A piezoelectric ceramic and its application

Abstract

This invention discloses a piezoelectric ceramic and its application. The piezoelectric ceramic uses barium titanate as a matrix and significantly improves piezoelectric performance and thermal stability by replacing some titanium ions with zirconium and tin ions. The piezoelectric ceramic adopts a lead-free formula, which is in line with the development trend of green and environmentally friendly products.

Description

Technical Field

[0001] This invention belongs to the field of power capacitors and relates to a piezoelectric ceramic and its applications. Background Technology

[0002] The piezoelectric effect was discovered in 1880 by Nobel laureates Pierre and Jacques Curie when they studied the effect of pressure on the generation of electric charge in crystals such as quartz, tourmaline, and Rochelle salt. This effect describes the generation of electric charge in crystals under mechanical pressure, or the mechanical deformation caused by the electric charge. However, a major drawback of natural piezoelectric materials is their relatively low piezoelectric properties.

[0003] The discovery of PZT and BaTiO3 in the 1950s brought about a major breakthrough, as these materials exhibited extremely high dielectric and piezoelectric properties. To date, PZT remains one of the most widely developed and used piezoelectric materials, holding a permanent place in materials science and engineering. They are widely used in sensors, actuators, multilayer capacitors, hydrophones, and more, with a global market estimated at tens of billions of dollars. However, lead oxide, a component of PZT, is highly toxic. Its toxicity is further enhanced by volatilization at high temperatures, particularly during calcination and sintering, causing environmental pollution. Researchers have made numerous attempts to develop lead-free alternatives, but their performance has fallen far short of that of PZT.

[0004] Lead-free materials with perovskite structure, such as Bi 0.5 Na 0.5 TiO3 (BNT), BaTiO3 (BT), and KNbO3 (KNN) are promising candidates for lead-free piezoelectric ceramics. BNT-based and KNN-based ceramics have advantages in terms of large electrostrain and high electromechanical coupling coefficient, respectively, along with high Curie temperatures. However, both suffer from the problem of alkali metals such as Bi, Na, and K volatilizing during high-temperature synthesis. Furthermore, their pure matrix piezoelectric responses are low, not exceeding 100 pC / N. BT-based ceramics, on the other hand, do not have the alkali metal volatilization problem, and pure BT has a piezoelectric response of approximately 130 pC / N, while also possessing good electrostrain and electromechanical coupling coefficients. However, their piezoelectric performance is still significantly lower than that of PZT. The main challenge lies in obtaining a lead-free piezoelectric ceramic system that balances high electroelectric coefficient and large electrostrain through effective control methods.

[0005] For the reasons mentioned above, there is an urgent need to provide a piezoelectric ceramic that combines high temperature stability and a large piezoelectric coefficient. Summary of the Invention

[0006] To overcome the above problems, this invention proposes a piezoelectric ceramic and its application. The piezoelectric ceramic uses BaTiO3 as a matrix and significantly improves piezoelectric performance and thermal stability by replacing some titanium ions with zirconium and tin ions.

[0007] Specifically, the object of the present invention is to provide the following aspects:

[0008] In a first aspect, a piezoelectric ceramic is provided, wherein the piezoelectric ceramic is obtained by replacing some titanium ions with zirconium ions and tin ions, using barium titanate as a matrix.

[0009] The piezoelectric ceramic grain size is 99~122μm.

[0010] The piezoelectric ceramic has a piezoelectric coefficient of 450~500 pC / N at 60℃.

[0011] The characteristic feature is that the piezoelectric ceramic has the following expression: BaTi 1-x-y Sn x Zr y O3.

[0012] Where 0.05≤x≤0.07.

[0013] Where 0.005≤y≤0.015.

[0014] In a second aspect, a method for preparing the piezoelectric ceramic described in the first aspect is provided, the method comprising:

[0015] Step 1: Mix barium source, zirconium source, tin source and titanium source, and obtain the first powder by one sintering;

[0016] Step 2: Granulate the first powder to obtain the second powder;

[0017] Step 3: The second powder is sintered a second time to obtain the piezoelectric ceramic.

[0018] In step 1, the barium source, zirconium source, tin source, and titanium source have the following atomic percentages:

[0019] 100 at% of barium source

[0020] Tin source 5~7 at%

[0021] Zirconium source 0.5~1.5 at%

[0022] Titanium source 91.5~94.5 at%.

