A high-voltage ceramic capacitor dielectric and its preparation method

Abstract

A high-voltage ceramic capacitor dielectric, characterized by being made of the following raw materials in the following weight ratios: BaTiO 3 56‑89%, SrTiO 3 1‑26%, NaAgMoO 4 1-14%, Na2WO 4 0.03‑9%, V2O5 0.02‑1.4%, ZnO 0.1‑1.7%, MnO 2 The present invention also provides a method for preparing the above-mentioned high-voltage ceramic capacitor dielectric. This high-voltage ceramic capacitor dielectric has a high dielectric constant, low dielectric loss, and high withstand voltage. It does not pollute the environment during preparation and use, and can be sintered at a relatively low temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic non-metallic materials, and in particular to a high-voltage ceramic capacitor dielectric and a preparation method of the high-voltage ceramic capacitor dielectric. Background Art

[0002] Color TVs, computers, communications, aerospace, missiles, navigation, and other fields urgently need ceramic capacitors with high breakdown voltage, good temperature stability, high reliability, miniaturization, and large capacity. The sintering temperature of the dielectric of a typical monolithic high-voltage ceramic capacitor is 1300-1430°C, which results in high energy consumption and increases the cost of the capacitor.

[0003] The dielectrics commonly used in the production of high-voltage ceramic capacitors often contain a certain amount of lead and cadmium, which not only poses a risk to humans and the environment during production, use, and disposal, but also adversely affects performance stability. Although some ceramic capacitor dielectrics are lead- and cadmium-free, their dielectric constant is too low, hindering the ability to increase the capacity and miniaturize ceramic capacitors. Furthermore, their poor voltage resistance hinders the expansion of their use and safety.

[0004] The Chinese journal "Electronic Components and Materials," in its article "High-Dielectric and High-Voltage 2B4 Dielectric Ceramics," published in Issue 5 of 1989, disclosed a high-voltage ceramic capacitor dielectric material. This dielectric material uses a formula of 97.8wt.% BaTiO3, 0.8wt.% Bi2O3, 0.7wt.% Nb2O5, 0.5wt.% CeO2, and 0.2wt.% MnO2. Samples were prepared using conventional processes. The dielectric constant ε = 2500-2600, tgδ = 0.5-1.4%, and a DC withstand voltage strength of 7 kV / mm. Although this dielectric material is lead-free, its withstand voltage is poor and its dielectric constant is too low.

[0005] Although the capacitor ceramic dielectric disclosed in the Chinese patent "A High-Voltage Ceramic Capacitor Dielectric" (patent number ZL00112050.6) is a lead-free dielectric material, its dielectric constant is too small (dielectric constant is 1860-3300), the withstand voltage can reach more than 10kV / mm (DC), and the sintering temperature is relatively high (sintering temperature is 1260-1400℃).

[0006] The article "BaTiO3-Based Low-Temperature-Fired High-Kinality X7R Capacitor Ceramic," published in the 2nd issue of the 1999 Chinese journal Jiangsu Ceramics, describes a BaTiO3-based capacitor ceramic material fired at a medium to low temperature, with high dielectric constants meeting X7R characteristics. The dielectric material's composition (by mass percentage) is: (BaTiO3 + Nd2O3) 89%-92% + Bi2O3·2TiO2 7.5-10% + 0.8% low-melting-point glass frit + 50% Mn(NO3)2 (aqueous solution) 0.205%. The low-melting-point glass frit is lead borosilicate, the dielectric contains lead, and the dielectric constant is less than 3500.

[0007] The article "X7R Characteristics of BaTiO3-Based Multiphase Ferroelectric Ceramics Sintered at Medium Temperature," published in the 3rd issue of the 1996 Chinese journal Journal of South China University of Technology (Natural Science Edition), explored the medium-temperature sintering mechanism of BaTiO3-based ceramics and analyzed the effects of the composition and heterogeneous structural distribution of medium-temperature sintered BaTiO3-based ceramics on their dielectric constant and temperature characteristics. The composition contained a certain amount of lead, but the withstand voltage was not discussed.

