A ceramic dielectric material capable of reducing the sintering temperature of MLCC and its preparation method

Abstract

The present invention belongs to the technical field of ceramic materials, and particularly relates to a dielectric ceramic material capable of reducing the sintering temperature of MLCC and a preparation method thereof. By modifying the main crystal phase magnesium titanate and introducing components such as carbon-doped titanium dioxide, strontium zirconium titanate, yttrium-modified alumina and lanthanum oxide composite material, the present invention prepares a dielectric ceramic material capable of reducing the sintering temperature of MLCC. The multi-component synergistic effect reduces the dielectric loss of the dielectric ceramic material, obtains a good temperature coefficient, and reduces the sintering temperature of MLCC through a high specific surface area.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic materials, and particularly relates to a ceramic dielectric material capable of reducing the sintering temperature of MLCC and a preparation method thereof. Background Art

[0002] At present, for electronic products such as mobile phones and computers, miniaturization, high performance, and low energy consumption have become the main development trends. The integration and miniaturization of passive chip components such as capacitors, inductors, and resistors used in these devices have also become an urgent need. Multilayer ceramic capacitors (MLCCs) have replaced single-layer ceramic capacitors as the current dominant capacitor products due to their high capacitance, high reliability, wide operating temperature, and excellent high-frequency characteristics. Ceramic dielectric materials, namely ceramic medium materials, are a class of non-metallic materials with high insulation resistance, excellent temperature stability, and mechanical strength, and they are widely used in electronic components.

[0003] Chinese Patent (publication number: CN112299839B) discloses a ceramic dielectric material for microwave high-stability and low-loss multilayer ceramic capacitors and a preparation method thereof. The ceramic dielectric material of this invention makes the grain size of the main crystal phase finer and the grain distribution more uniform by defining the preparation method of the main crystal phase. The refined grains will generate more grain boundaries, which will be beneficial to the diffusion of doping elements to improve the performance of the ceramic dielectric material; the cooperation of various added components makes a large amount of liquid phase appear in the grain boundaries during the sintering process of the ceramic dielectric material. The liquid phase has better fluidity, and the appearance of the liquid phase promotes the formation and growth of grains during sintering. However, this patent fails to solve the problems in the prior art such as the relatively high dielectric loss of the ceramic dielectric material, the temperature coefficient to be optimized, and the small specific surface area resulting in a relatively high MLCC sintering temperature, which seriously affects its actual use.

[0004] Therefore, how to modify the main crystal phase of the ceramic dielectric material, optimize other component materials at the same time, reduce the dielectric loss of the ceramic dielectric material, obtain a good temperature coefficient, and reduce the MLCC sintering temperature through a high specific surface area has become the key direction to be overcome. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a ceramic dielectric material capable of reducing the sintering temperature of MLCC and a preparation method thereof, aiming to solve the problems in the prior art such as the relatively high dielectric loss of the ceramic dielectric material, the temperature coefficient to be optimized, and the small specific surface area resulting in a relatively high MLCC sintering temperature.

[0006] The present invention prepares a dielectric ceramic material capable of reducing the sintering temperature of MLCC by modifying the main crystal phase magnesium titanate and introducing components such as carbon-doped titanium dioxide, strontium zirconium titanate, yttrium-modified alumina, and lanthanum oxide composite materials. The multi-component synergistic effect reduces the dielectric loss of the dielectric ceramic material, obtains a good temperature coefficient, and reduces the sintering temperature of MLCC through a high specific surface area.

[0007] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0008] In the first aspect of the present invention, a preparation method of a dielectric ceramic material capable of reducing the sintering temperature of MLCC is provided, including the following steps:

[0009] Step S1: By weight, add 2-4 parts of selenium powder and 3-5 parts of sodium borohydride to 300-400 parts of deionized water, stir and react for 4-6 h under an argon atmosphere to obtain solution A; add 2-4 parts of zinc acetate to 400-500 parts of absolute ethanol and mix evenly, adjust the pH to 10.2-10.6 with 1 mol / L sodium hydroxide solution, stir for 40-60 min under a nitrogen atmosphere to obtain solution B; mix 300-400 parts of solution A and 400-500 parts of solution B evenly, heat and reflux at 80-90 °C for 2-4 h to obtain a quantum dot solution, centrifuge, collect the precipitate, wash with absolute ethanol, and dry to obtain zinc selenide quantum dots;

[0010] Step S2: By weight, mix 40-50 parts of magnesium oxide, 40-50 parts of titanium dioxide, and 4-6 parts of zinc selenide quantum dots evenly, add 400-500 parts of deionized water for ball milling to obtain a mixed powder, and calcine the mixed powder at 1000-1100 °C for 4-6 h to obtain modified magnesium titanate;

[0011] Step S3: By weight, mix 90-100 parts of modified magnesium titanate, 6-8 parts of carbon-doped titanium dioxide, 6-10 parts of strontium titanate, 1-3 parts of alumina, and 0.4-0.8 parts of lanthanum oxide evenly, ball mill, dry, granulate, press into shape, and then sinter at 1120-1150 °C for 4-6 h to obtain a dielectric ceramic material capable of reducing the sintering temperature of MLCC.

