A borosilicate glass assisted X9R type MLCC dielectric material and a preparation method thereof

Abstract

The application discloses a borosilicate glass assisted X9R type MLCC dielectric material and a preparation method thereof. 1‑y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, wherein 0 The auxiliary component is a composite dopant composed of Nb2O5, MnO2, ZnO and MgO, and the molar percentage is 4-8%; and the sintering aid is borosilicate glass composed of SiO2, B2O3, CaO, Al2O3, ZrO2 and X2O, wherein X is one or more of Li, Na and K, and the addition amount is 1-5% of the total mass of the solid solution and the composite dopant. The MLCC dielectric material provided by the application meets the EIA X9R standard requirement in medium temperature characteristics, the sintering temperature is not higher than 1100 DEG C, the room temperature dielectric constant is 1650-1850, the dielectric loss is low, the low dielectric loss temperature range is wide, and the resistivity is high; the preparation method has the advantages of simple process flow, low preparation cost and good industrialization prospect.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electronic ceramic materials, in particular to a borosilicate glass-assisted X9R type MLCC dielectric material and a preparation method thereof. BACKGROUND

[0002] Multilayer ceramic capacitors (MLCC) are one of the most widely used chip passive devices in the electronic industry. Under the background of the accelerated development of aerospace, electric vehicles and other application directions, MLCC is facing increasingly severe temperature stability challenges. Under the above working conditions, X7R and X8R type MLCCs with a dielectric temperature stability temperature range of-55 to 125 DEG C and 150 DEG C cannot meet the capacitance change rate (ΔC / C 25℃ ≤±15%) requirement under high temperature environment. Therefore, X9R type MLCC and the dielectric material used therefor have become a research hotspot in recent years.

[0003] On the basis of BaTiO3-based composite perovskite dielectric materials composed of barium titanate (BaTiO3) and other perovskite structure complex oxide solid solutions, MLCC dielectric materials with dielectric temperature stability meeting the X9R standard requirement can be prepared. Some researchers obtained X9R type MLCC dielectric materials with high dielectric constant, low room temperature dielectric loss, wide dielectric temperature stability temperature range and good insulation characteristics by taking 0.9BT-0.1BNT as a "core" and a surface coating layer formed by Co elements and Nd elements as a "shell". However, the low-frequency dielectric loss of the material rises obviously at the high temperature section, which must be overcome by further improving the sintering quality. Considering that the "core-shell" structure of the dielectric material grain is directly related to the sintering process, simply changing the sintering system will affect the stable formation of the "core-shell" structure, and then deteriorate the dielectric temperature stability of the material, so it is not feasible. Introducing a sintering aid to improve the sintering quality of the dielectric material becomes a selectable means. In the existing work, a mixture of oxides such as SiO2, B2O3, Al2O3, CaO, TiO2 and their corresponding hydrates, carbonates is calcined below 1250 DEG C to prepare a glassy sintering aid, which often cannot obtain a uniform and stable amorphous glass. The residual oxides and crystalline substances generated by solid-phase reaction may interfere with the sintering process of the dielectric material, and then have an adverse effect on the dielectric properties and quality stability of the dielectric material. SUMMARY

[0004] The application provides a borosilicate glass sintering-assisted X9R type MLCC dielectric material and a preparation method thereof, which are used for overcoming the defects of the prior art, such as the sintering quality of the dielectric material to be improved, the high-frequency dielectric loss being high at a high-temperature section, and the performance stability of the sintering aid being poor, and provide the MLCC dielectric material with the characteristics of meeting the EIAX9R standard in terms of dielectric temperature stability, low sintering temperature, low dielectric loss, wide temperature range of low dielectric loss, and high resistivity.

[0005] To achieve the above-mentioned purpose, the application provides a borosilicate glass sintering-assisted X9R type MLCC dielectric material, characterized in that the main component of the MLCC dielectric material is (1-x) BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, the molar percentage of which is 92-96 %, wherein 0 < x <= 0.20 and 0.002 <= y <= 0.04; the auxiliary component is a composite dopant composed of Nb2O5, MnO2, ZnO and MgO, the molar percentage of which is 4-8 %; the sintering aid is borosilicate glass, the addition amount of which is 1-5 % of the total mass of the solid solution and the composite dopant; and the borosilicate glass is composed of SiO2, B2O3, CaO, Al2O3, ZrO2 and X2O, wherein X is one or more of Li, Na and K.

