A base metal high-voltage multilayer ceramic capacitor and a ceramic dielectric material and a preparation method thereof

Abstract

The application belongs to the field of porcelain dielectric capacitor preparation, and particularly relates to a base metal high-voltage multilayer porcelain dielectric capacitor and a ceramic dielectric material and a preparation method thereof. The ceramic dielectric material comprises the following molar parts of raw materials: 100 parts of a BST main matrix, and 0.5-2.0 parts of NBT material. The BST main matrix comprises the following raw materials: BT material, strontium titanate, magnesium oxide, trimanganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxide, niobium pentoxide, and silicon dioxide. The NBT material is composed of bismuth trioxide, sodium carbonate, and titanium dioxide in a molar ratio of 2:1:1. The application limits the composition of raw materials and the preparation method of the multilayer porcelain dielectric capacitor, and obtains excellent performances such as a dielectric constant (>=2000), low loss (<=2%), super-high withstand voltage (BDV >=100 V / um), high insulation resistance (RC@25 DEG C >=2000 M omega mu F, RC@125 DEG C >=200 M omega mu F), good temperature stability, and compliance with X7R requirements.

Description

Technical Field

[0001] This invention belongs to the field of ceramic capacitor manufacturing, specifically relating to a base metal high-voltage multilayer ceramic capacitor and its ceramic dielectric material and manufacturing method. Background Technology

[0002] Base metal electrode high voltage multilayer ceramic capacitors (MLCCs) are key passive components widely used in electronic devices requiring high voltage, high reliability, and high performance. They are developed from traditional multilayer ceramic capacitors (MLCCs) and are specifically designed for applications requiring high voltage and high temperature conditions.

[0003] Traditional MLCCs mostly use precious metal internal electrodes due to their excellent conductivity, oxidation resistance, and high-temperature stability, making them widely used in aerospace, military, and high-end communications. However, precious metals are expensive and resources are limited. To reduce manufacturing costs, the industry has gradually developed base metal electrode (BME) technology.

[0004] Electrodes in BME technology typically use materials such as nickel and copper, which are far less expensive than precious metal electrodes, while possessing good conductivity and sinterability. The matrix is ​​generally barium titanate. Since base metals oxidize when sintered in air, sintering in a reducing atmosphere is necessary. However, barium titanate sintering in a reducing atmosphere can lead to reduction and semiconductorization, resulting in decreased insulation resistance and poor reliability. Therefore, barium titanate needs to be doped to modify the ceramic material, giving it good electrical properties and reliability.

[0005] The technical challenge of base metal ultra-high voltage multilayer ceramic capacitors lies in how to simultaneously achieve ultra-high withstand voltage and excellent temperature stability under conditions of high dielectric thickness and high electric field strength. For ultra-high voltage MLCCs to achieve their target performance, the dielectric material formulation must first possess excellent ultra-high voltage characteristics. Therefore, the problem this invention aims to solve is how to obtain a high-performance formulation by controlling the material composition and doping process, and how to apply it to base metal, high-voltage, and highly reliable ultra-high voltage multilayer ceramic capacitors. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a base metal high-voltage multilayer ceramic capacitor, its ceramic dielectric material, and its preparation method.

[0007] The present invention adopts the following technical solution: A ceramic dielectric material for base metal high-voltage multilayer ceramic capacitors comprises the following molar amounts of raw materials: 100 parts of BST matrix and 0.5-2.0 parts of NBT material; The BST main matrix comprises the following molar amounts of raw materials: 100 parts BT material, 5 parts strontium titanate, 0.5-1.5 parts magnesium oxide, 0.05-0.2 parts manganese tetroxide, 0.2-1 parts zirconium dioxide, 0.2-1 parts calcium carbonate, 1-2 parts rare earth oxides, 0.2-1 parts niobium pentoxide, and 0.25-1 parts silicon dioxide; The NBT material is composed of bismuth trioxide, sodium carbonate, and titanium dioxide in a molar ratio of 2:1:1.

[0008] Furthermore, the rare earth oxide is one or more of ytterbium oxide, yttrium oxide, erbium oxide, and holmium oxide.

[0009] Furthermore, the BT material is barium titanate powder with an average particle size of 500 nm.

[0010] A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing a dielectric layer and a dielectric layer. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer is made of any of the ceramic dielectric materials described above.

[0011] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1: Solid-state synthesis of BST matrix; Step 2: Solid-state synthesis of NBT material; Step 3: Add ethanol, toluene, and dispersant to a sand mill, then add BST matrix and NBT material according to the formula, stir for 2-4 hours, and sand mill for 2-6 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2-4 hours, and sand mill for 2-6 hours to grind the average particle size to 300 nm, filter, and defoam to obtain the cast slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:15-35:15-35:0.5-2, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:1-5:6-10; Step 4: Cast the slurry into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode slurry onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 5: Degrease, sinter, and end-attach the green blank to obtain the base metal ultra-high voltage multilayer ceramic capacitor.