[0012] As a preferred technical solution of the present invention, the conditions of the ball milling process include: the ball milling speed is 300-400 r / min, and the ball milling time is 20-24 h.

[0013] The zinc selenide quantum dots introduced by modified magnesium titanate have a small size, can be evenly distributed in the magnesium titanate matrix, and provide a large number of surface active sites, significantly increasing the total specific surface area of the material. At the same time, the introduction of quantum dots will generate a certain amount of defects in the magnesium titanate lattice, and these defects can serve as additional active sites to further increase the specific surface area, promoting diffusion and reaction at a lower temperature through the high specific surface area, thereby achieving a reduction in the sintering temperature.

[0014] As a preferred technical solution of the present invention, the preparation method of the carbon-doped titanium dioxide includes: by weight, mixing 60-70 parts of absolute ethanol, 20-30 parts of deionized water, 1-3 parts of itaconic acid, and 6-8 parts of hydrochloric acid solution with a mass concentration of 30% and stirring for 20-30 min, then adding 70-80 parts of tetrabutyl titanate and stirring for 40-60 min, adjusting the pH to 3.2-3.6 with hydrochloric acid solution with a mass concentration of 30%, adding another 30-40 parts of deionized water and stirring for 120-180 min to form a gel, standing at room temperature for 12-14 h, drying, transferring to a tube furnace for calcination treatment, with the calcination temperature being 500-540 °C and the calcination time being 100-120 min, and cooling to room temperature to obtain carbon-doped titanium dioxide.

[0015] The carbon atoms in the carbon-doped titanium dioxide can enter the titanium dioxide lattice, replace part of the oxygen or titanium atoms to form a solid solution, and obtain a mesoporous structure through the solid solution. At the same time, the presence of carbon atoms can inhibit the grain growth of titanium dioxide during sintering, maintain a small particle size, thereby increasing the specific surface area of the ceramic dielectric material, and achieving a faster densification rate through the high specific surface area, thereby reducing the sintering temperature of the MLCC.

[0016] As a preferred technical solution of the present invention, the strontium titanate is zirconium-containing strontium titanate; the preparation method of the zirconium-containing strontium titanate includes: by weight, adding 20-30 parts of strontium titanate and 0.3-0.5 parts of zirconium dioxide to 90-100 parts of absolute ethanol, stirring at 70-80 °C for 40-60 min, drying, and grinding to obtain a mixed powder; mixing 1-3 parts of the mixed powder and 10-20 parts of strontium chloride hexahydrate evenly, transferring to a muffle furnace for high-temperature treatment, centrifuging, washing with water, and drying after the high-temperature treatment to obtain zirconium-containing strontium titanate.

[0017] As a preferred technical solution of the present invention, the conditions of the high-temperature treatment include: heating at a heating rate of 10 °C / min to 1060-1100 °C for a first heat preservation of 10-12 h, then cooling to 860-900 °C for a second heat preservation of 4-6 h, and finally naturally cooling to room temperature.

[0018] The valence states of zirconium ions and titanium ions in strontium zirconate titanate are the same, but the radius of zirconium ions is larger. It can effectively replace some titanium ions and enter the lattice, reducing the dielectric loss by reducing the formation of oxygen vacancies. At the same time, the introduction of zirconium can change the ferroelectric domain structure of strontium titanate, optimize the movement of domain walls, and reduce the energy dissipation of domain walls under an alternating electric field, thereby reducing the dielectric loss of the ceramic dielectric material.

[0019] As a preferred technical solution of the present invention, the alumina is yttrium-modified alumina; the preparation method of the yttrium-modified alumina includes: by weight, adding 40-50 parts of yttrium hydroxide and 90-100 parts of aluminum powder into 250-300 parts of a hydrochloric acid solution with a mass concentration fraction of 10%, stirring at 90-96 °C for 2-4 h to form a sol; then adding 50-60 parts of hexamethylenetetramine under the condition of 2-8 °C, mixing evenly, transferring to an aging reactor for aging treatment, washing, drying, calcining at 960-980 °C for 6-8 h, and cooling to room temperature to obtain yttrium-modified alumina.

[0020] As a preferred technical solution of the present invention, the conditions of the aging treatment include: the aging temperature is 150-160 °C, and the aging time is 4-6 h.

[0021] Yttrium-modified alumina changes the conduction path of the material by introducing yttrium elements, effectively reducing the leakage current and reducing the temperature dependence caused by the leakage current; at the same time, the introduction of yttrium can reduce the microstructural inhomogeneity inside the material, and obtain a low temperature coefficient by reducing the interfacial polarization.

[0022] As a preferred technical solution of the present invention, the lanthanum oxide is a lanthanum oxide composite material; the preparation method of the lanthanum oxide composite material includes: by weight, adding 30-40 parts of lanthanum oxide and 2-4 parts of europium oxide into 200-240 parts of concentrated nitric acid, mixing evenly, then adjusting the pH to 8.2-8.6 with ammonia water, stirring for 20-30 min and then carrying out a hydrothermal reaction. After the hydrothermal reaction is completed, the product is washed with deionized water and dried to obtain a precursor; transferring the precursor to a muffle furnace, calcining at 800-900 °C for 1-3 h, and cooling with the furnace to obtain the lanthanum oxide composite material.

