High-performance air-atmosphere-sintered barium titanate-based ceramic material of type Y5P and method for producing same

Abstract

The application belongs to the technical field of electronic ceramic materials, and particularly relates to a high-performance Y5P type barium titanate-based ceramic material sintered in air atmosphere and a preparation method thereof. The ceramic material takes BaTiO3 as a main raw material, is supplemented with MgCO3, ZnO, MnCO3, ZrO2, Nb2O5 and La2O3 as composite modification additives, and after sintering in air atmosphere, the ceramic material forms a dense and uniform microstructure, has excellent dielectric properties: a dielectric constant (ε) is 2800-3500, a dielectric loss tangent (tan δ) is as low as 1.1% or below, a volume resistivity (ρ) is 1.0*10 12 Ω·cm or above, a content temperature change rate is-9.8%-+9.1% in a temperature range of-30 DEG C to 85 DEG C, and meets a Y5P type temperature characteristic standard (ΔC / C 25 ℃≤±10%). The material can realize high insulation resistance, low loss and stable temperature characteristics by being directly sintered in air, does not need a complex reduction and reoxidation process, is suitable for preparing ceramic capacitors with high reliability and low cost, and is particularly suitable for the fields of consumer electronics and industrial electronics with medium-high voltage and high stability requirements.

Description

Technical Field

[0001] This invention belongs to the field of electronic ceramic materials, specifically relating to a high-performance Y5P type barium titanate-based ceramic material sintered in an air atmosphere and its preparation method, which is particularly suitable for manufacturing ceramic capacitors with high dielectric constant, high insulation resistance and excellent temperature stability. Background Technology

[0002] As modern electronic devices evolve towards higher frequencies, higher voltages, and higher power densities, higher demands are placed on the performance stability and volumetric efficiency of ceramic capacitors—key passive components in circuits. Especially in power management, motor drives, industrial control, and automotive electronics, ceramic capacitors with simple structures, controllable costs, and the ability to withstand high DC bias are often required. The performance of their core dielectric material directly determines the capacitance, temperature stability, and long-term reliability of the device. Y5P type ceramic dielectrics require a capacitance change rate not exceeding ±10% within an operating temperature range of -30℃ to 85℃, and must possess a high dielectric constant to achieve sufficient capacitance within a limited volume, meeting the stability requirements of the capacitor components in the aforementioned applications.

[0003] While general-purpose ceramic capacitors do not face the complex base metal internal electrode co-firing issues of multilayer ceramic capacitors (MLCCs), their performance improvement is still limited by the bottlenecks inherent in the dielectric material itself. Currently, to achieve a balance between higher dielectric constants and good temperature stability, some high-dielectric-constant ceramic materials still tend to adopt the doping and sintering processes used in the MLCC field, or sinter at higher temperatures, which may lead to increased production costs or greater difficulty in controlling the microstructure. Traditional Y5P formulations often rely on the addition of large amounts of peak shifting and peak extending agents to meet temperature characteristic requirements. While this can broaden the Curie peak, it often leads to a significant reduction in the material's dielectric constant, making it difficult to simultaneously meet the dual requirements of "high dielectric constant" and "strict temperature drift limits." Furthermore, conventional processes, in pursuing high dielectric performance, sometimes fail to ensure that the material has a sufficiently high insulation resistivity, affecting its long-term operational reliability under DC bias.

[0004] Therefore, developing a barium titanate-based ceramic material that can be sintered in a conventional air atmosphere under relatively mild process conditions, while simultaneously achieving high dielectric constant, high insulation resistance, and precise Y5P temperature characteristics, is of great significance for improving the performance of ceramic capacitors, reducing manufacturing costs, and expanding their applications in demanding electronic circuits. The objective of this invention is to provide such a material system and its simple and efficient preparation method.

