A BaTiO3-based dielectric ceramic co-doped at A and B sites and its preparation method

Abstract

The application discloses A and B site doped BaTiO3-based dielectric ceramic, characterized in that the chemical formula of the A and B site doped BaTiO3-based dielectric ceramic is (Ba x1 Ca x2 Sr 1‑x1‑x2 )(Ti 0.4 La 0.2 Ce 0.2 Ta 0.2 )O3, 0≤x1≤1, 0≤x2≤1, and x1+x2≤1. The application also discloses a preparation method thereof. The application introduces other elements into A and B of the barium titanate ceramic dielectric material, improves the high-temperature stability and energy storage performance, and overcomes the defects of poor temperature stability and low energy storage efficiency of the existing barium titanate ceramic dielectric material.

Description

Technical Field

[0001] This invention belongs to the field of inorganic dielectric ceramics, specifically relating to a BaTiO3-based dielectric ceramic doped at A and B sites and its preparation method. Technical Background

[0002] With the rapid development of electronic technology, the energy storage performance requirements of dielectric ceramics in increasingly demanding application environments are constantly increasing. Against this backdrop, barium titanate-based ceramics, as a typical lead-free dielectric ceramic, have attracted much attention due to their low cost, environmental friendliness, and excellent dielectric properties. However, barium titanate suffers from drawbacks such as high remanent polarization, low breakdown field strength, and unstable dielectric properties, resulting in relatively low energy storage density and efficiency.

[0003] Therefore, exploring innovative approaches to improve the dielectric and energy storage properties of barium titanate dielectric ceramics is of great significance.

[0004] Numerous studies have shown that doping BaTiO3 with multiple cations at the A-site or B-site can significantly improve its performance. Doping with different cations increases the disorder and complexity within the oxygen octahedron, contributing to improved energy storage and dielectric properties.

[0005] A-site doping and B-site doping. A-site doping elements include rare earth elements such as Dy, Eu, and Y, as well as Pb, Zn, Bi, Ca, and Sr; B-site doping elements include rare earth elements such as Mn, Nb, Mg, La, and Ce. Rare earth elements have a certain inhibitory effect on the grain growth of ceramics and improve dielectric properties to some extent.

[0006] CN114315350A discloses a lead-free wide-temperature energy storage ceramic of sodium bismuth titanate and barium zirconate titanate, and its preparation method. The molecular formula of the ceramic material is (1-x)Bi. 0.51 Na 0.47 TiO 3-x BaZr y Ti 1-y O 3-z Sm, where x, y, and z represent the mole fractions of barium zirconate titanate, zirconium ions, and samarium ions, respectively; wherein 0.45≤x≤0.55, 0.3≤y≤0.45, and 0≤z≤0.08. This invention improves both the high-temperature stability and energy storage performance of barium titanate ceramic dielectric materials by simultaneously introducing other elements into A and B. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of current barium titanate dielectric ceramics, such as poor temperature stability of dielectric properties and low energy storage efficiency, by proposing a barium titanate-based dielectric ceramic with co-doped A and B sites.

[0008] To achieve the objectives of this invention, the technical solution adopted is as follows:

[0009] A BaTiO3-based dielectric ceramic doped at A and B sites, wherein the chemical formula of the BaTiO3-based dielectric ceramic doped at A and B sites is as follows:

[0010] (Ba x1 Ca x2 Sr 1-x1-x2 (Ti) 0.4 La 0.2 Ce 0.2 Ta 0.2 O3, 0≤x1≤1, 0≤x2≤1, and x1+x2≤1.

[0011] A method for preparing A- and B-site doped BaTiO3-based dielectric ceramics, comprising:

[0012] Weigh out BaCO3, CaCO3, SrCO3, TiO2, La2O3, CeO2, and Ta2O5 according to the measured molar ratio, mix them well, and then dry them.

[0013] The dried product is compacted and then fired. The fired product is then ground to obtain sample powder.

[0014] The sample powder was subjected to cold isostatic pressing followed by high-temperature segmented sintering to obtain the BaTiO3-based dielectric ceramic doped at sites A and B.

