Barium titanate-based X9R type high-dielectric MLCC dielectric material and preparation method thereof

Abstract

The application discloses a barium titanate-based X9R type high-dielectric 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 < x <= 0.20, 0.002 <= y <= 0.04, the molar percentage is 95%-97%; and an additive composed of Nb2O5 and MgO, the molar percentage is 3%-5%. The preparation method comprises the following steps: synthesizing BaTi 1‑x Ce x O3 and (Bi 0.5 Na 0.5 )TiO3 by a solid phase method, proportioning, ball milling, drying and sieving, pre-sintering, adding Nb2O5 and MgO additives in a second ball milling process, drying and sieving to obtain raw material powder, granulating the raw material powder, pressing into a green body, and then sintering to obtain the MLCC dielectric material. The MLCC dielectric material provided by the application does not contain harmful elements, the dielectric temperature characteristic meets the EIA X9R standard requirement, the room temperature dielectric constant is 1800-2200, the dielectric loss is low, and the resistivity is high; the preparation method used has a simple process flow, low preparation cost and good industrialization prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic ceramic materials, and particularly relates to a barium titanate-based X9R type high-dielectric MLCC dielectric material and a preparation method thereof. BACKGROUND

[0002] In recent years, with the further expansion of the application field of electronic systems, the working conditions of electronic devices are increasingly harsh, and higher requirements are put forward for the reliability and performance stability of MLCC. Especially in the fields of aerospace, oil drilling, automobile control, etc., MLCC is required to have stable performance at a higher working temperature and in a wider temperature range. According to the ECA-EIA-198-1-F-2002 standard, the capacitance value of X7R and X8R capacitors should change within ±15% of the capacitance value at room temperature (25℃) in the temperature range of -55 to 125℃ and 150℃, that is, ΔC / C 25℃ ≤±15%. However, for some MLCC devices that need to work in extremely harsh temperature environments, X7R and X8R type dielectric materials cannot meet the requirements, and the upper limit of the capacitance value of the device needs to be increased to 200℃, that is, the dielectric material used needs to meet the EIA X9R standard.

[0003] Barium titanate (BaTiO3) has the advantages of high dielectric constant, low dielectric loss, low price, environmental protection and non-toxicity, and is a widely concerned MLCC dielectric material. However, the dielectric constant of BaTiO3 changes nonlinearly with the increase of temperature, especially near its Curie temperature (about 120℃), the dielectric constant will change abruptly and a peak value will appear, which seriously affects the capacitance stability of MLCC and makes it difficult to work stably at high temperature. In order to make the performance of BaTiO3 meet the application requirements, various means need to be used to optimize its temperature dependence. In recent years, by introducing other complex oxides with perovskite structure to form a solid solution with BaTiO3, and further modifying it, a BaTiO3-based composite perovskite dielectric material has become a popular means to obtain X9R type MLCC dielectric material. In order to obtain X9R type MLCC dielectric material, related work often only focuses on the doping modification of the BaTiO3-based composite perovskite dielectric material formed by solid solution, and ignores the modification of BaTiO3 ceramic itself in the solid solution, so that the dielectric constant of the obtained material still has a large gap compared with that of X7R and X8R type dielectric materials; and in order to make the doping elements achieve the required distribution state, liquid phase reaction methods such as coprecipitation, high-temperature hydrothermal method and sol-gel method are usually used, which have the disadvantages of many types of raw materials, complex process flow, long production cycle, low single yield, high production cost, etc. SUMMARY

[0004] The application provides a barium titanate-based X9R high-dielectric MLCC dielectric material and a preparation method thereof, which are used for overcoming the low dielectric constant of the dielectric material in the prior art, and the defects of the dielectric material, such as multiple raw materials, complex process flow, long production cycle, low single yield and high production cost in the preparation process, and the MLCC dielectric material has the characteristics of reaching the EIA X9R standard in dielectric temperature stability, high dielectric constant, low dielectric loss and high resistivity.

[0005] To achieve the above-mentioned purpose, the application provides a barium titanate-based X9R high-dielectric MLCC dielectric material, which mainly comprises (1-x) BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, and the molar percentage is 95-97 %, and the auxiliary component is an additive composed of Nb2O5 and MgO, and the molar percentage is 3-5 %; wherein, 0 < x <= 0.20, and 0.002 <= y <= 0.04.