[0005] Existing publicly available BaTiO3-based Y5P dielectric material technologies mainly face challenges related to dielectric constant (ε) and dielectric loss (ε). tanδ ), volume resistivity ( The technical bottleneck lies in the difficulty of balancing temperature characteristics and dielectric constant with Y5P. Specifically, existing technologies mainly focus on two approaches: The first approach attempts to improve sintering characteristics by adding a glass phase or flux, and combines this with doping with elements such as Nb to achieve a trade-off between temperature characteristics and dielectric constant. For example, Chinese invention patent CN101492293A (publication date: 2009-07-29) discloses a barium titanate-based Y5P dielectric. However, since the introduction of a non-ferroelectric glass phase or a large amount of flux will severely dilute the effective dielectric constant of the material, according to its published data, although this type of system satisfies the temperature characteristics of Y5P, the room temperature dielectric constant (ε) is usually limited to a low range of 2000~2500. At the same time, a large amount of flux additives intensifies grain boundary polarization, resulting in a high dielectric loss tangent (tanδ) (usually >2.0%), and failing to achieve extremely high volume resistivity, making it difficult to meet the high insulation requirements of capacitors in harsh environments. To further improve the dielectric constant, another technical approach has shifted to a reducing atmosphere sintering system matched with base metal internal electrodes (BME). For example, Chinese invention patent CN102531592A (publication date: 2012-07-04) proposes a Y5P dielectric that can be sintered in a reducing atmosphere. While this approach can achieve a high dielectric constant, reducing atmosphere sintering inevitably leads to a large number of oxygen vacancy defects within the barium titanate lattice. Reflected in specific electrical properties, its dielectric loss tanδ remains as high as approximately 1.5%, and more critically, its insulation performance deteriorates significantly, with a decrease in volume resistivity (…). Only 10 can be achieved 8 The insulation level is in the Ω·cm range, far below the high insulation standard (≥10) required for high-reliability passive devices. 12 (Ω·cm). Furthermore, to compensate for insulation and withstand voltage defects, existing technologies have also attempted to improve overall performance through complex multi-component composite modification. For example, Chinese invention patent CN103922732A (publication date: 2014-07-16) discloses a BaTiO3-based dielectric material whose withstand voltage and temperature stability are improved through composite modification with MnO2, Nb2O5, and CaZrO3. However, such strong modification often excessively suppresses the response of ferroelectric domains, making it difficult for the dielectric constant of the material to exceed 2600; and its tanδ remains at a relatively high level of 1.5%~2.0%, with the volume resistivity ρᵥ hovering around 10. 8 ~10 9 Between Ω·cm, the contradiction of mutual constraints on performance has not been fundamentally broken.

[0006] In summary, the key challenge lies in achieving a significant increase in dielectric constant (ε≥2800) while strictly adhering to the temperature characteristics of Y5P under conventional air atmosphere sintering conditions, without relying on a glass phase that easily leads to performance degradation, and solely through lattice doping control of the intrinsic formulation. This also involves reducing dielectric loss to below 1.1% and increasing volume resistivity to 1.0×10⁻⁶. 12 Achieving a comprehensive closed loop in indicators above Ω·cm is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a high-performance Y5P-type barium titanate-based ceramic material that can be sintered in air and its preparation method. This ceramic material exhibits high dielectric constant, high insulation resistance, low loss, and precisely meets the temperature characteristic standards for Y5P-type capacitors. Furthermore, this material system eliminates the need for complex reduction-re-oxidation processes, simplifying the production process and making it suitable for manufacturing high-reliability, small-size, high-capacity ceramic capacitors.

[0008] The technical solution of this invention is: A high-performance Y5P-type barium titanate-based ceramic material sintered in an air atmosphere is provided. The ceramic material uses BaTiO3 as the main raw material and is supplemented with MgCO3, ZnO, MnCO3, ZrO2, Nb2O5 and La2O3 as composite modifying additives. The total mass of the composite modifying additives accounts for 1.20%–2.30% of the mass of the BaTiO3.

[0009] Furthermore, the raw materials of the ceramic material are proportioned by mass as follows: BaTiO3 is 100 parts, MgCO3 is 0.35~0.70 parts, ZnO is 0.10~0.25 parts, Nb2O5 is 0.25~0.50 parts, MnCO3 is 0.05~0.15 parts, ZrO2 is 0.25~0.35 parts, and La2O3 is 0.20~0.35 parts.