[0015] In a preferred embodiment of the present invention, the purity of the raw material powders BaCO3, CaCO3, SrCO3, TiO2, La2O3, CeO2, and Ta2O5 is ≥99.7%, and the particle size is ≤45μm.

[0016] In a preferred embodiment of the present invention, the mixing is performed by ball milling, the ball milling medium is anhydrous ethanol, and the ball milling beads are ZrO2 beads. The mass ratio of the mixed powder to the ball milling beads to the anhydrous ethanol is 2:3:0.4. An omnidirectional planetary ball mill is used, the ball milling speed is ≥200 rpm, the ball milling time is ≥12 h, the drying temperature is 100-130℃, and the drying time is ≥8 h.

[0017] In a preferred embodiment of the present invention, the sample powder is compacted at a pressure ≥40MPa.

[0018] In a preferred embodiment of the present invention, the sample powder is sintered at a temperature of 1300-1550°C and held for 12-48 hours.

[0019] In a preferred embodiment of the present invention, the product grinding is carried out by dry grinding, the grinding balls are ZrO2 beads, the powder mass: grinding ball mass is 2:3, the grinding speed is 200-300 rpm, and the grinding time is ≥12h.

[0020] In a preferred embodiment of the present invention, the pressure of the isostatic pressing after cold isostatic pressing treatment and high-temperature segmented firing is ≥120MPa and the holding time is ≥5min.

[0021] High-temperature segmented firing involves placing the obtained green blank in a high-temperature sintering furnace. In the first stage, the temperature is increased from room temperature to 1300-1550℃ at a heating rate of 1.5-5℃ / min and held for 2-6 hours.

[0022] The second stage involves heating the temperature to 1650-1750℃ at a rate of 5-10℃ / min and holding it at that temperature for 4-8 hours; then cooling it to room temperature at a rate of 1.5-5℃ / min.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention improves the high-temperature stability and energy storage performance of barium titanate ceramic dielectric materials by simultaneously introducing other elements into A and B, thereby overcoming the shortcomings of poor temperature stability and low energy storage efficiency of existing barium titanate ceramic dielectric materials. Detailed Implementation

[0025] The following specific examples further illustrate this point:

[0026] Example 1

[0027] A BaTiO3-based dielectric ceramic doped at A and B sites and its preparation method are as follows:

[0028] (1) Mix BaCO3, CaCO3, SrCO3, TiO2, La2O3, CeO2, and Ta2O5 in a molar ratio of 5:2:3:4:2:2:2;

[0029] (2) Put the prepared powder into a ball mill, and add ZrO2 grinding beads and anhydrous ethanol at the same time. The ratio is 2:3:0.4. Adjust the speed of the ball mill to 200 rpm and the ball milling time is 12 hours.

[0030] (3) The mixture in step (2) is compacted at 40 MPa;

[0031] (4) Place the compacted mixture into a magnesium oxide crucible and heat it to 1300℃ at a rate of 5℃ / min, and keep it at that temperature for 12h.

[0032] (5) After the product is calcined, it is crushed and mixed with ZrO2 ball milling beads. The mass ratio of powder to ball milling beads is 2:3. The mixture is then placed in a ball mill at a speed of 200 rpm and milled for 12 hours to obtain the required sample powder.

[0033] (6) The sample powder was subjected to cold isostatic pressing at 120 MPa and held for 5 min. Then it was placed in a high-temperature sintering furnace and heated to 1300°C at a rate of 2°C / min and held for 2 h. Then it was heated to 1650°C at a rate of 5°C / min and held for 4 h to obtain the BaTiO3-based dielectric ceramic doped at A and B sites of Example 1.

[0034] Example 2

[0035] A BaTiO3-based dielectric ceramic doped at A and B sites and its preparation method are as follows:

[0036] (1) Mix BaCO3, CaCO3, SrCO3, TiO2, La2O3, CeO2, and Ta2O5 in a molar ratio of 5:3:2:4:2:2:2;

[0037] (2) Put the prepared powder into a ball mill, and add ZrO2 grinding beads and anhydrous ethanol at the same time. The ratio is 2:3:0.4. Adjust the speed of the ball mill to 200 rpm and the ball milling time is 12 hours.

