BaTiO3-based high dielectric ceramic with positive temperature coefficient at low temperature

Abstract

The invention discloses a BaTiO3-based high dielectric ceramic with a positive temperature coefficient at a low temperature, and belongs to the field of dielectric ceramic preparation. The BaTiO3-based high-dielectric ceramic is formed by sintering a substrate BaTiO3 and dopants MgO, XaOb, MnO2, RcOd, SiO2 and YeOf, the molar ratio of BaTiO3: MgO: XaOb: MnO2: RcOd: SiO2: YeOf is 100: x1: x2: x3: x4: x5: x6, a doping element X is at least one of Nb, W and Mo, a doping element R is at least one of rare earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb and Lu, and a doping element Y is at least one of Fe, Co and Ni; a, b, c, d, e and f are atomic ratio numbers. The BaTiO3-based dielectric ceramic of the system has a positive temperature coefficient at a low temperature, an ultrahigh dielectric constant between 4000 and 4600, dielectric loss of about 1% and high dielectric property, can meet the application of MLCC (Multiplayer Ceramic Chip Capacitors) and wafer capacitors, remarkably reduces the product size, reduces the circuit board volume, and is beneficial to miniaturization and lightweight design of electronic products.

Description

Technical Field

[0001] This invention relates to the field of dielectric ceramics, specifically to BaTiO3-based high dielectric ceramics with a positive temperature coefficient at low temperatures. Background Technology

[0002] Barium titanate (BaTiO3) (BT) was one of the earliest materials used to manufacture dielectric devices. Barium titanate is a ferroelectric ceramic with an ABO3-type perovskite crystal structure. Its ferroelectric properties near room temperature give it a very high dielectric constant, making it the preferred dielectric material for high-performance ceramic capacitors. However, the addition of impurity elements causes its resistivity to drop sharply, exhibiting semiconductor properties, thus attracting widespread attention and in-depth research in ceramics. Over the years, many scholars have utilized ionic Bi... 3+ / Zn 2 + / Ti 4+ Common methods such as replacing chemical components to form solid solutions are used to modify ceramics. The physical properties of doped ceramics, such as resistivity and dielectric constant, are improved to some extent. The changes in the composition, structure, microstructure, and electrical properties of the prepared ceramic materials are investigated. For BT ceramics, enhancing performance through the use of dopants or innovative processing is crucial. The influence of dopants on the structure and ferroelectric properties of BaTiO3 is very complex; often, multiple parameters change synergistically (such as the nature and number of point defects, grain size, crystal distortion, etc.).

[0003] Currently, the dielectric constant of pure BaTiO3-based dielectric ceramics at room temperature is generally around 1200℃, with relatively high dielectric loss. More importantly, it exhibits a negative temperature coefficient at low temperatures, which greatly hinders the application of BaTiO3-based dielectric ceramics. For example, in special equipment commonly used in low-temperature environments, the use of conventional BaTiO3-based lead-free dielectric ceramic capacitors requires consideration of the capacitance decay caused by the negative temperature coefficient at low temperatures. Therefore, under conditions of large temperature fluctuations, conventional BaTiO3-based dielectric ceramic capacitors cannot avoid the capacitance decay at low temperatures relative to room temperature, making them unsuitable for low-temperature applications.

[0004] Therefore, in order to solve the application problem of BaTiO3-based lead-free dielectric ceramics in low-temperature environments and meet good electrical performance requirements, it is urgent to obtain a BaTiO3-based lead-free dielectric ceramic with a positive temperature coefficient, high dielectric, low loss, and low resistance at low temperatures. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a high-dielectric BaTiO3-based dielectric ceramic with a positive temperature coefficient at low temperatures, its preparation method, and its application areas, aiming to solve the application challenges of BaTiO3-based ceramics in low-temperature applications.

[0006] The technical solution of this invention is: A BaTiO3-based high-dielectric ceramic exhibiting a positive temperature coefficient at low temperatures, characterized in that the BaTiO3-based high-dielectric ceramic comprises a BaTiO3 matrix and dopants MgO and X. a O b MnO2, R c O d SiO2, Y e O f It is sintered, wherein, in molar ratio, BaTiO3:MgO:X a O b MnO2: R c O d : SiO2 : Y e O f =100:x1:x2:x3:x4:x5:x6; Dopant element X is at least one of Nb, W, and Mo; dopant element R is at least one of rare earth elements La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, and Lu; and dopant element Y is at least one of Fe, Co, and Ni. a, b, c, d, e, and f are the atomic stoichiometric ratios; and x1, x2, x3, x4, x5, and x6 are the molar coefficients of different dopants.

