping amount of Sn element increases, the Curie temperature of the system fluctuates slightly, but is still higher than 250℃.

[0062] Figure 1 The PZT-based piezoelectric ceramic materials prepared in Examples 1-4 and the undoped Pb prepared in Comparative Example 1 1-2n- 1.5x La x Sr n Ba n (Zr y Ti 1-y ) Dielectric temperature spectrum of O3 piezoelectric ceramic material. It can be seen from the figure that after doping with Sn, the Curie temperature of the system decreases slightly, but is still above 250℃.

[0063] Figure 2 The lead-free piezoelectric ceramic materials prepared in Examples 1-4 and the undoped Pb prepared in Comparative Example 1 1-2n- 1.5x La x Sr n Ba n (Zr y Ti 1-y ) The unipolar electrostrain curve of O3 piezoelectric ceramic material under 2kV / mm electric field. As can be seen from the figure, after doping with Sn, the unipolar strain of the material under 2kV / mm electric field is significantly improved, and the unipolar strain of Example 3 is increased by nearly 20% compared with that of Comparative Example 1.

[0064] Curie temperature T of the piezoelectric ceramic material prepared in Example 1 of the present invention c =261.2℃, the electrostrain is 0.181%, which is comparable to the undoped Pb prepared in Comparative Example 1. 1-2n-1.5x La x Sr n Ba n (Zr y Ti 1-y )O3 piezoelectric ceramic material is more than 6% higher than the single pole electrostrain. The Curie temperature T of the piezoelectric ceramic prepared in Example 2 c =261.4℃, the electrostrain is 0.197%, which is comparable to the undoped Pb prepared in Comparative Example 1. 1-2n-1.5x La x Sr n Ba n (Zr y Ti 1-y)O3 piezoelectric ceramic material has an electrostrain increase of 16% compared to the single pole, and the overall performance is significantly improved. The piezoelectric performance of the piezoelectric ceramic material prepared in Example 3 is optimal. Piezoelectric coefficient d 33 The unipolar strain is 527pC / N, and the unipolar strain can reach 0.203%, which is comparable to the undoped Pb 1-2n-1.5x La x Sr n Ba n The electro-induced strain of the (ZryTi1-y)O3 piezoelectric ceramic material is increased by nearly 20% compared with the unipolar one, while the Curie temperature can still be maintained above 250°C. The electro-induced strain of the piezoelectric ceramic material prepared in Example 4 is 0.18%, the Curie temperature is 269.4°C, and the piezoelectric coefficient d 33 Although the strain and piezoelectric coefficient are lower than those of Example 3, they are still better than those of Comparative Example 1.

Claims

1. A PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature, characterized in that: The chemical composition of the PZT-based piezoelectric ceramic material is: Pb 1-2n-1.5x La x Sr n Ba n (Zr y Ti 1-y )O3-zwt%Sn, wherein 0.004≤x≤0.007, 0.52≤y≤0.6, 0.3≤z≤0.7, 0.01≤n≤0.

04.

2. The PZT-based piezoelectric ceramic material according to claim 1, characterized in that: 0.53≤y≤0.55, 0.5≤z≤0.

55.

3. The PZT-based piezoelectric ceramic material according to claim 1 or 2, characterized in that: The Curie temperature of the PZT-based piezoelectric ceramic material is at least 250° C.; the strain value of the PZT-based piezoelectric ceramic material under an electric field of 2 kV / mm is at least 0.16%.

4. The PZT-based piezoelectric ceramic material according to claim 3, characterized in that: The Curie temperature of the PZT-based piezoelectric ceramic material is 255-270° C.; the strain value of the PZT-based piezoelectric ceramic material under an electric field of 2 kV / mm is 0.197%-0.203%.

5. A method for preparing a PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature according to any one of claims 1 to 4, characterized in that: include: (1) weighing and mixing a Pb source, a Zr source, a Ti source, a Sr source, a Ba source, a La source and a Sn source according to the chemical composition ratio of the PZT-based piezoelectric ceramic material to obtain a raw material powder; (2) calcining the raw material powder to obtain a synthetic powder; (3) mixing the synthetic powder with a binder and granulating the mixture, and then forming the mixture to obtain a ceramic green body; (4) The ceramic green body is subjected to plastic disassembly and sintering to obtain the PZT-based piezoelectric ceramic material having both large electrostrain under low electric field and high Curie temperature.

6. The preparation method according to claim 5, characterized in that: The Pb source is Pb3O4 powder; the Zr source is ZrO2 powder; the Ti source is TiO2 powder; the Sr source is SrCO3 powder; the Ba source is BaCO3 powder; the La source is La2O3 powder; and the Sn source is SnO2 powder.

7. The preparation method according to claim 5 or 6, characterized in that: In step (2), the calcination temperature is 800-900° C., the time is 2-4 hours, and the heating rate is 1.5-3° C. / min.

8. The preparation method according to any one of claims 5 to 7, characterized in that: In step (3), the binder is at least one of polyvinyl alcohol (PVA) and polyvinyl butyral (PVB); the amount of the binder added is 5-7% of the mass of the synthetic powder.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The temperature of the plastic removal is 700-800° C., and the time is 2-3 hours.

10. The preparation method according to any one of claims 5 to 9, characterized in that: In step (4), the sintering temperature is 1280-1300° C., the sintering time is 2-4 hours, and the heating rate is 1.5-3° C. / minute.

Images