A directionally designed strontium lead titanate dielectric ceramic, a preparation method and a ceramic capacitor

Abstract

The application provides a kind of orientation design strontium lead titanate dielectric ceramic, preparation method and ceramic capacitor, the chemical general formula of dielectric ceramic is (PbxSr1-aBia) TiO3, a is Bi mole number and 0.02 ≦ a ≦ 0.05;The relationship between the target Curie temperature of dielectric ceramic and Pb mole number satisfies linear design equation;Wherein, Tc is target Curie temperature, x is Pb mole number, 398 ≦ k ≦ 402, -82 ≦ h ≦ -78.The element formula of dielectric ceramic of the application is directly determined according to the need of target Curie temperature by design equation, changes the traditional trial-and-error type formula design into quantitative calculation mode, reduces the deviation between actual Curie temperature of strontium lead titanate and target value, improves the controllability of capacitance-temperature characteristics of dielectric ceramic and reduces dielectric loss performance.Avoid the traditional iterative cycle trial-and-error formula design method, significantly shorten the development cycle of strontium lead titanate dielectric ceramic formula, improve the research and development efficiency.

Description

Technical Field

[0001] This invention belongs to the field of electronic ceramic materials technology, specifically providing a directional design of strontium lead titanate dielectric ceramic, its preparation method, and a ceramic capacitor. Background Technology

[0002] Perovskite titanate ceramics are essential basic materials for electronic ceramics, functional ceramics, and electrical ceramics. In power transmission, pulse power systems, and power electronic equipment, voltage-equalizing ceramic capacitors play a crucial role in voltage balancing, energy buffering, and resonant filtering. These applications require the dielectric ceramic to not only possess a suitable dielectric constant and low dielectric loss, but also to meet stringent requirements regarding the temperature stability of its dielectric constant. Typically, the material needs to maintain the capacitance change rate as smoothly and controllably as possible over a wide operating temperature range.

[0003] Currently, the most commonly used equalizing capacitors are barium titanate (BaTiO3) or barium strontium titanate (BaTiO3). x Sr 1-x TiO3 (BST)-based dielectric ceramic systems. BST solid solutions can adjust the Curie temperature and modulate the dielectric temperature spectrum by controlling the Ba / Sr ratio, thus meeting the temperature characteristic requirements of various voltage equalization devices to a certain extent. However, this type of barium-containing system has several inherent drawbacks: firstly, Ba... 2+ Ions exhibit a certain degree of migration under long-term electric and thermal field coupling conditions, which may accelerate device performance degradation. Secondly, barium-containing components are prone to surface carbonation in humid or CO2-containing environments, affecting the long-term insulation stability of the device. Thirdly, the Curie temperature shift of BST is extremely sensitive to changes in the Ba / Sr ratio, often requiring extremely stringent component control precision, and is often accompanied by problems such as dielectric peak broadening and increased loss.

[0004] Although pure strontium titanate (SrTiO3) is a barium-free perovskite, its intrinsic Curie temperature is extremely low (approximately -250°C), and it lacks a usable ferroelectric phase transition in the room temperature to low-temperature range. Lead titanate (PbTiO3), on the other hand, has a high Curie temperature (approximately 490°C) and can infinitely dissolve with SrTiO3 to form barium-free lead strontium titanate (PbTiO3). x Sr 1-x The TiO3 system, with this characteristic, theoretically makes it a potential replacement for BST in voltage equalization capacitors.

[0005] When designing Strontium lead titanate formulations, traditional formulation design usually relies on trial and error, which results in long development cycles and low R&D efficiency. Furthermore, the actual Curie temperature of Strontium lead titanate designed according to traditional formulations deviates significantly from the target value, which can easily lead to uncontrollable capacitance-temperature characteristics and dielectric loss affecting device performance.