[0006] The dielectric temperature characteristic of the MLCC dielectric material meets the EIAX9R standard, that is, Δε r / epsilon r25℃ <=+ / -15 % in the temperature range of -55-200 DEG C, the required sintering temperature is not higher than 1100 DEG C, the room-temperature dielectric constant is 1650-1850, the room-temperature dielectric loss is <=0.02, the temperature range of the dielectric loss <=0.02 is wider than 0-200 DEG C, and the room-temperature resistivity is >=10 11 ohm*cm.

[0007] The application further provides a preparation method of the above-mentioned borosilicate glass sintering-assisted X9R type MLCC dielectric material, which comprises the following steps:

[0008] S1: according to the value of y in the composition of BaTi 1-y Ce y O3, BaCO3, TiO2 and CeO2 are weighed according to the molar percentage, ball-milled, dried, sieved, heated and heat-preserved to obtain BaTi 1-y Ce y O3 powder;

[0009] S2: Bi2O3, Na2CO3 and TiO2 are weighed, ball-milled, dried, sieved, heated and heat-preserved to obtain (Bi 0.5 Na 0.5TiO3 powder;

[0010] S3: (1-x):x stoichiometric ratio of BaTi 1-y Ce y O3 powder and (Bi 0.5 Na 0.5 )TiO3 powder, ball milling, drying, sieving, heating and holding, to obtain (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution;

[0011] S4: SiO2, B2O3, CaO, Al2O3, ZrO2 and X2O are weighed according to the mass percentage, mixed, smelted, water quenched, to obtain borosilicate glass slag, and the borosilicate glass slag is ball milled, dried and sieved to obtain borosilicate glass powder;

[0012] S5: (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, a composite dopant composed of Nb2O5, MnO2, ZnO and MgO, and borosilicate glass powder are weighed according to the proportion, ball milled, dried and sieved to obtain raw material powder;

[0013] S6: The raw material powder is mixed with a polyvinyl alcohol solution and then granulated to obtain a green body by compression molding;

[0014] S7: The green body is placed in an air atmosphere, heated and held, then continuously heated and held, and cooled to obtain a borosilicate glass assisted X9R type MLCC dielectric material.

[0015] Compared with the prior art, the beneficial effects of the present application are:

[0016] 1. The barium titanate-based X9R type high-dielectric MLCC dielectric material provided by the present application mainly comprises (1-x)BaTi 1- y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution. In the preparation of the solid solution, pure BaTiO3 ceramic and (Bi 0.5 Na 0.5 )TiO3 ceramic are not used as raw materials, but a small amount of Ce and a slight excess of Ba are first added to the BaTiO3 ceramic to allow the appropriate amount of Ce element to be doped into the ceramic Ti site (B site), and then it is combined with an appropriate amount of (Bi 0.5 Na0.5 )TiO3 to further optimize the dielectric properties of the solid solution. Since Ce 4+ ions have a larger radius than Ti 4+ ions, they can locally expand the volume of adjacent Ti-O octahedra in the ceramic crystal structure, increasing the polarization ability of Ti 4+ ions, thus effectively increasing the peak dielectric constant of BaTiO3 ceramics without significantly reducing its Curie temperature. On this basis, (Bi 0.5 Na 0.5 )TiO3 is introduced to increase the Curie temperature of the solid solution, resulting in (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, which has a higher peak dielectric constant than existing BaTiO3-(Bi 0.5 Na 0.5 )TiO3 solid solution.

[0017] 2、The present application is based on (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, and introduces a composite additive composed of Nb2O5, MgO, MnO2 and ZnO. Nb2O5 introduces non-uniform Nb element doping in (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution grains, forming "core-shell" structure grains with special dielectric temperature characteristics, thereby enhancing the dielectric temperature stability of the ceramic; Mg 2+ ions in MgO can naturally form a "core-shell" structure in BaTiO3 ceramics. After additional addition of MgO, Mg 2+ ions and Nb 5+ ions diffuse into the interior of the solid solution grains during sintering, and the former effectively stabilizes the non-uniform distribution of the latter, preventing uncontrolled diffusion of Nb elements due to the introduction of Ce-doped elements in the B-site of the ceramic, which would otherwise destroy the "core-shell" structure in the ceramic grains. In addition, MnO2 and ZnO can have a synergistic effect with Nb2O5 and MgO, on the one hand ensuring the stable formation of the "core-shell" structure of the ceramic grains at lower sintering temperatures, and on the other hand partially inhibiting the interfacial reaction between borosilicate glass and the base ceramic, reducing its negative impact on the "core-shell" structure, thereby maintaining the dielectric temperature stability of the dielectric material.