[0007] Barium titanate (BaTiO3) is currently the most studied and widely used thermistor ceramic, and elemental doping is usually A / B site doping. In this invention, the doping element is Mg + at least one of Nb, W, Mo + Mn + at least one of rare earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu + Si + at least one of Fe, Co, Ni. By adding these elements in appropriate proportions, A / B site multi-element doping is achieved. According to the doping mechanism, Mg, Nb, W, and Mo, as typical metal ions, regulate the phase structure and ferroelectric domain structure; ferromagnetic elements Fe, Co, and Ni improve the temperature stability of the dielectric ceramic; Mn and the addition of trace amounts of rare earth elements such as La, Ce, Sm, and Y significantly improve the ceramic's resistivity; Si doping changes the distribution of the microstructure, achieving a balance in electrical properties. The synergistic effect of the above elements aims to obtain dielectric ceramics with excellent comprehensive properties such as low temperature positive temperature coefficient, low resistance, and high dielectric constant. Significant breakthroughs have been achieved in the overall performance of dielectric ceramics, resulting in unexpected technical effects.

[0008] More specifically, 0.1≤x1≤5, 0.5≤x2≤3, 0.1≤x3≤1, 0.5≤x4≤4, 0.2≤x5≤5 ， 0.5≤x6≤4.

[0009] More specifically, within the temperature range of -55 to 60°C, the TCC of high-dielectric BaTiO3-based dielectric ceramics is ≤ ±15%.

[0010] More specifically, the dielectric constant of high-dielectric BaTiO3-based dielectric ceramics is 4000 < ε. r <4600.

[0011] A method for preparing high-dielectric BaTiO3-based dielectric ceramics with a positive temperature coefficient at low temperatures includes the following steps: S1: Take BaCO3 and TiO2 powders in a molar ratio of 1:1 and process them in a wet planetary ball mill to obtain ceramic powder; S2: After the ceramic powder in step S1 is dried in an oven, it enters the pre-firing process. The pre-firing temperature is 1100~1200℃ and the pre-firing time is 1~4h to obtain perovskite type BaTiO3 dielectric ceramic, which is then ground into BaTiO3 ceramic powder. S3: Add powder containing each dopant element to the BaTiO3 ceramic powder obtained in step S2 according to the molar ratio, and then put it into a wet planetary ball mill for mixing and grinding to obtain ceramic powder. S4: The ceramic powder in step S3 is dried in an oven, then granulated and aged, then pressed into a green body, then heated to remove the binder, and finally pressed into a sheet to obtain a ceramic body. S5: Place the ceramic blank obtained in step S4 into a sintering furnace for secondary sintering at a temperature of 1200~1350℃ for 1~4h to obtain BaTiO3-based dielectric ceramic. S6: Electrode polarization was performed on BaTiO3-based dielectric ceramics, and the relevant electrical properties were tested.

[0012] In the preparation method of this invention, perovskite BaTiO3 ceramic powder is obtained by pre-firing BaCO3 and TiO2 powders. The pre-firing process increases the ceramic grain size, which directly leads to an increase in grain size during the secondary sintering process, resulting in a significant enhancement of the electrical properties of the doped BaTiO3-based dielectric ceramic. This mechanism can also be explained by the fact that small particles are composed of single ferroelectric domains, and even smaller grains are almost entirely cubic phases, while large BaTiO3 grains generally have a multi-domain magnetic structure. The orientation of pure domain magnetic fields under an electric field is a kind of slow relaxation mechanism. For large BaTiO3 grains containing multi-domain ferroelectric cores, the orientation of the domains causes significant stress, making polarity orientation difficult, which greatly increases the electrical properties.

[0013] More specifically, in steps S1 and S3, when ball milling with a wet planetary ball mill, anhydrous ethanol is used as the dispersion medium, the ball milling time is 8~24h, and the rotation speed is 150~250rpm; More specifically, in step S3, powder containing each dopant element is added according to the molar ratio, wherein the dopant element Si is taken from one or more glass system powders selected from Zn-B-Si, Ba-B-Si, Ba-B-Si-Al, and Ba-Ca-Si. More specifically, in step S4, the binder added during granulation is polyvinyl alcohol, and the green body is heated to 400~600℃ at a heating rate not exceeding 3℃ / min, and held for 2-4 hours.