[0023] As a preferred technical solution of the present invention, the temperature of the hydrothermal reaction is 140-150 °C, and the time is 24-30 h.

[0024] Europium ions in the lanthanum oxide composite material can replace some lanthanum ions and enter the lattice, stabilize the cubic phase of lanthanum oxide, reduce phase transformation and defect formation, thereby improving the crystallinity and uniformity of the material, and reducing the temperature coefficient of the ceramic dielectric material by stabilizing the crystal structure.

[0025] The second aspect of the present invention provides a ceramic dielectric material prepared by the method described in the first aspect, which can reduce the sintering temperature of MLCC.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The carbon-doped titanium dioxide of the present invention can form a solid solution by carbon atoms entering the titanium dioxide lattice to obtain a mesoporous structure. During the MLCC sintering process, the mesoporous structure with a high specific surface area can act as a carrier to absorb the zinc selenide quantum dots modified with magnesium titanate. At the same time, the zirconium element in strontium zirconate titanate, the yttrium element in yttrium-modified alumina, and the europium element in the lanthanum oxide composite material will also partially migrate into the mesoporous structure and form a composite structure with the zinc selenide quantum dots at high temperature, effectively reducing the dielectric loss of the ceramic dielectric material, obtaining a good temperature coefficient, and at the same time reducing the MLCC sintering temperature by increasing the specific surface area.

[0028] (2) The zinc selenide quantum dots introduced by the modified magnesium titanate of the present invention have a small size, can be evenly distributed in the magnesium titanate matrix, and provide a large number of surface active sites, significantly increasing the total specific surface area of the material; at the same time, the introduction of quantum dots will generate a certain amount of defects in the magnesium titanate lattice, and these defects can be used as additional active sites to further increase the specific surface area; the carbon atoms in the carbon-doped titanium dioxide can enter the titanium dioxide lattice, replace part of the oxygen or titanium atoms to form a solid solution, and obtain a mesoporous structure through the solid solution; at the same time, the presence of carbon atoms can inhibit the grain growth of titanium dioxide during the sintering process, maintain a small particle size, thereby increasing the specific surface area of the ceramic dielectric material, and achieving a faster densification rate through the high specific surface area, thereby reducing the sintering temperature of MLCC.

[0029] (3) The zirconium ions in the strontium zirconate titanate of the present invention have the same valence state as the titanium ions, but the zirconium ion radius is larger, and it can effectively replace part of the titanium ions to enter the lattice, reducing the dielectric loss by reducing the formation of oxygen vacancies; at the same time, the introduction of zirconium can change the ferroelectric domain structure of strontium titanate, optimize the movement of domain walls, and reduce the energy dissipation of domain walls under an alternating electric field, thereby reducing the dielectric loss of the ceramic dielectric material.

[0030] (4) The yttrium-modified alumina of the present invention changes the conduction path of the material by introducing yttrium elements, effectively reducing the leakage current and reducing the temperature dependence caused by the leakage current; the europium ions in the lanthanum oxide composite material can replace part of the lanthanum ions to enter the lattice, stabilize the cubic phase of lanthanum oxide, reduce the phase change and defect formation, thereby improving the crystallinity and uniformity of the material, and reducing the temperature coefficient of the ceramic dielectric material by stabilizing the crystal structure. Detailed implementation manners

[0031] To facilitate the understanding of the present invention, the following embodiments are listed. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0032] The sources of some components in the examples and comparative examples are as follows:

[0033] Magnesium titanate, CAS No. 12032-30-3, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0034] Titanium dioxide, CAS No. 13463-67-7, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0035] Strontium titanate, CAS No. 12060-59-2, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0036] Aluminum oxide, CAS No. 1344-28-1, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0037] Lanthanum oxide, CAS No. 1312-81-8, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0038] Selenium powder, CAS No. 7782-49-2, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0039] Sodium borohydride, CAS No. 16940-66-2, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0040] Zinc acetate, CAS No. 557-34-6, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0041] Absolute ethanol, CAS No. 64-17-5, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0042] Magnesium oxide, CAS No. 1309-48-4, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0043] Hydrochloric acid, CAS No. 7647-01-0, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0044] Tetrabutyl titanate, CAS No. 5593-70-4, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0045] Itaconic acid, product number PA54343, purchased from Shanghai ChuangSai Technology Co., Ltd.