[0018] 3、The X9R type MLCC dielectric material provided by the application uses borosilicate glass composed of SiO2, B2O3, CaO, Al2O3, ZrO2 and X2O as a sintering aid, the formula glass uses appropriate proportions of SiO2 and B2O3 as glass network formers, supplemented by glass network intermediates Al2O3 and glass network outsiders CaO and X2O, so that it has the outstanding characteristics of low softening point, no second phase precipitation after heat treatment, and good wettability with the base ceramic. Therefore, it can change the sintering process of the ceramic from solid phase sintering to liquid phase sintering on the basis of slightly reducing the dielectric constant of the dielectric material, effectively improve the sintering density of the dielectric material, and further significantly improve its dielectric loss characteristics. At the same time, the introduction of the sintering aid can reduce the sintering temperature of the dielectric material and improve its process performance, thereby reducing the energy consumption in the preparation process of the dielectric material.

[0019] 4、The borosilicate glass used as a sintering aid is prepared by a melt water quenching method, which basically does not contain residual oxides and crystalline precipitated phase components compared with the glassy sintering aid obtained by calcining solid phase raw materials, has better composition uniformity and more significant amorphous characteristics, has better sintering aid effect, and has lower interface reaction degree with the base ceramic, thereby effectively reducing the deterioration of the dielectric properties of the dielectric material caused by the introduction of the sintering aid, and ensuring the quality stability of the dielectric material.

[0020] 5、The borosilicate glass sintered X9R type MLCC dielectric material provided by the application does not contain harmful elements and meets the environmental protection requirements; the preparation method used has simple process, short preparation period, stable product performance and low production cost. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of the drawings shown.

[0022] Figure 1 The flowchart of the preparation method of the borosilicate glass sintered X9R type MLCC dielectric material;

[0023] Figure 2 The dielectric temperature spectrum of the sample of example 1 after being silver electrode.

[0024] The implementation, functional characteristics and advantages of the application will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort should fall within the protection scope of the present application.

[0026] In addition, the technical solutions among various embodiments of the present application can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize the combination. When the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the protection scope of the present application.

[0027] The present application provides a borosilicate glass assisted X9R type MLCC dielectric material, characterized in that the main component of the MLCC dielectric material is (1-x) BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, the molar percentage of which is 92-96%, wherein 0

[0028] The sintering aid is borosilicate glass, the addition amount of which is 1-5% of the total mass of the solid solution and the composite dopant, and the borosilicate glass is composed of SiO2, B2O3, CaO, Al2O3, ZrO2 and X2O, wherein X is one or more of Li, Na and K. After conversion, B2O3 can be introduced in the form of H3BO3, CaO and X2O can be introduced in the form of CaCO3 and X2CO3, respectively.

[0029] The dielectric temperature characteristics of the above-mentioned MLCC dielectric material meet the EIA X9R standard, that is, Δε / ε r / ε r25℃ ≤±15% in the temperature range of -55-200 ℃, the required sintering temperature is not higher than 1100 ℃, the room temperature dielectric constant is 1650-1850, the room temperature dielectric loss is ≤0.02, the temperature range in which the dielectric loss is ≤0.02 is wider than 0-200 ℃, and the room temperature resistivity is ≥10 11 Ω·cm.

[0030] Preferably, the molar percentages of the components in the composite dopant are as follows: Nb2O5: 2-4%; MnO2: 1-2%; ZnO: 0.5-1%; and MgO: 0.5-1%.

[0031] If the doping ratio of each component in the composite dopant deviates from the corresponding component interval, the solid solution grain cannot form a core-shell structure with a suitable core-shell ratio, and the dielectric temperature stability of the obtained medium material cannot meet the EIAX9R standard requirements.

[0032] Preferably, the mass percentage of each component in the borosilicate glass is as follows: SiO2: 55-58%; B2O3: 25-29%; CaO: 5-8%; Al2O3: 1-3%; ZrO2: 1-3%; X2O: 0-3%.

[0033] If the addition ratio of SiO2 and B2O3 in the borosilicate glass deviates from the corresponding component interval, amorphous glass cannot be formed; if the addition ratio of CaO, Al2O3, ZrO2 and X2O deviates from the corresponding component interval, uncontrollable crystallization of the glass may occur during the subsequent sintering process, affecting the performance of the final product.