[0014] More specifically, in step S4, the ceramic blank is finally pressed into a sheet at a pressure of 1-1.5 MPa.

[0015] Applications of high-dielectric BaTiO3-based dielectric ceramics with positive temperature coefficients at low temperatures, including their use in MLCCs and disc capacitors.

[0016] The beneficial technical effects of this invention are: 1. The BaTiO3-based high dielectric ceramic with a positive temperature coefficient at low temperatures obtained by this invention has an ultra-high dielectric constant between 4000 and 4600 and a dielectric loss of about 1%. Its high dielectric performance can meet the application requirements of MLCC and wafer capacitors, and can significantly reduce product size and circuit board volume, which is beneficial to the miniaturization and lightweight design of electronic products. 2. This invention innovatively proposes adding dopants MgO and X to the BaTiO3 system. a O b MnO2, R c O d SiO2, Y e O f (Doping element X is at least one of Nb, W, and Mo; doping element R is at least one of rare earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, and Lu; and doping element Y is at least one of Fe, Co, and Ni.) Through appropriate proportions, the doping elements work synergistically to ultimately obtain dielectric ceramics with excellent comprehensive properties such as low-temperature positive temperature coefficient, low resistance, and high dielectric constant. This represents a significant breakthrough in the overall performance of dielectric ceramics and yields unexpected technical results.

[0017] 3. The BaTiO3 system dielectric ceramic of this invention overcomes the application obstacles of BaTiO3 system dielectric ceramics at low temperatures, meets the X7T temperature characteristic curve, conforms to the EIA X7T temperature characteristic, can be used in the range of -55~125℃, and has no capacity decay in low temperature scenarios. It makes an important contribution to the high performance and stable dielectric performance design of lead-free dielectric ceramics in the low temperature region. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the TCC curve of the BaTiO3-based dielectric ceramic in Example 2. Detailed Implementation

[0019] In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0020] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0021] Example 1: A method for preparing high-dielectric BaTiO3-based dielectric ceramics with a positive temperature coefficient at low temperatures includes the following steps: S1: Take 100 mol of BaCO3 and TiO2 powders according to the molar ratio, put them into a wet planetary ball mill for processing to obtain ceramic powder, use anhydrous ethanol as the dispersion medium, ball mill for 10 h, and rotate at 200 rpm. S2: After the ceramic powder in step S1 is dried in an oven at 80°C for 12 hours, it enters the pre-firing process. The pre-firing temperature is 1200°C and the pre-firing time is 3 hours to obtain perovskite-type BaTiO3 dielectric ceramic, which is then ground into BaTiO3 ceramic powder. S3: To the BaTiO3 ceramic powder obtained in step S2, add 1.5 mol MgO, 1.98 mol Nb2O5, 0.28 mol MnO, 0.85 mol Ce2O3, 0.14 mol Nd2O3, 0.8 mol 0.8 Zn-0.1 B-0.1 Si, and 0.99 mol Co3O4 respectively, and then mix and grind them again in a planetary ball mill to obtain ceramic powder. Use anhydrous ethanol as the dispersion medium, and the ball milling time is 10 h and the speed is 200 rpm. S4: After the ceramic powder in step S3 is dried in an oven at 80℃ for 12 hours, polyvinyl alcohol is added for granulation, aged for 24 hours, pre-pressed, ground, and sieved through a 40-mesh sieve. The powder is then pressed into a ceramic green body at 1.2 MPa. The green body is then heated to remove the binder at a rate of 2℃ / min to 500℃ and held for 3 hours. Finally, the green body is pressed into a sheet to obtain the ceramic green body. S5: Place the ceramic blank obtained in step S4 into a sintering furnace for secondary sintering at a temperature of 1300℃ for 4 hours to obtain BaTiO3-based dielectric ceramic. S6: Conduct electrical performance tests on BaTiO3-based dielectric ceramics, including tests on relevant electrical properties such as dielectric constant, dielectric loss, TCC, and insulation impedance.