[0046] Zirconium dioxide, CAS No. 1314-23-4, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0047] Strontium chloride hexahydrate, CAS No. 10025-70-4, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0048] Yttrium hydroxide, CAS No. 16469-22-0, was purchased from Shanghai Macklin Biochemical Co., Ltd.;

[0049] Aluminum powder, CAS No. 7429-90-5, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0050] Hexamethylenetetramine, CAS No. 100-97-0, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0051] Europium oxide, CAS No. 1308-96-9, was purchased from Shanghai Macklin Biochemical Co., Ltd.;

[0052] Concentrated nitric acid, CAS No. 7697-37-2, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0053] Ammonia water, CAS No. 1336-21-6, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0054] Example 1

[0055] This example provides a preparation method of a ceramic dielectric material that can reduce the sintering temperature of MLCCs, including the following steps:

[0056] Preparation of carbon-doped titanium dioxide: By weight, 70 parts of absolute ethanol, 30 parts of deionized water, 3 parts of itaconic acid, and 8 parts of hydrochloric acid solution with a mass concentration of 30% were mixed and stirred for 30 min, then 80 parts of tetrabutyl titanate were added and stirred for 60 min. The pH was adjusted to 3.6 with hydrochloric acid solution with a mass concentration of 30%, and then 40 parts of deionized water were added and stirred for 180 min to form a gel. It was left standing at room temperature for 14 h, dried, transferred to a tube furnace for calcination treatment. The calcination temperature was 540 °C, the calcination time was 100 min, and it was cooled to room temperature to obtain carbon-doped titanium dioxide.

[0057] Preparation of strontium zirconate titanate: By weight, 30 parts of strontium titanate and 0.5 part of zirconium dioxide were added to 100 parts of absolute ethanol, stirred at 80 °C for 60 min, dried, and ground to obtain a mixed powder; 3 parts of the mixed powder and 20 parts of strontium chloride hexahydrate were mixed evenly, transferred to a muffle furnace for high-temperature treatment (heated to 1100 °C at a heating rate of 10 °C / min for the first heat preservation for 10 h, then cooled to 900 °C for the second heat preservation for 4 h, and finally naturally cooled to room temperature). After high-temperature treatment, it was centrifuged, washed with water, and dried to obtain strontium zirconate titanate.

[0058] Preparation of yttrium-modified alumina: By weight, 50 parts of yttrium hydroxide and 100 parts of aluminum powder are added to 300 parts of a hydrochloric acid solution with a mass concentration of 10%, and stirred at 96 °C for 2 h to form a sol; then 60 parts of hexamethylenetetramine are added and mixed evenly at 8 °C, transferred to an aging reactor for aging treatment (aging temperature is 160 °C, aging time is 4 h), washed, dried, calcined at 980 °C for 6 h, and cooled to room temperature to obtain yttrium-modified alumina.

[0059] Preparation of lanthanum oxide composite material: By weight, 40 parts of lanthanum oxide and 4 parts of europium oxide are added to 240 parts of concentrated nitric acid and mixed evenly, then the pH is adjusted to 8.6 with ammonia water, stirred for 30 min and then subjected to hydrothermal reaction (temperature is 150 °C, time is 24 h). After the hydrothermal reaction is completed, the product is washed with deionized water and dried to obtain a precursor; the precursor is transferred to a muffle furnace and calcined at 900 °C for 1 h, and cooled with the furnace to obtain a lanthanum oxide composite material.

[0060] Step S1: By weight, 4 parts of selenium powder and 5 parts of sodium borohydride are added to 400 parts of deionized water, and stirred and reacted in an argon atmosphere for 6 h to obtain solution A; 4 parts of zinc acetate are added to 500 parts of absolute ethanol and mixed evenly, and the pH is adjusted to 10.6 with 1 mol / L sodium hydroxide solution, and stirred for 60 min in a nitrogen atmosphere to obtain solution B; 400 parts of solution A and 500 parts of solution B are mixed evenly, heated under reflux at 90 °C for 2 h to obtain a quantum dot solution, centrifuged, the precipitate is collected, washed with absolute ethanol, and dried to obtain zinc selenide quantum dots;

[0061] Step S2: By weight, 50 parts of magnesium oxide, 50 parts of titanium dioxide and 6 parts of zinc selenide quantum dots are mixed evenly, 500 parts of deionized water are added for ball milling treatment (ball milling speed is 400 r / min, ball milling time is 20 h) to obtain a mixed powder, and the mixed powder is calcined at 1100 °C for 4 h to obtain modified magnesium titanate;

[0062] Step S3: By weight, 100 parts of modified magnesium titanate, 8 parts of carbon-doped titanium dioxide, 10 parts of strontium zirconate titanate, 3 parts of yttrium-modified alumina and 0.8 part of lanthanum oxide composite material are mixed evenly, ball milled, dried, granulated, pressed into shape, and then sintered at 1150 °C for 4 h to obtain a ceramic dielectric material that can reduce the sintering temperature of MLCC.

[0063] Example 2

[0064] This example provides a preparation method of a ceramic dielectric material that can reduce the sintering temperature of MLCC, including the following steps:

[0065] Preparation of carbon-doped titanium dioxide: By weight, 60 parts of absolute ethanol, 20 parts of deionized water, 1 part of itaconic acid and 6 parts of hydrochloric acid solution with a mass concentration of 30% are mixed and stirred for 20 min, then 70 parts of tetrabutyl titanate are added and stirred for 40 min. The pH is adjusted to 3.2 with hydrochloric acid solution with a mass concentration of 30%, and then 30 parts of deionized water are added and stirred for 120 min to form a gel. It is left standing at room temperature for 12 h, dried, transferred to a tube furnace for calcination treatment. The calcination temperature is 500 °C and the calcination time is 120 min. After cooling to room temperature, carbon-doped titanium dioxide is obtained.