[0006] Therefore, in the field of equalizing ceramic capacitors, there is an urgent need for a barium-free, one-step directional design strategy for strontium lead titanate-based dielectric ceramic formulations and their preparation methods. Summary of the Invention

[0007] The purpose of this invention is to solve the problem that the actual Curie temperature of strontium lead titanate designed with traditional formulations deviates significantly from the target value, which easily leads to uncontrollable capacitance-temperature characteristics and dielectric loss affecting device performance.

[0008] This invention provides a directionally designed lead strontium titanate dielectric ceramic, wherein the general chemical formula of the dielectric ceramic is (Pb x Sr 1-x-a Bi a TiO3, where a is the molar number of Bi and 0.02 ≤ a ≤ 0.05; the relationship between the target Curie temperature of the dielectric ceramic and the molar number of Pb satisfies a linear design equation. ;in, The target Curie temperature is given, x is the number of Pb moles, 398≦K≦402, -82≦h≦-78.

[0009] Preferably, the target Curie temperature is designed to be in the range of -60℃ to 20℃, k=400, h=-80.

[0010] Preferably, the deviation between the target Curie temperature and the measured Curie temperature of the dielectric ceramic is ≤ ±3℃.

[0011] Preferably, the A-site of the dielectric ceramic contains Bi. 3+ Inequivalent substitution of Pb 2+ The cation vacancy induced at the A site is represented by the general chemical formula (Pb). x Sr 1-x-a Bi a a / 2 TiO3; among which, This represents position A being empty. It contains 1 / 2 Bi content.

[0012] Preferably, the dielectric ceramic is a pure perovskite phase at room temperature; and / or the relative density of the dielectric ceramic at room temperature is ≥95%; and / or the dielectric loss of the dielectric ceramic at 1 kHz at room temperature is ≤0.02.

[0013] Based on the same inventive concept, this invention also provides a method for preparing the directionally designed strontium lead titanate dielectric ceramic, comprising the following steps: component ratio design: determining the preset target Curie temperature of the dielectric ceramic. And the number of moles of Bi, a, and using linear design equations Determine the number of Pb moles x corresponding to the target Curie temperature; according to the general chemical formula (Pb x Sr 1-x-a Bi a TiO3 was used to obtain the molar number of Sr 1-xa, thus confirming the molar number of all component elements; Mixing: According to the confirmed molar number of all component elements, raw materials PbO, SrCO3, Bi2O3 and TiO2 were weighed respectively, and anhydrous ethanol and zirconium oxide balls were added for ball milling and mixing. After drying, the mixture was sieved to obtain a dry powder; Pre-firing treatment: The dry powder was pre-firing to obtain a pre-firing synthetic powder; Granulation and molding: A binder was added to the pre-firing synthetic powder and granulated. After sieving, the mixture was pressed into a green body; Debinding and sintering: The green body was heated to remove the binder. After debinding, it was sintered at high temperature. After sintering, it was cooled in an air atmosphere to obtain the dielectric ceramic.

[0014] Preferably, a planetary ball mill is used in the ingredient mixing step, with a ball milling speed of 250 rpm to 350 rpm and a ball milling time of 6 h to 12 h.

[0015] Preferably, in the ingredient mixing step, the mass of the zirconia grinding ball is 2-3 times the total mass of the raw materials.

[0016] Preferably, in the granulation and molding steps, the binder is an aqueous solution of polyvinyl alcohol, and the amount of binder added is 4%-6% of the mass of the pre-calcined synthetic powder.

[0017] Preferably, in the pre-firing process, the pre-firing temperature is 800℃~950℃ and the pre-firing time is 2h~4h.

[0018] Preferably, in the granulation and molding steps, the pressing pressure is 150MPa~250MPa.

[0019] Preferably, in the debinding and sintering steps, the heating rate for debinding is 0.5℃ / min to 1℃ / min, the debinding temperature is 550℃ to 650℃, and the debinding time is 2h to 3h.

[0020] Preferably, in the debinding and sintering steps, the sintering temperature is 1250℃~1320℃ and the sintering time is 2h~4h.

[0021] Preferably, in the debinding and sintering steps, the green body is surrounded by a PbO-Bi2O3 mixed atmosphere powder or the pre-sintered synthetic powder during sintering to synergistically suppress the volatilization of Pb and Bi elements.