[0023] In step 2, the first powder is mixed with the molding aid during granulation.

[0024] Thirdly, a power capacitor is provided, the power capacitor comprising the piezoelectric ceramic described in the first aspect or the piezoelectric ceramic prepared according to the method described in the second aspect.

[0025] The beneficial effects of this invention include:

[0026] (1) The piezoelectric ceramic provided by the present invention uses BaTiO3 as the matrix and replaces part of the titanium ions with zirconium ions and tin ions, which significantly improves the piezoelectric coefficient, thereby improving the performance in energy conversion and signal transmission.

[0027] (2) The piezoelectric ceramics provided by the present invention have large electro-induced strain, which makes piezoelectric ceramics have a wider range of application potential in precision driving and deformation control.

[0028] (3) The piezoelectric ceramic provided by the present invention exhibits a phase transition at 24~26℃ and 64~66℃. These two temperatures are slightly higher than room temperature, which is beneficial to maintaining stable piezoelectric performance in practical applications and reducing the impact of temperature fluctuations on device performance.

[0029] (4) The preparation method of piezoelectric ceramics provided by the present invention is simple and easy to implement, and the raw materials are made of lead-free formula, which avoids the environmental pollution problems that may be generated during the high-temperature treatment of lead-based piezoelectric ceramics, and is in line with the development trend of green and environmental protection. Attached Figure Description

[0030] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0031] In the attached diagram:

[0032] Figure 1 The SEM image of the piezoelectric ceramic prepared in Example 1 is shown.

[0033] Figure 2 The particle size distribution of the piezoelectric ceramics prepared in Example 1 is shown.

[0034] Figure 3 The graph shows the change of dielectric constant and dielectric loss of the piezoelectric ceramic prepared in Example 1 with temperature.

[0035] Figure 4 The graph shows the piezoelectric coefficient of the piezoelectric ceramic prepared in Example 1 as a function of temperature.

[0036] Figure 5The electro-strain diagram of the piezoelectric ceramic prepared in Example 1 is shown;

[0037] Figure 6 The SEM image of the piezoelectric ceramic prepared in Example 2 is shown.

[0038] Figure 7 The particle size distribution of the piezoelectric ceramics prepared in Example 2 is shown.

[0039] Figure 8 The graph shows the piezoelectric coefficient of the piezoelectric ceramic prepared in Example 2 as a function of temperature. Detailed Implementation

[0040] The following will refer to the appendix. Figures 1 to 8 Specific embodiments of the invention will be described in more detail below. While specific embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0041] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0042] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this invention, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0044] In a first aspect, according to the present invention, a piezoelectric ceramic is obtained by using barium titanate (BaTiO3) as a matrix and replacing some titanium ions with zirconium ions and tin ions.

[0045] In this invention, the piezoelectric properties of BaTiO3 change with temperature, especially near the phase transition temperature. By replacing some titanium (Ti) ions with zirconium (Zr) and tin (Sn) ions, the crystal structure is altered, the phase transition temperature is adjusted, and the operating temperature range of the piezoelectric ceramic is broadened, allowing it to maintain good piezoelectric properties under a wider range of temperature conditions. In addition, the appropriate amount of zirconium and tin ions replacing some titanium ions reduces the influence of temperature on piezoelectric properties, enabling the piezoelectric ceramic to maintain stable performance under different environments. The introduction of zirconium and tin ions also changes the dielectric constant of the piezoelectric ceramic.

[0046] In a preferred embodiment, the piezoelectric ceramic has the following expression: BaTi 1-x-y Sn x Zr y O3, 0.05≤x≤0.07, 0.005≤y≤0.015; for example, x=0.06, y=0.01.

[0047] In this invention, the grain size distribution of the piezoelectric ceramic conforms to a log-normal distribution, with an average grain size of 99~122μm; the piezoelectric coefficient is between 230~500pC / N in the range of 20~80℃, and reaches 450~500pC / N at 60℃; the maximum strain reaches 0.129% when an external electric field of 30 kV / cm is applied, that is, it has a large electroinduced strain.