[0006] The application also provides a preparation method of the above-mentioned barium titanate-based X9R high-dielectric MLCC dielectric material, which comprises the following steps:

[0007] 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 milling, drying, sieving, heating and heat preservation, so as to obtain BaTi 1-y Ce y O3 powder;

[0008] S2: Bi2O3, Na2CO3 and TiO2 are weighed, ball milling, drying, sieving, heating and heat preservation, so as to obtain (Bi 0.5 Na 0.5 )TiO3 powder;

[0009] 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, so as to obtain (1-x) BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution;

[0010] S4: (1-x) BaTi 1-y Ce y O3-x(Bi 0.5 Na0.5 )TiO3 solid solution and Nb2O5, MgO additives, ball milling, drying, sieving, to obtain raw material powder;

[0011] S5: mixing the raw material powder with polyvinyl alcohol solution, granulating, and pressing to obtain green body;

[0012] S6: placing the green body in an air atmosphere, heating and holding, then continuing to heat and hold, and cooling, to obtain barium titanate-based X9R high-dielectric MLCC dielectric material.

[0013] Compared with the prior art, the beneficial effects of the present application are:

[0014] 1. The barium titanate-based X9R high-dielectric MLCC dielectric material provided by the present application has the following main components: (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, instead of using pure BaTiO3 ceramic and (Bi 0.5 Na 0.5 )TiO3 ceramic as raw materials, 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 solid-soluted with an appropriate amount of (Bi 0.5 Na 0.5 )TiO3, thereby producing an additional optimization effect on the dielectric temperature characteristics of the solid solution. Since the Ce 4+ ion has a larger radius than the Ti 4+ ion, it can locally expand the volume of adjacent Ti-O octahedra in the ceramic crystal structure, increasing the polarization ability of the Ti 4+ ion, thus effectively increasing the peak dielectric constant of BaTiO3 ceramic without excessively lowering its Curie temperature. On this basis, (Bi 0.5 Na 0.5 )TiO3 is introduced to increase the Curie temperature of the solid solution, and the resulting (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution has a higher peak dielectric constant than the existing BaTiO3-(Bi 0.5 Na 0.5 )TiO3 solid solution. After further adding an additive composed of Nb2O5 and MgO, the barium titanate-based X9R high-dielectric MLCC dielectric material ultimately provided by the present application has a room temperature dielectric constant higher than that of existing dielectric materials, reaching 1800-2200, and has excellent comprehensive performance.

[0015] 2、The application uses an additive composed of Nb2O5 and MgO, wherein Nb2O5 diffuses into the solid solution crystal grains through (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 The Nb element doping with non-uniform distribution is introduced into the BaTiO3 solid solution crystal grains, and a "core-shell" structure crystal grain with special dielectric temperature characteristics is formed, thereby enhancing the dielectric temperature stability of the ceramic; the Mg 2+ Ions can form a "core-shell" structure in the BaTiO3 ceramic, and after the additional addition of MgO, the Mg 2+ Ions and the Nb 5+ Ions diffuse into the solid solution crystal grains at the same time during the sintering process, and the former effectively stabilizes the non-uniform distribution state of the latter, avoiding the uncontrolled diffusion of the Nb element due to the introduction of the Ce doping element in the B position of the ceramic, and further destroying the "core-shell" structure in the ceramic crystal grain. Based on the dielectric material preparation method provided by the application, by sequentially introducing Ce, Nb and Mg element doping in different process steps of the synthesized material, the barium titanate-based X9R type high-dielectric MLCC dielectric material provided by the application finally has good dielectric temperature stability, meeting the EIA X9R standard requirements.

[0016] 3、The barium titanate-based X9R type high-dielectric MLCC dielectric material provided by the application does not contain harmful elements, the preparation raw materials are simple, the preparation process is simple, the preparation period is short, the single preparation amount is large, and the production cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0017] 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 embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from the structures shown in the drawings without creative labor.

[0018] Figure 1 The flowchart of the preparation method of the barium titanate-based X9R type high-dielectric MLCC dielectric material;

[0019] Figure 2 The dielectric temperature spectrum of the sample of Example 1 after being silver electrode;

[0020] Figure 3 The dielectric temperature spectrum of the sample of Comparative Example 1 after being silver electrode.

[0021] The objectives, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application.

[0023] In addition, the technical solutions in the embodiments of the present application can be combined with each other, but it must be based on that a person of ordinary skill in the art can realize the combination. When the combination of the technical solutions appears to be contradictory or unachievable, it should be considered that the combination of the technical solutions does not exist and is not within the protection scope of the present application.