[0008] Another patent is "High-dielectric and high-performance medium-temperature sintered chip multilayer ceramic capacitor ceramic material" (patent application number: 97117286.2), which uses a solid-phase method to synthesize equivalent and heterovalent ions to replace (Sr 2+ ,Zr 4+ ,Sn 4+ ,Nb 5+ ) BaTiO3 solid solution, adding an appropriate amount of boron lead zinc copper glass sintering agent, so that the porcelain material is sintered at medium temperature. Its performance is: dielectric constant greater than or equal to 16000, and voltage resistance is 700V / mm. Although the dielectric constant is high, the material's voltage resistance is too poor. In addition, its components contain a certain amount of lead.

[0009] Another patent, "Method for Manufacturing High-Voltage Ceramic Capacitor Dielectrics" (Patent No. 91101958.8), uses an unconventional process to prepare dielectrics, namely, tape-casting films, then laminating dielectric bodies, vacuum heating and uniformly pressing the multi-layer dielectric bodies, punching them, and then debinding and firing them. The resulting high-voltage capacitor ceramics have a dielectric constant of 1800-7200, which is high, but the dielectric loss is large and the withstand voltage is not high enough. In addition, the preparation method of this patent is complex, which leads to increased product manufacturing costs.

[0010] There is also a Chinese patent for a "High-Performance Medium-Temperature Sintered Chip Multilayer Ceramic Capacitor Material" (patent application number: 97117287.0). This material utilizes a unique formula (by weight percentage) of BaTiO₃93-96% + Nb₂O₅0.8-1.5% + Bi₂O₃1.0-2.2% + flux 1.8-3.5% + modifier 0.25-1.0%) to produce a medium-temperature sintered capacitor ceramic that meets the following performance requirements: a dielectric constant of 3000, dielectric loss less than 1.5%, and a withstand voltage of 860 V / mm. However, the flux used contains a certain amount of lead, resulting in poor withstand voltage and a low dielectric constant.

[0011] There is also a Chinese patent for "A medium-low temperature sintered high-voltage ceramic capacitor dielectric" (patent application number: 200410041863.x). It uses a unique formula (weight percentage) (BaTiO3 60-90%, SrTiO3 1-20%, CaZrO3 0.1-10%, Nb2O5 0.01-1%, MgO 0.01-1%, CeO2 0.01-0.8%, ZnO 0.01-0.6%, Co2O3 0.03-1%, bismuth-lithium solid solution 0.05-10%) to obtain a medium-temperature sintered capacitor ceramic that meets the following properties: a dielectric constant of 2000-3000 and a withstand voltage of more than 6kV / mm. Its dielectric constant and withstand voltage are both low. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to provide a high-voltage ceramic capacitor dielectric and a method for preparing the high-voltage ceramic capacitor dielectric. The high-voltage ceramic capacitor dielectric has a high dielectric constant, low dielectric loss, and high voltage resistance. It does not pollute the environment during preparation and use, and can be sintered at a relatively low temperature. The technical solution adopted is as follows:

[0013] A high-voltage ceramic capacitor dielectric is characterized by being made of the following raw materials in the following weight ratios: BaTiO3 56-89%, SrTiO3 1-26%, NaAgMoO4 1-14%, Na2WO4 0.03-9%, V2O5 0.02-1.4%, ZnO 0.1-1.7%, and MnO2 0.01-0.95%.

[0014] In a preferred embodiment, the high-voltage ceramic capacitor dielectric is made of the following raw materials in the following weight ratio: BaTiO3 61-85%, SrTiO3 2-21%, NaAgMoO4 2-13%, Na2WO4 0.6-7%, V2O5 0.1-0.5%, ZnO 0.1-0.6%, and MnO2 0.02-0.9%.

[0015] In another preferred embodiment, the high-voltage ceramic capacitor dielectric is made of the following raw materials in the following weight ratio: BaTiO3 64-84%, SrTiO3 2-18%, NaAgMoO4 3-9%, Na2WO4 0.5-7%, V2O5 0.1-0.5%, ZnO 0.1-0.6%, and MnO2 0.02-0.9%.

[0016] In another preferred embodiment, the high-voltage ceramic capacitor dielectric is made of the following raw materials in the following weight ratio: BaTiO3 71-81.5%, SrTiO3 3-18%, NaAgMoO4 2-7.5%, Na2WO4 2-6%, V2O5 0.1-0.65%, ZnO 0.1-0.6%, and MnO2 0.02-0.9%.

[0017] Preferably, the above-mentioned BaTiO3, SrTiO3, NaAgMoO4 and Na2WO4 are synthesized by solid phase method using conventional chemical raw materials.