[0048] Furthermore, the piezoelectric ceramic exhibits a phase transition temperature from orthorhombic to tetragonal phase at 24–26 °C and a phase transition temperature from tetragonal to cubic phase at 64–66 °C. It is precisely because the phase transition temperatures at 24–26 °C and 64–66 °C, slightly above room temperature, have lower energy barriers and weaker anisotropy, that polarization reversal is easier, resulting in greater piezoelectric and dielectric responses, far exceeding the piezoelectric coefficient and dielectric constant of undoped BaTiO3.

[0049] Secondly, according to the method for preparing the piezoelectric ceramic described in the first aspect of the present invention, the method includes:

[0050] Step 1: Mix barium source, zirconium source, tin source and titanium source, and obtain the first powder by one sintering;

[0051] Step 2: Granulate the first powder to obtain the second powder;

[0052] Step 3: The second powder is sintered a second time to obtain the piezoelectric ceramic.

[0053] Specifically:

[0054] Step 1: Mix barium source, zirconium source, tin source and titanium source, and obtain the first powder by one sintering.

[0055] In step 1, the barium source is preferably barium carbonate and / or barium titanate, more preferably barium carbonate.

[0056] In this process, barium ions in the barium source help improve the dielectric constant. They combine with oxides from zirconium, tin, and titanium sources to form stable perovskite structures such as BaZrO3, BaSnO3, and BaTiO3, thereby enhancing piezoelectric properties. Barium carbonate decomposes into barium oxide during the primary sintering process, which then reacts with other raw materials, resulting in more stable high-temperature performance. The generated carbon dioxide can act as a sintering aid, promoting densification.

[0057] In step 1, the zirconium source is preferably barium zirconate and / or zirconium dioxide, preferably zirconium dioxide.

[0058] In this process, zirconium ions in the zirconium source partially replace titanium ions, stabilizing the crystal structure of barium titanate. Titanium ions help suppress grain growth and improve the piezoelectric resistance of the piezoelectric ceramic, making it more stable under an electric field. Zirconium dioxide is also less expensive and has good chemical stability at high temperatures. It reacts with barium oxide to form a BaZrO3 solid solution.

[0059] In step 1, the tin source is preferably tin dioxide.

[0060] The tin dioxide typically maintains a stable tetragonal phase at high temperatures, reacting with barium oxide to form BaSnO3 or forming a solid solution with a titanium source such as titanium dioxide, such as Ba(Ti,Sn)O3.

[0061] In step 1, the titanium source is preferably titanium dioxide and / or barium titanate, with titanium dioxide being more preferred.

[0062] In this process, titanium ions in the titanium source help form and modulate electric domains, which is key to the piezoelectric effect. High-purity titanium dioxide is beneficial for preparing high-performance piezoelectric ceramics.

[0063] In this invention, the barium source, zirconium source, tin source, and titanium source have the following atomic percentages:

[0064] 100 at% of barium source

[0065] Tin source 5~7 at%

[0066] Zirconium source 0.5~1.5 at%

[0067] Titanium source 91.5~94.5 at%.

[0068] Here, the atomic percentage is understood as the percentage of the number of atoms of a certain element in a certain raw material relative to the total number of atoms of all elements at that position. Let A-position atom include barium atoms, and the total percentage of atoms at A-position is 100 at%. In this case, barium atoms account for 100 at% of the atomic number of A-position atom. Let B-position atom include zirconium atoms, tin atoms, and titanium atoms, and the total percentage of atoms at B-position is 100 at%. In this case, zirconium atoms account for 0.5~1.5 at% of the atomic number of B-position atom, tin atoms account for 5~7 at% of the atomic number of B-position atom, and the remainder is the atomic number of titanium atoms.

[0069] In a preferred embodiment, the barium source, zirconium source, tin source, and titanium source have the following atomic percentages:

[0070] Barium carbonate 100 at%

[0071] 6 at% tin dioxide

[0072] Zirconium dioxide 1 at%

[0073] Titanium dioxide 93at%.

[0074] According to a preferred embodiment, step 1 includes the following steps:

[0075] Step 1-1: Mix the barium source, zirconium source, tin source and titanium source, and then grind them once to obtain a mixed slurry;

[0076] Steps 1-2 involve drying and sieving the mixed slurry, followed by a single sintering process to obtain the first powder.

[0077] In step 1-1, the grinding medium used in the first grinding is an alcohol solvent, preferably anhydrous ethanol, which is non-toxic and safe to handle. The grinding medium protects the mixture during the first grinding process. Ethanol has a low boiling point, is easily volatile, and can be easily removed in the subsequent sintering process. It also has low surface tension, which prevents the mixed slurry from clumping.

