A lead zirconate titanate target material, a method of manufacturing the same, and a piezoelectric device

Abstract

This application relates to the field of target material preparation technology, providing a lead zirconate titanate target material, its preparation method, and a piezoelectric device. The preparation method includes: preparing lead zirconate titanate powder; mixing, ball milling, and drying the lead zirconate titanate powder, glass powder, dispersant, and solvent to obtain a sintering precursor powder; subjecting the sintering precursor powder to pre-pressing and hot-pressing treatment, followed by heat treatment in an oxygen-containing atmosphere, and then machining to obtain the lead zirconate titanate target material. In this application, the PbO content is gradually increased from the bottom to the top of the crucible during raw material filling to compensate for the volatilization loss of upper-layer PbO, thereby generating a more uniform lead zirconate titanate powder. Then, it is sintered with glass powder containing a specific formulation at a low temperature using hot pressing. This not only compensates for the volatilization loss of PbO and improves the accuracy of the target material's chemical composition ratio, but also lowers the sintering temperature, inhibiting the migration and aggregation of Pb elements during sintering and improving the uniformity of the target material. Simultaneously, other components of the glass powder also enhance the piezoelectric properties of the PZT target material.

Description

Technical Field

[0001] This application belongs to the field of target material preparation technology, and particularly relates to a lead zirconate titanate target material, its preparation method, and a piezoelectric device. Background Technology

[0002] Lead zirconate titanate (PZT) possesses excellent piezoelectric, ferroelectric, pyroelectric, and high dielectric properties, making it the most widely used piezoelectric ceramic material. Various piezoelectric devices made with PZT as the core functional material, such as sensors, transducers, filters, and resonators, are widely used in aerospace, electronics, industrial machinery, biomedicine, and automotive fields. Currently, PZT piezoelectric devices are mainly manufactured in bulk ceramic form. The process typically involves mixing raw materials such as PbO, TiO2, and ZrO2, pre-firing them to synthesize PZT powder, and then molding and sintering at high temperatures to obtain the ceramic element. Although these bulk ceramic devices exhibit stable performance, they suffer from inherent drawbacks such as large size and weight, high energy consumption in the manufacturing process, and difficulty in direct integration with silicon-based microelectronic circuits.

[0003] With the rapid development of IoT technology, wearable electronic devices, high-end medical imaging systems, and next-generation communication technologies, the market demands increasingly higher levels of miniaturization, integration, and low power consumption from microelectromechanical systems (MEMS). Against this backdrop, the aforementioned shortcomings of traditional PZT bulk ceramic devices have become a technological bottleneck restricting their further application in highly integrated systems. Therefore, PZT piezoelectric thin films, which can be directly integrated onto chip substrates using semiconductor-compatible processes such as magnetron sputtering, have become an important development direction.

[0004] PZT sputtering targets are a key raw material for the preparation of high-performance PZT piezoelectric thin films, and their quality directly affects the performance of piezoelectric devices. Currently, the preparation process of PZT sputtering targets, especially the crucial high-temperature sintering step, suffers from PbO volatilization and migration. This not only causes the actual chemical composition of the sputtering target to deviate from the preset stoichiometry, ultimately affecting the piezoelectric properties of the sputtered film, but also leads to uneven component distribution and microstructure within the target, resulting in performance fluctuations and poor reproducibility.

[0005] Therefore, developing a method for preparing PZT ceramic targets that can precisely control the stoichiometry and achieve uniform densification has become a key challenge in promoting the development of PZT piezoelectric films towards high performance and high reliability. Summary of the Invention

[0006] The purpose of this application is to provide a lead zirconate titanate (PZT) target material, its preparation method, and a piezoelectric device, aiming to solve the problems of existing PZT target material preparation methods, such as the inability to accurately control the stoichiometry of the target material, uneven composition, and the presence of spots.

