CN107098695B - A kind of high breakdown strength X7R capacitor ceramic material and preparation method thereof - Google Patents

Abstract

The invention discloses an X7R capacitor ceramic material with high breakdown strength and a preparation method thereof. The X7R capacitor ceramic material is composed of 0.3BiAlO ₃ -0.7BaTiO ₃ +xmol% MnO ₂ +ywt% BAS, x is 0.2-1.0, y is 2-6, and the amount of _MnO added is 0.3BiAlO ₃ ‑0.7BaTiO ₃ is 0.2-1.0 mol%, and the amount of BAS alkali-free glass added is 2-8% of the total mass of MnO ₂ and BiAlO ₃ ‑BaTiO ₃ . The high breakdown strength X7R capacitor ceramic material prepared by the invention has the characteristics of high breakdown strength, high dielectric constant at room temperature and good temperature stability.

Description

A kind of high breakdown strength X7R capacitor ceramic material and preparation method thereof

technical field

The invention relates to a high breakdown strength X7R capacitor ceramic material and a preparation method thereof.

Background technique

Due to the continuous development of electronic technology and the extensive use of electronic devices, high-voltage ceramic capacitors have always been one of the widely used electronic devices, ranging from voltage-doubling rectifier circuits in displays to high-voltage power supplies for lasers, radars and electron microscopes. High-voltage ceramic capacitors can be seen everywhere. In order to meet the needs of miniaturization and high energy storage density of _pulsed power systems, material workers from all over Dielectric materials with high penetration strength, the current dielectric constant ε _25°C >1000 at room temperature and the wide temperature stability satisfy X7R (|ΔC/C|≤15% temperature range is -55°C ~ 125°C) The breakdown of ceramic materials The strength is generally around 8kV/mm, and such breakdown strength has been difficult to meet today's production requirements.

As a ferroelectric ceramic material, _{BiAlO 3 -BaTiO 3} has a high relative permittivity, a relatively slow change with temperature, and a low sintering temperature, so it is more suitable as a dielectric material. Therefore, it is necessary to improve its compressive strength while ensuring a certain dielectric strength and temperature stability through improvements such as doping and process optimization.

Therefore, it is urgent to research and provide a dielectric constant ε _25°C >1000 at room temperature with high breakdown strength and wide temperature stability satisfying X7R (the temperature range of |ΔC/C|≤15% is -55°C～125°C) ceramic material.

SUMMARY OF THE INVENTION

Based on the above deficiencies of the prior art, the technical problem solved by the present invention is to provide a method for preparing an X7R capacitor energy storage ceramic material with high breakdown strength, and the X7R capacitor dielectric ceramic material prepared by the method has the characteristics of high breakdown strength .

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is as follows:

Provide a high breakdown strength X7R capacitor ceramic material, the X7R capacitor ceramic material is composed of 0.3BiAlO ₃ -0.7BaTiO ₃ +xmol% MnO ₂ +ywt% BAS, x is 0.2-1.0, y is 0.2-1.0 2-6, the addition amount of MnO ₂ is 0.2-1.0 mol% of 0.3BiAlO ₃ -0.7BaTiO ₃ , and the addition amount of BAS alkali-free glass is 2-8% of the total mass of MnO ₂ and BiAlO ₃ -BaTiO ₃ .

As an improvement of the above technical solution, the above-mentioned high breakdown strength X7R capacitor ceramic material is obtained by solid phase method 0.3BiAlO ₃ -0.7BaTiO ₃ +xmol% MnO ₂ powder, x is 0.2～1.0, and then doped with BAS without Alkali glass sintered.

As an improvement of the above technical scheme, the sintering temperature of the doped BAS alkali-free glass is 1000-1100°C.

As an improvement of the above technical solution, the addition amount of the BAS alkali-free glass is 2% to 6% of the total mass of MnO ₂ and BiAlO ₃ -BaTiO ₃ .