[0034] The application also provides a preparation method of an X9R type MLCC medium material assisted by borosilicate glass, comprising the following steps:

[0035] S1: according to BaTi 1-y Ce y O3 composition, BaCO3, TiO2 and CeO2 are weighed according to the mole percentage, ball milling, drying, sieving, heating and heat preservation to obtain BaTi 1-y Ce y O3 powder;

[0036] S2: Bi2O3, Na2CO3 and TiO2 are weighed, ball milling, drying, sieving, heating and heat preservation to obtain (Bi 0.5 Na 0.5 )TiO3 powder;

[0037] S3: BaTi 1-y Ce y O3 powder and (Bi 0.5 Na 0.5 )TiO3 powder are weighed according to the stoichiometric ratio of (1-x):x, ball milling, drying, sieving, heating and heat preservation to obtain (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution;

[0038] S4: SiO2, B2O3, CaO, Al2O3, ZrO2 and X2O are weighed according to the mass percentage, mixed, smelted, water quenched to obtain borosilicate glass slag, and the borosilicate glass slag is ball milled, dried and sieved to obtain borosilicate glass powder;

[0039] S5: proportionally weigh (1-x) BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, a composite dopant composed of Nb2O5, MnO2, ZnO and MgO, and borosilicate glass powder, ball-milling, drying, and sieving to obtain raw material powder;

[0040] S6: mixing the raw material powder with polyvinyl alcohol solution, granulating, and pressing to obtain green body;

[0041] S7: placing the green body in air atmosphere, heating and holding, then continuously heating and holding, and cooling to obtain borosilicate glass-assisted X9R type MLCC dielectric material.

[0042] As Figure 1 shown, a flowchart of the preparation method of borosilicate glass-assisted X9R type MLCC dielectric material is provided. The technical idea of the present application is to use borosilicate glass as sintering aid on the basis of (1-x) BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, on the one hand, and to introduce additional MnO2, ZnO for doping modification when adding Nb2O5, MgO additives, thereby obtaining the final MLCC dielectric material. This scheme not only utilizes the sintering aid effect of borosilicate glass on the sintering density of dielectric material and the reduction effect of sintering temperature, but also utilizes the stabilizing effect of MnO2, ZnO additives on the "core-shell" structure of Nb2O5, MgO, so that the obtained dielectric material has low sintering temperature, low dielectric loss, wide low dielectric loss temperature range, wide dielectric temperature stability range and good insulation properties.

[0043] Preferably, in step S1, the ball-milling is ball-milling in a ball mill at a speed of 300-500 rpm for 8-36 h.

[0044] Preferably, in step S1, the drying is drying at 90-120℃ for 6-24 h.

[0045] Preferably, in step S1, the sieving uses nylon screen with mesh size of 150-200. By using fine mesh screen of non-metal material, the fineness of ceramic powder can be ensured without introducing additional metal impurities.

[0046] Preferably, in step S1, the heating and holding is heating from room temperature to 1200-1300℃ at a heating rate of 3-5℃ / min and holding at the corresponding temperature for 2-4h. If the heating rate is too fast, the uniformity of the solid phase reaction inside the ceramic is low, and impurity phases are easily formed; if the heating rate is too slow, the sintering process takes a long time and consumes a lot of energy. If the target temperature is too low or the holding time is too short, the solid phase reaction is difficult to complete; if the target temperature is too high or the holding time is too long, the ceramic grains easily abnormally grow, leading to the degradation of the dielectric properties of the ceramic.

[0047] Preferably, in step S2, the mass ratio of Bi2O3, Na2CO3 and TiO2 is (1-1.05):1:4. A slight excess of 5mol% of Bi2O3 is introduced relative to Na2CO3 to offset the volatilization of Bi element at high temperature. If no slight excess of Bi2O3 is introduced, the volatilization of Bi element at high temperature may change the perovskite structure of the ceramic to an excess state of B site elements, promote the transfer of Ce element to A site, and cause the degradation of the dielectric properties of the ceramic; if too much Bi2O3 is introduced, the dielectric constant of the ceramic easily decreases significantly.

[0048] Preferably, in step S2, the ball milling is ball milling in a ball mill at a speed of 300-500rpm for 8-36h.

[0049] Preferably, in step S2, the drying is drying at 90-120℃ for 6-24h.

[0050] Preferably, in step S2, the sieving uses a nylon sieve with a mesh size of 150-200. The sieve needs to be made of nylon, otherwise metal impurities are easily introduced into the ceramic powder. If the mesh size is too small, the fineness of the ceramic powder is not enough, and if the mesh size is too large, it is not conducive to smooth sieving.

[0051] Preferably, in step S2, the heating and holding is heating from room temperature to 850-900℃ at a heating rate of 3-5℃ / min and holding at the corresponding temperature for 2-4h. If the heating rate is too fast, the uniformity of the solid phase reaction inside the ceramic is low, and impurity phases are easily formed; if the heating rate is too slow, the sintering process takes a long time and consumes a lot of energy. If the target temperature is too low or the holding time is too short, the solid phase reaction is difficult to complete; if the target temperature is too high or the holding time is too long, the ceramic grains easily abnormally grow, and the volatilization of Bi element is too large, leading to the degradation of the dielectric properties of the ceramic.