[0078] In step 1-1, the weight ratio of the mixture of barium source, calcium source, zirconium source and titanium source to the grinding media is 1:(1~3), preferably 1:(1~2), and more preferably 1:1.4.

[0079] If there are too few grinding media, the mixture cannot be fully protected; if there are too many grinding media, the grinding efficiency will be reduced.

[0080] In step 1-1, the grinding speed is 100~500 r / min, preferably 200~400 r / min, for example 300 r / min.

[0081] As the grinding speed increases, the powder particles become finer and more evenly distributed; however, excessively fast grinding speeds can cause the mixed slurry to agglomerate.

[0082] In step 1-1, the grinding time is 1 to 10 hours, preferably 3 to 5 hours, and more preferably 4 hours.

[0083] As the grinding time increases, the mixed slurry becomes more and more uniformly dispersed. However, if the grinding time is too long, the refining effect is not obvious. Instead, the activity of the mixed slurry increases continuously during the grinding process, resulting in severe work hardening.

[0084] In steps 1-2, the drying temperature is 60~80℃ and the time is 12~16h; for example, the drying temperature is 80℃ and the time is 12h.

[0085] In steps 1-2, in order to refine the particle size of the mixed slurry, the dried mixed slurry is sieved through 60-mesh and 100-mesh screens in sequence.

[0086] In steps 1-2, the temperature of the first sintering is 1100~1350℃, preferably 1200~1300℃, for example 1250℃; the sintering time is 1~5h, preferably 2~4h, for example 3h.

[0087] The chosen temperature is to ensure the material reacts fully to form the target compound. Increasing the temperature or extending the sintering time in the first sintering stage increases grain size and blurs grain boundaries. During high-temperature sintering, grain boundary atoms diffuse more easily; the longer the sintering time, the more severe the diffusion and the more blurred the grain boundaries. Within the aforementioned temperature and time range for the first sintering stage, it is beneficial to obtain the desired first powder.

[0088] Step 2: Granulate the first powder to obtain the second powder.

[0089] In step 2, the granulation includes: secondary grinding and mixing with molding aids.

[0090] In step 2, in order to refine the particle size of the first powder, it is preferable to sieve the first powder through 60-mesh and 100-mesh sieves in sequence.

[0091] Furthermore, secondary grinding helps to pulverize the first powder, making it easier to mix evenly with the molding aid.

[0092] In step 2, the secondary grinding medium is an alcohol solvent, preferably anhydrous ethanol, which is non-toxic and safe to operate.

[0093] In step 2, the weight ratio of the first powder to the secondary grinding media is 1:(1~3), preferably 1:(1~2), and more preferably 1:1.4.

[0094] In step 2, the secondary grinding speed is 100~500 r / min, preferably 200~400 r / min, for example 300 r / min; the secondary grinding time is 5~12 h, preferably 6~10 h, more preferably 8 h.

[0095] If the alcohol solvent used in the secondary grinding is not removed, it will affect the mixing effect of the subsequent molding aids and easily cause agglomeration. Drying can effectively reduce agglomeration and improve dispersibility; drying is beneficial to improving the stability and reliability of the final product.

[0096] Furthermore, the drying temperature and time only need to be sufficient to remove the alcohol solvent. Typically, the drying temperature is 60–80°C, and the time is 12–16 hours; for example, a drying temperature of 80°C and a time of 12 hours.

[0097] In step 2, the molding aid is a water-soluble polymer, preferably polyvinyl alcohol glue.

[0098] Among them, water-soluble polymers have good adhesion, especially polyvinyl alcohol adhesives, which help with the molding and quality control of the final product, and are biodegradable and environmentally friendly.

[0099] Furthermore, the molding aid is added at a rate of 6-10 wt% of the mass of the powder after secondary grinding and drying, for example, 8 wt%. Excessive molding aid leads to an overly soft or deformed preform, while insufficient molding aid results in insufficient preform strength and structural instability. An addition of 6-10 wt% provides sufficient adhesive force to ensure the powder does not scatter during pressing, while also maintaining the structural stability of the preform.

[0100] In step 2, after mixing with molding aids, a second powder with a particle size between 60 and 100 mesh is obtained.