As an improvement of the above technical solution, the addition amount of the BAS alkali-free glass is 4% of the total mass of MnO ₂ and BiAlO ₃ -BaTiO ₃ .

The present invention also provides a preparation method of the above-mentioned high breakdown strength X7R capacitor ceramic material, comprising the following steps:

Step 1. Prepare 0.3BiAlO ₃ -0.7BaTiO ₃ +xmol% MnO by solid-phase method with Bi ₂ O ₃ , Al ₂ O ₃ , BaCO ₃ , TiO ₂ and MnO ₂ according to the theoretical ratio, and in the case of excess Bi ₂ powder, the value of x is 0.2 to 1.0;

Step 2: Take the BAS glass fine powder with a mass percentage of 2-6% of the ceramic powder and mix it with ball milling, drying, granulating, tableting and degumming, and then heating up to 1000-1100 ° C, heat preservation and sintering to obtain the high Breakdown strength of X7R capacitor ceramic material.

As an improvement of the above technical solution, the excess of Bi ₂ O ₃ in step 1 is 3-5wt%, that is, the molar ratio of Bi element, Al element, Ba element, Ti element and Mn element is 0.1545～0.1575:0.15:0.35:0.35:x *0.01.

As an improvement of the above technical solution, in step ₁ , the solid _- phase sintering temperature is 850-950° C., and the solid _- phase sintering time is _{2h -} 4h _{; 2} Fully ball-milled and dried.

As an improvement of the above technical solution, in step 1, the heating rate of the pre-sintering process is 2°C to 4°C/min.

As an improvement of the above technical solution, the sintering time in step 2 is 2h to 4h.

As an improvement of the above technical solution, the heating rate in the second step is 2°C to 4°C/min.

As an improvement of the above technical solution, the BAS alkali-free glass fine powder in the second step is based on the mass percentage of H ₃ BO ₃ , Al ₂ O ₃ and SiO ₂ : 50wt% H ₃ BO ₃ , 30wt% Al ₂ O _3. Put 20wt% SiO ₂ into a ball mill, mill it for 6h-8h, dry it, then place it in a corundum crucible, heat it up to 1400℃-1500℃ to melt, keep it warm for 2h-4h, take it out at high temperature, pour it into water and quench it into a filamentous shape and large granular BAS glass fragments, which are obtained by sieving the BAS glass fragments into a ball mill and crushing them.

As an improvement of the above technical solution, the sieving selects a 100-mesh sieve; the heating rate is 2°C to 5°C/min

As an improvement of the above technical solution, before granulation in the second step, a binder with a mass of 3% to 5% of the mass of the dried powder is added to the dried powder and mixed uniformly.

As an improvement of the above technical solution, the adhesive is a 5% polyvinyl alcohol solution.

As an improvement of the above technical solution, the debinding method in the second step is to keep the temperature at 600° C. for 2 hours.

Through research, the inventors of the present invention found that the present invention can obtain a temperature with a dielectric constant ε _25°C >1000 and a wide temperature stability satisfying X7R(|ΔC/C|≤15% by introducing an appropriate amount of MnO ₂ and BAS alkali-free glass. X7R capacitor ceramic material with breakdown strength above 20kV/mm. Among them, a small amount of MnO ₂ can refine the grains and reduce the dielectric loss of ceramics to a certain extent. The glass frit added to the ceramics gradually melts during high temperature sintering, and the flowing liquid phase reduces the porosity, which greatly promotes the sintering of the ceramics, makes the ceramics denser at a lower temperature, and improves the breakdown strength of the ceramics.

Compared with the prior art, the technical scheme of the present invention has the following beneficial effects:

1. High breakdown strength: The pressure resistance of BiAlO ₃ -BaTiO ₃ ceramic matrix is greatly improved. Before adding BAS alkali-free glass, the pressure resistance of ceramics is only about 10kV/mm, while adding BAS alkali-free glass After that, the compressive strength was increased to more than 20kV/mm.