[0022] Based on the same inventive concept, the present invention also provides a ceramic capacitor made of the aforementioned directionally designed strontium lead titanate dielectric ceramic.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a directionally designed lead strontium titanate dielectric ceramic, the general chemical formula of which is (Pb). x Sr 1-x- a Bi a TiO3, where a is the molar number of Bi and 0.02 ≤ a ≤ 0.05; the relationship between the target Curie temperature of the dielectric ceramic and the molar number of Pb satisfies a linear design equation. ;in, Here, x represents the target Curie temperature, x represents the number of moles of Pb, and 398 ≤ K ≤ 402, -82 ≤ h ≤ -78. The elemental formulation of the dielectric ceramic in this invention is directly determined by the design equation based on the target Curie temperature requirement. This transforms the traditional trial-and-error formulation design into a quantitative calculation model, reducing the deviation between the actual Curie temperature of SLT lead titanate and the target value, improving the controllability of the capacitance-temperature characteristics of the dielectric ceramic, and reducing dielectric loss performance. It avoids the traditional iterative trial-and-error formulation design method, significantly shortening the formulation development cycle of SLT lead titanate dielectric ceramics and improving R&D efficiency. Attached Figure Description

[0024] Figure 1 The XRD pattern of Example 1 of the Strontium Lead Titanate Dielectric Ceramic of the present invention; Figure 2 The XRD pattern of Example 2 of the Strontium Lead Titanate Dielectric Ceramic of the present invention; Figure 3 The XRD pattern of Example 3 of the Strontium Lead Titanate Dielectric Ceramic of the present invention; Figure 4 The graph shows the dielectric constant and dielectric loss of the lead strontium titanate dielectric ceramic of the present invention as a function of temperature in Example 1. Figure 5 The graph shows the dielectric constant and dielectric loss of the lead strontium titanate dielectric ceramic of the present invention as a function of temperature in Example 2. Figure 6 The graph shows the dielectric constant and dielectric loss of the lead strontium titanate dielectric ceramic of the present invention as a function of temperature in Example 3. Figure 7 This is a Curie temperature prediction curve for the strontium lead titanate dielectric ceramic of the present invention. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other instances that are improved or modified by those skilled in the art are within the scope of protection of the present invention. It should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the methods used in the embodiments are conventional methods.

[0026] This invention provides a directionally designed lead strontium titanate dielectric ceramic, the general chemical formula of which is (Pb). x Sr 1-x- a Bi a TiO3, where a is the molar number of Bi and 0.02 ≤ a ≤ 0.05; the relationship between the target Curie temperature of the dielectric ceramic and the molar number of Pb satisfies a linear design equation. ;in, The target Curie temperature is given by x, where x is the number of Pb moles, 398≦K≦402, and -82≦h≦-78.

[0027] Understandably, according to the linear design equation, the number of Pb moles x is the only design variable for controlling the target Curie temperature. By setting a preset target Curie temperature and substituting it into the linear design equation, the number of Pb moles x can be uniquely determined, and thus the Sr content can be determined as 1-xa. This achieves a function-oriented formulation design based on the target Curie temperature, avoiding the traditional iterative trial-and-error formulation design method. This significantly shortens the formulation development cycle of Strontium Lead Titanate dielectric ceramics, improves R&D efficiency, greatly reduces the deviation between the actual Curie temperature and the target value of Strontium Lead Titanate, enhances the controllability of the capacitance-temperature characteristics of dielectric ceramics, and reduces dielectric loss performance.

[0028] In addition, based on actual needs, those skilled in the art can fine-tune the slope parameter k and intercept h based on the designed temperature range so that the deviation between the target Curie temperature and the measured Curie temperature in different ranges is within a reasonable deviation range.

[0029] like Figure 7 As shown, in the linear design equation of this embodiment, the design range of the target Curie temperature is -60℃ to 20℃, k=400, h=-80, and the deviation range between the target Curie temperature and the measured Curie temperature of the dielectric ceramic is ≤±3℃. Figure 7 The horizontal axis represents the number of Pb moles (x), and the vertical axis represents the Curie temperature (T). c / ℃.