[0038] (3) The mixture in step (2) is compacted at 40 MPa;

[0039] (4) Place the compacted mixture into a magnesium oxide crucible and heat it to 1300℃ at a rate of 5℃ / min, and keep it at that temperature for 12h.

[0040] (5) After the product is calcined, it is crushed and mixed with ZrO2 ball milling beads. The mass ratio of powder to ball milling beads is 2:3. The mixture is then placed in a ball mill at a speed of 200 rpm and milled for 12 hours to obtain the required sample powder.

[0041] (6) The sample powder was subjected to cold isostatic pressing at 120 MPa and held for 5 min. Then it was placed in a high-temperature sintering furnace and heated to 1300°C at a rate of 2°C / min and held for 2 h. Then it was heated to 1650°C at a rate of 5°C / min and held for 4 h to obtain the BaTiO3-based dielectric ceramic doped at A and B sites of Example 2.

[0042] Example 3

[0043] A BaTiO3-based dielectric ceramic doped at A and B sites and its preparation method are as follows:

[0044] (1) Mix BaCO3, CaCO3, SrCO3, TiO2, La2O3, CeO2, and Ta2O5 in a molar ratio of 5:2:3:4:2:2:2;

[0045] (2) Put the prepared powder into a ball mill, and add ZrO2 grinding beads and anhydrous ethanol at the same time. The ratio is 2:3:0.4. Adjust the speed of the ball mill to 200 rpm and the ball milling time is 12 hours.

[0046] (3) The mixture in step (2) is compacted at 40 MPa;

[0047] (4) Place the compacted mixture into a magnesium oxide crucible and heat it to 1400℃ at a rate of 5℃ / min, and keep it at that temperature for 24h.

[0048] (5) After the product is calcined, it is crushed and mixed with ZrO2 ball milling beads. The mass ratio of powder to ball milling beads is 2:3. The mixture is then placed in a ball mill at a speed of 200 rpm and milled for 12 hours to obtain the required sample powder.

[0049] (6) The sample powder was subjected to cold isostatic pressing at 120 MPa and held for 5 min. Then it was placed in a high-temperature sintering furnace and heated to 1300 °C at a rate of 2 °C / min and held for 2 h. Then it was heated to 1650 °C at a rate of 5 °C / min and held for 4 h to obtain the BaTiO3-based dielectric ceramic doped at A and B sites of Example 3.

[0050] Example 4

[0051] A BaTiO3-based dielectric ceramic doped at A and B sites and its preparation method are as follows:

[0052] (1) Mix BaCO3, CaCO3, SrCO3, TiO2, La2O3, CeO2, and Ta2O5 in a molar ratio of 5:2:3:4:2:2:2;

[0053] (2) Put the prepared powder into a ball mill, and add ZrO2 grinding beads and anhydrous ethanol at the same time. The ratio is 2:3:0.4. Adjust the speed of the ball mill to 200 rpm and the ball milling time is 24 hours.

[0054] (3) The mixture in step (2) is compacted at 40 MPa;

[0055] (4) Place the compacted mixture into a magnesium oxide crucible and heat it to 1400℃ at a rate of 5℃ / min, and keep it at that temperature for 24h.

[0056] (5) After the product is calcined, it is crushed and mixed with ZrO2 ball milling beads. The mass ratio of powder to ball milling beads is 2:3. The mixture is then placed in a ball mill at 300 rpm and milled for 24 hours to obtain the required sample powder.

[0057] (6) The sample powder was subjected to cold isostatic pressing at 120 MPa and held for 5 min. Then it was placed in a high-temperature sintering furnace and heated to 1300 °C at a rate of 2 °C / min and held for 2 h. Then it was heated to 1650 °C at a rate of 5 °C / min and held for 4 h to obtain the BaTiO3-based dielectric ceramic doped at A and B sites of Example 4.