2. Small loss of dielectric properties: The dielectric properties of the BiAlO ₃ -BaTiO ₃ ceramic matrix are basically lost very little, the dielectric constant ε _r is still maintained above 1000, and the temperature stability also meets the X7R standard (at -55 ° C ~ 125 ΔC/C≤15% in the range of °C).

The above description is only an overview of the technical solutions of the present invention, in order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand , in conjunction with the preferred embodiments, the detailed description is as follows.

Description of drawings

In order to describe the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings of the embodiments will be briefly introduced below.

Fig. 1 is the XRD test chart of BAS alkali-free glass;

Fig. 2 is the XRD test chart of 0.3BiAlO ₃ -0.7BaTiO ₃ -xmol% MnO ₂ -ywt% BAS ceramic added with BAS glass;

Figure 3 is a graph of the dielectric constant of BiAlO ₃ -BaTiO ₃ ceramics with BAS glass added at 25°C;

Fig. 4 is the volume temperature change rate of BiAlO ₃ -BaTiO ₃ ceramics added with BAS glass;

Figure 5 is a graph of the dielectric loss of BiAlO ₃ -BaTiO ₃ ceramics with BAS glass added at 25°C;

Figure 6 is the breakdown strength of BiAlO ₃ -BaTiO ₃ ceramics with BAS glass added at 25°C.

Detailed ways

The specific embodiments of the present invention will be described in detail below. As part of this specification, the principles of the present invention will be illustrated by examples. Other aspects, features and advantages of the present invention will become apparent from the detailed description.

Example 1:

1) The molar ratio of Bi element in Bi ₂ O ₃ , Al element in Al ₂ O ₃ , Ba element in BaCO ₃ , Ti element in TiO ₂ and Mn element in MnO ₂ is 0.15:0.15:0.35 : 0.35: 0.02, wherein Bi ₂ O ₃ is in excess of 3% based on the mass calculated above. Put the weighed Bi ₂ O ₃ , Al ₂ O ₃ , BaCO ₃ , TiO ₂ and MnO ₂ into a ball mill and mix them uniformly for 24 hours. The obtained mixture was pre-fired at 850°C for 2 hours after drying, and the heating rate was 2°C/min to prepare ceramic powder for use. The ceramic powder was a sample with 0 BAS alkali-free glass added.

2) According to the mass percentage of H ₃ BO ₃ , Al ₂ O ₃ , SiO ₂ : 50wt% H ₃ BO ₃ , 30wt% Al ₂ O ₃ , 20wt% SiO ₂ , put them into a ball mill, and dry them after ball milling for 8 hours. Then put it in a corundum crucible, heat up to 1400°C at a heating rate of 5°C/min to melt, keep it for 2 hours, take it out at high temperature and pour it into water to quench into filamentous and large granular BAS alkali-free glass fragments. Put it into a ball mill to pulverize and pass through a 100-mesh sieve to obtain BAS glass fine powder for later use.

3) According to the addition amount of the BAS glass powder being 2% of the mass of the ceramic powder, the ceramics and the BAS glass powder are batched and then subjected to secondary ball milling for 24 hours, and the obtained mixture is dried; The amount of the mixture is 3% of the mass of the mixture, and the binder is added, then granulated, pressed into tablets, and kept at 600 °C for 2 hours to exhaust the binder to obtain ceramic tablets; finally, the temperature is raised to 1050 °C at a rate of 2 °C/min, and the temperature is kept for 2 hours for sintering. , to obtain a capacitor ceramic material sample with BAS alkali-free glass added in an amount of 2wt%.