[0030] From another perspective, by changing the Pb content x within the range of 0.05-0.25, the target Curie temperature can be directionally adjusted within the range of -60℃ to 20℃, thus achieving the designability of the capacitance-temperature characteristics.

[0031] The A-site of the dielectric ceramic contains Bi. 3+ Inequivalent substitution of Pb 2+ The cation vacancy induced at the A site is represented by the general chemical formula (Pb). x Sr 1-x-a Bi a a / 2 TiO3; among which, This represents position A being empty. It contains 1 / 2 Bi content.

[0032] Bi is doped at a fixed amount of 0.02~0.05, with low concentrations of Bi. 3+ Inequivalent substitution of Pb 2+ This induces the spontaneous formation of A-site vacancies to achieve charge balance, avoiding the complexity of introducing other foreign ions to compensate for the charge. In other words, the vacancy concentration is naturally determined by the Bi doping amount, without significantly affecting the target Curie temperature or interfering with the established linear design equation for the Curie temperature. Simultaneously, Bi... 3+ The high polarizability can effectively improve the room temperature dielectric constant of the material, and the pinning effect of A-site vacancies on domain walls can effectively reduce dielectric loss.

[0033] Based on the same inventive concept, this invention also provides a method for preparing directionally designed lead strontium titanate dielectric ceramics, comprising the following steps: S1. Component Proportioning Design: Determine the preset target Curie temperature of the dielectric ceramic. And the number of moles of Bi, a, and using linear design equations Determine the number of Pb moles x corresponding to the target Curie temperature; based on the general chemical formula (Pb... x Sr 1-x-a Bi a TiO3 was used to obtain the molar number of Sr 1-xa, thus confirming the molar number of all component elements.

[0034] Specifically, the above-mentioned linear design equations are adopted. The target Curie temperature is designed to be between -60℃ and 20℃, with k=400, h=-80, and 0.02≦a≦0.05.

[0035] S2. Ingredient Mixing: Based on the confirmed molar amounts of all component elements, weigh out the raw materials PbO, SrCO3, Bi2O3 and TiO2 respectively, add anhydrous ethanol and zirconium oxide balls for ball milling and mixing, and then sieve to obtain dry powder.

[0036] Specifically, a planetary ball mill is used, with a milling speed of 250 rpm to 350 rpm and a milling time of 6 h to 12 h. The mass of the zirconia milling balls is 2 to 3 times the total mass of the raw materials. After drying, the powder is obtained by passing it through a 60-100 mesh sieve. The raw materials used in the formulation, PbO, SrCO3, Bi2O3, and TiO2, all have a purity of ≥99.5%.

[0037] S3. Pre-calcination treatment: The dried powder is pre-calcined to obtain pre-calcined synthetic powder; Specifically, the pre-firing temperature is 800℃~950℃, and the pre-firing time is 2h~4h. A portion of the pre-firing synthesized powder is retained as an inhibitor for the subsequent sintering environment.

[0038] S4. Granulation and molding: Add a binder to the pre-calcined synthetic powder and granulate it. After sieving, press it into a green body. Specifically, the binder is an aqueous solution of polyvinyl alcohol, and the amount of binder added is 4%-6% of the mass of the pre-calcined synthetic powder. The granulated powder is placed in a steel mold and pressed into shape in a press. The pressing pressure is 150MPa~250MPa, and the blank is pressed into a round disc with a diameter of 10mm and a thickness of about 1.5mm.

[0039] S5. Debinding and Sintering: The blank is heated to remove the binder, and then sintered at high temperature. After sintering, it is cooled in the furnace in an air atmosphere to obtain dielectric ceramic.