[0007] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: In a first aspect, this application provides a method for preparing a lead zirconate titanate target, comprising the following steps: N kinds of raw material mixed powders with different PbO contents are provided, each of the raw material mixed powders contains PbO powder, ZrO2 powder and TiO2 powder, wherein N≥3; The raw material mixture powder is filled into a crucible in layers from bottom to top according to the PbO content from low to high. After being covered, it is calcined to form lead zirconate titanate blocks. The lead zirconate titanate block was ball-milled to obtain lead zirconate titanate powder; The lead zirconate titanate powder, glass powder, dispersant and solvent are mixed, ball-milled and dried to obtain sintering precursor powder; The sintering precursor powder is pre-pressed and hot-pressed to obtain a lead zirconate titanate sintered body. The sintered lead zirconate titanate body is heat-treated in an oxygen-containing atmosphere and then machined to obtain the lead zirconate titanate target.

[0008] Secondly, this application provides a lead zirconate titanate target material, which is prepared by the method for preparing lead zirconate titanate target material provided in this application.

[0009] Thirdly, this application provides a piezoelectric device, including a piezoelectric thin film, which is obtained by sputtering coating with a lead zirconate titanate target provided in this application.

[0010] Compared with the prior art, this application has the following beneficial effects: (1) Based on the characteristic that the upper layer of PbO volatilizes more violently during high-temperature calcination, the PbO content is gradually increased from the bottom to the top of the crucible when filling the raw materials, so as to compensate for the loss of upper layer PbO volatilization, thereby generating lead zirconate titanate powder with more uniform composition, alleviating the problem of uneven composition and uncontrolled chemical composition ratio caused by the rapid volatilization of the upper layer in the traditional method, and laying the foundation for the preparation of uniform and precise target materials.

[0011] (2) Adding glass powder with a specific formulation can not only utilize the PbO contained therein to dynamically compensate for the loss of PbO during hot pressing and sintering, thereby improving the accuracy of the chemical composition ratio of the target material, but also act as a sintering aid to lower the sintering temperature, inhibit Pb migration and aggregation, and improve the uniformity of the target material. At the same time, other components of the glass powder can also optimize the grain boundaries and lattice of PZT, thereby improving the piezoelectric properties of the PZT target material.

[0012] (3) The process first uses high-temperature calcination to synthesize lead zirconate titanate powder, then introduces glass powder and uses low-temperature hot pressing sintering, which effectively inhibits PbO volatilization and Pb migration and aggregation during the target sintering process, thereby avoiding problems such as uncontrolled chemical composition ratio, component segregation and red spots caused by high-temperature sintering in traditional methods. Therefore, the target material obtained has accurate chemical composition ratio, uniform composition and no red spot defects.

[0013] (4) After hot pressing sintering, the lead zirconate titanate sintered body is heat-treated in an oxygen-containing atmosphere, which can eliminate oxygen vacancy defects that may be generated during hot pressing sintering, resulting in fewer defects in the target material and greater stability during sputtering coating. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a physical image of the lead zirconate titanate target material prepared in Example 1 of this application; Figure 2 This is a physical image of the lead zirconate titanate target material prepared in Comparative Example 1 of this application. Detailed Implementation

[0016] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0017] The first aspect of this application provides a method for preparing lead zirconate titanate target material, comprising the following steps: S1: Preparation of lead zirconate titanate powder; S2: Lead zirconate titanate powder, glass powder, dispersant and solvent are mixed, ball-milled and dried to obtain sintering precursor powder; S3: Pre-press and hot-press the sintering precursor powder to obtain lead zirconate titanate sintered body; S4: The lead zirconate titanate sintered body is heat-treated in an oxygen-containing atmosphere and then machined to obtain the lead zirconate titanate target material.