[0101] Step 3: The second powder is sintered a second time to obtain the piezoelectric ceramic.

[0102] In step 3, before the second sintering, the second powder is pressed into a blank. The pressed blank is more likely to be densified during the second sintering process because pressing has already provided a preliminary shape and structure. During the second sintering, it is only necessary to further eliminate pores and promote grain growth.

[0103] In step 3, the pressing pressure is 4~5 MPa, for example 4.3 MPa.

[0104] In step 3, the temperature of the secondary sintering is 1450~1700℃, preferably 1500~1600℃, for example 1550℃; the secondary sintering time is 3~5h, preferably 4~5h, for example 4h.

[0105] Higher sintering temperatures and longer sintering times significantly increase grain size. Grain growth depends on grain boundary migration; higher sintering temperatures lead to faster migration rates, while longer sintering times result in more complete grain boundary migration, significantly reducing porosity and ultimately increasing ceramic density. The aforementioned secondary sintering temperatures and times are used to obtain piezoelectric ceramics with excellent structures.

[0106] Thirdly, according to the present invention, a power capacitor includes the piezoelectric ceramic described in the first aspect or the piezoelectric ceramic prepared according to the method described in the second aspect.

[0107] The present invention is further described below through specific examples; however, these examples are merely exemplary and do not constitute any limitation on the scope of protection of the present invention.

[0108] Example 1

[0109] (1) Mix barium carbonate, tin dioxide, zirconium dioxide and titanium dioxide according to the following atomic percentages and place them in a grinding jar:

[0110] Barium carbonate 100 at%

[0111] 6 at% tin dioxide

[0112] Zirconium dioxide 1 at%

[0113] Titanium dioxide 93at%.

[0114] Next, 200 mL of anhydrous ethanol was added to the grinding jar (at this time, the mass ratio of the mixed powder to anhydrous ethanol was 1:1.4), and the grinding jar was placed in a planetary mill and ground at 300 r / min for 4 hours to obtain a mixed slurry. The mixed slurry was dried at 80℃ for 12 hours and then sieved through 60 mesh and 100 mesh screens in sequence. The sieved mixed slurry was sintered at 1250℃ for 3 hours to obtain the first powder.

[0115] (2) The first powder was sieved through 60 mesh and 100 mesh screens in sequence. The sieved powder was then put into a planetary mill and ground for 8 hours at 300 r / min (at this time, the mass ratio of the first powder to anhydrous ethanol was 1:1.4). After that, it was dried at 80℃ for 12 hours. Then, it was mixed with 8wt% polyvinyl alcohol to obtain a second powder with a particle size between 60 and 100 mesh.

[0116] (3) The second powder was placed in a tablet press and pressed into a blank at 4.3 MPa, and then sintered again at 1550℃ for 4 hours to obtain the piezoelectric ceramic BaTi. 0.93 Sn 0.06 Zr 0.01 O3.

[0117] Figure 1 The SEM image of the prepared piezoelectric ceramic is shown, which shows that there are independent grains and clear grain boundaries, and very few pores.

[0118] Figure 2 The particle size distribution of the piezoelectric ceramic is shown, and it can be seen that the grain size distribution conforms to a log-normal distribution with an average grain size of 121.29 μm.

[0119] Figure 3 The graphs showing the dielectric constant and dielectric loss of the fabricated piezoelectric ceramic as a function of temperature reveal anomalies around 25°C and 65°C, corresponding to the phase transition temperatures from orthorhombic to tetragonal and from tetragonal to cubic phases, respectively. It is precisely because these phase transition temperatures are located slightly above room temperature that the energy barriers are lower and the anisotropy is weaker, making polarization reversal easier and thus resulting in greater piezoelectric and dielectric responses.

[0120] Figure 4 The graph shows the piezoelectric coefficient of the prepared piezoelectric ceramic as a function of temperature. It can be seen that the maximum piezoelectric coefficient of 500 pC / N is obtained at 60℃, which is much higher than the 120 pC / N of pure barium titanate, indicating that it has a large piezoelectric coefficient.

[0121] Figure 5 The electro-strain diagram of the prepared piezoelectric ceramic is shown. At 25℃, the maximum strain is 0.129% when an electric field of 30 kV / cm is applied, which is much higher than that of pure barium titanate (0.04%), indicating a large electro-strain.