[0052] Preferably, in step S3, the ball milling is ball milling in a ball mill at a speed of 1000-1200rpm for 8-16h. By controlling the ball milling time, the particle size of the ceramic powder can be controlled within the desired range.

[0053] Preferably, in step S3, the drying is drying at 90-120℃ for 6-24h.

[0054] Preferably, in step S3, the sieving uses a nylon sieve with a mesh size of 150-200.

[0055] Preferably, in step S3, the heating and holding is heating from room temperature to 950-1000℃ at a heating rate of 3-5℃ / min and holding at the corresponding temperature for 2-4h. If the heating rate is too fast, the internal solid phase reaction of the solid solution is less uniform, and complete solid solution cannot be achieved. If the heating rate is too slow, the sintering process takes a long time and consumes a lot of energy. If the target temperature is too low or the holding time is too short, the solid solution process cannot be completed. If the target temperature is too high or the holding time is too long, the ceramic grains are prone to abnormal growth, which is not conducive to the formation of a "core-shell" structure in the subsequent doping process, and leads to degradation of the dielectric properties of the ceramic.

[0056] Preferably, in step S4, the melting is heating from room temperature to 1500-1550℃ at a heating rate of 5-10℃ / min and holding at the corresponding temperature for 2-4h to obtain a molten glass liquid. If the heating rate is too fast, the oxide is not uniformly melted, resulting in segregation or phase separation. If the heating rate is too slow, the energy consumption increases. If the target temperature is too low or the holding time is too short, it is difficult to form a glass liquid with uniform composition and appropriate viscosity, and even the glass liquid directly solidifies in the crucible. If the target temperature is too high or the holding time is too long, the low-melting-point components in the glass liquid are prone to volatilization, causing the glass composition to deviate from the original design and affecting the performance of the obtained glass.

[0057] Preferably, in step S4, the water quenching is rapidly pouring the molten glass liquid into deionized water.

[0058] Preferably, in step S4, the ball milling is ball milling in a ball mill at a speed of 1000-1200rpm for 12-24h.

[0059] Preferably, in step S4, the drying is drying at 90-120℃ for 6-24h.

[0060] Preferably, in step S4, the sieving uses a nylon sieve with a mesh size of 150-200.

[0061] Preferably, in step S5, the ball milling is ball milling in a ball mill at a speed of 1000-1200rpm for 8-16h.

[0062] Preferably, in step S5, the drying is drying at 90-120℃ for 6-24h.

[0063] Preferably, in step S5, the sieving uses a nylon sieve with a mesh size of 150-200.

[0064] Preferably, in step S6, the ratio of the raw material powder to the polyvinyl alcohol solution is (8-10) g: 1 mL, and the mass fraction of polyvinyl alcohol in the polyvinyl alcohol solution is 5 wt%. The polyvinyl alcohol solution is used as a binder to granulate the raw material powder. After granulation, the forming property of the powder is significantly improved, and the green body can be pressed into various sizes and shapes, such as a circular green body with a diameter of 10 mm and a thickness of 1 mm.

[0065] Preferably, the specific process of step S7 is as follows: the green body is placed in a muffle furnace, heated from room temperature to 400-500℃ at a heating rate of 3-5℃ / min in an air atmosphere, and then held at the corresponding temperature for 2-4 h, and then heated to 1000-1100℃ at a heating rate of 3-5℃ / min, and then held at the corresponding temperature for 2-3 h, and then cooled in the furnace to obtain a borosilicate glass-assisted X9R type MLCC dielectric material. This process first removes the polyvinyl alcohol and other organic matter introduced during ceramic forming by holding at a lower temperature to ensure the sintering quality of the ceramic at high temperature, and then continues to heat and hold to promote the densification of the ceramic and the diffusion of the doping elements. If the heating rate is too fast, the glue removal and doping element diffusion processes will be adversely affected; if the heating rate is too slow, the sintering process will take a long time and consume more energy. If the target temperature is too low or the holding time is too short, the glue removal, "core-shell" structure formation, and ceramic densification processes will not be completed; if the target temperature is too high or the holding time is too long, the doping elements will easily diffuse too much, affecting the formation of the ceramic "core-shell" structure, and the borosilicate glass and the ceramic matrix interface will react too much, resulting in degradation of the ceramic dielectric properties.