Example 2:

1) The molar ratio of Bi element in Bi ₂ O ₃ , Al element in Al ₂ O ₃ , Ba element in BaCO ₃ , Ti element in TiO ₂ and Mn element in MnO ₂ is 0.15:0.15:0.35 : 0.35: 0.002, where Bi ₂ O ₃ is in 5% excess on a calculated mass basis. Put the weighed Bi ₂ O ₃ , Al ₂ O ₃ , BaCO ₃ , TiO ₂ and MnO ₂ into a ball mill and mix them uniformly for 24 hours. The obtained mixture was dried and then pre-fired at 900° C. for 2 hours, and the heating rate was 2° C./min, to prepare ceramic powder for later use.

2) According to the mass percentage of H ₃ BO ₃ , Al ₂ O ₃ , SiO ₂ : 50wt% H ₃ BO ₃ , 30wt% Al ₂ O ₃ , 20wt% SiO ₂ , put them into a ball mill, and dry them after ball milling for 8 hours. Then put it in a corundum crucible, heat up to 1450°C at a heating rate of 5°C/min to melt, keep for 2 hours, take it out at high temperature and pour it into water to quench into filamentous and large granular BAS alkali-free glass fragments. Put it into a ball mill to pulverize and pass through a 100-mesh sieve to obtain BAS alkali-free glass fine powder for later use.

3) According to the addition amount of the BAS alkali-free glass powder being 4% of the mass of the ceramic powder, the ceramics and the BAS glass powder are batched and then subjected to secondary ball milling for 24 hours, and the obtained mixture is dried; The addition amount of the mixture is 3% of the mass of the mixture. Add binder, then granulate, press into tablets, and keep at 600 °C for 2 hours to exhaust the binder to obtain ceramic tablets; After sintering for 2 hours, a sample of capacitor ceramic material with the addition amount of BAS alkali-free glass of 4 wt% was obtained.

Example 3:

1) The molar ratio of Bi element in Bi ₂ O ₃ , Al element in Al ₂ O ₃ , Ba element in BaCO ₃ , Ti element in TiO ₂ and Mn element in MnO ₂ is 0.15:0.15:0.35 : 0.35: 0.002, where Bi ₂ O ₃ is in 5% excess on a calculated mass basis. Put the weighed Bi ₂ O ₃ , Al ₂ O ₃ , BaCO ₃ , TiO ₂ and MnO ₂ into a ball mill and mix them uniformly for 24 hours. The obtained mixture was dried and then pre-fired at 900° C. for 2 hours, and the heating rate was 2° C./min, to prepare ceramic powder for later use.

2) According to the mass percentage of H ₃ BO ₃ , Al ₂ O ₃ , SiO ₂ : 50wt% H ₃ BO ₃ , 30wt% Al ₂ O ₃ , 20wt% SiO ₂ , put them into a ball mill, and dry them after ball milling for 8 hours. Then put it in a corundum crucible, heat up to 1500°C at a heating rate of 5°C/min, melt for 2 hours, take it out at high temperature and pour it into water to quench into filamentous and large granular BAS glass fragments, and put the BAS alkali-free glass fragments into the After being pulverized by a ball mill, pass through a 100-mesh sieve to obtain BAS alkali-free glass fine powder for later use.

3) According to the addition amount of the BAS alkali-free glass powder being 6% of the mass of the ceramic powder, the ceramic and the BAS glass powder are batched and then subjected to secondary ball milling for 24 hours, and the obtained mixture is dried; The addition amount of the mixture is 3% of the mass of the mixture. Add binder, then granulate, press into tablets, and keep at 600 °C for 2 h to exhaust the binder to obtain ceramic tablets; After sintering for 2 hours, a sample of capacitor ceramic material with the addition amount of BAS alkali-free glass of 6 wt% was obtained.