[0066] Preparation of strontium zirconate titanate: By weight, 20 parts of strontium titanate and 0.3 part of zirconium dioxide are added to 90 parts of absolute ethanol, and stirred at 70 °C for 60 min, dried and ground to obtain a mixed powder; 1 part of the mixed powder and 10 parts of strontium chloride hexahydrate are mixed evenly, transferred to a muffle furnace for high-temperature treatment (heating at a rate of 10 °C / min to 1060 °C for the first heat preservation for 12 h, then cooling to 860 °C for the second heat preservation for 6 h, and finally naturally cooling to room temperature). After high-temperature treatment, it is centrifuged, washed with water and dried to obtain strontium zirconate titanate.

[0067] Preparation of yttrium-modified alumina: By weight, 40 parts of yttrium hydroxide and 90 parts of aluminum powder are added to 250 parts of hydrochloric acid solution with a mass concentration of 10%, and stirred at 90 °C for 4 h to form a sol; then 50 parts of hexamethylenetetramine are added and mixed evenly at 2 °C, transferred to an aging reactor for aging treatment (aging temperature is 150 °C, aging time is 6 h), washed, dried, calcined at 960 °C for 8 h, and cooled to room temperature to obtain yttrium-modified alumina.

[0068] Preparation of lanthanum oxide composite: By weight, 30 parts of lanthanum oxide and 2 parts of europium oxide are added to 200 parts of concentrated nitric acid and mixed evenly, then the pH is adjusted to 8.2 with ammonia water, stirred for 20 min and then subjected to hydrothermal reaction (temperature is 140 °C, time is 30 h). After the hydrothermal reaction is completed, the product is washed with deionized water and dried to obtain a precursor; the precursor is transferred to a muffle furnace and calcined at 800 °C for 3 h, and cooled with the furnace to obtain a lanthanum oxide composite.

[0069] Step S1: By weight, add 2 parts of selenium powder and 3 parts of sodium borohydride to 300 parts of deionized water, stir and react for 4 h under an argon atmosphere to obtain solution A; add 2 parts of zinc acetate to 400 parts of absolute ethanol and mix evenly, adjust the pH to 10.2 with 1 mol / L sodium hydroxide solution, stir for 40 min under a nitrogen atmosphere to obtain solution B; mix 300 parts of solution A and 400 parts of solution B evenly, heat and reflux at 80 °C for 4 h to obtain a quantum dot solution, centrifuge, collect the precipitate, wash with absolute ethanol, dry to obtain zinc selenide quantum dots;

[0070] Step S2: By weight, mix 40 parts of magnesium oxide, 40 parts of titanium dioxide and 4 parts of zinc selenide quantum dots evenly, add 400 parts of deionized water and carry out ball milling treatment (ball milling speed is 300 r / min, ball milling time is 24 h) to obtain a mixed powder, calcine the mixed powder at 1000 °C for 6 h to obtain modified magnesium titanate;

[0071] Step S3: By weight, mix 90 parts of modified magnesium titanate, 6 parts of carbon-doped titanium dioxide, 6 parts of strontium zirconate titanate, 1 part of yttrium-modified alumina and 0.4 part of lanthanum oxide composite material evenly, ball mill, dry, granulate, press into shape, and then sinter at 1120 °C for 6 h to obtain a ceramic dielectric material that can reduce the sintering temperature of MLCC.

[0072] Example 3

[0073] This example provides a preparation method of a ceramic dielectric material that can reduce the sintering temperature of MLCC, including the following steps:

[0074] Preparation of carbon-doped titanium dioxide: By weight, mix 65 parts of absolute ethanol, 25 parts of deionized water, 2 parts of itaconic acid and 7 parts of hydrochloric acid solution with a mass concentration of 30% and stir for 25 min, then add 75 parts of tetrabutyl titanate and stir for 50 min, adjust the pH to 3.4 with hydrochloric acid solution with a mass concentration of 30%, add another 35 parts of deionized water and stir for 160 min to form a gel, let it stand at room temperature for 13 h, dry, transfer to a tubular furnace for calcination treatment, the calcination temperature is 520 °C, the calcination time is 110 min, and cool to room temperature to obtain carbon-doped titanium dioxide.

[0075] Preparation of strontium zirconium titanate: By weight, 25 parts of strontium titanate and 0.4 part of zirconium dioxide are added to 95 parts of absolute ethanol, stirred at 75 °C for 50 min, dried, and ground to obtain a mixed powder; 2 parts of the mixed powder and 15 parts of strontium chloride hexahydrate are mixed evenly, transferred to a muffle furnace for high-temperature treatment (heated to 1080 °C at a heating rate of 10 °C / min for the first heat preservation for 11 h, then cooled to 880 °C for the second heat preservation for 5 h, and finally naturally cooled to room temperature). After high-temperature treatment, it is centrifuged, washed with water, and dried to obtain strontium zirconium titanate.