[0018] The NaAgMoO4 can be prepared by the following process: Na2CO3, Ag2CO3, and MoO3 are prepared in a molar ratio of 0.5:0.5:1, then the Na2CO3, Ag2CO3, and MoO3 are ground and mixed uniformly, and the mixture of Na2CO3, Ag2CO3, and MoO3 is placed in an alumina crucible and kept at 350-450°C for 120 minutes to obtain NaAgMoO4. After cooling, the obtained NaAgMoO4 is ground and passed through a 200-mesh sieve for later use.

[0019] The Na2WO4 can be prepared by the following process: Na2CO3 and WO3 are prepared in a 1:1 molar ratio, then ground and mixed. The mixture is then placed in an alumina crucible and kept at 500-600°C for 120 minutes to obtain Na2WO4. The obtained Na2WO4 is cooled, ground, and passed through a 200-mesh sieve for later use.

[0020] The above-mentioned NaAgMoO4 can improve the dielectric constant and withstand voltage, and can reduce the sintering temperature. Na2WO4 can improve the dielectric constant and withstand voltage, and can reduce the sintering temperature.

[0021] The present invention also provides a method for preparing the above-mentioned high-voltage ceramic capacitor dielectric, characterized by comprising the following steps:

[0022] (1) BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2 are prepared in proportion;

[0023] (2) crushing and uniformly mixing the BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2 prepared in step (1) to obtain a mixed powder;

[0024] (3) drying the mixed powder obtained in step (2) to obtain a dry powder;

[0025] (4) Adding a binder to the dry powder and granulating it to obtain a granular material;

[0026] (5) pressing the granular material obtained in step (4) into green sheets;

[0027] (6) The green sheet is placed at 1050-1100° C. and kept at this temperature for 1-4 hours to allow the green sheet to discharge the binder and sinter to obtain the high-voltage ceramic capacitor dielectric.

[0028] The obtained high-voltage ceramic capacitor medium is a ceramic sheet, which is kept at 780-870°C for 15 minutes to sinter silver to form a silver electrode, and then welded with a lead and encapsulated to obtain a ceramic capacitor.

[0029] In step (2), the various raw materials can be pulverized separately and then mixed evenly; alternatively, the various raw materials can be mixed and then pulverized, and then mixed while pulverizing, or the various raw materials can be mixed evenly after pulverization. The pulverization equipment can be a ball mill, or other pulverization equipment can be used. Preferably, a planetary ball mill is used to ball mill the prepared raw materials, and the weight ratio of the raw materials to be ball milled, the balls used, and the water used is: raw materials: balls: water = 1:3: (0.6-1.0), and the ball milling process lasts for 4-8 hours. Distilled water or deionized water can be used.

[0030] The binder in step (4) can be a polyvinyl alcohol aqueous solution (i.e., PVA solution). Preferably, the binder in step (4) is a polyvinyl alcohol solution with a weight percentage concentration of 10%, and the weight of the added polyvinyl alcohol solution is 8-10% of the weight of the dry powder.

[0031] In step (4), the mixture can be ground after granulation and passed through a 40-mesh sieve.

[0032] Preferably, in step (5), the granular material is dry-pressed at a pressure of 20-30 MPa to obtain a green sheet.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] (1) The ceramic capacitor dielectric of the present invention is a low-temperature sintered (1050-1100°C) barium strontium titanate-based capacitor ceramic, which can greatly reduce the cost of high-voltage ceramic capacitors. The dielectric component of the present invention does not contain lead and cadmium and is environmentally friendly.

[0035] (2) The dielectric constant of the ceramic capacitor of the present invention is high, exceeding 8600; the withstand voltage is high, reaching over 30 kV / mm for DC and over 18 kV / mm for AC; and the dielectric loss is low, less than 0.1%. Due to the high dielectric constant, the dielectric of the ceramic capacitor of the present invention can achieve miniaturization and high capacity of ceramic capacitors while reducing costs.

[0036] (3) The ceramic capacitor dielectric of the present invention has a low capacitance temperature change rate, which meets the requirements of Y5U characteristics. At the same time, due to the low dielectric loss, the performance stability is good and the safety is high during use.

[0037] (4) The ceramic capacitor dielectric of the present invention can be manufactured by using ceramic capacitor grade pure raw materials.