Example 4:

1) The molar ratio of Bi element in Bi ₂ O ₃ , Al element in Al ₂ O ₃ , Ba element in BaCO ₃ , Ti element in TiO ₂ and Mn element in MnO ₂ is 0.15:0.15:0.35 : 0.35: 0.002, where Bi ₂ O ₃ is in 5% excess on a calculated mass basis. Put the weighed Bi ₂ O ₃ , Al ₂ O ₃ , BaCO ₃ , TiO ₂ and MnO ₂ into a ball mill and mix them uniformly for 24 hours. The obtained mixture was dried and then pre-fired at 950° C. for 2 hours, and the heating rate was 2° C./min, to prepare ceramic powder for later use.

2) According to the mass percentage of H ₃ BO ₃ , Al ₂ O ₃ , SiO ₂ : 50wt% H ₃ BO ₃ , 30wt% Al ₂ O ₃ , 20wt% SiO ₂ , put them into a ball mill, and dry them after ball milling for 8 hours. Then put it in a corundum crucible, heat up to 1500°C to melt at a heating rate of 2°C/min, keep for 2 hours, take it out at high temperature and pour it into water to quench into filamentous and large-granular BAS glass fragments, and put the BAS alkali-free glass fragments into the After being pulverized by a ball mill, pass through a 100-mesh sieve to obtain BAS alkali-free glass fine powder for later use.

3) According to the addition amount of the BAS alkali-free glass powder being 8% of the mass of the ceramic powder, the ceramic and the BAS glass powder are batched and then subjected to secondary ball milling for 24 hours, and the obtained mixture is dried; The addition amount of the mixture is 3% of the mass of the mixture. Add binder, then granulate, press into tablets, and keep at 600 °C for 2 h to exhaust the binder to obtain ceramic tablets; After sintering for 2 hours, a sample of capacitor ceramic material with the addition amount of BAS alkali-free glass of 8 wt% was obtained.

Example 5;

1) The molar ratio of Bi element in Bi ₂ O ₃ , Al element in Al ₂ O ₃ , Ba element in BaCO ₃ , Ti element in TiO ₂ and Mn element in MnO ₂ is 0.15:0.15:0.35 : 0.35: 0.005, where Bi ₂ O ₃ is in 5% excess on a calculated mass basis. Put the weighed Bi ₂ O ₃ , Al ₂ O ₃ , BaCO ₃ , TiO ₂ and MnO ₂ into a ball mill and mix them uniformly for 24 hours. The obtained mixture was dried and then pre-fired at 900° C. for 2 hours, and the heating rate was 2° C./min, to prepare ceramic powder for later use.

2) According to the mass percentage of H ₃ BO ₃ , Al ₂ O ₃ , SiO ₂ : 50wt% H ₃ BO ₃ , 30wt% Al ₂ O ₃ , 20wt% SiO ₂ , put them into a ball mill, and dry them after ball milling for 8 hours. Then put it in a corundum crucible, heat up to 1450°C at a heating rate of 5°C/min to melt, keep for 2 hours, take it out at high temperature and pour it into water to quench into filamentous and large granular BAS alkali-free glass fragments. Put it into a ball mill to pulverize and pass through a 100-mesh sieve to obtain BAS alkali-free glass fine powder for later use.

3) According to the addition amount of the BAS alkali-free glass powder being 4% of the mass of the ceramic powder, the ceramics and the BAS glass powder are batched and then subjected to secondary ball milling for 24 hours, and the obtained mixture is dried; The addition amount of the mixture is 3% of the mass of the mixture. Add binder, then granulate, press into tablets, and keep at 600 °C for 2 hours to exhaust the binder to obtain ceramic tablets; After sintering for 2 h, a capacitor ceramic material sample with the addition amount of BAS alkali-free glass of 4 wt % and the content of MnO ₂ of 0.5 mol % was obtained.

Comparative ratio:

1) The molar ratio of Bi element in Bi ₂ O ₃ , Al element in Al ₂ O ₃ , Ba element in BaCO ₃ , Ti element in TiO ₂ and Mn element in MnO ₂ is 0.15:0.15:0.35 : 0.35:0, where Bi ₂ O ₃ is in 5% excess on a calculated mass basis. Put the weighed Bi ₂ O ₃ , Al ₂ O ₃ , BaCO ₃ , TiO ₂ and MnO ₂ into a ball mill and mix them uniformly for 24 hours. The obtained mixture was dried and then pre-fired at 900° C. for 2 hours, and the heating rate was 2° C./min, to prepare ceramic powder for later use.