[0058] Example 5

[0059] A BaTiO3-based dielectric ceramic doped at A and B sites and its preparation method are as follows:

[0060] (1) Mix BaCO3, CaCO3, SrCO3, TiO2, La2O3, CeO2, and Ta2O5 in a molar ratio of 5:2:3:4:2:2:2;

[0061] (2) Put the prepared powder into a ball mill, and add ZrO2 grinding beads and anhydrous ethanol at the same time. The ratio is 2:3:0.4. Adjust the speed of the ball mill to 200 rpm and the ball milling time is 24 hours.

[0062] (3) The mixture in step (2) is compacted at 40 MPa;

[0063] (4) Place the compacted mixture into a magnesium oxide crucible and heat it to 1400℃ at a rate of 5℃ / min, and keep it at that temperature for 24h.

[0064] (5) After the product is calcined, it is crushed and mixed with ZrO2 ball milling beads. The mass ratio of powder to ball milling beads is 2:3. The mixture is then placed in a ball mill at 300 rpm and milled for 24 hours to obtain the required sample powder.

[0065] (6) The sample powder was subjected to cold isostatic pressing at 160 MPa and held for 10 min. Then it was placed in a high-temperature sintering furnace and heated to 1300 °C at a rate of 2 °C / min and held for 2 h. Then it was heated to 1650 °C at a rate of 5 °C / min and held for 4 h to obtain the BaTiO3-based dielectric ceramic doped at A and B sites of Example 5.

[0066] Example 6

[0067] A BaTiO3-based dielectric ceramic doped at A and B sites and its preparation method are as follows:

[0068] (1) Mix BaCO3, CaCO3, SrCO3, TiO2, La2O3, CeO2, and Ta2O5 in a molar ratio of 5:2:3:4:2:2:2;

[0069] (2) Put the prepared powder into a ball mill, and add ZrO2 grinding beads and anhydrous ethanol at the same time. The ratio is 2:3:0.4. Adjust the speed of the ball mill to 200 rpm and the ball milling time is 24 hours.

[0070] (3) The mixture in step (2) is compacted at 40 MPa;

[0071] (4) Place the compacted mixture into a magnesium oxide crucible and heat it to 1400℃ at a rate of 5℃ / min, and keep it at that temperature for 24h.

[0072] (5) After the product is calcined, it is crushed and mixed with ZrO2 ball milling beads. The mass ratio of powder to ball milling beads is 2:3. The mixture is then placed in a ball mill at 300 rpm and milled for 24 hours to obtain the required sample powder.

[0073] (6) The sample powder was subjected to cold isostatic pressing at 160 MPa and held for 10 min. Then it was placed in a high-temperature sintering furnace and heated to 1400°C at a rate of 2°C / min and held for 4 h. Then it was heated to 1750°C at a rate of 5°C / min and held for 6 h to obtain the BaTiO3-based dielectric ceramic doped at A and B sites of Example 6.

[0074] Table 1 is a comparison table of important steps in each embodiment.

[0075]

[0076]

[0077] Table 2 shows the performance test results for each embodiment.

[0078] The dielectric constant was tested using an automatic bridging tester under the following conditions: 0.5 Vrms, 1 kHz ± 10%, and a temperature of 300 °C. The electrostatic capacitance C was measured, and the dielectric constant and dielectric loss were calculated in conjunction with the sample size.

[0079]

[0080] Comparative Example 1

[0081] This invention provides a comparative example of a ceramic dielectric material. The difference between this comparative example and Example 6 is in step (4), where the compacted mixture is placed in a magnesium oxide crucible and heated to 1200°C at a rate of 5°C / min, and held at that temperature for 6 hours; the other steps are the same as in Example 6.

[0082] The measured dielectric constant is only 1035 F / m, and the dielectric loss is 118.