[0024] Unless otherwise specified, the used drugs / reagents are commercially available.

[0025] The present application provides a barium titanate-based X9R type high-dielectric MLCC dielectric material, which mainly comprises (1-x) BaTi 1- y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, the molar percentage of which is 95-97 %, and an additive composed of Nb2O5 and MgO, the molar percentage of which is 3-5 %; wherein 0 < x ≤ 0.20, 0.002 ≤ y ≤ 0.04.

[0026] The present application realizes the introduction of Ce doping only in the B site by regulating the Ba / Ti ratio in BaTiO3. Since the chemical general formula of the synthesized ceramic is BaTi 1-y Ce y O3, the Ba / Ti ratio is greater than 1 at this time, and Ba is in an excess state. The Ce element will basically completely enter the B site of BaTiO3 in this state under controlled conditions.

[0027] The present application uses Mg element mainly to utilize its ability to form a "core-shell" structure in BaTiO3 and solid solution grains, so as to form a stabilizing effect on the non-uniform distribution state of the Nb element when diffusing into the interior of the solid solution grains.

[0028] The dielectric temperature characteristics of the above-mentioned MLCC dielectric material meet the EIA X9R standard, that is, Δε r / ε r25℃≤±15%, room temperature dielectric constant is 1800-2200, room temperature dielectric loss is ≤0.02, room temperature resistivity is ≥10 11 Ω·cm.

[0029] Preferably, the molar ratio of Nb2O5 and MgO is (1-9):1. If the addition ratio of the additive composed of Nb2O5 and MgO deviates from the component interval of 3-5%, or the molar ratio of Nb2O5 and MgO deviates from the component interval of (1-9):1, the solid solution grain cannot form a reasonable "core-shell" structure of the shell-core ratio, so that the dielectric temperature stability of the obtained medium material cannot meet the EIA X9R standard requirements.

[0030] The application also provides a preparation method of the barium titanate-based X9R type high-dielectric MLCC medium material.

[0031] S1: according to BaTi 1-y Ce y O3 composition, BaCO3, TiO2 and CeO2 are weighed according to the molar percentage, ball milling, drying, sieving, heating and heat preservation, to obtain BaTi 1-y Ce y O3 powder; the molar percentage of each component is 50mol% BaCO3, 48-49.9mol% TiO2 and 0.1-2mol% CeO2.

[0032] S2: Bi2O3, Na2CO3 and TiO2 are weighed, ball milled, dried, sieved, heated and heat preserved, to obtain (Bi 0.5 Na 0.5 )TiO3 powder;

[0033] 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 milled, dried, sieved, heated and heat preserved, to obtain (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution;

[0034] S4: (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution and Nb2O5, MgO additives are weighed in proportion, ball milled, dried and sieved, to obtain raw material powder;

[0035] S5: The raw material powder is mixed with polyvinyl alcohol solution and then granulated and pressed into a green body;

[0036] S6: Place the green blank in an air atmosphere, heat and hold it at that temperature, then continue heating and holding it at that temperature, and then cool it to obtain barium titanate-based X9R type high dielectric MLCC dielectric material.

[0037] like Figure 1 The diagram shows a flow chart of a method for preparing barium titanate-based X9R type high-dielectric MLCC dielectric material. The MLCC dielectric material preparation method provided by this invention features simple raw materials, a concise preparation process, a short preparation cycle, large single-batch production capacity, low production cost, and excellent product performance. The technical concept of this invention lies in first doping the Ti sites (B sites) of BaTiO3 ceramic with Ce element, and then using the doped BaTiCeO3 ceramic with (Bi... 0.5 Na 0.5 A solid solution of TiO3 ceramic is formed, and then the solid solution is further modified by secondary doping with an additive composed of Nb2O5 and MgO to obtain the final MLCC dielectric material. This scheme utilizes both the effect of appropriate B-site Ce doping on improving the peak dielectric constant of BaTiO3 ceramic and the effect of (Bi2O5) on the dielectric constant of TiO3 ceramic. 0.5 Na 0.5 The solution treatment of TiO3 with the resulting BaTiCeO3 ceramic increases its Curie temperature. Finally, Nb2O5 is doped with MgO to form a stable "core-shell" structure, thus the resulting dielectric material has high dielectric constant, low dielectric loss, wide dielectric temperature stability range and good insulation properties.

[0038] Preferably, in step S1, ball milling is performed in a ball mill at a rotation speed of 300-500 rpm for 8-36 hours.