[0018] The method for preparing lead zirconate titanate (PZT) targets provided in this application is based on the characteristic that the upper layer of PbO volatilizes more violently during high-temperature calcination. When filling the raw materials, the PbO content is gradually increased from the bottom to the top of the crucible to compensate for the loss of upper layer PbO volatilization, thereby generating lead zirconate titanate powder with a more uniform composition. This alleviates the problems of uneven composition and uncontrolled chemical composition ratio caused by rapid upper layer volatilization in traditional methods, laying the foundation for preparing uniform and precisely proportioned targets. Then, by adding a glass powder with a specific formulation, not only can the PbO contained in the glass powder dynamically compensate for PbO during hot pressing sintering, improving the accuracy of the target's chemical composition ratio, but it can also act as a sintering aid to lower the sintering temperature, inhibit Pb migration and aggregation, and improve the uniformity of the target. Simultaneously, other components of the glass powder can optimize the PZT grain boundaries and lattice, improving the piezoelectric properties of the PZT target. The process first involves high-temperature calcination to synthesize lead zirconate titanate powder, followed by the introduction of glass powder and low-temperature hot-pressing sintering. This effectively suppresses PbO volatilization and Pb migration and aggregation, thus avoiding problems such as uncontrolled chemical composition, component segregation, and red spots caused by high-temperature sintering in traditional methods. Therefore, the resulting target material has a precise chemical composition, uniform composition, and is free of red spot defects. Furthermore, after hot-pressing sintering, the sintered lead zirconate titanate body is heat-treated in an oxygen-containing atmosphere, which eliminates oxygen vacancy defects that may arise during hot-pressing sintering, resulting in fewer defects in the target material and greater stability during sputtering coating.

[0019] Step S1, in this embodiment, the step of preparing lead zirconate titanate powder includes: providing N kinds of raw material mixed powders with different PbO contents, each raw material mixed powder containing PbO powder, ZrO2 powder and TiO2 powder, N≥3; filling the raw material mixed powders into a crucible layer by layer from bottom to top according to the order of PbO content from low to high, covering and calcining to form lead zirconate titanate blocks; and ball milling the lead zirconate titanate blocks to obtain lead zirconate titanate powder. Specifically, the crucible can be a square crucible. Based on the reason that the upper layer of PbO volatilizes more violently during high-temperature calcination, the PbO content in the raw material mixed powder is gradually increased from the bottom to the top of the crucible during filling. This can accurately compensate for the more severe volatilization loss of the upper layer of PbO, thereby generating lead zirconate titanate powder with uniform composition. This alleviates the problem of uneven composition and uncontrolled chemical composition ratio caused by rapid volatilization of the upper layer in traditional methods, laying the foundation for preparing uniform and precisely proportioned target materials.

[0020] In the embodiments, N is 3 to 5. Providing 3 to 5 kinds of raw material mixed powders with different PbO contents not only makes the batching easy, but also effectively compensates for the loss of PbO volatilization in the upper layer, effectively solving the problems of uneven composition and uncontrolled chemical composition ratio caused by rapid volatilization in the upper layer in traditional methods.

[0021] In the embodiments, the molar ratios of PbO powder, ZrO2 powder, and TiO2 powder in the N raw material mixtures with different PbO contents are (1.0~1.1):(0.4~0.9):(0.1~0.6), (1.1~1.2):(0.4~0.9):(0.1~0.6), ..., (1.3~1.5):(0.4~0.9):(0.1~0.6). These mass ratio ranges of the raw material mixtures effectively compensate for the volatilization loss of the upper layer of PbO during high-temperature calcination, effectively solving the problems of uneven composition and uncontrolled chemical composition caused by rapid volatilization of the upper layer in traditional methods. Furthermore, they enable the generated lead zirconate titanate powder to possess excellent piezoelectric properties.

[0022] In the embodiments, the lead zirconate titanate powder has a particle size of 0.5~5μm. Ball milling the lead zirconate titanate bulk to this range helps to improve the sintering activity and uniformity of the powder, reduce the migration and aggregation of PbO during sintering, and thus improve the uniformity of the target material composition distribution.

[0023] In the embodiments, the calcination temperature is 1100~1300℃ and the time is 1~8h. This calcination time and temperature range can ensure that the raw material mixed powder reacts fully to generate lead zirconate titanate powder, and can also reduce the impact on the composition ratio of the solid solution powder caused by excessive volatilization of the upper PbO due to excessive temperature or time.