[0010] The preparation method of the above-mentioned ceramic material includes the following steps: Step 1: Batching and primary ball milling: Weigh out BaTiO3 powder, MgCO3, ZnO, MnCO3, ZrO2, Nb2O5 and La2O3 raw materials according to the above mass ratio, and place them together in a ball mill jar; add deionized water and grinding media to the ball mill jar, wherein the mass ratio of deionized water, grinding media and raw material powder is (1.5~2.5):(1.5~2.0):1; ball mill at a speed of 200~400 rpm for 4~12 hours to obtain a uniformly mixed slurry; Step 2: Drying, pulverizing and secondary mixing: The slurry obtained in Step 1 is dried at 80~120℃ to constant weight to obtain a mixed powder; the dried mixed powder is pulverized to ensure that there are no hard agglomerates; then, 3%~8% of the total mass of an organic binder solution is added to the pulverized mixed powder, wherein the organic binder solution is a polyvinyl alcohol aqueous solution with a mass concentration of 5%~10%, and the mixture is thoroughly mixed; Step 3: Granulation and molding: Granulate the mixed powder containing the organic binder solution from Step 2, controlling the particle size distribution of the granulated powder to be between 80 and 150 mesh; load the granulated powder into a mold and mold it under a pressure of 80 to 200 MPa to obtain a ceramic green body of the specified shape and size; heat the green body to 500 to 650°C at a heating rate of 1 to 3°C / min and hold it at this temperature for 2 hours to completely remove the organic binder; Step 4: Air Atmosphere Sintering: The green body after debinding in Step 3 is heated to a sintering temperature of 1280℃~1350℃ at a rate of 2~5℃ / min in an air atmosphere and held for 2~6 hours to achieve densification. The entire sintering process is carried out in an air atmosphere without the need for a reducing atmosphere. After sintering, the cooling rate is controlled at 5℃ / min to reduce the furnace temperature to below 200℃. Then, the furnace is allowed to cool naturally to room temperature to obtain a dense Y5P type barium titanate-based ceramic material.

[0011] Furthermore, the sintering process in step 4 is completed in one go, without the need to switch between reducing and oxidizing atmospheres, nor is a separate re-oxidation treatment step required.

[0012] Compared with the prior art, the present invention has the following advantages: (1) Achieving a high-level closed-loop balance between dielectric properties and temperature characteristics: This invention successfully solves the technical bottleneck of low dielectric constant or insufficient insulation resistance in traditional air-sintered Y5P materials through precise composite doping of MgCO3, ZnO, MnCO3, ZrO2, Nb2O5, and La2O3. While satisfying the Y5P (ΔC / C25℃≤±10%) requirements within the temperature range of -30℃ to 85℃, it further improves ε = 2800~3500, tanδ≤1.1%, and ρᵥ≥1.0×10 12 The Ω·cm index forms a closed loop, thus representing a significant technological advancement in terms of "process simplification + low loss + high insulation + temperature stability consistency".

[0013] (2) The sintering process is greatly simplified and the manufacturing cost is significantly reduced: The special formulation system of this invention enables the material to be sintered and densified in a single step under normal air atmosphere, completely avoiding the reducing atmosphere sintering required by the anti-reduction system and the subsequent complex re-oxidation treatment steps. This not only fundamentally eliminates the risk of the material becoming "semiconductor" due to reduction sintering, but also greatly reduces energy consumption, raw material costs and equipment requirements, making the process more green and environmentally friendly.

[0014] (3) Microstructure optimization, giving the device excellent reliability: The above-mentioned composite additive system with specific proportions can effectively suppress abnormal grain growth during sintering and promote the formation of a dense, uniform and fine grain structure. This optimized microstructure is beneficial to further improve dielectric strength and long-term operational reliability in miniaturized ceramic capacitor applications.

[0015] (4) Good process compatibility and broad industrialization prospects: This material system is highly compatible with existing conventional dry molding processes for ceramic components, and has good formability and sintering adaptability. This provides a more cost-effective new material solution for large-capacity ceramic capacitors that do not require precious metal internal electrodes, and is particularly suitable for large-scale industrial production in fields such as communications, automotive electronics and industrial control where there are stringent requirements for dielectric performance, temperature stability and cost control. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the preparation process of the high-performance Y5P type barium titanate-based ceramic material of the present invention.