[0039] Preferably, in step S1, the drying is performed at 90–120°C for 6–24 hours.

[0040] Preferably, in step S1, a nylon sieve with a mesh size of 150 to 200 is used for sieving. By using a fine-mesh sieve made of non-metallic material, the fineness of the ceramic powder can be ensured without introducing additional metallic impurities.

[0041] 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.

[0042] Preferably, in step S2, the molar 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.

[0043] Preferably, in step S2, the ball milling is ball milling in a ball mill at a speed of 300-500rpm for 8-36h.

[0044] Preferably, in step S2, the drying is drying at 90-120℃ for 6-24h.

[0045] Preferably, in step S2, a nylon screen with a mesh size of 150-200 is used for sieving. The screen 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.

[0046] 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.

[0047] 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.

[0048] Preferably, in step S3, the drying is drying at 90-120℃ for 6-24h.

[0049] Preferably, in step S3, the sieving uses a nylon sieve with a mesh size of 150-200.

[0050] 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 cannot be completely solid-solved; if the heating rate is too slow, the sintering process takes a long time and consumes more energy. If the target temperature is too low or the holding time is too short, the solid-solution process is difficult to complete; 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.

[0051] Preferably, in step S4, the ball milling is carried out in a ball mill at a speed of 1000-1200rpm for 8-16h.

[0052] Preferably, in step S4, the drying is carried out at 90-120℃ for 6-24h.

[0053] Preferably, in step S4, the sieving uses a nylon sieve with a mesh size of 150-200.

[0054] Preferably, in step S5, the ratio of the raw material powder to the polyvinyl alcohol solution is (8-10)g:1mL, and the mass fraction of polyvinyl alcohol in the polyvinyl alcohol solution is 5wt%. The polyvinyl alcohol solution is used as a binder to granulate the raw material powder. After granulation, the forming performance of the powder is significantly improved, and green bodies of various sizes and shapes can be pressed, such as a circular green body with a diameter of 10mm and a thickness of 1mm.

[0055] Preferably, the specific process of step S6 is as follows: the green body is placed in a muffle furnace, and heated from room temperature to 400-500℃ at a heating rate of 3-5℃ / min in an air atmosphere, and then kept at the corresponding temperature for 2-4h, and then heated to 1150-1250℃ at a heating rate of 3-5℃ / min, and kept at the corresponding temperature for 2-3h, and then cooled in the furnace to obtain the barium titanate-based X9R high-dielectric MLCC dielectric material. This process first removes the polyvinyl alcohol and other organic substances introduced during the ceramic forming process through heat preservation at a lower temperature, to ensure the sintering quality of the ceramic at high temperature, and then continues to heat and keep warm 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 greatly 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 heat preservation time is too short, the glue removal and "core-shell" structure formation processes will be difficult to complete; if the target temperature is too high or the heat preservation time is too long, the doping elements will easily diffuse too much, affecting the formation of the ceramic "core-shell" structure, and the amount of Bi element volatilization will be too large, resulting in degradation of the ceramic dielectric properties.

[0056] Example 1

[0057] The present embodiment provides a method for preparing a barium titanate-based X9R high-dielectric MLCC dielectric material, comprising:

[0058] 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:

[0059] S1: The raw materials are weighed according to the molar percentage: 50mol% BaCO3, 49.75mol% TiO2 and 0.25mol% CeO2, ball milled in a ball mill at a speed of 500rpm for 18h, dried at 90℃ for 12h, and then sieved through a 200-mesh nylon screen, and then heated to 1200℃ at a rate of 5℃ / min from room temperature in a corundum crucible, and kept at 1200℃ for 2h to obtain BaTi 0.995 Ce 0.005 O3 powder;

[0060] S2: Bi2O3, Na2CO3 and TiO2 are weighed according to the stoichiometric ratio of 1:1:4, ball milled in a ball mill at a speed of 500rpm for 18h, dried at 90℃ for 12h, and then sieved through a 200-mesh nylon screen, and then heated to 900℃ at a rate of 5℃ / min from room temperature in a corundum crucible, and kept at 900℃ for 3h to obtain (Bi 0.5 Na 0.5 )TiO3 powder;

[0061] S3: The obtained BaTi 0.995 Ce 0.005 O3 and (Bi 0.5 Na 0.5 )TiO3 powders 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°C for 12 h, and then sieved through a 200-mesh nylon screen. Subsequently, the powders were heated from room temperature to 1000°C at a rate of 3°C / min in a corundum crucible and kept at 1000°C for 2 h to obtain 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution powders.