[0040] Specifically, the heating rate for debinding is 0.5℃ / min to 1℃ / min, the debinding temperature is 550℃-650℃, and the debinding time is 2h to 3h; subsequently, the temperature is increased at 5℃ / min to the sintering temperature of 1250℃ to 1320℃, and the sintering time is 2h to 4h. During the sintering process, the green body is surrounded by a PbO-Bi2O3 mixed atmosphere powder or the pre-sintered synthetic powder reserved in step S2 to synergistically suppress the volatilization of Pb and Bi elements; after sintering, it is naturally cooled to room temperature in the furnace to obtain a dielectric ceramic sheet.

[0041] The dielectric ceramic prepared by the present invention using the above-mentioned general chemical formula and linear design equation has the characteristics of phase purity, directional designable Curie temperature, and low dielectric loss, and can be applied to ceramic capacitors in different operating temperature ranges. Specifically, the target Curie temperature of the dielectric ceramic deviates from the measured value by ≤±3℃, the relative density at room temperature is ≥95%, the dielectric loss tanδ at 1kHz at room temperature is ≤0.02, and it is a pure perovskite phase at room temperature.

[0042] By fixing the Bi content range and establishing a quantitative linear equation between the target Curie temperature and Pb content, the iterative process of traditional trial-and-error methods can be avoided. The component element ratio can be determined in one go with the target Curie temperature as the objective, achieving precise designability of the target Curie temperature. At the same time, it ensures that the prepared dielectric material has high density, phase purity, and low dielectric loss, making it suitable for electrical ceramic fields such as equal-voltage ceramic capacitors where there are strict requirements for capacitance-temperature characteristics.

[0043] Based on the same inventive concept, the present invention also provides a ceramic capacitor made of the directionally designed strontium lead titanate dielectric ceramic prepared above.

[0044] In this process, silver electrodes are coated on both sides of the sintered dielectric ceramic sheet and infiltrated at 600°C. After infiltration, the ceramic capacitor is encapsulated to obtain the finished product.

[0045] Based on the above linear design equations, different Curie temperatures were designed, dielectric ceramic samples were prepared, and their performance was tested.

[0046] Examples 1-5 and Comparative Example 1 Table 1

[0047] Table 1 compares the composition ratios and preparation parameters of dielectric ceramics designed for different target Curie temperatures in Examples 1-5 and Comparative Example 1. The preparation parameters for Comparative Example 1 are identical to those for Example 3, the only difference being the molar number of chemical elements corresponding to the target Curie temperature. In all examples, the slope k in the linear design equation is 400, and the intercept h is -80.

[0048] It should be noted that for preparation parameters not listed, those skilled in the art can use the defined range or conventional values.

[0049] Results Analysis The dielectric constant of the samples prepared in Examples 1-5 and Comparative Example 1 was measured at a frequency of 1 kHz using a dielectric temperature spectrometer, and the measured Curie temperature was confirmed by the peak temperature.

[0050] Table 2 is a performance comparison table of Examples 1-5 and Comparative Example 1.

[0051] Table 2

[0052] Comparison shows that, taking Examples 1-3 as examples, as the fixed Bi doping amount varied within the range of 0.02~0.05, the target Curie temperature and the measured Curie temperature were both within the deviation range, without significant drift (the Pb content in Examples 1 and 3 was 0.10, the Bi content was 0.02 and 0.05 respectively, the measured Curie temperatures were -41℃ and -37℃ respectively, and the predicted Curie temperature was -40℃, with a deviation within ±3℃). This verifies the conclusion that a small amount of Bi doping has no significant effect on the Curie temperature, indicating that the design equation Tc=400x-80 is suitable for the bismuth-containing body defined in this invention. The system exhibits universality; with increasing Pb content, the Curie temperature moves systematically towards higher temperatures (in Example 2, the Pb content was 0.15, and the measured Curie temperature was -21℃; in Example 1, the Pb content was 0.10, and the measured Curie temperature was -41℃), and the trend is consistent with the negative slope of the design equation; by comparing with Comparative Example 1, the deviations of the measured Curie temperatures from the design target values ​​in Examples 1-5 are all ≤±3℃, the density is all ≥96%, XRD detection shows that all are single perovskite phases, and the dielectric loss at 1kHz is all below 0.0005, indicating that the material possesses both excellent phase purity and dielectric properties.