[0024] Step S2, in this embodiment, the glass powder comprises PbO, TiO2, Ta2O5, MnO2, and ZnO in a mass ratio of (30~60):(10~20):(10~30):(1~5):(5~15). PbO, as a glass network former, lowers the glass softening temperature, promotes low-temperature sintering of the target material, reduces Pb migration and aggregation, improves the uniformity of the target material, and can also compensate for the PbO volatilization from lead zirconate titanate powder, further improving the accuracy of the target material's chemical composition ratio. TiO2, as a nucleating agent, is distributed at the PZT grain boundaries, inhibiting PZT grain growth and increasing the target material's density. Ta2O5 contains Ta... 5+ As donor ions, they enter the PZT lattice, generating oxygen vacancy compensation and improving the piezoelectric and dielectric properties of the PZT thin film. MnO2 can reduce dielectric loss and improve device stability. ZnO, as a fluxing agent, lowers the glass melting point, allowing the glass powder to flow fully within the 700-800℃ hot-pressing window, promoting the densification of the target material during sintering. Simultaneously, Zn... 2+ It also acts as an acceptor dopant in the PZT lattice, improving piezoelectric properties. Therefore, the glass powder formulation in this embodiment can not only compensate for PbO and improve the accuracy of the target's chemical composition ratio, but also lower the sintering temperature, reduce Pb migration and aggregation, and improve the target's uniformity. Furthermore, it can also improve the piezoelectric properties of the PZT target.

[0025] In the embodiments, the glass powder has a particle size of 0.5~2μm. This particle size range helps the glass powder to be uniformly dispersed in the lead zirconate titanate powder, forming a continuous and uniform liquid phase during hot pressing and sintering, significantly promoting sintering densification, and acting more precisely at the grain boundaries between PZT particles to achieve in-situ compensation and reduce segregation caused by long-range migration of PbO.

[0026] In the embodiments, the mass ratio of lead zirconate titanate powder to glass powder is (0.9~0.95):(0.05~0.1). This mass ratio range can accurately compensate for PbO volatilization, reduce sintering temperature, reduce Pb migration and aggregation, improve the uniformity and density of the target material composition, and also enhance the dielectric properties of PZT.

[0027] In the examples, the dispersant is selected from at least one of polyethylene glycol, hexadecyl sulfonate, polycarboxylate, polyacrylate, or triethanolamine. The amount of dispersant added is 0.3-1% of the total mass of lead zirconate titanate powder and glass powder.

[0028] In the examples, the solvent is selected from ethanol or deionized water.

[0029] Step S3, in this embodiment, the hot pressing process includes: first heating to 400~500℃ and holding for 20~40 minutes; then heating to 600~700℃ and holding for 60~90 minutes; then heating to 700~880℃ and pressurizing to 10~30MPa, and holding for 60~120 minutes; after the holding is completed, the pressure is released and the furnace is cooled to room temperature. In the 400~500℃ stage, the adsorbed water, bound water, and organic matter in the powder are slowly decomposed and fully discharged to avoid cracks or pores in the green body due to excessive volatilization. In the 600~700℃ stage, the powder particles come into contact with each other and form necks under thermal activation, achieving pre-shrinkage and laying the structural foundation for subsequent high-temperature densification. In the pressure densification stage, the temperature is set above the glass softening point and significantly lower than the PbO volatilization temperature (1100~1200℃), which effectively avoids PbO volatilization. Furthermore, by applying high pressure, a strong sintering driving force is provided, which promotes particle rearrangement and accelerates pore shrinkage, thereby quickly eliminating closed pores and enabling the target material to achieve densification in a short time. This reduces Pb migration and aggregation and improves the uniformity of the target material.

[0030] Step S4: In this embodiment, the heat treatment temperature is 500~700℃ and the time is 4~8h.

[0031] In this embodiment, the oxygen-containing atmosphere is oxygen.

[0032] The second aspect of this application provides a lead zirconate titanate target material, which is prepared by the method for preparing lead zirconate titanate target material provided in this application.