[0076] Preparation of yttrium-modified alumina: By weight, 45 parts of yttrium hydroxide and 95 parts of aluminum powder are added to 280 parts of a hydrochloric acid solution with a mass concentration of 10%, stirred at 94 °C for 3 h to form a sol; then 55 parts of hexamethylenetetramine are added and mixed evenly at 6 °C, transferred to an aging reactor for aging treatment (aging temperature is 155 °C, aging time is 5 h), washed, dried, calcined at 970 °C for 7 h, and cooled to room temperature to obtain yttrium-modified alumina.

[0077] Preparation of lanthanum oxide composite material: By weight, 35 parts of lanthanum oxide and 3 parts of europium oxide are added to 220 parts of concentrated nitric acid and mixed evenly, then the pH is adjusted to 8.4 with ammonia water, stirred for 25 min and then subjected to hydrothermal reaction (temperature is 145 °C, time is 28 h). After the hydrothermal reaction is completed, the product is washed with deionized water, dried to obtain a precursor; the precursor is transferred to a muffle furnace and calcined at 850 °C for 2 h, and cooled with the furnace to obtain a lanthanum oxide composite material.

[0078] Step S1: By weight, 3 parts of selenium powder and 4 parts of sodium borohydride are added to 350 parts of deionized water, stirred and reacted under an argon atmosphere for 5 h to obtain solution A; 3 parts of zinc acetate are added to 450 parts of absolute ethanol and mixed evenly, the pH is adjusted to 10.4 with 1 mol / L sodium hydroxide solution, and stirred under a nitrogen atmosphere for 50 min to obtain solution B; 350 parts of solution A and 450 parts of solution B are mixed evenly, heated under reflux at 85 °C for 3 h to obtain a quantum dot solution, centrifuged, the precipitate is collected, washed with absolute ethanol, and dried to obtain zinc selenide quantum dots;

[0079] Step S2: By weight, 45 parts of magnesium oxide, 45 parts of titanium dioxide and 5 parts of zinc selenide quantum dots are mixed evenly, 450 parts of deionized water are added for ball milling treatment (ball milling speed is 350 r / min, ball milling time is 22 h) to obtain a mixed powder, and the mixed powder is calcined at 1050 °C for 5 h to obtain modified magnesium titanate;

[0080] Step S3: Mix 95 parts of modified magnesium titanate, 7 parts of carbon-doped titanium dioxide, 8 parts of strontium zirconate titanate, 2 parts of yttrium-modified alumina, and 0.6 part of lanthanum oxide composite material evenly, ball mill, dry, granulate, press into shape, and then sinter at 1140 °C for 5 h to obtain a ceramic dielectric material that can reduce the sintering temperature of MLCC.

[0081] Comparative Example 1

[0082] This comparative example provides a method for preparing a ceramic dielectric material, which is different from Example 1 in that commercially available magnesium titanate is used to replace the modified magnesium titanate, commercially available titanium dioxide is used to replace the carbon-doped titanium dioxide, commercially available strontium titanate is used to replace the strontium zirconate titanate, commercially available alumina is used to replace the yttrium-modified alumina, and commercially available lanthanum oxide is used to replace the lanthanum oxide composite material.

[0083] Comparative Example 2

[0084] This comparative example provides a method for preparing an MLCC ceramic material, which is different from Comparative Example 1 in that the modified magnesium titanate is used to replace the commercially available magnesium titanate.

[0085] Comparative Example 3

[0086] This comparative example provides a method for preparing an MLCC ceramic material, which is different from Comparative Example 1 in that the carbon-doped titanium dioxide is used to replace the commercially available titanium dioxide.

[0087] Comparative Example 4

[0088] This comparative example provides a method for preparing an MLCC ceramic material, which is different from Comparative Example 1 in that the strontium zirconate titanate is used to replace the commercially available strontium titanate.

[0089] Comparative Example 5

[0090] This comparative example provides a method for preparing an MLCC ceramic material, which is different from Comparative Example 1 in that the yttrium-modified alumina is used to replace the commercially available alumina.

[0091] Comparative Example 6

[0092] This comparative example provides a method for preparing an MLCC ceramic material, which is different from Comparative Example 1 in that the lanthanum oxide composite material is used to replace the commercially available lanthanum oxide.

[0093] Comparative Example 7

[0094] This comparative example provides a method for preparing a ceramic dielectric material, which is different from Example 1 in that commercially available magnesium titanate is used to replace the modified magnesium titanate.

[0095] Comparative Example 8

[0096] This comparative example provides a method for preparing a ceramic dielectric material, which is different from Example 1 in that commercially available titanium dioxide is used to replace carbon-doped titanium dioxide.

[0097] Comparative Example 9

[0098] This comparative example provides a method for preparing a ceramic dielectric material, which is different from Example 1 in that commercially available strontium titanate is used to replace strontium zirconate titanate.