[0053] like Figures 1-3 As shown, in Examples 1-3, the XRD patterns of Examples 1, 2, and 3 all exhibit a single perovskite phase structure. All diffraction peaks are consistent with the characteristic peaks of standard perovskite, and no diffraction peaks of any impurity phases were detected. This indicates that the Strontium lead titanate dielectric ceramic prepared in this invention has a complete solid solution reaction and is phase-pure at room temperature. Comparing Example 1 (Pb=0.10) and Example 2 (Pb=0.15), the increase in the molar number of Pb did not cause a significant shift in the diffraction peaks, indicating that Bi... 3+ Inequivalent substitution of Pb 2+ The induced A-site vacancies still maintain the perovskite crystal structure. Figures 1-3 The method of this invention has been verified to obtain high-purity perovskite phase ceramics, providing structural assurance for excellent dielectric properties. Figures 1-3 The horizontal axis 2θ (deg.) represents the X-ray diffraction angle, and the vertical axis intensity (au) represents the diffraction intensity.

[0054] like Figures 4-6As shown, in Examples 1-3, the temperatures corresponding to the peak dielectric constant values ​​at 1 kHz are the measured Curie temperatures, which are approximately -41℃, -21℃, and -37℃, respectively. The Curie temperature deviation between Example 1 (Pb=0.10) and Example 3 (Pb=0.10) is +4℃, but both are within ±3℃ of the target value of -40℃, indicating that variations in Bi content within the range of 0.02~0.05 have no significant effect on the Curie temperature. The measured Curie temperature of Example 2 (Pb=0.15) is -21℃, deviating only -1℃ from the predicted value of -20℃ from the design equation. Regarding dielectric loss, the three examples show good performance near room temperature. δ All values ​​were below 0.0005, and remained below 0.002 within a wide temperature range of -60℃ to 40℃, indicating that the Bi-induced A-site vacancies effectively pinned the domain walls and significantly suppressed dielectric loss. Figures 4-6 This invention demonstrates that it achieves accurate directional design of the Curie temperature while also possessing extremely low dielectric loss. Figures 4-6 The horizontal axis represents temperature in °C, the left side of the vertical axis represents dielectric constant, and the right side of the vertical axis represents dielectric loss.

[0055] As can be seen, the method for preparing directionally designed lead strontium titanate dielectric ceramics of this invention can complete sintering in an air atmosphere using a traditional solid-state reaction method. The formula is directly calculated and determined by linear design equations, transforming the traditional trial-and-error formula design into a quantitative calculation mode. This avoids iterative cycles of repeated batching, sintering, and testing, significantly shortening the formula development cycle and improving R&D efficiency. This preparation method is simple, reproducible, and suitable for direct promotion on existing capacitor ceramic production lines. The deviation between the target Curie temperature and the measured value of the directionally designed lead strontium titanate dielectric ceramics can be controlled within ±3℃.

[0056] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A directionally designed strontium lead titanate dielectric ceramic, characterized in that, The general chemical formula of the dielectric ceramic is (Pb x Sr 1-x-a Bi a TiO3, where a is the number of moles of Bi and 0.02 ≤ a ≤ 0.05; The relationship between the target Curie temperature of the dielectric ceramic and the number of Pb moles satisfies a linear design equation. ;in, The target Curie temperature is given, x is the number of Pb moles, 398≦K≦402, -82≦h≦-78.

2. The directionally designed strontium lead titanate dielectric ceramic according to claim 1, characterized in that, The target Curie temperature is designed to be within the range of -60℃ to 20℃, k=400, h=-80.

3. The directionally designed strontium lead titanate dielectric ceramic according to claim 2, characterized in that, The deviation between the target Curie temperature and the measured Curie temperature of the dielectric ceramic is ≤ ±3℃.