[0033] The lead zirconate titanate target provided in this application embodiment is prepared by the method provided in this application embodiment, and therefore has the advantages of good compositional uniformity, high density, and accurate chemical composition ratio.

[0034] A third aspect of this application provides a piezoelectric device, including a piezoelectric thin film, which is obtained by sputtering coating of a lead zirconate titanate target provided in this application.

[0035] The piezoelectric device provided in this application embodiment contains a piezoelectric thin film obtained by sputtering the lead zirconate titanate target provided in this application embodiment. Therefore, the PZT thin film is uniform and dense with few defects, resulting in low dielectric loss and stable performance of the device.

[0036] The following description is based on specific embodiments.

[0037] Example 1 This embodiment provides a method for preparing lead zirconate titanate target material, including the following steps: (1) Preparation of lead zirconate titanate powder: Weigh appropriate amounts of PbO powder, ZrO2 powder and TiO2 powder in a molar ratio of 1.05:0.7:0.3, mix them evenly to obtain the first raw material mixed powder; Weigh appropriate amounts of PbO powder, ZrO2 powder, and TiO2 powder in a molar ratio of 1.1:0.7:0.3, mix them evenly, and obtain the second raw material mixed powder; Weigh appropriate amounts of PbO powder, ZrO2 powder, and TiO2 powder in a molar ratio of 1.2:0.7:0.3, mix them evenly, and obtain the third raw material mixed powder; Weigh appropriate amounts of PbO powder, ZrO2 powder and TiO2 powder in a molar ratio of 1.3 : 0.7 : 0.3, mix them evenly to obtain the fourth raw material mixed powder; Equal masses of the first raw material mixture powder, the second raw material mixture powder, the third raw material mixture powder, and the fourth raw material mixture powder were sequentially filled into the crucible from bottom to top. Then, another crucible was placed on top of the first crucible. The temperature of the sintering furnace was raised to 1200℃ and held for 6 hours before being cooled with the furnace to obtain lead zirconate titanate blocks. Lead zirconate titanate blocks were ball-milled to obtain lead zirconate titanate powder with a particle size of 0.5~5μm.

[0038] (2) Preparation of glass powder: Weigh appropriate amounts of PbO powder, TiO2 powder, Ta2O5 powder, MnO2 powder and ZnO powder in a mass ratio of 50:15:20:3:12, mix them and put them into an alumina ceramic crucible in a melting furnace; then heat the melting furnace to 1200℃ and keep it at that temperature for 1 hour to obtain glass melt; The molten glass was quenched in a cooling water tank with low-speed stirring. The quenching temperature was 25°C. After the quenching was completed, the glass was soaked in deionized water for 30 minutes to obtain a glass block. The glass frit was dried at 120℃, mechanically crushed, and passed through a 50-mesh sieve. It was then loaded into a ball mill, and ethanol and deionized water were added in a 1:1 ratio as the ball milling media. The mass ratio of the ball milling media to the glass frit was 1:1, and the mass ratio of the ball milling beads to the glass frit was 1:3. The mixture was first ground at medium speed for 18 hours, and then at high speed for 12 hours to obtain a slurry. The slurry was then sieved and centrifuged for solid-liquid separation. It was dried at 100℃ for 8 hours and then sieved again to obtain glass powder with a particle size of 0.5~2μm.

[0039] (3) Mixing treatment of lead zirconate titanate powder and glass powder: Weigh appropriate amounts of lead zirconate titanate powder and glass powder with a mass ratio of 0.92:0.08, add polyethylene glycol and deionized water and ball mill to mix, dry the resulting slurry and pass it through a 100-mesh sieve to obtain sintering precursor powder; the amount of polyethylene glycol added is 0.5% of the total mass of lead zirconate titanate powder and glass powder.