2) According to the mass percentage of H ₃ BO ₃ , Al ₂ O ₃ , SiO ₂ : 50wt% H ₃ BO ₃ , 30wt% Al ₂ O ₃ , 20wt% SiO ₂ , put them into a ball mill, and dry them after ball milling for 8 hours. Then put it in a corundum crucible, heat up to 1500°C to melt at a heating rate of 2°C/min, keep for 2 hours, take it out at high temperature and pour it into water to quench into filamentous and large-granular BAS glass fragments, and put the BAS alkali-free glass fragments into the After being pulverized by a ball mill, pass through a 100-mesh sieve to obtain BAS alkali-free glass fine powder for later use.

3) According to the addition amount of the BAS alkali-free glass powder being 4% of the mass of the ceramic powder, the ceramics and the BAS glass powder are batched and then subjected to secondary ball milling for 24 hours, and the obtained mixture is dried; The addition amount of the mixture is 3% of the mass of the mixture. Add binder, then granulate, press into tablets, and keep at 600 °C for 2 h to exhaust the binder to obtain ceramic tablets; After sintering for 2 h, a capacitor ceramic material sample with BAS alkali-free glass added in an amount of 4 wt % and MnO ₂ content of 0 was obtained.

The measured XRD of the BAS alkali-free glass prepared in the above example 1 is shown in Figure 1, which shows that the prepared BAS has no obvious diffraction peak, indicating that the prepared BAS is a glass phase.

The amount of BAS alkali-free glass prepared in the above examples 1-4 is 0wt%, the amount of BAS alkali-free glass is 2wt%, the amount of BAS alkali-free glass is 4wt%, the amount of BAS alkali-free glass is 6wt%, and the amount of BAS alkali-free glass is 6wt%. The XRD phase analysis of the ceramic sample with an alkali-free glass content of 8wt% is shown in Figure 2. The figure shows that the main crystal phase is BaTiO ₃ phase, and the peak near 45° does not produce splitting, indicating that the cubic BaTiO ₃ crystal phase is produced. , BiAlO ₃ is mainly solid-dissolved in BaTiO ₃ , and some BiAlO ₃ is not completely solid-dissolved in BaTiO _3. From the characteristic peak analysis, impurity BaAl ₂ O ₄ is generated. After adding BAS alkali-free glass, the corresponding impurity phase corresponds to Diffraction peaks increased significantly, and the peak intensity became stronger.

The amount of BAS alkali-free glass prepared in the above examples 1-4 is 0wt%, the amount of BAS alkali-free glass is 2wt%, the amount of BAS alkali-free glass is 4wt%, the amount of BAS alkali-free glass is 6wt%, and the amount of BAS alkali-free glass is 6wt%. The amount of alkali-free glass added is 8wt% of the ceramic sample. After coating the silver paste electrode, the dielectric properties are tested as shown in Figure 3. It can be seen that the amount of BAS alkali-free glass added in Examples 1-3 is 2-6wt% of the ceramic material ε _r is above 1000;

The amount of BAS alkali-free glass prepared in the above examples 1-4 is 0wt%, the amount of BAS alkali-free glass is 2wt%, the amount of BAS alkali-free glass is 4wt%, the amount of BAS alkali-free glass is 6wt%, and the amount of BAS alkali-free glass is 6wt%. The amount of alkali-free glass added is 8wt% of the ceramic sample. After coating the silver paste electrode, the dielectric properties of the variable temperature are tested and the temperature change rate is calculated. As shown in Figure 4, it can be seen that the amount of BAS alkali-free glass is added. It can meet the requirements of the volume temperature change rate of X7R (in the range of -55℃～125℃, meet |ΔC/C|≤15%). When BAS alkali-free glass is added with 4%, it is the component with the highest compressive strength.