[0038] The ceramic capacitor dielectric of the present invention is suitable for preparing monolithic ceramic capacitors and multi-layer ceramic capacitors, can greatly reduce the cost of ceramic capacitors, and can also improve the withstand voltage to expand the application range of ceramic capacitors. DETAILED DESCRIPTION

[0039] Example 1

[0040] First, NaAgMoO4 and Na2WO4 were synthesized by solid phase method.

[0041] NaAgMoO4 was prepared using the following process: Na2CO3, Ag2CO3, and MoO3 were prepared in a molar ratio of 0.5:0.5:1, then ground and mixed thoroughly. The mixture of Na2CO3, Ag2CO3, and MoO3 was placed in an alumina crucible and kept at 400°C for 120 minutes to obtain NaAgMoO4. The resulting NaAgMoO4 was cooled, ground, and passed through a 200-mesh sieve for later use.

[0042] Na2WO4 can be prepared by the following process: Na2CO3 and WO3 are prepared in a 1:1 molar ratio, then ground and mixed. The mixture of Na2CO3 and WO3 is then placed in an alumina crucible and kept at 550°C for 120 minutes to obtain Na2WO4. After cooling, the obtained Na2WO4 is ground and passed through a 200-mesh sieve for later use.

[0043] Then, prepare the high voltage ceramic capacitor dielectric according to the following steps:

[0044] (1) BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2 are prepared in proportion;

[0045] The weight percentages of various raw materials are shown in Table 1;

[0046] (2) crushing and uniformly mixing the BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2 prepared in step (1) to obtain a mixed powder;

[0047] In this step (2), the prepared raw materials are ball-milled using a planetary ball mill. The weight ratio of the raw materials, balls, and water to be ball-milled is: raw materials: balls: water = 1:3:1. The ball milling process lasts for 5 hours.

[0048] (3) drying the mixed powder obtained in step (2) to obtain a dry powder;

[0049] (4) Adding a binder to the dry powder and granulating (after granulation, mixing and grinding and passing through a 40-mesh sieve) to obtain a granular material;

[0050] The binder in step (4) is a polyvinyl alcohol solution with a weight percentage concentration of 10%, and the weight of the added polyvinyl alcohol solution is 9% of the weight of the dry powder;

[0051] (5) pressing the granular material obtained in step (4) into green sheets;

[0052] In this step (5), the granular material is dry-pressed under a pressure of 25 MPa to obtain a green sheet;

[0053] (6) The green sheet is placed at 1060° C. and kept warm for 3.5 hours to allow the green sheet to discharge the binder and sinter, thereby obtaining the high-voltage ceramic capacitor dielectric.

[0054] The obtained high-voltage ceramic capacitor medium is a ceramic sheet, which is kept at 800°C for 15 minutes to sinter silver to form a silver electrode, and then welded with a lead and encapsulated to obtain a ceramic capacitor.

[0055] Example 2

[0056] First, NaAgMoO4 and Na2WO4 were synthesized by solid phase method.

[0057] NaAgMoO4 was prepared using the following process: Na2CO3, Ag2CO3, and MoO3 were prepared in a molar ratio of 0.5:0.5:1, then ground and mixed thoroughly. The mixture of Na2CO3, Ag2CO3, and MoO3 was placed in an alumina crucible and kept at 450°C for 120 minutes to obtain NaAgMoO4. The resulting NaAgMoO4 was cooled, ground, and passed through a 200-mesh sieve for later use.

[0058] Na2WO4 is prepared by the following process: Na2CO3 and WO3 are prepared in a 1:1 molar ratio, then ground and mixed. The mixture is then placed in an alumina crucible and held at 500°C for 120 minutes to obtain Na2WO4. The resulting Na2WO4 is cooled, ground, and passed through a 200-mesh sieve for later use.

[0059] Then, prepare the high voltage ceramic capacitor dielectric according to the following steps:

[0060] (1) BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2 are prepared in proportion;

[0061] The weight percentages of various raw materials are shown in Table 1;

[0062] (2) crushing and uniformly mixing the BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2 prepared in step (1) to obtain a mixed powder;

[0063] In this step (2), a planetary ball mill is used to ball mill the prepared raw materials. The weight ratio of the raw materials to the balls to the water is: raw materials: balls: water = 1:3:0.8. The ball milling process lasts for 6 hours.