[0040] (4) Hot pressing sintering: The precursor powder for sintering is filled into a graphite mold and pre-formed under a pressure of 30 MPa. Then, the vacuum hot pressing furnace is evacuated until the vacuum degree reaches 10. -2 When the pressure is below Pa, the temperature is initially increased to 450℃ at 2℃ / min and held for 30min to fully degas and degrease; then the temperature is increased to 650℃ at 1.5℃ / min and held for 60min; then the temperature is increased to 800℃ at 1℃ / min, and the pressure is gradually increased to 20MPa and maintained at this temperature and pressure for 90min. After the holding and pressure holding are completed, the pressure is released and the furnace is cooled to room temperature to obtain the sintered lead zirconate titanate. (5) Heat treatment: The lead zirconate titanate sintered body is placed in an atmosphere sintering furnace, oxygen is introduced, and the temperature is raised to 600℃ and held for 5 hours. It is then naturally cooled to room temperature to obtain the lead zirconate titanate target semi-finished product.

[0041] (6) Machining: Cut the lead zirconate titanate target semi-finished product, grind the surface and trim the size to obtain the lead zirconate titanate target.

[0042] Example 2 This embodiment provides a method for preparing lead zirconate titanate target material, which differs from Example 1 in that: In step (2), replace “PbO powder, TiO2 powder, Ta2O5 powder, MnO2 powder, and ZnO powder in a mass ratio of 50:15:20:3:12” with “Bi2O3 powder, B2O3 powder, SiO2 powder, ZnO powder, and Al2O3 powder in a mass ratio of 49:25:15:6:5”.

[0043] Example 3 This embodiment provides a method for preparing lead zirconate titanate target material, which differs from Example 1 in that: (4) Hot pressing sintering: The precursor powder for sintering is filled into a graphite mold and pre-formed under a pressure of 30 MPa. Then, the vacuum hot pressing furnace is evacuated until the vacuum degree reaches 10. -2 When the pressure is below Pa, the temperature is initially increased to 450℃ at 2℃ / min and held for 30min to fully degas and degrease. Then, the temperature is increased to 650℃ at 1.5℃ / min and held for 60min. After that, the temperature is increased to 1150℃ at 1℃ / min, and then the pressure is gradually increased to 20MPa and maintained at this temperature and pressure for 90min. After the holding and pressure holding are completed, the pressure is released and the furnace is cooled to room temperature to obtain the sintered lead zirconate titanate target.

[0044] Example 4 This embodiment provides a method for preparing lead zirconate titanate target material, which differs from Example 1 in that: (1) Preparation of lead zirconate titanate powder: Weigh appropriate amounts of PbO powder, ZrO2 powder and TiO2 powder in a molar ratio of 1.15:0.7:0.3, mix them evenly to obtain raw material mixed powder; The raw material mixture powder is filled into a crucible, and then another crucible is placed on top of it. The temperature of the sintering furnace is then raised to 1200℃ and held for 6 hours before being cooled with the furnace to obtain lead zirconate titanate blocks. Lead zirconate titanate blocks were ball-milled to obtain lead zirconate titanate powder with a particle size of 0.5~5μm.

[0045] Comparative Example 1 This comparative example provides a method for preparing lead zirconate titanate target material, including the following steps: (1) Preparation of lead zirconate titanate powder: Weigh appropriate amounts of PbO powder, ZrO2 powder and TiO2 powder in a molar ratio of 1.15:0.7:0.3, mix them evenly to obtain raw material mixed powder; The raw material mixture powder is filled into a crucible, and then another crucible is placed on top of it. The temperature of the sintering furnace is then raised to 850°C and held for 8 hours before being cooled with the furnace to obtain lead zirconate titanate blocks. Lead zirconate titanate blocks were ball-milled to obtain lead zirconate titanate powder with a particle size of 0.5~5μm.

[0046] (2) Mixing treatment: Weigh an appropriate amount of lead zirconate titanate powder and mix it with polyethylene glycol and deionized water by ball milling. After drying the resulting slurry, pass it through a 100-mesh sieve to obtain sintering precursor powder. The amount of polyethylene glycol added is 0.5% of the total mass of lead zirconate titanate powder.