[0012] Further, in step 1, the specific operation of solid-state synthesis of the BST matrix is ​​as follows: BT material, strontium titanate, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, niobium pentoxide, and silicon dioxide are prepared according to the specified ratio. The mixture is then sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 2-12 hours. Subsequently, the mixture is dried, pulverized, and sieved. Solid-state synthesis is then performed at a synthesis temperature of 1000-1100℃ for 2-4 hours to obtain the BST matrix.

[0013] Further, in step 2, the specific operation of solid-state synthesis of NBT material is as follows: Bismuth trioxide, sodium carbonate, and titanium dioxide are prepared according to the formula, and sand milled with zirconia balls as the grinding medium and alcohol as the dispersion medium for 2-12 hours. Then, the mixture is dried, pulverized, and sieved. Solid-state synthesis is performed at a synthesis temperature of 1000-1100℃ and a holding time of 2-4 hours to obtain the NBT material.

[0014] Furthermore, in step 5, sintering specifically includes: sintering the degreased green body in a reducing atmosphere, introducing H2 / N2 during the sintering process, humidifying simultaneously, raising the temperature to 1200-1300℃ at a rate of 2-10℃ / min and holding for 1-5 hours; then re-oxygenating at 800-1000℃ with an oxygen content of 5-50ppm and holding for 1-6 hours.

[0015] Furthermore, in step 5, the end-attachment specifically includes: chamfering the sintered green blank and attaching it with copper electrodes at a sintering temperature of 800-900℃, using nitrogen protection, holding it at that temperature for 0.5-2 hours, and then cooling it to obtain the base metal high-voltage multilayer ceramic capacitor.

[0016] Furthermore, in step 5, the degreasing environment for the green body is: 270-400℃, under a nitrogen atmosphere, for 6-30 hours.

[0017] As can be seen from the above description of the present invention, compared with the prior art, the beneficial effects of the present invention are: First, the present invention, through the raw material composition and preparation method of ceramic capacitors, enables the prepared ceramic capacitors to have excellent properties such as high withstand voltage (≥100V / μm), stable dielectric temperature characteristic curve (meeting X7R requirements), low loss (≤2.5%), dielectric constant (≥2000), and long-term high voltage reliability. Second, using BST material as the main substrate: Strontium titanate has a low dielectric constant and good temperature stability. By forming a solid solution between barium titanate and strontium titanate, the Curie temperature and dielectric properties of the material can be effectively controlled. At the same time, strontium titanate, as a paraelectric phase, has high intrinsic breakdown strength. When added to the barium titanate matrix, it can reduce residual polarization by disrupting the long-range ferroelectric order of barium titanate, significantly enhancing maximum polarization and dielectric constant, while maintaining low dielectric loss, which helps to improve the breakdown strength of the material. Third, the overall dielectric properties of the material are improved by pre-doping multiple elements into the main substrate. Mg is mainly dissolved in the grain shell and interacts with rare earth elements such as Y, Ho, and Er to form a compositional gradient, making the dielectric constant-temperature curve flatter. Simultaneously, Mg effectively inhibits grain boundary migration and suppresses abnormal grain growth, resulting in finer grains. Finer grains improve mechanical strength and disperse electric field stress, thereby increasing the breakdown field strength. Nb, through segregation at grain boundaries, effectively inhibits grain boundary migration and abnormal grain growth, significantly refining the grains and increasing the breakdown field strength. Nb doping also lowers the sintering temperature of the ceramic, which helps to achieve densification, reduce porosity, and thus improve dielectric breakdown strength. Co-doping of Mn and Nb forms stable defect complexes, effectively suppressing the formation of oxygen vacancies and improving the insulation resistance and thermal stability of the material. Fourth, NBT material was synthesized as a dopant phase, resulting in improved breakdown strength. NBT material is a relaxor ferroelectric material, with Bi and Na randomly occupying A sites, leading to uneven local charge distribution, disrupting long-range ferroelectric order, and inducing polar nanoregions (PNRs). A gradient change in dielectric constant exists between PNRs and the matrix, and the numerous PNRs / matrix interfaces provide abundant interfacial polarization sites. Compositional fluctuations near PNRs can compensate for local defects, helping to reduce electric field concentration points, homogenize the electric field distribution, and thus improve the breakdown strength of the material. Fifth, a multiphase structure is adopted, consisting of a BT ferroelectric phase, a strontium titanate paraelectric phase, and an NBT relaxor phase. BT is a normal ferroelectric phase; strontium titanate possesses intrinsically high breakdown strength; and NBT, added last as the relaxor phase, generates stable, independent polar nanoregions that homogenize the electric field and block breakdown paths. This multiphase coexistence achieves ultra-high breakdown strength in the dielectric material. Attached Figure Description

[0018] Figure 1 The dielectric constant of the multilayer ceramic capacitor prepared in Example 1 varies with temperature. Figure 2 The capacitance change rate of the multilayer ceramic capacitor prepared in Example 1 is shown as a function of temperature. Detailed Implementation

[0019] The present invention will be further described below through specific embodiments.