[0099] Comparative Example 10

[0100] This comparative example provides a method for preparing a ceramic dielectric material, which is different from Example 1 in that commercially available alumina is used to replace yttrium-modified alumina.

[0101] Comparative Example 11

[0102] This comparative example provides a method for preparing a ceramic dielectric material, which is different from Example 1 in that commercially available lanthanum oxide is used to replace the lanthanum oxide composite material.

[0103] The properties of the ceramic dielectric materials provided in the above examples and comparative examples were tested, and the test methods are as follows: The specific surface area was tested according to the requirements of "GB / T 5596-1996 Ceramic Dielectric Materials for Capacitors"; The double sides of the ceramic dielectric materials prepared in the examples and comparative examples were coated with silver paste and fired to form silver electrodes to make test samples, and the dielectric loss and temperature coefficient of the test samples were tested according to the requirements of "GB / T 5596-1996 Ceramic Dielectric Materials for Capacitors".

[0104] The above performance test data are shown in Table 1.

[0105] Table 1 Performance Test Results

[0106]

[0107] As can be seen from the above content, in the present invention, by modifying the main crystal phase magnesium titanate and introducing components such as carbon-doped titanium dioxide, strontium zirconate titanate, yttrium-modified alumina, and lanthanum oxide composite material, a ceramic dielectric material (Examples 1 to 3) that can reduce the sintering temperature of MLCC is prepared. The specific surface area of the ceramic dielectric material is 6183-6205 cm 2 / g, the dielectric loss is 1.6×10 -4 ~1.9×10 -4 , and the temperature coefficient TCC (125 °C) is 9.7-10.2 ppm / °C.

[0108] Compared with Example 1, when using commercially available magnesium titanate to replace the modified magnesium titanate, commercially available titanium dioxide to replace carbon-doped titanium dioxide, commercially available strontium titanate to replace strontium zirconium titanate, commercially available aluminum oxide to replace yttrium-modified aluminum oxide, and commercially available lanthanum oxide to replace lanthanum oxide composite material, the specific surface area decreases, the dielectric loss increases, and the temperature coefficient becomes larger (Comparative Example 1); compared with Comparative Example 1, when using the modified magnesium titanate to replace the commercially available magnesium titanate, the specific surface area increases (Comparative Example 2); compared with Comparative Example 1, when using carbon-doped titanium dioxide to replace the commercially available titanium dioxide, the specific surface area increases (Comparative Example 3); compared with Comparative Example 1, when using strontium zirconium titanate to replace the commercially available strontium titanate, the dielectric loss decreases (Comparative Example 4); compared with Comparative Example 1, when using yttrium-modified aluminum oxide to replace the commercially available aluminum oxide, the temperature coefficient becomes smaller (Comparative Example 5); compared with Comparative Example 1, when using lanthanum oxide composite material to replace the commercially available lanthanum oxide, the temperature coefficient becomes smaller (Comparative Example 6); compared with Example 1, when using commercially available magnesium titanate to replace the modified magnesium titanate, the specific surface area decreases, the dielectric loss increases, and the temperature coefficient becomes larger (Comparative Example 7); compared with Example 1, when using commercially available titanium dioxide to replace carbon-doped titanium dioxide, the specific surface area decreases, the dielectric loss increases, and the temperature coefficient becomes larger (Comparative Example 8); compared with Example 1, when using commercially available strontium titanate to replace strontium zirconium titanate, the specific surface area decreases, the dielectric loss increases, and the temperature coefficient becomes larger (Comparative Example 9); compared with Example 1, when using commercially available aluminum oxide to replace yttrium-modified aluminum oxide, the specific surface area decreases, the dielectric loss increases, and the temperature coefficient becomes larger (Comparative Example 10); compared with Example 1, when using commercially available lanthanum oxide to replace lanthanum oxide composite material, the specific surface area decreases, the dielectric loss increases, and the temperature coefficient becomes larger (Comparative Example 11).

[0109] In summary, the present invention modifies the main crystal phase magnesium titanate, and simultaneously introduces components such as carbon-doped titanium dioxide, strontium zirconium titanate, yttrium-modified aluminum oxide, and lanthanum oxide composite material to prepare a dielectric ceramic material that can reduce the sintering temperature of MLCC. The multi-components act synergistically to reduce the dielectric loss of the dielectric ceramic material, obtain a good temperature coefficient, and reduce the sintering temperature of MLCC through a high specific surface area.