[0062] Subsequently, on the basis of the above, 96 mol% of 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution, 2 mol% of Nb2O5 and 2 mol% of MgO were used to prepare a barium titanate-based X9R high-dielectric MLCC dielectric material:

[0063] S4: The raw materials were weighed according to the molar percentage, ball-milled in a ball mill at a speed of 1000 rpm for 12 h, dried at 90°C for 12 h, and then sieved through a 200-mesh nylon screen to obtain raw material powders;

[0064] S5: The raw material powders were mixed with a polyvinyl alcohol solution (5 wt% of polyvinyl alcohol) at a ratio of 10 g:1 mL, and then granulated. The granulated raw material powders were pressed into green bodies in the form of circular discs with a diameter of 10 mm and a thickness of 1 mm under a uniaxial pressure of 50 MPa;

[0065] S6: The green bodies were placed in a muffle furnace and heated from room temperature to 450°C at a rate of 3°C / min in an air atmosphere and kept at 450°C for 2 h. Then, the temperature was further increased from 450°C to 1200°C at a rate of 3°C / min and kept at 1200°C for 2 h. The furnace was then cooled to obtain a barium titanate-based X9R high-dielectric MLCC dielectric material.

[0066] Figure 2 The dielectric temperature spectrum of the sample of Example 1 after silver electrode was measured. From the Figure 2It can be seen that the ceramic dielectric temperature spectrum has obvious double dielectric peaks, reflecting the formation of the "core-shell" structure in the ceramic grains. The high-temperature direction dielectric peak corresponds to the ferroelectric phase core of the ceramic grains, and the low-temperature direction dielectric peak corresponds to the paraelectric phase shell of the grains. As a result, the dielectric temperature curve of the ceramic is smooth within the test temperature range, and meets the condition of Δε r / ε r25℃ ≤±15% within the temperature range of -60-203℃, meeting the X9R standard. The room temperature dielectric constant is 2156, and the room temperature dielectric loss is 0.019, having excellent dielectric properties.

[0067] Example 2

[0068] The present embodiment provides a preparation method of a barium titanate-based X9R type high-dielectric MLCC dielectric material. Compared with Example 1, in the present embodiment, when preparing the (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, the values of x and y are x=0.15 and y=0.01 respectively, and other preparation processes are the same as those in Example 1.

[0069] Example 3

[0070] The present embodiment provides a preparation method of a barium titanate-based X9R type high-dielectric MLCC dielectric material. Compared with Example 1, in the present embodiment, when preparing the (1-x)BaTi 1-y Ce y O3-x(Bi 0.5 Na 0.5 )TiO3 solid solution, the values of x and y are x=0.15 and y=0.03 respectively, and other preparation processes are the same as those in Example 1.

[0071] After the barium titanate-based X9R type high-dielectric MLCC dielectric material (round sheet sample) prepared in Examples 1-3 is coated with silver electrodes on both sides, the dielectric constant ε r , dielectric loss tanδ of the sample at -60-250℃ are tested by using a Wayne-Kerr 6500B type precision impedance analyzer equipped with a BALAB DMS-2000 type high-low temperature dielectric temperature spectrum analyzer, and the resistivity ρ v of the sample is tested by using a Keithley 6517B high resistance meter, and the results are shown in Table 1.

[0072] Table 1 Comparison of properties of MLCC dielectric materials prepared in Examples 1-5

[0073]

[0074] Comparative Example 1

[0075] Compared with Example 1, in this comparative example, 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution was prepared, but no Nb2O5 and MgO were added, and other preparation processes were the same as those in Example 1.

[0076] Figure 3 The dielectric temperature spectrum of the sample in Comparative Example 1 after being silver electrode was measured. As can be seen from the figure, because no Nb2O5 and MgO additives were introduced into the ceramic, there is only a single dielectric peak on the ceramic dielectric temperature spectrum near 170°C.

[0077] Comparative Example 2

[0078] Compared with Example 1, in this comparative example, 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution was prepared, but only Nb2O5 was added, and no MgO was added, and other preparation processes were the same as those in Example 1.

[0079] Comparative Example 3

[0080] Compared with Example 1, in this comparative example, 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution was prepared, but only MgO was added, and no Nb2O5 was added, and other preparation processes were the same as those in Example 1.