[0020] A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer is made of ceramic dielectric material.

[0021] Ceramic dielectric material, comprising the following molar amounts of raw materials: 100 parts of BST matrix and 0.5-2.0 parts of NBT material.

[0022] The BST matrix comprises the following molar amounts of raw materials: 100 parts BT material, 5 parts strontium titanate, 0.5-1.5 parts magnesium oxide, 0.05-0.2 parts manganese tetroxide, 0.2-1 parts zirconium dioxide, 0.2-1 parts calcium carbonate, 1-2 parts rare earth oxides, 0.2-1 parts niobium pentoxide, and 0.25-1 parts silicon dioxide; wherein the rare earth oxides are one or more of ytterbium oxide, yttrium oxide, erbium oxide, and holmium oxide; and the BT material is barium titanate powder with an average particle size of 500 nm.

[0023] NBT material is composed of bismuth trioxide, sodium carbonate, and titanium dioxide in a molar ratio of 2:1:1.

[0024] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1, Solid-state synthesis of BST matrix: The BT material, strontium titanate, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, niobium pentoxide, and silicon dioxide are formulated according to the specified ratio. The mixture is then sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 2-12 hours. Subsequently, the mixture is dried, pulverized, and sieved. It is then synthesized using a solid-state method at a synthesis temperature of 1000-1100℃ for 2-4 hours to obtain the BST matrix. Step 2, solid-state synthesis of NBT material: Bismuth trioxide, sodium carbonate, and titanium dioxide were prepared according to the specified ratio, and then sand-milled using zirconia balls as the grinding medium and alcohol as the dispersion medium for 2-12 hours. After that, the mixture was dried, pulverized, and sieved. The NBT material was then synthesized using a solid-state method at a temperature of 1000-1100℃ and a holding time of 2-4 hours. Step 3: Add ethanol, toluene, and dispersant to a sand mill, then add BST matrix and NBT material according to the formula, stir for 2-4 hours, and sand mill for 2-6 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2-4 hours, and sand mill for 2-6 hours to grind the average particle size to 300 nm, filter, and defoam to obtain the cast slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:15-35:15-35:0.5-2, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:1-5:6-10; Step 4: Cast the slurry into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode slurry onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 5: Degrease the green body under the following conditions: 270-400℃, nitrogen atmosphere, for 6-30 hours. Step 6: Sinter the degreased green body under a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is raised to 1200-1300℃ at a rate of 2-10℃ / min and held for 1-5 hours. Then, oxygen is restored at 800-1000℃ with an oxygen content of 5-50ppm and held for 1-6 hours. Step 7: Chamfer the sintered green blank and attach it with copper electrodes at a sintering temperature of 800-900℃ under nitrogen protection for 0.5-2 hours. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained. Example 1

[0025] A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer is made of ceramic dielectric material.

[0026] The ceramic dielectric material comprises the following molar amounts of raw materials: 100 parts of BST matrix and 1.0 part of NBT material.

[0027] The BST matrix comprises the following molar amounts of raw materials: 100 parts BT material, 5 parts strontium titanate, 1.0 part magnesium oxide, 0.1 part manganese tetroxide, 0.5 parts zirconium dioxide, 0.5 parts calcium carbonate, 1.5 parts rare earth oxides, 0.5 parts niobium pentoxide, and 0.5 parts silicon dioxide; wherein the rare earth oxides are composed of yttrium oxide and erbium oxide in a molar ratio of 2:1.

[0028] NBT material is composed of bismuth trioxide, sodium carbonate, and titanium dioxide in a molar ratio of 2:1:1.

[0029] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1, Solid-state synthesis of BST matrix: The BT material, strontium titanate, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, niobium pentoxide, and silicon dioxide were formulated according to the specified ratio. The mixture was then sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 6 hours. Subsequently, the mixture was dried, pulverized, and sieved. It was then synthesized using a solid-state method at a synthesis temperature of 1100℃ for 3 hours to obtain the BST matrix. Step 2, solid-state synthesis of NBT material: Bismuth trioxide, sodium carbonate, and titanium dioxide were prepared according to the specified ratio, and then sand-milled using zirconia balls as the grinding medium and alcohol as the dispersion medium for 4 hours. After that, the mixture was dried, pulverized, and sieved. The NBT material was then synthesized using a solid-state method at a synthesis temperature of 1050℃ and a holding time of 2.5 hours. Step 3: Add ethanol, toluene, and dispersant to a sand mill, then add BST matrix and NBT material according to the formula, stir for 2 hours, and sand mill for 4 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2 hours, and sand mill for 4 hours to grind the average particle size to 300 nm, filter, and defoam to obtain the cast slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:20:20:1, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:2:10; Step 4: Cast the slurry into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode slurry onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 5: Degrease the green body. The degreasing environment for the green body is: 300℃, nitrogen atmosphere, and heat preservation for 30 hours. Step 6: Sinter the degreased green body under a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1270℃ at a rate of 10℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 30ppm and held for 4 hours. Step 7: Chamfer the sintered green blank and attach it with copper electrodes at a sintering temperature of 850°C. Protect the blank with nitrogen and hold it at that temperature for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained. Example 2

[0030] A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer is made of ceramic dielectric material.