[0017] Figure 2 This is a characteristic curve of the dielectric constant of the samples in Examples 1-10 of the present invention as a function of temperature.

[0018] Figure 3 This is a graph showing the change rate of the sample capacitance temperature as a function of temperature in Examples 1-10 of the present invention.

[0019] Figure 4 These are the XRD and SEM images of the sample prepared in Example 4 of this invention. Detailed Implementation

[0020] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] This invention provides a high-performance Y5P type barium titanate-based ceramic material sintered in an air atmosphere. The ceramic material uses BaTiO3 as the main raw material and is supplemented with MgCO3, ZnO, MnCO3, ZrO2, Nb2O5 and La2O3 as composite modifying additives. The total mass of the composite modifying additives accounts for 1.20%–2.30% of the mass of the BaTiO3.

[0022] Furthermore, the raw materials of the ceramic material are proportioned by mass as follows: BaTiO3 is 100 parts, MgCO3 is 0.35~0.70 parts, ZnO is 0.10~0.25 parts, Nb2O5 is 0.25~0.50 parts, MnCO3 is 0.05~0.15 parts, ZrO2 is 0.25~0.35 parts, and La2O3 is 0.20~0.35 parts.

[0023] Examples 1-10 Combination Figure 1 As shown, a method for preparing a high-performance Y5P-type barium titanate-based ceramic material that can be sintered in air atmosphere according to the present invention includes the following steps: Step 1: Ingredient preparation. Accurately weigh BaTiO3 powder (average particle size approximately 200 nm), MgCO3, ZnO, MnCO3, ZrO2, Nb2O5, and La2O3 according to the mass ratio (in parts by mass) of each raw material in Table 1.

[0024] Step 2: Ball Milling. Place the weighed raw material powder into a ball mill jar, add deionized water and grinding media (zirconia balls, used only as grinding media and not constituting a component of the ceramic material formulation). The mass ratio of deionized water, grinding media, and raw material powder should be within the range of (1.5~2.5):(1.5~2.0):1 (Example 1 uses the lower limit of 1.5:1.5:1, Example 10 uses the upper limit of 2.5:2.0:1, and Examples 2-9 use the median value of 2:1.5:1). Control the ball milling speed within the range of 200~400 rpm (Example 1 uses 200 rpm, Example 10 uses 400 rpm, and Examples 2-9 use 280 rpm), and ball mill according to the milling time specified in Table 2 to ensure thorough mixing, refinement, and formation of a uniform slurry.

[0025] Step 3: Drying, pulverizing, and secondary mixing. The ball-milled slurry was completely dried in an oven at a temperature between 80 and 120°C (80°C in Example 1, 120°C in Example 10, and 110°C in Examples 2-9), resulting in a mixed powder, which was then pulverized. An aqueous solution of polyvinyl alcohol (PVA) was added as an organic binder solution. The mass concentration of the PVA aqueous solution was between 5% and 10% (5% in Example 1, 10% in Example 10, and 8% in Examples 2-9), and the amount added was between 3% and 8% of the total powder mass (3% in Example 1, 8% in Example 10, and 5% in Examples 2-9). After thorough mixing, the mixture was granulated, controlling the particle size distribution of the granulated powder to be between 80 and 150 mesh (80 mesh in Example 1, 150 mesh in Example 10, and 100 mesh in Examples 2-9).

[0026] Step 4: Molding. Place an appropriate amount of granulated powder in a mold and press it under a pressure of 80~200 MPa (80 MPa in Example 1, 200 MPa in Example 10, and 150 MPa in Examples 2-9) to obtain a circular ceramic green body with a diameter of 10 mm and a thickness of about 1.0 mm.