[0066] Example 1:

[0067] The present embodiment provides a method for preparing a borosilicate glass-assisted X9R type MLCC dielectric material, comprising:

[0068] According to the values of x=0.15 and y=0.005, (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution:

[0069] S1: weigh the raw materials according to the mole percentage: 50 mol% BaCO3, 49.75 mol% TiO2, and 0.25 mol% CeO2, ball mill in a ball mill at a speed of 500 rpm for 18 h, dry at 90℃ for 12 h, then pass through a 200 mesh nylon screen, and then heat from room temperature to 1200℃ at a rate of 5℃ / min in a corundum crucible, and hold at 1200℃ for 2 h to obtain BaTi 0.995 Ce 0.005 O3 powder;

[0070] S2: Bi2O3, Na2CO3 and TiO2 were weighed according to the stoichiometric ratio of 1:1:4, ball-milled in a ball mill at a speed of 500 rpm for 18 h, dried at 90℃ for 12 h, and then sieved through a 200-mesh nylon screen. Subsequently, the mixture was heated from room temperature to 900℃ at a heating rate of 5℃ / min in a corundum crucible, and then held at 900℃ for 3 h to obtain (Bi 0.5 Na 0.5 )TiO3 powder;

[0071] S3: The obtained BaTi 0.995 Ce 0.005 O3 and (Bi 0.5 Na 0.5 )TiO3 powder were weighed according to the stoichiometric ratio of 0.85:0.15, ball-milled in a ball mill at a speed of 1000 rpm for 12 h, dried at 90℃ for 12 h, and then sieved through a 200-mesh nylon screen. Subsequently, the mixture was heated from room temperature to 1000℃ at a heating rate of 3℃ / min in a corundum crucible, and then held at 1000℃ for 2 h to obtain 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution powder.

[0072] Preparation of borosilicate glass:

[0073] S4: The raw materials were weighed according to the mass percentage of 57.2wt% SiO2, 27.8wt% B2O3, 7.5wt% CaO, 2.5wt% Al2O3, 2.0wt%, ZrO2, 1.0wt% Li2O, 1.0wt% Na2O, 1.0wt% K2O, mixed and then placed in a corundum crucible, heated from room temperature to 1550℃ at a heating rate of 10℃ / min, and then held at the corresponding temperature for 2 h. The molten glass liquid was quickly poured into deionized water for water quenching. The obtained glass slag was ball-milled in a ball mill at a speed of 1000 rpm for 12 h, dried at 90℃ for 12 h, and then sieved through a 200-mesh nylon screen to obtain borosilicate glass powder;

[0074] Subsequently, on the basis of the above operation, 95mol% of 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution, 2mol% Nb2O5, 1mol% MnO2, 1mol% ZnO and 1mol% MgO to form a composite dopant, and borosilicate glass in an amount of 1% of the total mass of the solid solution and the composite dopant were used to prepare borosilicate glass-assisted X9R type MLCC dielectric material:

[0075] S5: The raw materials were weighed in proportion, ball-milled in a ball mill at a speed of 1000 rpm for 12 h, dried at 90℃ for 12 h, and then sieved through a 200-mesh nylon screen to obtain the raw material powder;

[0076] S6: The raw material powder was mixed with a polyvinyl alcohol solution (5wt% of polyvinyl alcohol) at a ratio of 10g:1mL, and then granulated. The granulated raw material powder was pressed into a green body in the form of a circular disc with a diameter of 10 mm and a thickness of 1 mm under a uniaxial pressure of 50 MPa;

[0077] S7: The green body was placed in a muffle furnace and heated from room temperature to 450℃ at a rate of 3℃ / min in an air atmosphere, and then held at 450℃ for 2 h. The temperature was then increased from 450℃ to 1100℃ at a rate of 3℃ / min, and then held at 1100℃ for 2 h. The furnace was then allowed to cool, and a borosilicate glass-assisted X9R type MLCC dielectric material was obtained.

[0078] Figure 2 The dielectric temperature spectrum of the sample of Example 1 after silver electrode was measured. The results are shown in Figure 1. Figure 2 As can be seen, the dielectric temperature spectrum of the dielectric material has a clear double dielectric peak, which reflects the formation of the "core-shell" structure in the ceramic grains. The high-temperature dielectric peak corresponds to the ferroelectric phase core in the ceramic grains, and the low-temperature dielectric peak corresponds to the paraelectric phase shell in the ceramic grains. As a result, the dielectric temperature curve of the ceramic is smooth within the test temperature range, and satisfies the condition of Δε r / ε r25℃ ≤±15% within the temperature range of -60-218℃, meeting the X9R standard. The room temperature dielectric constant is 1812, the room temperature dielectric loss is 0.016, and the temperature range with a dielectric loss of ≤0.02 is -12-203℃, which has excellent dielectric properties.