[0031] The ceramic dielectric material comprises the following molar amounts of raw materials: 100 parts of BST matrix and 0.5 parts of NBT material.

[0032] The BST matrix comprises the following molar amounts of raw materials: 100 parts BT material, 5 parts strontium titanate, 0.5 parts magnesium oxide, 0.05 parts manganese tetroxide, 0.2 parts zirconium dioxide, 0.2 parts calcium carbonate, 1.0 part rare earth oxides, 0.2 parts niobium pentoxide, and 0.4 parts silicon dioxide; wherein the rare earth oxides are composed of yttrium oxide and holmium oxide in a molar ratio of 1:1.

[0033] NBT material is composed of bismuth trioxide, sodium carbonate, and titanium dioxide in a molar ratio of 2:1:1.

[0034] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1, Solid-state synthesis of BST matrix: The BT material, strontium titanate, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, niobium pentoxide, and silicon dioxide were formulated according to the specified ratio. The mixture was then sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 6 hours. Subsequently, the mixture was dried, pulverized, and sieved. It was then synthesized using a solid-state method at a synthesis temperature of 1100℃ for 3 hours to obtain the BST matrix. Step 2, solid-state synthesis of NBT material: Bismuth trioxide, sodium carbonate, and titanium dioxide were prepared according to the specified ratio, and then sand-milled using zirconia balls as the grinding medium and alcohol as the dispersion medium for 4 hours. After that, the mixture was dried, pulverized, and sieved. The NBT material was then synthesized using a solid-state method at a synthesis temperature of 1050℃ and a holding time of 2.5 hours. Step 3: Add ethanol, toluene, and dispersant to a sand mill, then add BST matrix and NBT material according to the formula, stir for 2 hours, and sand mill for 4 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2 hours, and sand mill for 4 hours to grind the average particle size to 300 nm, filter, and defoam to obtain the cast slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:20:20:1, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:2:10; Step 4: Cast the slurry into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode slurry onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 5: Degrease the green body. The degreasing environment for the green body is: 300℃, nitrogen atmosphere, and heat preservation for 30 hours. Step 6: Sinter the degreased green body under a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1270℃ at a rate of 10℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 30ppm and held for 4 hours. Step 7: Chamfer the sintered green blank and attach it with copper electrodes at a sintering temperature of 850°C. Protect the blank with nitrogen and hold it at that temperature for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained. Example 3

[0035] A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer is made of ceramic dielectric material.

[0036] The ceramic dielectric material comprises the following molar amounts of raw materials: 100 parts of BST matrix and 1.5 parts of NBT material.

[0037] The BST matrix comprises the following molar amounts of raw materials: 100 parts BT material, 5 parts strontium titanate, 1.5 parts magnesium oxide, 0.2 parts manganese tetroxide, 1.0 part zirconium dioxide, 1.0 part calcium carbonate, 2.0 parts rare earth oxides, 1.0 part niobium pentoxide, and 0.6 parts silicon dioxide; wherein the rare earth oxides are composed of yttrium oxide and ytterbium oxide in a molar ratio of 3:1.

[0038] NBT material is composed of bismuth trioxide, sodium carbonate, and titanium dioxide in a molar ratio of 2:1:1.

[0039] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1, Solid-state synthesis of BST matrix: The BT material, strontium titanate, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, niobium pentoxide, and silicon dioxide were formulated according to the specified ratio. The mixture was then sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 6 hours. Subsequently, the mixture was dried, pulverized, and sieved. It was then synthesized using a solid-state method at a synthesis temperature of 1100℃ for 3 hours to obtain the BST matrix. Step 2, solid-state synthesis of NBT material: Bismuth trioxide, sodium carbonate, and titanium dioxide were prepared according to the specified ratio, and then sand-milled using zirconia balls as the grinding medium and alcohol as the dispersion medium for 4 hours. After that, the mixture was dried, pulverized, and sieved. The NBT material was then synthesized using a solid-state method at a synthesis temperature of 1050℃ and a holding time of 2.5 hours. Step 3: Add ethanol, toluene, and dispersant to a sand mill, then add BST matrix and NBT material according to the formula, stir for 2 hours, and sand mill for 4 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2 hours, and sand mill for 4 hours to grind the average particle size to 300 nm, filter, and defoam to obtain the cast slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:20:20:1, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:2:10; Step 4: Cast the slurry into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode slurry onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 5: Degrease the green body. The degreasing environment for the green body is: 300℃, nitrogen atmosphere, and heat preservation for 30 hours. Step 6: Sinter the degreased green body under a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1270℃ at a rate of 10℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 30ppm and held for 4 hours. Step 7: Chamfer the sintered green blank and attach it with copper electrodes at a sintering temperature of 850°C. Protect the blank with nitrogen and hold it at that temperature for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained.