[0022] Example 2: A method for preparing high-dielectric BaTiO3-based dielectric ceramics with a positive temperature coefficient at low temperatures includes the following steps: S1: Take 100 mol of BaCO3 and TiO2 powders according to the molar ratio, put them into a wet planetary ball mill for processing to obtain ceramic powder, use anhydrous ethanol as the dispersion medium, ball mill for 10 h, and rotate at 200 rpm. S2: After the ceramic powder in step S1 is dried in an oven at 80°C for 12 hours, it enters the pre-firing process. The pre-firing temperature is 1200°C and the pre-firing time is 3 hours to obtain perovskite-type BaTiO3 dielectric ceramic, which is then ground into BaTiO3 ceramic powder. S3: To the BaTiO3 ceramic powder obtained in step S2, add 0.75 mol MgO, 1.68 mol WO3, 0.17 mol MnO, 0.63 mol LaO, 0.2 mol Nd2O3, 1.35 mol 0.6Ba-0.4Ca-Si, and 0.83 mol Fe2O3 respectively, and then mix and grind them again in a planetary ball mill to obtain ceramic powder. Use anhydrous ethanol as the dispersion medium, and ball mill for 10 hours at a speed of 200 rpm. S4: After the ceramic powder in step S3 is dried in an oven at 80℃ for 12 hours, polyvinyl alcohol is added for granulation, aged for 24 hours, pre-pressed, ground, and sieved through a 40-mesh sieve. The powder is then pressed into a ceramic green body at 1.2 MPa. The green body is then heated to remove the binder at a rate of 2℃ / min to 500℃ and held for 3 hours. Finally, the green body is pressed into a sheet to obtain the ceramic green body. S5: Place the ceramic blank obtained in step S4 into a sintering furnace for secondary sintering at a temperature of 1300℃ for 4 hours to obtain BaTiO3-based dielectric ceramic. S6: Conduct electrical performance tests on BaTiO3-based dielectric ceramics, including tests on relevant electrical properties such as dielectric constant, dielectric loss, TCC, and insulation impedance.

[0023] Example 3: A method for preparing high-dielectric BaTiO3-based dielectric ceramics with a positive temperature coefficient at low temperatures includes the following steps: S1: Take 100 mol of BaCO3 and TiO2 powders according to the molar ratio, put them into a wet planetary ball mill for processing to obtain ceramic powder, use anhydrous ethanol as the dispersion medium, ball mill for 10 h, and rotate at 200 rpm. S2: After the ceramic powder in step S1 is dried in an oven at 80°C for 12 hours, it enters the pre-firing process. The pre-firing temperature is 1200°C and the pre-firing time is 3 hours to obtain perovskite-type BaTiO3 dielectric ceramic, which is then ground into BaTiO3 ceramic powder. S3: To the BaTiO3 ceramic powder obtained in step S2, add 2 mol MgO, 2.24 mol Nb2O5, 0.46 mol MnO, 0.22 mol LaO, 0.9 mol Ce2O3, 2.1 mol 0.6 Ba-0.4 Ca-Si, and 1.12 mol Ni2O3 respectively, and then mix and grind them again in a planetary ball mill to obtain ceramic powder. Use anhydrous ethanol as the dispersion medium, and ball mill for 10 hours at a speed of 200 rpm. S4: After the ceramic powder in step S3 is dried in an oven at 80℃ for 12 hours, polyvinyl alcohol is added for granulation, aged for 24 hours, pre-pressed, ground, and sieved through a 40-mesh sieve. The powder is then pressed into a ceramic green body at 1.2 MPa. The green body is then heated to remove the binder at a rate of 2℃ / min to 500℃ and held for 3 hours. Finally, the green body is pressed into a sheet to obtain the ceramic green body. S5: Place the ceramic blank obtained in step S4 into a sintering furnace for secondary sintering at a temperature of 1300℃ for 4 hours to obtain BaTiO3-based dielectric ceramic. S6: Conduct electrical performance tests on BaTiO3-based dielectric ceramics, including tests on relevant electrical properties such as dielectric constant, dielectric loss, TCC, and insulation impedance.

[0024] Comparative Example 1: The difference from Example 1 is that, in step S3: 1.5 mol MgO, 1.98 mol Nb2O5, 0.28 mol MnO, 0.85 mol Ce2O3, 0.14 mol Nd2O3, and 0.8 mol 0.8 Zn-0.1 B-0.1 Si were added to the BaTiO3 ceramic powder obtained in step S2, and the mixture was mixed and ground again in a planetary ball mill to obtain ceramic powder. Anhydrous ethanol was used as the dispersion medium, the ball milling time was 10 h, and the speed was 200 rpm.

[0025] Comparative Example 2: The difference from Example 1 is that, in step S3: 0.28 mol MnO, 0.85 mol Ce2O3, 0.14 mol Nd2O3, 0.8 mol 0.8 Zn-0.1 B-0.1 Si, and 0.99 mol Co3O4 were added to the BaTiO3 ceramic powder obtained in step S2, and the mixture was mixed and ground again in a planetary ball mill to obtain ceramic powder. Anhydrous ethanol was used as the dispersion medium, the ball milling time was 10 h, and the speed was 200 rpm.