[0079] Example 2:

[0080] The present example provides a method for preparing a borosilicate glass-assisted X9R type MLCC dielectric material. Compared with Example 1, in the preparation of the borosilicate glass-assisted X9R type MLCC dielectric material, 95mol% of 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution, 2.5mol% Nb2O5, 1.5mol% MnO2, 0.5mol% ZnO, and 0.5mol% MgO are used to form a composite dopant, and 1% of borosilicate glass based on the total mass of the solid solution and the composite dopant is added to prepare the borosilicate glass-assisted X9R type MLCC dielectric material. The other preparation processes are the same as those of Example 1.

[0081] Example 3:

[0082] The present example provides a method for preparing a borosilicate glass sintered X9R type MLCC dielectric material. Compared with Example 1, in the present example, the amount of borosilicate glass added is 2% of the total mass of the solid solution and the composite dopant, the final sintering temperature in step S7 is 1085°C, and the other preparation processes are the same as in Example 1.

[0083] After the borosilicate glass sintered X9R type MLCC dielectric material (round wafer sample) prepared in Examples 1-3 is coated with silver electrodes on both sides, the precision impedance analyzer Wayne-Kerr 6500B equipped with BALAB DMS-2000 high-low temperature dielectric spectrometer is used to test the dielectric constant εr r , dielectric loss tanδ of the sample at -60-250°C, and the resistivity p v of the sample is tested using Keithley 6517B high resistance meter, and the results are shown in Table 1.

[0084] Table 1 Comparison of properties of MLCC dielectric materials prepared in Examples 1-3

[0085]

[0086] Comparative Example 1

[0087] Compared with Example 1, in the present comparative example, after preparing a 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution, only Nb2O5, MgO and borosilicate glass are added, and MnO2 and ZnO are not added, and the other preparation processes are the same as in Example 1.

[0088] Comparative Example 2

[0089] Compared with Example 1, in the present comparative example, after preparing a 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution, only Nb2O5, MnO2, MgO and borosilicate glass are added, and ZnO is not added, and the other preparation processes are the same as in Example 1.

[0090] Comparative Example 3

[0091] Compared with Example 1, in the present comparative example, after preparing a 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi0.5 Na 0.5 )TiO3 solid solution, only Nb2O5, MnO2, ZnO and MgO were added, and no borosilicate glass was added, and other preparation processes were the same as those in Example 1.

[0092] After the two surfaces of the dielectric material (circular sheet sample) prepared in Comparative Example 1-3 were coated with silver electrodes, the dielectric constant ε, dielectric loss tan δ of the sample at -60-250℃ were tested by the same method as in Examples 1-3, and the resistivity p of the sample was tested, and the results are shown in Table 2. r v

[0093] Table 2 Comparative table of properties of dielectric materials prepared in Comparative Examples 1-3

[0094]

[0095] As can be seen from the table, since no MnO2 and ZnO additives were introduced in the sample of Comparative Example 1, a serious interface reaction occurred between the ceramic and the borosilicate glass, which affected the normal formation of the "core-shell" structure of the ceramic grains, resulting in that the dielectric temperature stability, dielectric constant, dielectric loss and insulation properties of the dielectric material were all significantly affected. In the sample of Comparative Example 2, no ZnO additive was introduced, which resulted in that the synergistic effect between MnO2 and Nb2O5, MgO was not significant, and the stabilizing effect on the "core-shell" structure of the ceramic grains was limited, so that the dielectric temperature stability of the obtained dielectric material was still significantly lower than that of the sample of Example 1. In the sample of Comparative Example 3, no borosilicate glass was introduced, which resulted in that although a stable "core-shell" structure could be formed in the ceramic grains, the dielectric material could not be densified at a relatively low sintering temperature, the dielectric constant was low, the dielectric loss was high, and the insulation properties were greatly affected.

[0096] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. Therefore, the scope of protection of the present application should be subject to the protection scope of the claims.​​