[0040] Comparative Example 1 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer is made of ceramic dielectric material.

[0041] The ceramic dielectric material comprises the following molar amounts of raw materials: 100 parts of BT matrix and 1.0 part of NBT material.

[0042] The BT matrix comprises the following molar amounts of raw materials: 100 parts BT material, 1.0 part magnesium oxide, 0.1 part manganese tetroxide, 0.5 parts zirconium dioxide, 0.5 parts calcium carbonate, 1.5 parts rare earth oxides, 0.5 parts niobium pentoxide, and 0.5 parts silicon dioxide; wherein the rare earth oxides are composed of yttrium oxide and erbium oxide in a molar ratio of 2:1.

[0043] NBT material is composed of bismuth trioxide, sodium carbonate, and titanium dioxide in a molar ratio of 2:1:1.

[0044] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1, Solid-state synthesis of BT matrix: The BT material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, niobium pentoxide, and silicon dioxide were formulated according to the specified ratio. The mixture was then sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 6 hours. Subsequently, the mixture was dried, pulverized, and sieved. It was then synthesized using a solid-state method at a synthesis temperature of 1100℃ for 3 hours to obtain the BT matrix. Step 2, solid-state synthesis of NBT material: Bismuth trioxide, sodium carbonate, and titanium dioxide were prepared according to the specified ratio, and then sand-milled using zirconia balls as the grinding medium and alcohol as the dispersion medium for 4 hours. After that, the mixture was dried, pulverized, and sieved. The NBT material was then synthesized using a solid-state method at a synthesis temperature of 1050℃ and a holding time of 2.5 hours. Step 3: Add ethanol, toluene, and dispersant to a sand mill, then add BT matrix and NBT material according to the formula, stir for 2 hours, and sand mill for 4 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2 hours, and sand mill for 4 hours to grind the average particle size to 300 nm, filter, and defoam to obtain the cast slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:20:20:1, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:2:10; Step 4: Cast the slurry into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode slurry onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 5: Degrease the green body. The degreasing environment for the green body is: 300℃, nitrogen atmosphere, and heat preservation for 30 hours. Step 6: Sinter the degreased green body under a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1270℃ at a rate of 10℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 30ppm and held for 4 hours. Step 7: Chamfer the sintered green blank and attach it with copper electrodes at a sintering temperature of 850°C. Protect the blank with nitrogen and hold it at that temperature for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained.

[0045] Comparative Example 2 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer is made of ceramic dielectric material.

[0046] The ceramic dielectric material comprises the following molar amounts of raw materials: 100 parts of BT matrix, 1.0 part of NBT material, and 5.0 parts of strontium titanate.

[0047] The BT matrix comprises the following molar amounts of raw materials: 100 parts BT material, 1.0 part magnesium oxide, 0.1 part manganese tetroxide, 0.5 parts zirconium dioxide, 0.5 parts calcium carbonate, 1.5 parts rare earth oxides, 0.5 parts niobium pentoxide, and 0.5 parts silicon dioxide; wherein the rare earth oxides are composed of yttrium oxide and erbium oxide in a molar ratio of 2:1.

[0048] NBT material is composed of bismuth trioxide, sodium carbonate, and titanium dioxide in a molar ratio of 2:1:1.

[0049] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1, Solid-state synthesis of BT matrix: The BT material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, niobium pentoxide, and silicon dioxide were formulated according to the specified ratio. The mixture was then sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 6 hours. Subsequently, the mixture was dried, pulverized, and sieved. It was then synthesized using a solid-state method at a synthesis temperature of 1100℃ for 3 hours to obtain the BT matrix. Step 2, solid-state synthesis of NBT material: Bismuth trioxide, sodium carbonate, and titanium dioxide were prepared according to the specified ratio, and then sand-milled using zirconia balls as the grinding medium and alcohol as the dispersion medium for 4 hours. After that, the mixture was dried, pulverized, and sieved. The NBT material was then synthesized using a solid-state method at a synthesis temperature of 1050℃ and a holding time of 2.5 hours. Step 3: Add ethanol, toluene, and dispersant to a sand mill, then add BT matrix, NBT material, and strontium titanate according to the formula, stir for 2 hours, and sand mill for 4 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2 hours, and sand mill for 4 hours to grind the average particle size to 300 nm, filter, and defoam to obtain the cast slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:20:20:1, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:2:10; Step 4: Cast the slurry into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode slurry onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 5: Degrease the green body. The degreasing environment for the green body is: 300℃, nitrogen atmosphere, and heat preservation for 30 hours. Step 6: Sinter the degreased green body under a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1270℃ at a rate of 10℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 30ppm and held for 4 hours. Step 7: Chamfer the sintered green blank and attach it with copper electrodes at a sintering temperature of 850°C. Protect the blank with nitrogen and hold it at that temperature for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained.