[0026] Comparative Example 3: The difference from Example 1 is that, in step S3: 1.5 mol MgO, 1.98 mol Nb2O5, 0.8 mol 0.8Zn-0.1B-0.1Si, and 0.99 mol Co3O4 were added to the BaTiO3 ceramic powder obtained in step S2, and the mixture was mixed and ground again in a planetary ball mill to obtain ceramic powder. Anhydrous ethanol was used as the dispersion medium, the ball milling time was 10 h, and the speed was 200 rpm.

[0027] To further illustrate the beneficial technical effects of dielectric constant, dielectric loss, resistance, and TCC (-55℃ / 125℃) involved in the various embodiments of the present invention, the dielectric constant, dielectric loss, resistance, and TCC (-55℃ / 125℃) involved in Examples 1-3 and Comparative Examples 1-3 were tested for relevant electrical performance according to conventional methods in the industry.

[0028] Dielectric performance testing, dielectric loss testing, insulation impedance testing: Commercially available dielectric ceramic dielectric constant tester, used to test dielectric loss and dielectric constant; commercially available insulation resistance tester, used to measure insulation impedance value.

[0029] TCC test: Low temperature is controlled by liquid nitrogen, and high temperature is controlled by electric heating. The TCC curve of the ceramic sample is tested.

[0030] The electrical performance test results of Examples 1-3 and Comparative Examples 1-3 are shown in Table 1 below: Table 1. Test results of electrical properties of BaTiO3-based dielectric ceramics <![CDATA[ε r ]]> Tanδ (%) -55℃（%） 125℃（%） <![CDATA[IR(×10 10 Oh)]]> Example 1 4581 1.02 0.3 -27.1 141 Example 2 4367 1.08 3.7 -24.6 134 Example 3 4057 0.79 0.4 -29.3 127 Comparative Example 1 2902 4.32 -6.2 -35.1 203 Comparative Example 2 2695 4.82 -4.7 -31.6 265 Comparative Example 3 3003 3.95 -4.1 -32.2 1006

[0031] As can be seen from Table 1, the performance parameters of the dielectric ceramics obtained in Examples 1-3 are all superior to those in Comparative Examples 1-4. From the perspective of microscopic doping of dielectric ceramics, the addition of x1MgOmol%+ x2X in Examples 1-3 is more effective. a O b mol%+ x3MnO2 mol%+x4R c O d mol%+ x5SiO2 mol%+ x6Y e O fThe doping element X is at least one of Nb, W, and Mo; the doping element R is at least one of rare earth elements La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, and Lu; and the doping element Y is at least one of Fe, Co, and Ni. These doping elements work synergistically. Mg, Nb, W, and Mo, as typical metal ions, regulate the phase structure and ferroelectric domain structure; ferromagnetic elements Fe, Co, and Ni improve the temperature stability of the dielectric ceramic; Mn and trace rare earth elements such as La, Ce, Sm, and Y significantly improve the resistivity of the ceramic; and Si doping alters the distribution of the microstructure, achieving a balance in electrical properties. The synergistic effect of these elements results in dielectric ceramics obtained in Examples 1-3 exhibiting excellent comprehensive properties, including a positive temperature coefficient at low temperatures, low resistance, and high dielectric constant. This represents a significant breakthrough in the overall performance of dielectric ceramics and yields unexpected technical effects.

[0032] Other, Figure 1 The figure shown is the TCC curve of the BaTiO3-based dielectric ceramic shown in Example 1 within the temperature range of -55 to 145°C. Figure 1 It can be seen that the lead-free dielectric ceramic system with the composition of 100mol BaTiO3, 1.5mol MgO, 1.98mol Nb2O5, 0.28mol MnO, 0.85mol Ce2O3, 0.14mol Nd2O3, 0.8mol 0.8Zn-0.1B-0.1Si, and 0.99mol Co3O4 meets the application requirements in the temperature range of -55~145℃ and -55~125℃. More specifically, in the temperature range of -55~60℃, the TCC of BaTiO3-based dielectric ceramics is ≤±15%, exhibiting extremely wide temperature stability. Furthermore, the TCC temperature coefficient is positive in the low-temperature range of -55℃ to the room temperature range of 30℃. This has extremely important technical value for the low-temperature application of BaTiO3-based dielectric ceramics.