The amount of BAS alkali-free glass prepared in the above examples 1-4 is 0wt%, the amount of BAS alkali-free glass is 2wt%, the amount of BAS alkali-free glass is 4wt%, the amount of BAS alkali-free glass is 6wt%, and the amount of BAS alkali-free glass is 6wt%. The results obtained after the dielectric loss test of the ceramic sample with the addition amount of alkali-free glass of 8wt% are shown in Figure 5. It can be seen that the dielectric loss increases after the addition of BAS alkali-free glass, but it does not exceed 5%. Among them, the addition of BAS At 2%, the increase is the least, and the dielectric loss tanδ=3.59%. Among them, the BAS increases the most when 6% is added, and the dielectric loss tanδ=4.81%. When BAS is added with 4%, it is the highest compressive strength component. Electrical loss tanδ=4.04%;

The amount of BAS alkali-free glass prepared in the above examples 1-4 is 0wt%, the amount of BAS alkali-free glass is 2wt%, the amount of BAS alkali-free glass is 4wt%, the amount of BAS alkali-free glass is 6wt%, and the amount of BAS alkali-free glass is 6wt%. The breakdown strength of the ceramic sample with an alkali-free glass content of 8wt% is shown in Figure 6, which shows that the original BiAlO ₃ -BaTiO ₃ ceramic matrix without BAS has a breakdown strength of only 8.23kV/mm, and the mass fraction of BAS added is 4% and At 6%, the breakdown strengths are 25.53kV/mm and 24.04kV/mm respectively, and when the BAS mass fraction is 2% and 8%, the breakdown strengths are also 22.32kV/mm and 23.25kV/mm, respectively, indicating the present invention Indeed, the pressure resistance of the BiAlO ₃ -BaTiO ₃ ceramic matrix is greatly improved.

The capacitor ceramic material sample prepared in the above example 5 with the addition amount of BAS alkali-free glass of 4wt% and the content of MnO ₂ is 0.5mol%, the dielectric constant _εr at room temperature is above 1000, and the dielectric loss is 3.46%, breakdown The intensity is 21.74kV/mm, indicating that the requirements can also be met within the given MnO ₂ doping range.

The sample of the above comparative example, without adding MnO ₂ and only adding 4wt% BAS alkali-free glass component, has a dielectric loss of 6.23%, which cannot meet the requirements, which proves that the addition of MnO ₂ and BAS has played a synergistic effect.

The above are only the preferred embodiments of the present invention, of course, the scope of the rights of the present invention cannot be limited by this. Several improvements and changes are made, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims (7)

1. A high-breakdown-strength X7R capacitor ceramic material, which is characterized in that: the composition of the X7R capacitor ceramic material is 0.3BiAlO₃-0.7BaTiO₃+xmol%MnO₂+ ywt% BAS, x is 0.2-1.0, y is 2-6, MnO₂Is added in an amount of 0.3BiAlO₃-0.7BaTiO₃0.2-1.0 mol% of (A), and the addition amount of the BAS alkali-free glass is MnO₂And BiAlO₃-BaTiO₃2% -6% of the total mass; the X7R capacitor ceramic material is 0.3BiAlO prepared by a solid phase method₃-0.7BaTiO₃+xmol%MnO₂Powder is obtained by sintering BAS-doped alkali-free glass, wherein the sintering temperature of the BAS-doped alkali-free glass is 1000-1100 ℃; the dielectric constant of the X7R capacitor ceramic material is Ɛ_25℃More than 1000, and the wide temperature stability meets the conditions that the temperature range of | delta C/C | is less than or equal to 15 percent is-55-125 ℃, and the breakdown strength is more than 20 kV/mm;