[0050] Comparative Example 3 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer is made of ceramic dielectric material.

[0051] Ceramic dielectric material, comprising the following molar amounts of raw materials: 100 parts of BST matrix.

[0052] The BST matrix comprises the following molar amounts of raw materials: 100 parts BT material, 5 parts strontium titanate, 1.0 part magnesium oxide, 0.1 part manganese tetroxide, 0.5 parts zirconium dioxide, 0.5 parts calcium carbonate, 1.5 parts rare earth oxides, 0.5 parts niobium pentoxide, and 0.5 parts silicon dioxide; wherein the rare earth oxides are composed of yttrium oxide and erbium oxide in a molar ratio of 2:1.

[0053] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1, Solid-state synthesis of BST matrix: The BT material, strontium titanate, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, niobium pentoxide, and silicon dioxide were formulated according to the specified ratio. The mixture was then sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 6 hours. Subsequently, the mixture was dried, pulverized, and sieved. It was then synthesized using a solid-state method at a synthesis temperature of 1100℃ for 3 hours to obtain the BST matrix. Step 2: Add ethanol, toluene, and dispersant to a sand mill, then add BST matrix according to the formula, stir for 2 hours, and sand mill for 4 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2 hours, and sand mill for 4 hours to grind the average particle size to 300 nm, filter, and defoam to obtain the casting slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:20:20:1, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:2:10; Step 3: Cast the paste into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode paste onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 4: Degrease the green body. The degreasing environment for the green body is: 300℃, nitrogen atmosphere, and heat preservation for 30 hours. Step 5: Sinter the degreased green body in a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1270℃ at a rate of 10℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 30ppm and held for 4 hours. Step 6: Chamfer the sintered green blank and attach it with copper electrodes at a sintering temperature of 850°C. Protect the blank with nitrogen and hold it at that temperature for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained.

[0054] Comparative Example 4 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer is made of ceramic dielectric material.

[0055] The ceramic dielectric material comprises the following molar amounts of raw materials: 100 parts of BST matrix and 1.0 part of TB material.

[0056] The BST matrix comprises the following molar amounts of raw materials: 100 parts BT material, 5 parts strontium titanate, 1.0 part magnesium oxide, 0.1 part manganese tetroxide, 0.5 parts zirconium dioxide, 0.5 parts calcium carbonate, 1.5 parts rare earth oxides, 0.5 parts niobium pentoxide, and 0.5 parts silicon dioxide; wherein the rare earth oxides are composed of yttrium oxide and erbium oxide in a molar ratio of 2:1.

[0057] TB material is composed of sodium carbonate and titanium dioxide in a 1:1 molar ratio.

[0058] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1, Solid-state synthesis of BST matrix: The BT material, strontium titanate, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, niobium pentoxide, and silicon dioxide were formulated according to the specified ratio. The mixture was then sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 6 hours. Subsequently, the mixture was dried, pulverized, and sieved. It was then synthesized using a solid-state method at a synthesis temperature of 1100℃ for 3 hours to obtain the BST matrix. Step 2, Solid-state synthesis of TB material: Sodium carbonate and titanium dioxide were prepared according to the specified ratio, and then sand-milled using zirconia balls as the grinding medium and alcohol as the dispersion medium for 4 hours. After sand-milling, the mixture was dried, pulverized, and sieved. The TB material was then synthesized using a solid-state method at a synthesis temperature of 1050℃ and a holding time of 2.5 hours. Step 3: Add ethanol, toluene, and dispersant to a sand mill, then add BST matrix and TB material according to the formula, stir for 2 hours, and sand mill for 4 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2 hours, and sand mill for 4 hours to grind the average particle size to 300nm, filter, and defoam to obtain the casting slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:20:20:1, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:2:10; Step 4: Cast the slurry into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode slurry onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 5: Degrease the green body. The degreasing environment for the green body is: 300℃, nitrogen atmosphere, and heat preservation for 30 hours. Step 6: Sinter the degreased green body under a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1270℃ at a rate of 10℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 30ppm and held for 4 hours. Step 7: Chamfer the sintered green blank and attach it with copper electrodes at a sintering temperature of 850°C. Protect the blank with nitrogen and hold it at that temperature for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained.

[0059] Comparative Example 5 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer is made of ceramic dielectric material.

[0060] The ceramic dielectric material comprises the following molar amounts of raw materials: 100 parts of BST matrix and 1.0 part of NBT material.