Claims

1. A preparation method of a ceramic dielectric material capable of reducing the sintering temperature of MLCC, characterized in that It includes the following steps: Step S1: By weight, add 2-4 parts of selenium powder and 3-5 parts of sodium borohydride to 300-400 parts of deionized water, stir and react for 4-6 h under an argon atmosphere to obtain liquid A; add 2-4 parts of zinc acetate to 400-500 parts of absolute ethanol and mix evenly, adjust the pH to 10.2-10.6 with 1 mol / L sodium hydroxide solution, stir for 40-60 min under a nitrogen atmosphere to obtain liquid B; mix 300-400 parts of the liquid A and 400-500 parts of the liquid B evenly, heat and reflux at 80-90 °C for 2-4 h to obtain a quantum dot solution, centrifuge, collect the precipitate, wash with absolute ethanol, dry, and obtain zinc selenide quantum dots; Step S2: By weight, mix 40-50 parts of magnesium oxide, 40-50 parts of titanium dioxide and 4-6 parts of zinc selenide quantum dots evenly, add 400-500 parts of deionized water for ball milling to obtain a mixed powder, and calcine the mixed powder at 1000-1100 °C for 4-6 h to obtain modified magnesium titanate; Step S3: By weight, mix 90-100 parts of modified magnesium titanate, 6-8 parts of carbon-doped titanium dioxide, 6-10 parts of strontium zirconate titanate, 1-3 parts of yttrium-modified alumina and 0.4-0.8 part of lanthanum oxide evenly, ball mill, dry, granulate, press into shape, and then sinter at 1120-1150 °C for 4-6 h to obtain a ceramic dielectric material that can reduce the sintering temperature of MLCC; The preparation method of the strontium zirconate titanate includes: by weight, add 20-30 parts of strontium titanate and 0.3-0.5 part of zirconium dioxide to 90-100 parts of absolute ethanol, stir at 70-80 °C for 40-60 min, dry, grind to obtain a mixed powder; mix 1-3 parts of the mixed powder and 10-20 parts of strontium chloride hexahydrate evenly, transfer to a muffle furnace for high-temperature treatment, centrifuge, wash with water, dry after high-temperature treatment to obtain strontium zirconate titanate; The preparation method of the yttrium-modified alumina includes: by weight, add 40-50 parts of yttrium hydroxide and 90-100 parts of aluminum powder to 250-300 parts of a hydrochloric acid solution with a mass concentration of 10%, stir at 90-96 °C for 2-4 h to form a sol; then add 50-60 parts of hexamethylenetetramine and mix evenly at 2-8 °C, transfer to an aging reactor for aging treatment, wash, dry, calcine at 960-980 °C for 6-8 h, and cool to room temperature to obtain yttrium-modified alumina.

2. The preparation method of a ceramic dielectric material capable of reducing the sintering temperature of MLCC according to claim 1, characterized in that, The conditions of the ball milling treatment include: the ball milling speed is 300-400 r / min, and the ball milling time is 20-24 h.

3. The preparation method of a ceramic dielectric material capable of reducing the sintering temperature of MLCC according to claim 1, characterized in that, The preparation method of the carbon-doped titanium dioxide includes: by weight, mixing 60-70 parts of absolute ethanol, 20-30 parts of deionized water, 1-3 parts of itaconic acid and 6-8 parts of hydrochloric acid solution with a mass concentration of 30% and stirring for 20-30 min, then adding 70-80 parts of tetrabutyl titanate and stirring for 40-60 min, adjusting the pH to 3.2-3.6 with hydrochloric acid solution with a mass concentration of 30%, adding 30-40 parts of deionized water and stirring for 120-180 min to form a gel, standing at room temperature for 12-14 h, drying, transferring to a tubular furnace for calcination treatment, the calcination temperature is 500-540 °C, the calcination time is 100-120 min, and cooling to room temperature to obtain carbon-doped titanium dioxide.

4. The preparation method of a ceramic dielectric material capable of reducing the sintering temperature of MLCC according to claim 1, characterized in that, The conditions of the high-temperature treatment include: heating to 1060-1100 °C at a heating rate of 10 °C / min for the first heat preservation for 10-12 h, then cooling to 860-900 °C for the second heat preservation for 4-6 h, and finally naturally cooling to room temperature.

5. The preparation method of a ceramic dielectric material capable of reducing the sintering temperature of an MLCC according to claim 1, characterized in that, The conditions of the aging treatment include: the aging temperature is 150-160 °C and the aging time is 4-6 h.

6. The preparation method of a ceramic dielectric material capable of reducing the sintering temperature of MLCC according to claim 1, characterized in that, The lanthanum oxide is a lanthanum oxide composite material; The preparation method of the lanthanum oxide composite material includes: by weight, adding 30-40 parts of lanthanum oxide and 2-4 parts of europium oxide into 200-240 parts of concentrated nitric acid and mixing evenly, then adjusting the pH to 8.2-8.6 with ammonia water, stirring for 20-30 min and then carrying out a hydrothermal reaction. After the hydrothermal reaction is completed, washing the product with deionized water and drying to obtain a precursor; transferring the precursor to a muffle furnace and calcining at 800-900 °C for 1-3 h, and cooling with the furnace to obtain the lanthanum oxide composite material.

7. The preparation method of a ceramic dielectric material capable of reducing the sintering temperature of an MLCC according to claim 6, characterized in that, The temperature of the hydrothermal reaction is 140-150 °C and the time is 24-30 h.

8. A ceramic dielectric material capable of reducing the sintering temperature of MLCC, characterized in that, Prepared by the method according to any one of claims 1-7.

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