[0064] (3) drying the mixed powder obtained in step (2) to obtain a dry powder;

[0065] (4) Adding a binder to the dry powder and granulating (after granulation, mixing and grinding and passing through a 40-mesh sieve) to obtain a granular material;

[0066] The binder in step (4) is a polyvinyl alcohol solution with a weight percentage concentration of 10%, and the weight of the added polyvinyl alcohol solution is 8.5% of the weight of the dry powder;

[0067] (5) pressing the granular material obtained in step (4) into green sheets;

[0068] In this step (5), the granular material is dry-pressed under a pressure of 28 MPa to obtain a green sheet;

[0069] (6) The green sheet is placed at 1100° C. and kept warm for 1.5 hours to allow the green sheet to discharge the binder and sinter, thereby obtaining the high-voltage ceramic capacitor dielectric.

[0070] The obtained high-voltage ceramic capacitor medium is a ceramic sheet, which is kept at 850°C for 15 minutes to sinter silver to form a silver electrode, and then welded with a lead and encapsulated to obtain a ceramic capacitor.

[0071] Example 3

[0072] First, NaAgMoO4 and Na2WO4 were synthesized by solid phase method.

[0073] NaAgMoO4 was prepared using the following process: Na2CO3, Ag2CO3, and MoO3 were prepared in a molar ratio of 0.5:0.5:1, then ground and mixed thoroughly. The mixture of Na2CO3, Ag2CO3, and MoO3 was placed in an alumina crucible and kept at 360°C for 120 minutes to obtain NaAgMoO4. The resulting NaAgMoO4 was cooled, ground, and passed through a 200-mesh sieve for later use.

[0074] Na2WO4 is prepared by mixing Na2CO3 and WO3 in a 1:1 molar ratio, grinding and mixing the Na2CO3 and WO3, placing the mixture in an alumina crucible and incubating at 580°C for 120 minutes to obtain Na2WO4. The resulting Na2WO4 is then cooled, ground, and passed through a 200-mesh sieve for later use.

[0075] Then, prepare the high voltage ceramic capacitor dielectric according to the following steps:

[0076] (1) BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2 are prepared in proportion;

[0077] The weight percentages of various raw materials are shown in Table 1;

[0078] (2) crushing and uniformly mixing the BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2 prepared in step (1) to obtain a mixed powder;

[0079] In this step (2), a planetary ball mill is used to ball mill the prepared raw materials. The weight ratio of the raw materials to the balls to the water is: raw materials: balls: water = 1:3:0.6. The ball milling process lasts for 8 hours.

[0080] (3) drying the mixed powder obtained in step (2) to obtain a dry powder;

[0081] (4) Adding a binder to the dry powder and granulating (after granulation, mixing and grinding and passing through a 40-mesh sieve) to obtain a granular material;

[0082] The binder in step (4) is a polyvinyl alcohol solution with a weight percentage concentration of 10%, and the weight of the added polyvinyl alcohol solution is 10% of the weight of the dry powder;

[0083] (5) pressing the granular material obtained in step (4) into green sheets;

[0084] In this step (5), the granular material is dry-pressed under a pressure of 20 MPa to obtain a green sheet;

[0085] (6) The green sheet is placed at 1050° C. and kept warm for 4 hours to allow the green sheet to discharge the binder and sinter, thereby obtaining the high-voltage ceramic capacitor dielectric.

[0086] The obtained high-voltage ceramic capacitor medium is a ceramic sheet, which is kept at 780°C for 15 minutes to sinter silver to form a silver electrode, and then welded with a lead and encapsulated to obtain a ceramic capacitor.

[0087] Examples 4-9

[0088] In Examples 4-9, the proportions of various raw materials are shown in Table 1. The methods for preparing high-voltage ceramic capacitor dielectrics in Examples 4 and 5 are the same as in Example 1; the methods for preparing high-voltage ceramic capacitor dielectrics in Examples 6 and 7 are the same as in Example 2; and the methods for preparing high-voltage ceramic capacitor dielectrics in Examples 8 and 9 are the same as in Example 3.

[0089] The ceramic capacitors produced in the above examples were then tested for performance. The dielectric properties of the ceramic capacitors in each example are shown in Table 2. Table 2 shows that the prepared ceramic capacitors exhibit high withstand voltages, exceeding 30 kV / mm for DC and 18 kV / mm for AC. The dielectric constant is above 8600, the dielectric loss is less than 0.1%, and the capacitance temperature variation is low, meeting the requirements of the Y5U characteristic.