4. The directionally designed strontium lead titanate dielectric ceramic according to claim 2, characterized in that, The A-site of the dielectric ceramic contains Bi. 3+ Inequivalent substitution of Pb 2+ The cation vacancy induced at the A site is represented by the general chemical formula (Pb). x Sr 1-x-a Bi a a / 2 TiO3; among which, This represents position A being empty. It contains 1 / 2 Bi content.

5. The directionally designed strontium lead titanate dielectric ceramic according to claim 1, characterized in that, The dielectric ceramic is a pure perovskite phase at room temperature; and / or The dielectric ceramic has a room temperature relative density ≥95%; and / or The dielectric ceramic has a dielectric loss tanδ≤0.02 at room temperature and 1kHz.

6. A method for preparing the directionally designed lead strontium titanate dielectric ceramic according to any one of claims 1 to 5, characterized in that, Includes the following steps: Component ratio design: Determine the preset target Curie temperature of the dielectric ceramic. And the number of moles of Bi, a, and using linear design equations Determine the number of Pb moles x corresponding to the target Curie temperature; according to the general chemical formula (Pb x Sr 1-x-a Bi a TiO3 was used to obtain the molar number of Sr 1-xa, thus confirming the molar number of all component elements; Ingredient mixing: Based on the confirmed molar amounts of all component elements, weigh out the raw materials PbO, SrCO3, Bi2O3 and TiO2 respectively, add anhydrous ethanol and zirconium oxide balls, ball mill and mix, dry and sieve to obtain dry powder; Pre-calcination treatment: The dried powder is pre-calcined to obtain pre-calcined synthetic powder; Granulation and molding: Add a binder to the pre-calcined synthetic powder and granulate it. After sieving, press it into a green body to obtain a green body. Debinding and sintering: The blank is heated to remove the binder, and then sintered at high temperature. After sintering, it is cooled in the furnace in an air atmosphere to obtain the dielectric ceramic.

7. The method for preparing directionally designed lead strontium titanate dielectric ceramics according to claim 6, characterized in that, In the ingredient mixing step, a planetary ball mill is used with a ball milling speed of 250 rpm to 350 rpm and a ball milling time of 6 h to 12 h.

8. The method for preparing directionally designed lead strontium titanate dielectric ceramics according to claim 6, characterized in that, In the ingredient mixing step, the mass of the zirconia grinding ball is 2-3 times the total mass of the raw materials.

9. The method for preparing directionally designed lead strontium titanate dielectric ceramics according to claim 6, characterized in that, In the granulation and molding steps, the binder is an aqueous solution of polyvinyl alcohol, and the amount of binder added is 4%-6% of the mass of the pre-calcined synthetic powder.

10. The method for preparing directionally designed lead strontium titanate dielectric ceramics according to claim 6, characterized in that, In the pre-firing process, the pre-firing temperature is 800℃~950℃ and the pre-firing time is 2h~4h.

11. The method for preparing directionally designed strontium lead titanate dielectric ceramics according to claim 6, characterized in that, In the granulation and molding steps, the pressure of the compression molding is 150MPa~250MPa.

12. The method for preparing directionally designed lead strontium titanate dielectric ceramics according to claim 6, characterized in that, In the debinding and sintering steps, the heating rate for debinding is 0.5℃ / min to 1℃ / min, the debinding temperature is 550℃ to 650℃, and the debinding time is 2h to 3h.

13. The method for preparing directionally designed lead strontium titanate dielectric ceramics according to claim 6, characterized in that, In the debinding and sintering steps, the sintering temperature is 1250℃~1320℃ and the sintering time is 2h~4h.

14. The method for preparing directionally designed strontium lead titanate dielectric ceramics according to claim 6, characterized in that, In the debinding and sintering steps, the green body is surrounded by a PbO-Bi2O3 mixed atmosphere powder or the pre-sintered synthetic powder during sintering to synergistically suppress the volatilization of Pb and Bi elements.

15. A ceramic capacitor, characterized in that, It is made using the directionally designed strontium lead titanate dielectric ceramic as described in any one of claims 1 to 5.

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