[0027] Step 5: Debinding and Sintering. The green body is heated to a debinding temperature range of 500-650°C at a heating rate of 1-3°C / min (2.5°C / min for Examples 1-10 of this invention), and held at this temperature for 2 hours to completely remove the organic binder. Subsequently, the debinding green body was placed in a sintering furnace under an air atmosphere and heated at a rate of 2-5°C / min (2°C / min for Examples 1, 6, and 7; 2.5°C / min for Examples 2-4; 3°C / min for Example 5; 4°C / min for Examples 8 and 9; and 5°C / min for Example 10) to a sintering temperature range of 1280-1350°C (1280°C for Examples 1, 4, and 6; 1290°C for Examples 5 and 7; 1300°C for Examples 2 and 8; 1330°C for Example 9; 1340°C for Example 3; and 1350°C for Example 10). This temperature was then maintained for 2-6 hours (2 hours for Examples 3, 5, 9, and 10; 4 hours for Examples 2, 7, and 8; and 6 hours for Examples 1, 4, and 6). After sintering, the green body was cooled to room temperature in the furnace at a rate of 5°C / min to obtain a dense ceramic sample.

[0028] Step 6: Performance Testing. The sintered ceramic sample is treated with an electrode (silver-impregnated electrode), and then its dielectric constant (ε), dielectric loss tangent (tanδ), and volume resistivity (ε) are tested according to relevant national or industry standards. The capacitance change rate within the temperature range of -30℃ to 85℃ is also shown in Table 1. Specific raw material ratios for different embodiments are shown in Table 2, key sintering process parameters are shown in Table 2, and the final performance test results of the obtained ceramic materials are shown in Table 3.

[0029] Table 1. Ingredient list for high-performance Y5P type ceramic materials, Examples 1-10

[0030] Note: The values ​​of each additive component listed in the table are relative to 100 parts by mass of BaTiO3.

[0031] Table 2 Process Tables for Examples 1-10 of High-Performance Y5P Type Ceramic Materials

[0032] Table 3 Performance Table of High-Performance Y5P Type Ceramic Materials Examples 1-10

[0033] Figure 2 This is a graph showing the dielectric constant of the samples from Examples 1-10 of this invention as a function of temperature. Figure 2 As can be seen, within a temperature range of -30℃ to 85℃, the dielectric constant (ε) of all samples remained relatively stable within a high range of 2800 to 3500. Combined with formulation adjustments, it was found that the content of the donor doping elements Nb₂O₅ and La₂O₃ plays a decisive role in the dielectric constant: for example, when Nb₂O₅ is 0.35 parts and La₂O₃ is 0.20 parts (Example 3), the polarization response of the material is the strongest, and the room temperature dielectric constant reaches a peak of 3485; while when the donor doping is moderately reduced, such as when Nb₂O₅ is reduced to 0.25 parts (Example 4), the dielectric constant gradually decreases to 2934. This demonstrates that by precisely controlling the doping ratio of Nb and La, this invention effectively overcomes the technical bottleneck of low dielectric constant in traditional air-atmosphere sintered materials, achieving excellent high-dielectric energy storage characteristics.

[0034] Figure 3 This is a graph showing the rate of change of the capacitance temperature of the samples in Examples 1-10 of this invention as a function of temperature. Figure 3 As can be seen, in the wide temperature range of -30℃ to 85℃, the capacity temperature change rate (ΔC / C25℃) of Examples 1-10 was strictly controlled within the range of -9.8% to +9.1%, fully meeting the stringent standards of Y5P type ceramics (≤±10%). Among them, the adjustment of the content of ZrO2 and MgCO3, which play a synergistic role in "peak shifting" and "peak expansion", significantly changed the flatness of the curve: for example, the curve of Example 4 (with moderate ZrO2 0.25 parts and MgCO3 0.35 parts) was the flattest, with a change rate of only -2.3% to +1.3% from -30℃ to 85℃; while when the content of peak shifting and peak expansion agents increased (such as Example 10, ZrO2 0.30 parts and MgCO3 0.65 parts), the fluctuation range at both ends of the curve was moderately widened (+9.1% at -30℃ and -9.1% at 85℃), but it still remained within the red line. This demonstrates that the multi-component composite system of the present invention achieves perfect broadening and shifting of the Curie peak, giving the material excellent temperature control precision.