[0122] Example 2

[0123] (1) Mix barium carbonate, tin dioxide, zirconium dioxide and titanium dioxide according to the following atomic percentages and place them in a grinding jar:

[0124] Barium carbonate 100 at%

[0125] 6 at% tin dioxide

[0126] Zirconium dioxide 1 at%

[0127] Titanium dioxide 93at%.

[0128] Next, 200 mL of anhydrous ethanol was added to the grinding jar (at this time, the mass ratio of the mixed powder to anhydrous ethanol was 1:1.4), and the grinding jar was placed in a planetary mill and ground at 300 r / min for 4 hours to obtain a mixed slurry. The mixed slurry was dried at 80℃ for 12 hours and then sieved through 60 mesh and 100 mesh screens in sequence. The sieved mixed slurry was sintered at 1250℃ for 3 hours to obtain the first powder.

[0129] (2) The first powder was sieved through 60 mesh and 100 mesh screens in sequence. The sieved powder was then put into a planetary mill and ground for 8 hours at 300 r / min (at this time, the mass ratio of the first powder to anhydrous ethanol was 1:1.4). After that, it was dried at 80℃ for 12 hours. Then, it was mixed with 8wt% polyvinyl alcohol to obtain a second powder with a particle size between 60 and 100 mesh.

[0130] (3) The second powder was placed in a tablet press and pressed into a blank at 4.3 MPa, and then sintered at 1500℃ for 4 hours to obtain the piezoelectric ceramic BaTi. 0.93 Sn 0.06 Zr 0.01 O3.

[0131] Figure 6 The SEM image of the prepared piezoelectric ceramic is shown, which shows that there are independent grains and clear grain boundaries, and very few pores.

[0132] Figure 7 The particle size distribution of the piezoelectric ceramic is shown, and it can be seen that the grain size distribution conforms to a log-normal distribution with an average grain size of 99.85 μm.

[0133] Figure 8 The graph shows the piezoelectric coefficient of the prepared piezoelectric ceramic as a function of temperature. It can be seen that the maximum piezoelectric coefficient of 453 pC / N is obtained at 60℃, which is much higher than the 120 pC / N of pure barium titanate, indicating that it has a large piezoelectric coefficient.

[0134] The present invention has been described in detail above with reference to preferred embodiments and exemplary examples. However, it should be noted that these specific embodiments are merely illustrative explanations of the invention and do not constitute any limitation on the scope of protection of the invention. Various improvements, equivalent substitutions, or modifications can be made to the technical content and embodiments of the present invention without departing from the spirit and scope of protection of the invention, and all such modifications fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A piezoelectric ceramic, characterized in that, The piezoelectric ceramic is obtained by replacing some titanium ions with zirconium and tin ions, using barium titanate as the matrix.

2. The piezoelectric ceramic according to claim 1, characterized in that, Preferably, the piezoelectric ceramic grain size is 99~122μm.

3. The piezoelectric ceramic according to claim 1, characterized in that, The piezoelectric ceramic has a piezoelectric coefficient of 450~500 pC / N at 60℃.

4. The piezoelectric ceramic according to claim 1, characterized in that, The piezoelectric ceramic has the following expression: BaTi 1-x-y Sn x Zr y O3.

5. The piezoelectric ceramic according to claim 4, characterized in that, 0.05≤x≤0.07。 6. The piezoelectric ceramic according to claim 4, characterized in that, 0.005≤y≤0.015。 7. A method for preparing the piezoelectric ceramic according to any one of claims 1 to 6, characterized in that, The method includes: Step 1: Mix barium source, zirconium source, tin source and titanium source, and obtain the first powder by one sintering; Step 2: Granulate the first powder to obtain the second powder; Step 3: The second powder is sintered a second time to obtain the piezoelectric ceramic.

8. The method according to claim 7, characterized in that, In step 1, the barium source, zirconium source, tin source, and titanium source have the following atomic percentages: 100 at% of barium source Tin source 5~7 at% Zirconium source 0.5~1.5 at% Titanium source 91.5~94.5 at%.

9. The method according to claim 7, characterized in that, In step 2, the first powder is mixed with the molding aid during granulation.

10. A power capacitor, characterized in that, The power capacitor includes the piezoelectric ceramic as described in any one of claims 1 to 6 or the piezoelectric ceramic prepared by the method described in any one of claims 7 to 9.

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