[0083] Comparative Example 2

[0084] Yang Dianlai, Zhang Yingying, Liu Kun, et al. Preparation of Ho by hydrothermal method 3+ / Y 3+ Study on the Dielectric Properties of Co-doped BaTiO3-based Powders [J]. Synthetic Materials Aging and Application, 2021, 50(06):78-80. DOI:10.16584 / j.cnki.issn1671-5381.2021.06.025. The authors prepared Ho using a hydrothermal method. 3+ / Y 3+ Co-doped BaTiO3-based dielectric ceramics, when w(Ho) 3+ ):w(Y 3+ When the ratio is 3:1, it exhibits the highest dielectric constant of 4542 F / m.

[0085] Comparative Example 3

[0086] Wang Lingxu, Guo Xiaodong, Zhang Fengqing, et al. Sr2Bi5FeTi5O 21 Study on dielectric properties of ceramics [J]. Rare Metal Materials and Engineering, 2018, 47(S1): 415-419. The authors prepared Sr2Bi5FeTi5O by sol-gel method. 21 (SBFTi) ceramic, whose dielectric constant increases with increasing temperature, exhibiting the highest dielectric constant of approximately 3300 F / m at 500°C.

[0087] Compared with the prior art, the present invention has the following advantages:

[0088] Compared to the sol-gel method and hydrothermal method, the preparation method of this invention requires no complex equipment or chemical reagents, only mixing, slurry coating, and sintering. The process is simple, low-cost, and suitable for large-scale industrial production. The dielectric properties of the prepared dielectric ceramics are 1 to 3 times higher than those prepared by the hydrothermal and sol-gel methods. The dielectric ceramics prepared by this invention have a high dielectric constant and low dielectric loss, which promotes the development of dielectric ceramics.

Claims

1. A BaTiO3-based dielectric ceramic doped at A and B sites, characterized in that, The chemical formula of the BaTiO3-based dielectric ceramic doped at sites A and B is: (Ba x1 Ca x2 Sr 1-x1-x2 )(Ti 0.4 La 0.2 Ce 0.2 Ta 0.2 )O3, 0 < x1 < 1, 0 < x2 < 1, and x1 + x2 < 1, where x1:x2 is 5:2 or 5:

3.

2. The method for preparing A- and B-site doped BaTiO3-based dielectric ceramics as described in claim 1, characterized in that, include: Weigh out BaCO3, CaCO3, SrCO3, TiO2, La2O3, CeO2, and Ta2O5 according to the measured molar ratio, mix them well, and then dry them. The dried product is compacted and then fired. The fired product is then ground to obtain sample powder. The sample powder was subjected to cold isostatic pressing followed by high-temperature segmented sintering to obtain the BaTiO3-based dielectric ceramic doped at sites A and B; the purity of the raw material powders BaCO3, CaCO3, SrCO3 and TiO2, La2O3, CeO2 and Ta2O5 was ≥99.7% and the particle size was ≤45μm. The mixing process is performed by ball milling, using anhydrous ethanol as the milling medium and ZrO2 beads as the milling beads. The mass ratio of the mixed powder to the milling beads to the anhydrous ethanol is 2:3:0.

4. An omnidirectional planetary ball mill is used, with a milling speed ≥200 rpm and a milling time ≥12 h. The drying temperature is 100-130℃ and the drying time is ≥8 h. The sample powder was compacted at a pressure ≥40MPa; The sample powder is sintered at a temperature of 1300-1550℃ for 12-48 hours. The product is ground by dry grinding using ZrO2 grinding beads at a powder-to-grinding-bead ratio of 2:

3. The grinding speed is 200-300 rpm, and the grinding time is ≥12 hours. The isostatic pressing process, followed by high-temperature segmented sintering, involves a pressure ≥120 MPa and a holding time ≥5 minutes. High-temperature segmented firing involves placing the obtained green blank in a high-temperature sintering furnace. In the first stage, the temperature is increased from room temperature to 1300-1550℃ at a heating rate of 1.5-5℃ / min and held for 2-6 hours. The second stage involves heating the temperature to 1650-1750℃ at a rate of 5-10℃ / min and holding it at that temperature for 4-8 hours; then cooling it to room temperature at a rate of 1.5-5℃ / min.

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