[0035] Figure 4 The images show X-ray diffraction (XRD) and scanning electron microscopy (SEM) images of the sample prepared in Example 4 of this invention, wherein the SEM images are interpolated with a histogram of the statistical distribution of grain size. Figure 4The XRD pattern on the left shows that the sample exhibits typical diffraction peaks of a single perovskite crystal phase, with no obvious second phase or impurity phase formation. The SEM image and size statistics on the right show that the ceramic's internal microstructure is extremely dense, with uniform polyhedral grains. The majority of grains are concentrated between 400 and 800 nm in size, with a small average grain size. This indicates that the MgCO3, ZnO, and MnCO3 added to the formulation not only dissolved well into the barium titanate lattice but also exerted a strong pinning effect at the grain boundaries, effectively suppressing abnormal grain growth during sintering. It is precisely this dense, uniform, and fine microstructure that significantly reduces conduction losses, resulting in a volume resistivity of 1.6 × 10⁻⁶ in this embodiment. 12 With a dielectric loss tangent as low as 0.8% (Ω·cm), the device provides microstructure assurance for long-term reliability.

Claims

1. A high-performance Y5P-type barium titanate-based ceramic material sintered in an air atmosphere, characterized in that, The ceramic material uses BaTiO3 as the main raw material, supplemented with MgCO3, ZnO, MnCO3, ZrO2, Nb2O5 and La2O3 as composite modifying additives; the total mass of the composite modifying additives accounts for 1.20%–2.30% of the mass of BaTiO3.

2. The high-performance Y5P-type barium titanate-based ceramic material according to claim 1, characterized in that, The raw materials of the ceramic material are proportioned by mass as follows: BaTiO3 is 100 parts, MgCO3 is 0.35~0.70 parts, ZnO is 0.10~0.25 parts, Nb2O5 is 0.25~0.50 parts, MnCO3 is 0.05~0.15 parts, ZrO2 is 0.25~0.35 parts, and La2O3 is 0.20~0.35 parts.

3. A method for preparing a high-performance Y5P-type barium titanate-based ceramic material as described in claim 1 or 2, characterized in that, Includes the following steps: Step 1: Batching and primary ball milling: Weigh out BaTiO3 powder, MgCO3, ZnO, MnCO3, ZrO2, Nb2O5 and La2O3 raw materials according to the set composition ratio, and place them together in a ball mill jar; add deionized water and zirconia balls as grinding media to the ball mill jar, wherein the mass ratio of deionized water, grinding media and raw material powder is (1.5~2.5):(1.5~2.0):1; ball mill at a speed of 200~400 rpm for 4~12 hours to obtain a uniformly mixed slurry; Step 2: Drying, pulverizing and secondary mixing: Dry the slurry obtained in Step 1 at 80~120℃ to constant weight to obtain a mixed powder; pulverize and sieve the dried mixed powder to ensure that there are no hard agglomerates; Subsequently, 3% to 8% of the total mass of the pulverized mixed powder is added to the mixed powder, wherein the organic binder solution is a polyvinyl alcohol aqueous solution with a mass concentration of 5% to 10%, and the mixture is thoroughly mixed. Step 3: Granulation and molding: Granulate the mixed powder containing the organic binder solution from Step 2, controlling the particle size distribution of the granulated powder to be between 80 and 150 mesh; load the granulated powder into a mold and press it under a pressure of 80 to 200 MPa to obtain a ceramic green body of the specified shape and size. Step 4: Debinding and sintering in air atmosphere: The green body obtained in Step 3 is heated to 500-650℃ at a heating rate of 1-3℃ / min and held at this temperature for 2 hours to completely remove the organic binder; then, in an air atmosphere, the temperature is increased to a sintering temperature of 1280℃-1350℃ at a rate of 2-5℃ / min and held for 2-6 hours to sinter and densify; the entire sintering process is carried out in an air atmosphere; after sintering, the cooling rate is controlled at 5℃ / min to reduce the furnace temperature to below 200℃, and then the furnace is allowed to cool naturally to room temperature to obtain a dense Y5P type barium titanate-based ceramic material.

4. The method for preparing high-performance Y5P-type barium titanate-based ceramic material according to claim 3, characterized in that, The sintering process in step 4 is completed in one go, without the need to switch between reducing and oxidizing atmospheres, or a separate re-oxidation treatment step.

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