the X7R capacitor ceramic material with high breakdown strength is prepared by the following method:

step one, adding Bi₂O₃、Al₂O₃、BaCO₃、TiO₂And MnO₂Preparing 0.3BiAlO by a solid phase method according to a theoretical metering ratio under the condition of excessive Bi₃-0.7BaTiO₃+xmol%MnO₂Powder, wherein x is 0.2-1.0; wherein, Bi₂O₃An excess of 3 to 5 wt%;

step two, taking 0.3BiAlO₃-0.7BaTiO₃+xmol%MnO₂Mixing and ball-milling 2-6% of BAS glass fine powder, drying, granulating, tabletting, removing glue, heating to 1000-1100 ℃, and carrying out heat preservation and sintering to obtain the X7R capacitor ceramic material with high breakdown strength; the BAS alkali-free glass fine powder is prepared by mixing with H₃BO₃、Al₂O₃、SiO₂The weight percentage is as follows: 50wt% H₃BO₃、30wt%Al₂O₃、20wt%SiO₂。

2. The method for preparing the high breakdown strength X7R capacitor ceramic material as claimed in claim 1, wherein the method comprises the following steps: the method comprises the following steps:

step one, adding Bi₂O₃、Al₂O₃、BaCO₃、TiO₂And MnO₂Preparing 0.3BiAlO by a solid phase method according to a theoretical metering ratio under the condition of excessive Bi₃-0.7BaTiO₃+xmol%MnO₂Powder, wherein x is 0.2-1.0;

step two, taking 0.3BiAlO₃-0.7BaTiO₃+xmol%MnO₂Mixing and ball-milling 2-6% of BAS glass fine powder, drying, granulating, tabletting, removing glue, heating to 1000-1100 ℃, and carrying out heat preservation and sintering to obtain the X7R capacitor ceramic material with high breakdown strength.

3. The method for preparing the high-breakdown-strength X7R capacitor ceramic material as claimed in claim 2, wherein the method comprises the following steps: in step one, Bi₂O₃An excess of 3 to 5 wt%.

4. The method for preparing the high-breakdown-strength X7R capacitor ceramic material as claimed in claim 2, wherein the method comprises the following steps: step one, the solid phase sintering temperature is 850-950 ℃, and the solid phase sintering time is 2-4 h; bi is added before solid phase sintering₂O₃、Al₂O₃、BaCO₃、TiO₂And MnO₂Fully ball-milling and drying.

5. The method for preparing the high-breakdown-strength X7R capacitor ceramic material as claimed in claim 2, wherein the method comprises the following steps: and in the second step, the sintering time is 2-4 h.

6. The method for preparing the high-breakdown-strength X7R capacitor ceramic material as claimed in claim 2, wherein the method comprises the following steps: the BAS alkali-free glass fine powder is prepared by mixing with H₃BO₃、Al₂O₃、SiO₂OccupiedThe mass percentage is as follows: 50wt% H₃BO₃、30wt%Al₂O₃、20wt%SiO₂The preparation method comprises the steps of mixing materials, putting the mixture into a ball mill, carrying out ball milling for 6-8 h, drying, putting the mixture into a corundum crucible, heating to 1400-1500 ℃ to melt the mixture, carrying out heat preservation for 2-4 h, taking out the mixture at high temperature, pouring the mixture into water to quench the mixture into filiform and large-particle BAS alkali-free glass fragments, putting the BAS alkali-free glass fragments into the ball mill, crushing the BAS alkali-free glass fragments, and sieving the crushed BAS.

7. The method for preparing the high-breakdown-strength X7R capacitor ceramic material as claimed in claim 2, wherein the method comprises the following steps: before granulation in the second step, adding a binder with the mass being 3-5% of the mass of the dried powder into the dried powder and uniformly mixing;

and the glue discharging method in the second step is to keep the temperature at 600 ℃ for 2 h.

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