[0061] The BST matrix comprises the following molar amounts of raw materials: 100 parts BT material, 5 parts strontium titanate, 1.0 part magnesium oxide, 0.1 part manganese tetroxide, 0.5 parts zirconium dioxide, 0.5 parts calcium carbonate, 1.5 parts rare earth oxides, and 0.5 parts silicon dioxide; wherein the rare earth oxides are composed of yttrium oxide and erbium oxide in a molar ratio of 2:1.

[0062] NBT material is composed of bismuth trioxide, sodium carbonate, and titanium dioxide in a molar ratio of 2:1:1.

[0063] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1, Solid-state synthesis of BST matrix: The BT material, strontium titanate, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, and silicon dioxide were formulated according to the specified ratio. The mixture was then sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 6 hours. Subsequently, the mixture was dried, pulverized, and sieved. It was then synthesized using a solid-state method at a synthesis temperature of 1100℃ for 3 hours to obtain the BST matrix. Step 2, solid-state synthesis of NBT material: Bismuth trioxide, sodium carbonate, and titanium dioxide were prepared according to the specified ratio, and then sand-milled using zirconia balls as the grinding medium and alcohol as the dispersion medium for 4 hours. After that, the mixture was dried, pulverized, and sieved. The NBT material was then synthesized using a solid-state method at a synthesis temperature of 1050℃ and a holding time of 2.5 hours. Step 3: Add ethanol, toluene, and dispersant to a sand mill, then add BST matrix and NBT material according to the formula, stir for 2 hours, and sand mill for 4 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2 hours, and sand mill for 4 hours to grind the average particle size to 300 nm, filter, and defoam to obtain the cast slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:20:20:1, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:2:10; Step 4: Cast the slurry into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode slurry onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 5: Degrease the green body. The degreasing environment for the green body is: 300℃, nitrogen atmosphere, and heat preservation for 30 hours. Step 6: Sinter the degreased green body under a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1270℃ at a rate of 10℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 30ppm and held for 4 hours. Step 7: Chamfer the sintered green blank and attach it with copper electrodes at a sintering temperature of 850°C. Protect the blank with nitrogen and hold it at that temperature for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained.

[0064] Comparative Example 6 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on it. The dielectric layer is made of a ceramic dielectric material. The dielectric layer comprises the following raw materials in molar proportions: 100 parts BT material, 5 parts strontium titanate, 1.0 part magnesium oxide, 0.1 part manganese tetroxide, 0.5 parts zirconium dioxide, 0.5 parts calcium carbonate, 1.0 part yttrium oxide, 0.5 parts erbium oxide, 0.5 parts niobium pentoxide, 0.5 parts silicon dioxide, 0.55 parts bismuth trioxide, 0.27 parts sodium carbonate, and 0.27 parts titanium dioxide. The BT material is barium titanate powder with an average particle size of 500 nm. A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1: Add ethanol, toluene, and dispersant to a sand mill. Then, add BT material, strontium titanate, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, yttrium oxide, erbium oxide, niobium pentoxide, silicon dioxide, bismuth trioxide, sodium carbonate, and titanium dioxide according to the specified ratio. Stir for 2 hours and sand mill for 4 hours. Then, add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio. Stir for 2 hours and sand mill for 4 hours to grind the average particle size to 300 nm. Filter and defoam to obtain the casting slurry. The weight ratio of the medium layer material is ethanol:toluene:dispersant = 100:20:20:1, and the ratio of the medium layer material to dioctyl phthalate:polyvinyl butyral resin is 100:2:10. Step 2: The paste is cast into a dielectric layer with a thickness of 25μm. Then, nickel electrode paste is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together to a preset thickness. Then, the green body is manufactured by water pressing and slicing. Step 3: Degrease the green body. The degreasing environment for the green body is: 300℃, nitrogen atmosphere, and heat preservation for 30 hours. Step 4: Sinter the degreased green body under a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1270℃ at a rate of 10℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 30ppm and held for 4 hours. Step 5: Chamfer the sintered green blank and attach copper electrodes at 850°C under nitrogen protection for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained. The multilayer ceramic capacitors prepared in Examples 1-3 and Comparative Examples 1-6 were subjected to various performance tests, and the results are shown in the table below.

[0065] Table 1 Test results for each capacitor

[0066] Where K refers to the dielectric constant, DF refers to the loss tangent, TCC refers to the temperature coefficient of capacitance, and BDV refers to the breakdown voltage.

[0067] Through the above table and appendix Figure 1 ,2 It is understood that the base metal high-voltage multilayer ceramic capacitor prepared in this patent application achieves low loss, ultra-high withstand voltage, high insulation resistance, and good temperature stability by synthesizing the BST main matrix and NBT material through a solid-state method and doping the BST main matrix with NBT material under the condition of high dielectric thickness.