Claims

1. A borosilicate glass-assisted sintering X9R type MLCC dielectric material, characterized in that, The main component of the MLCC dielectric material is (1- x )BaTi 1-y Ce y O3– x (Bi 0.5 Na 0.5 TiO3 solid solution, with a molar percentage of 92-96%, wherein 0 < x ≤0.20, 0.002≤ y ≤0.04; the auxiliary component is a composite dopant composed of Nb2O5, MnO2, ZnO and MgO, with a molar percentage of 4~8%. The molar percentage of each component in the composite dopant is as follows: Nb2O5: 2~4%; MnO2: 1~2%; ZnO: 0.5~1%; MgO: 0.5~1%; the sintering aid is borosilicate glass, and its addition amount is 1~5% of the total mass of the solid solution and the composite dopant; the borosilicate glass is composed of SiO2, B2O3, CaO, Al2O3, ZrO2 and X2O, where X is one or more of Li, Na and K. The mass percentage of each component in the borosilicate glass is as follows: SiO2: 55~58%; B2O3: 25~29%; CaO: 5~8%; Al2O3: 1~3%; ZrO2: 1~3%; X2O: 0~3%; The dielectric properties of the MLCC dielectric material conform to the EIA X9R standard, i.e., within a temperature range of -55~200℃, Δ ε r / ε r25℃ ≤±15%, required sintering temperature not exceeding 1100℃, room temperature dielectric constant 1650~1850, room temperature dielectric loss ≤0.02, temperature range for dielectric loss ≤0.02 wider than 0~200℃, room temperature resistivity ≥10 11 Ω·cm; The method for preparing the borosilicate glass-assisted X9R type MLCC dielectric material includes the following steps: S1: According to BaTi 1-y Ce y O3 composition y The values ​​of BaCO3, TiO2, and CeO2 were weighed out as molar percentages, ball-milled, dried, sieved, heated, and kept at a constant temperature to obtain BaTi 1-y Ce y O3 powder; the ball milling is performed in a ball mill at a speed of 300~500 rpm for 8~36 h; the heating and holding are performed by heating from room temperature to 1200~1300℃ at a heating rate of 3~5℃ / min and holding at the corresponding temperature for 2~4 h; S2: Weigh Bi2O3, Na2CO3 and TiO2, ball mill, dry, sieve, heat and keep warm to obtain (Bi 0.5 Na 0.5 TiO3 powder; the mass ratio of Bi2O3, Na2CO3 and TiO2 is (1~1.05):1:4; the ball milling is carried out in a ball mill at a speed of 300~500 rpm for 8~36 h; the heating and holding are carried out by heating from room temperature to 850~900℃ at a heating rate of 3~5℃ / min and holding at the corresponding temperature for 2~4 h; S3: According to (1- x ): x Weigh BaTi in stoichiometric ratio 1-y Ce y O3 powder and (Bi) 0.5 Na 0.5 TiO3 powder was ball-milled, dried, sieved, heated and held at a constant temperature to obtain (1- x )BaTi 1-y Ce y O3– x (Bi 0.5 Na 0.5 TiO3 solid solution; the ball milling is performed in a ball mill at a speed of 1000~1200 rpm for 8~16 h; The heating and holding process involves raising the temperature from room temperature to 950-1000℃ at a heating rate of 3-5℃ / min and holding it at the corresponding temperature for 2-4 hours. S4: Weigh SiO2, B2O3, CaO, Al2O3, ZrO2 and X2O by mass percentage, mix, melt, and quench in water to obtain borosilicate glass slag. Ball mill the borosilicate glass slag, dry it, and sieve it to obtain borosilicate glass powder. The melting is carried out by heating from room temperature to 1500-1550℃ at a heating rate of 5-10℃ / min and holding at the corresponding temperature for 2-4 hours to obtain molten glass. The water quenching is carried out by rapidly pouring the molten glass into deionized water. The ball milling is carried out in a ball mill at a speed of 1000-1200 rpm for 12-24 hours. S5: Weigh out (1-) according to the proportion. x )BaTi 1-y Ce y O3– x (Bi 0.5 Na 0.5 TiO3 solid solution, a composite dopant composed of Nb2O5, MnO2, ZnO and MgO, and the borosilicate glass powder are ball-milled, dried and sieved to obtain raw material powder; the ball milling is performed in a ball mill at a speed of 1000~1200 rpm for 8~16 h. S6: The raw material powder is mixed with a polyvinyl alcohol solution and then granulated and pressed into a green body. The ratio of raw material powder to polyvinyl alcohol solution is (8~10) g: 1 mL; the mass fraction of polyvinyl alcohol in the polyvinyl alcohol solution is 5 wt%. S7: The green blank is placed in a muffle furnace and heated from room temperature to 400-500°C in an air atmosphere at a heating rate of 3-5°C / min, and held at the corresponding temperature for 2-4 hours. Then, the temperature is further increased to 1000-1100°C at a heating rate of 3-5°C / min, and held at the corresponding temperature for 2-3 hours. The blank is then cooled with the furnace to obtain the X9R type MLCC dielectric material with borosilicate glass sintering.

2. The borosilicate glass-assisted sintering X9R type MLCC dielectric material according to claim 1, characterized in that, In steps S1 to S5, The drying process involves drying at 90-120℃ for 6-24 hours. The sieving process uses a nylon screen with a mesh size of 150-200.

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