[0033] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A BaTiO3-based high-dielectric ceramic with a positive temperature coefficient at low temperatures, characterized in that, The BaTiO3-based high-dielectric ceramic consists of a BaTiO3 matrix and dopants MgO and X. a O b MnO2, R c O d SiO2, Y e O f It is sintered, wherein, in molar ratio, BaTiO3:MgO:X a O b MnO2: R c O d : SiO2 : Y e O f =100:x1:x2:x3:x4:x5:x6; Dopant element X is at least one of Nb, W, and Mo; dopant element R is at least one of rare earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, and Lu; and dopant element Y is at least one of Fe, Co, and Ni. a, b, c, d, e, and f are the atomic stoichiometric ratios; and x1, x2, x3, x4, x5, and x6 are the molar coefficients of different dopants.

2. The BaTiO3-based high-dielectric ceramic with a positive temperature coefficient at low temperatures according to claim 1, characterized in that, 0.1≤x1≤5,0.5≤x2≤3,0.1≤x3≤1,0.5≤x4≤4,0.2≤x5≤5 ， 0.5≤x6≤4。 3. The BaTiO3-based high-dielectric ceramic with a positive temperature coefficient at low temperatures according to claim 2, characterized in that, Within a temperature range of -55 to 60°C, the TCC of high-dielectric BaTiO3-based dielectric ceramics is ≤ ±15%.

4. The BaTiO3-based high-dielectric ceramic with a positive temperature coefficient at low temperatures according to claim 2, characterized in that, The dielectric constant of the BaTiO3-based high-dielectric ceramic is 4000 < ε. r <4600.

5. The method for preparing BaTiO3-based high-dielectric ceramics with a positive temperature coefficient at low temperatures according to claim 1, characterized in that, Includes the following steps: S1: Take BaCO3 and TiO2 powders in a molar ratio of 1:1 and process them in a wet planetary ball mill to obtain ceramic powder; S2: After the ceramic powder in step S1 is dried in an oven, it enters the pre-firing process to obtain perovskite-type BaTiO3 dielectric ceramic, which is then ground into BaTiO3 ceramic powder. S3: Add powder containing each dopant element to the BaTiO3 ceramic powder obtained in step S2 according to the molar ratio, and then put it into a wet planetary ball mill for mixing and grinding to obtain ceramic powder. S4: The ceramic powder in step S3 is dried in an oven, then granulated and aged, then pressed into a green body, then heated to remove the binder, and finally pressed into a sheet to obtain a ceramic body. S5: Place the ceramic blank obtained in step S4 into a sintering furnace for secondary sintering to obtain BaTiO3-based dielectric ceramic. S6: Test the relevant electrical properties of BaTiO3-based dielectric ceramics.

6. The method for preparing BaTiO3-based high-dielectric ceramics with a positive temperature coefficient at low temperatures according to claim 5, characterized in that, In steps S1 and S3, during wet planetary ball milling, anhydrous ethanol is used as the dispersion medium, the ball milling time is 8~24h, and the rotation speed is 150~250rpm. In step S2, the pre-firing process is as follows: the pre-firing temperature is 1100~1200℃, and the pre-firing time is 1~4h; In step S5, the secondary sintering process is carried out at a sintering temperature of 1200~1350℃ and a sintering time of 1~4h.

7. The method for preparing BaTiO3-based high-dielectric ceramics with a positive temperature coefficient at low temperatures according to claim 5, characterized in that, In step S3, powder containing each dopant element is added according to the molar ratio, wherein the dopant element Si is taken from one or more glass system powders selected from Zn-B-Si, Ba-B-Si, Ba-B-Si-Al, and Ba-Ca-Si.

8. The method for preparing BaTiO3-based high-dielectric ceramics with a positive temperature coefficient at low temperatures according to claim 5, characterized in that, In step S4, the binder added during granulation is polyvinyl alcohol. The green body is heated to 400~600℃ at a heating rate not exceeding 3℃ / min, and held at that temperature for 2-4 hours.

9. The method for preparing BaTiO3-based high-dielectric ceramics with a positive temperature coefficient at low temperatures according to claim 5, characterized in that, In step S4, the ceramic blank is finally pressed into a sheet at a pressure of 1-1.5 MPa.

10. The application of the BaTiO3-based high-dielectric ceramic with a positive temperature coefficient at low temperatures according to claim 1, characterized in that, The BaTiO3-based high-dielectric ceramics are used in MLCCs and disc capacitors.

Images