[0047] (3) Cold isostatic pressing: The sintering precursor powder is filled into the mold and then placed in a cold isostatic press (CIP) machine for pressing. The CIP pressure is 220 MPa, and a green blank with a relative density of 60% is obtained.

[0048] (4) Air sintering: The green blank is placed in a sintering furnace and heated to 450°C at 1.5°C / min in an air atmosphere. It is held for 12 hours, then heated to 1200°C at 1.5°C / min and held for 8 hours. It is then cooled in the furnace to obtain the semi-finished lead zirconate titanate target material.

[0049] (5) Machining: Cut the semi-finished lead zirconate titanate target, grind the surface and trim the dimensions to obtain the lead zirconate titanate target.

[0050] Comparative Example 2 This comparative example provides a method for preparing lead zirconate titanate target material, which differs from Example 1 in that: No glass powder is added, that is, step (2) is omitted, and step (3) is to weigh an appropriate amount of lead zirconate titanate powder and mix it with polyethylene glycol and deionized water by ball milling.

[0051] Relevant performance test analysis: 1. After the target material was encapsulated, the actual density of the lead zirconate titanate targets prepared in Examples 1-4 and Comparative Examples 1-2 was tested using the Archimedes density test method. The relative density was calculated using the following formula based on the theoretical density: Relative density = Actual density / Theoretical density × 100%; The test results are shown in Table 1 below.

[0052] 2. The Pb element content of the lead zirconate titanate targets prepared in Examples 1-4 and Comparative Examples 1-2 was tested using X-ray fluorescence spectrometry (XRF). Specifically, five test points were evenly selected along the cross-section of the lead zirconate titanate target, and the actual Pb element content at each point was measured. Based on the molar ratio of PbO, ZrO2, and TiO2 powders, the Pb content in the raw material mixture was calculated to be 64.85 wt%. The test results are shown in Table 2 below.

[0053] Table 1 Table 2 From Table 1, Table 2 and Figure 1 , Figure 2As can be seen, the lead zirconate titanate target material prepared in Example 1 has a high relative density, a small difference in Pb content at various points, and a uniform surface color without red spots. This is mainly due to the following: First, in this application example, the PbO content is gradually increased from bottom to top during filling, compensating for the PbO volatilization loss in the upper layer during calcination, thereby obtaining lead zirconate titanate powder with uniform composition. Second, the lead zirconate titanate powder is mixed with glass powder of a specific composition and then subjected to low-temperature hot pressing sintering. In this process, the PbO in the glass powder can compensate for the PbO volatilization during calcination and sintering, making the chemical composition ratio of the target material more accurate. At the same time, the glass powder acts as a sintering aid, promoting the densification of the green body at a lower temperature and inhibiting Pb migration and aggregation. Therefore, the target material has a precise composition ratio, good density, and good uniformity.

[0054] The lead zirconate titanate target material prepared in Example 2 has a significantly different Pb content from the raw material at various points, and the color is slightly uneven with a small number of red spots. The main reason is that Example 2 used ordinary glass powder, which cannot compensate for the volatilization of PbO during the calcination and sintering stages, and it only plays a role in assisting calcination. Its components do not inhibit the migration and aggregation of Pb.

[0055] The lead zirconate titanate target material prepared in Example 3 has a relatively low density, cracks, and Pb metal precipitation, and the Pb content varies greatly at different points. The main reason is that Example 3 uses high-temperature hot pressing sintering. The excessively high temperature causes PbO to volatilize violently and unevenly, and at the same time accelerates the migration and local reduction of Pb elements, resulting in compositional fluctuations, structural defects and Pb metal precipitation, which is also not conducive to the formation of a high-density target material.

[0056] The lead zirconate titanate target material prepared in Example 4 was uneven in color and had red spots, and the Pb content at each point varied greatly. The main reason was that the same ratio of raw material mixed powder was used in Example 4 when filling, which failed to compensate for the loss of PbO volatilization in the upper layer during calcination, resulting in uneven lead zirconate titanate powder. This led to differences in composition and microstructure in the target material produced by subsequent hot pressing and sintering.