[0081] After the dielectric materials (circular sheet samples) prepared in Comparative Examples 1-3 were silver electrode on both sides, the dielectric constant ε r , dielectric loss tanδ of the samples at -60-250°C were tested by the same method as in Examples 1-3, and the resistivity p v of the samples was tested, and the results are shown in Table 2.

[0082] Table 2 Comparative table of properties of dielectric materials prepared in Comparative Examples 1-3

[0083]

[0084] As shown in the table, since no Nb2O5 and MgO additives are introduced into the sample of Comparative Example 1, no double dielectric peaks are formed on the dielectric temperature spectrum of the dielectric material, that is, no "core-shell" structure is formed in the ceramic grains, resulting in poor dielectric properties and dielectric temperature stability. In the sample of Comparative Example 2, no MgO additive is introduced, and in the sample of Comparative Example 3, no Nb2O5 additive is introduced, and the dielectric temperature stability of the dielectric material is significantly lower than that of the sample of Example 1. In the sample of Comparative Example 2, uncontrolled diffusion of Nb element occurs, and in the sample of Comparative Example 3, Mg element is non-uniformly distributed to form a "core-shell" structure, but the ratio between the core and the shell is unreasonable, both of which result in incomplete "core-shell" structure in the ceramic grains. At the same time, the resistivity of the samples of Comparative Examples 2 and 3 is also lower than that of the sample of Example 1, indicating that when Nb and Mg elements are not simultaneously introduced into the dielectric material, the insulation properties of the dielectric material will also be negatively affected.

[0085] 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 protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A barium titanate-based X9R type high dielectric 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 is 96%, the auxiliary component is an additive composed of Nb2O5 and MgO, the molar percentage is 4%; wherein, x = 0.15, y = 0.005; the molar ratio of Nb2O5 and MgO is 1:1; The temperature-voltage characteristics of the MLCC dielectric material meet the EIA X9R standard, i.e. ΔC ε r / ε r25℃ ≤±15%, the room temperature dielectric constant is 2156, the room temperature dielectric loss is 0.019, and the room temperature resistivity is 1.8×10 11 Ω·cm; The preparation method of the barium titanate-based X9R type high-dielectric MLCC dielectric material comprises the following steps: S1 : Take raw materials by 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°C for 12 h, then pass through a 200 mesh nylon screen, then heat from room temperature to 1200°C at a rate of 5°C / min in a corundum crucible, and keep at 1200°C for 2 h to obtain BaTi 0.995 Ce 0.005 O3 powder; 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°C for 12 h, and then passed through a 200-mesh nylon screen, followed by heating from room temperature to 900°C at a heating rate of 5°C / min in a corundum crucible, and holding at 900°C for 3 h to obtain (Bi 0.5 Na 0.5 )TiO3 powder; S3: The obtained BaTi 0.995 Ce 0.005 O3 and (Bi 0.5 Na 0.5 )TiO3 powders 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°C for 12 h, and then sieved through a 200-mesh nylon screen. Subsequently, the powders were heated from room temperature to 1000°C at a rate of 3°C / min in a corundum crucible and held at 1000°C for 2 h to obtain 0.85BaTi 0.995 Ce 0.005 O3-0.15(Bi 0.5 Na 0.5 )TiO3 solid solution powders. Subsequently, on the basis of this, using 96 mol% of 0.85BaTi 0.995 Ce 0.005 O3–0.15(Bi 0.5 Na 0.5 )TiO3 solid solution, 2 mol% Nb2O5, and 2 mol% MgO to produce a barium titanate-based X9R type high-dielectric MLCC dielectric material: S4: The raw materials are weighed according to the molar percentage, ball-milled in a ball mill at a speed of 1000 rpm for 12 h, dried at 90 DEG C for 12 h, and then passed through a 200-mesh nylon screen to obtain raw material powder; S5: The raw material powder is mixed with a polyvinyl alcohol solution at a ratio of 10 g:1 mL, wherein the mass fraction of the polyvinyl alcohol is 5 wt%, and the granulated raw material powder is 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 the action of a uniaxial pressure of 50 MPa; S6: The green body is placed in a muffle furnace, heated from room temperature to 450 DEG C at a heating rate of 3 DEG C / min in an air atmosphere, and then held at 450 DEG C for 2 h, and then heated from 450 DEG C to 1200 DEG C at a heating rate of 3 DEG C / min, and held at 1200 DEG C for 2 h, and then cooled in the furnace to obtain a barium titanate-based X9R type high-dielectric MLCC dielectric material.

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