[0068] A comparison of Example 1 with Comparative Examples 1-5 shows that by limiting the synthesis of the BST matrix and coordinating the various dopants, excellent properties such as dielectric constant (≥2000), low loss (≤2%), ultra-high withstand voltage (BDV≥100V / μm), high insulation resistance (RC@25℃≥2000 MΩ·μF, RC@125℃≥200 MΩ·μF), good temperature stability, and compliance with X7R requirements can be obtained.

[0069] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A ceramic dielectric material for base metal high-voltage multilayer ceramic capacitors, characterized in that: It includes the following molar amounts of raw materials: 100 parts of BST matrix and 0.5-2.0 parts of NBT material; The BST main matrix comprises the following molar amounts of raw materials: 100 parts BT material, 5 parts strontium titanate, 0.5-1.5 parts magnesium oxide, 0.05-0.2 parts manganese tetroxide, 0.2-1 parts zirconium dioxide, 0.2-1 parts calcium carbonate, 1-2 parts rare earth oxides, 0.2-1 parts niobium pentoxide, and 0.25-1 parts silicon dioxide; The NBT material is composed of bismuth trioxide, sodium carbonate, and titanium dioxide in a molar ratio of 2:1:

1.

2. The ceramic dielectric material for a base metal high-voltage multilayer ceramic capacitor according to claim 1, characterized in that: The rare earth oxide is one or more of ytterbium oxide, yttrium oxide, erbium oxide, and holmium oxide.

3. The ceramic dielectric material for a base metal high-voltage multilayer ceramic capacitor according to claim 1, characterized in that: The BT material is barium titanate powder with an average particle size of 500 nm.

4. A base metal high-voltage multilayer ceramic capacitor, characterized in that: It is formed by stacking and firing a dielectric layer and a dielectric layer, wherein the dielectric layer includes a dielectric layer and an electrode printed on the dielectric layer, and the dielectric layer is made of the ceramic dielectric material according to any one of claims 1 to 3.

5. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 4, characterized in that: Includes the following steps: Step 1: Solid-state synthesis of BST matrix; Step 2: Solid-state synthesis of NBT material; Step 3: Add ethanol, toluene, and dispersant to a sand mill, then add BST matrix and NBT material according to the formula, stir for 2-4 hours, and sand mill for 2-6 hours; then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2-4 hours, and sand mill for 2-6 hours to grind the average particle size to 300 nm, filter, and defoam to obtain the cast slurry; wherein, according to the weight ratio, the medium layer material: ethanol: toluene: dispersant = 100:15-35:15-35:0.5-2, and the medium layer material: dioctyl phthalate: polyvinyl butyral resin = 100:1-5:6-10; Step 4: Cast the slurry into a dielectric layer with a thickness of 25μm. Then, print the nickel electrode slurry onto the dielectric layer to form a dielectric layer. Stack the dielectric layer and the dielectric layer together to a preset thickness. Then, through water pressure and slicing, a green blank is produced. Step 5: Degrease, sinter, and end-attach the green blank to obtain the base metal ultra-high voltage multilayer ceramic capacitor.

6. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 5, characterized in that: Step 1, the specific operation of solid-state synthesis of BST matrix is ​​as follows: BT material, strontium titanate, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, rare earth oxides, niobium pentoxide, and silicon dioxide are prepared according to the formula. The mixture is sand-milled using zirconium oxide balls as the grinding medium and deionized water as the dispersion medium for 2-12 hours. Subsequently, it is dried, pulverized, and sieved. Solid-state synthesis is performed at a synthesis temperature of 1000-1100℃ for 2-4 hours to obtain the BST matrix.

7. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 5, characterized in that: Step 2, the specific operation of solid-state synthesis of NBT material is as follows: Bismuth trioxide, sodium carbonate and titanium dioxide are prepared according to the formula, and sand milled with zirconia balls as grinding medium and alcohol as dispersion medium for 2-12 hours. Then, the mixture is dried, pulverized and sieved. Solid-state synthesis is carried out at a synthesis temperature of 1000-1100℃ and a holding time of 2-4 hours to obtain the NBT material.

8. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 5, characterized in that: In step 5, sintering specifically includes: sintering the degreased green body in a reducing atmosphere, introducing H2 / N2 during the sintering process, humidifying at the same time, raising the temperature to 1200-1300℃ at a rate of 2-10℃ / min and holding for 1-5h; then re-oxygenating at 800-1000℃ with an oxygen content of 5-50ppm and holding for 1-6h.

9. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 5, characterized in that: In step 5, the end-attachment specifically includes: chamfering the sintered green blank and attaching it with copper electrodes at a sintering temperature of 800-900℃, using nitrogen protection, holding it at that temperature for 0.5-2 hours, and then cooling it to obtain the base metal high-voltage multilayer ceramic capacitor.

10. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 5, characterized in that: In step 5, the degreasing environment for the green body is: 270-400℃, under a nitrogen atmosphere, for 6-30 hours.

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