[0090] Table 1 Raw material ratios (weight percentages) of various embodiments of the present invention

[0091]

[0092] Table 2 Properties of ceramic capacitor dielectrics prepared in various embodiments of the present invention

[0093]

Claims

1. A high voltage ceramic capacitor dielectric, characterized in that It is made of the following raw materials in the following weight ratios: BaTiO3 56-89%, SrTiO3 1-26%, NaAgMoO4 1-14%, Na2WO4 0.03-9%, V2O5 0.02-1.4%, ZnO 0.1-1.7%, and MnO2 0.01-0.95%; The high-voltage ceramic capacitor dielectric is obtained by uniformly mixing BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2, drying, granulating, pressing green sheets and sintering.

2. The high voltage ceramic capacitor dielectric according to claim 1, characterized in that The high-voltage ceramic capacitor dielectric is made of the following raw materials in the following weight ratios: BaTiO3 61-85%, SrTiO3 2-21%, NaAgMoO4 2-13%, Na2WO4 0.6-7%, V2O5 0.1-0.5%, ZnO 0.1-0.6%, and MnO2 0.02-0.9%.

3. The high voltage ceramic capacitor dielectric according to claim 1, wherein The high-voltage ceramic capacitor dielectric is made of the following raw materials in the following weight ratios: BaTiO3 64-84%, SrTiO3 2-18%, NaAgMoO4 3-9%, Na2WO4 0.5-7%, V2O5 0.1-0.5%, ZnO 0.1-0.6%, and MnO2 0.02-0.9%.

4. The high voltage ceramic capacitor dielectric according to claim 1, wherein The high-voltage ceramic capacitor dielectric is made of the following raw materials in the following weight ratios: BaTiO3 71-81.5%, SrTiO3 3-18%, NaAgMoO4 2-7.5%, Na2WO4 2-6%, V2O5 0.1-0.65%, ZnO 0.1-0.6%, and MnO2 0.02-0.9%.

5. The high voltage ceramic capacitor dielectric according to any one of claims 1 to 4, characterized in that The NaAgMoO4 is prepared by the following process: Na2CO3, Ag2CO3 and MoO3 are prepared in a molar ratio of 0.5:0.5:1, then the Na2CO3, Ag2CO3 and MoO3 are ground and mixed evenly, and then the mixture of Na2CO3, Ag2CO3 and MoO3 is placed in an alumina crucible and kept warm at 350-450°C for 120 minutes to obtain NaAgMoO4.

6. The high voltage ceramic capacitor dielectric according to any one of claims 1 to 4, characterized in that The Na2WO4 is prepared by the following process: Na2CO3 and WO3 are prepared in a molar ratio of 1:1, then the Na2CO3 and WO3 are ground and mixed evenly, and then the mixture of Na2CO3 and WO3 is placed in an alumina crucible and kept warm at 500-600°C for 120 minutes to obtain Na2WO4.

7. The method for preparing a high voltage ceramic capacitor dielectric according to claim 1, characterized in that The steps include: (1) BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2 are prepared in proportion; (2) The BaTiO3, SrTiO3, NaAgMoO4, Na2WO4, V2O5, ZnO and MnO2 prepared in step (1) are crushed and mixed uniformly to obtain a mixed powder; (3) drying the mixed powder obtained in step (2) to obtain a dry powder; (4) Adding a binder to the dry powder and granulating it to obtain a granular material; (5) pressing the granular material obtained in step (4) into green sheets; (6) The green sheet is placed at 1050-1100° C. and kept at this temperature for 1-4 hours to allow the green sheet to discharge the binder and sinter to obtain the high-voltage ceramic capacitor dielectric.

8. The method for preparing a high-voltage ceramic capacitor dielectric according to claim 7, wherein: In step (2), a planetary ball mill is used to ball mill the prepared raw materials. The weight ratio of the raw materials to the balls and the water used is: raw materials: balls: water = 1:3: (0.6-1.0). The ball milling process lasts for 4-8 hours.

9. The method for preparing a high-voltage ceramic capacitor dielectric according to claim 7, wherein: The binder in step (4) is a polyvinyl alcohol solution with a weight percentage concentration of 10%, and the weight of the added polyvinyl alcohol solution is 8-10% of the weight of the dry powder.

10. The method for preparing a high-voltage ceramic capacitor dielectric according to claim 7, wherein: In step (5), the granular material is dry-pressed at a pressure of 20-30 MPa to obtain a green sheet.

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