[0057] The lead zirconate titanate target material prepared in Comparative Example 1 has a low relative density, uneven color, and red spots, and the Pb content varies greatly from point to point. The main reason is that Comparative Example 1 uses low-temperature calcination to synthesize lead zirconate titanate powder, followed by high-temperature atmospheric pressure sintering. High temperature will aggravate the uneven volatilization of PbO and the migration and aggregation of Pb. In addition, the lack of external pressure leads to insufficient driving force, making it difficult to achieve densification.

[0058] The lead zirconate titanate target material prepared in Comparative Example 2 has a lower relative density and the Pb content at each point is lower than that of the raw material. The main reason is that no glass powder was added in Comparative Example 2, which resulted in the lead zirconate titanate solid powder lacking effective PbO compensation, sintering aid and PbO volatilization inhibition during the hot pressing sintering stage, which led to further loss of Pb element and insufficient densification process.

[0059] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a lead zirconate titanate target, characterized in that, Includes the following steps: N kinds of raw material mixed powders with different PbO contents are provided, each of the raw material mixed powders contains PbO powder, ZrO2 powder and TiO2 powder, wherein N≥3; The raw material mixture powder is filled into a crucible in layers from bottom to top according to the PbO content from low to high. After being covered, it is calcined to form lead zirconate titanate blocks. The lead zirconate titanate block was ball-milled to obtain lead zirconate titanate powder; The lead zirconate titanate powder, glass powder, dispersant and solvent are mixed, ball-milled and dried to obtain sintering precursor powder; The sintering precursor powder is pre-pressed and hot-pressed to obtain a lead zirconate titanate sintered body. The sintered lead zirconate titanate body is heat-treated in an oxygen-containing atmosphere and then machined to obtain the lead zirconate titanate target.

2. The preparation method according to claim 1, characterized in that, At least one of the following conditions must be met: The value of N is 3 to 5; In the N kinds of raw material mixed powders with different PbO contents, the molar ratios of PbO powder, ZrO2 powder and TiO2 powder are (1.0~1.1):(0.4~0.9):(0.1~0.6), (1.1~1.2):(0.4~0.9):(0.1~0.6), ..., (1.3~1.5):(0.4~0.9):(0.1~0.6); The particle size of the lead zirconate titanate powder is 0.5~5μm.

3. The preparation method according to claim 1, characterized in that, The calcination treatment is carried out at a temperature of 1100~1300℃ for 1~8 hours.

4. The preparation method according to claim 1, characterized in that, The glass powder comprises PbO, TiO2, Ta2O5, MnO2, and ZnO in a mass ratio of (30~60):(10~20):(10~30):(1~5):(5~15); And / or, the particle size of the glass powder is 0.5~2μm.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the lead zirconate titanate powder to the glass powder is (0.9~0.95):(0.05~0.1).

6. The preparation method according to claim 1, characterized in that, The hot pressing process includes: first, heating to 400~500℃ and holding for 20~40 minutes; then heating to 600~700℃ and holding for 60~90 minutes; then heating to 700~880℃ and pressurizing to 10~30MPa, and holding for 60~120 minutes; after the holding is completed, the pressure is released and the furnace is cooled to room temperature.

7. The preparation method according to claim 1, characterized in that, The heat treatment is performed at a temperature of 500~700℃ for 4~8 hours. And / or, the oxygen-containing atmosphere is oxygen.

8. The preparation method according to claim 1, characterized in that, The dispersant is selected from at least one of polyethylene glycol, hexadecyl sulfonate, polycarboxylate, polyacrylate, or triethanolamine; And / or, the solvent is selected from ethanol or deionized water.

9. A lead zirconate titanate target, characterized in that, It is prepared by the method for preparing lead zirconate titanate target according to any one of claims 1 to 8.

10. A piezoelectric device comprising a piezoelectric thin film, characterized in that, The piezoelectric thin film is obtained by sputtering coating with the lead zirconate titanate target as described in claim 9.

Images