Strontium barium calcium niobate / CaAl2Si2O8 dielectric composite ceramic with high energy storage density and preparation method of strontium barium calcium niobate / CaAl2Si2O8 dielectric composite ceramic

Abstract

The invention provides high-energy-storage-density strontium barium calcium niobate / CaAl2Si2O8 dielectric composite ceramic and a preparation method thereof, belongs to the technical field of composite ceramic materials, and aims to solve the technical problem of low energy storage density of composite ceramic. According to the invention, high-entropy ceramic is combined with a second phase composite technology to enhance the energy storage characteristic of strontium barium calcium niobate dielectric ceramic, Sr < 1 / 3 > Ba1 / 3 > Ca < 1 / 3 > Nb < 1-0.2 x > Zr < 0.2 x > Mg < 0.2 x > Ti < 0.2 x > Hf < 0.2 x > Ta < 0.2 x > O < 3 > nano powder is prepared by a microwave sol-gel method, and the strontium barium calcium niobate / CaAl < 2 > Si < 2 > O < 8 > dielectric composite ceramic is prepared by a spark plasma sintering method. The composite dielectric ceramic prepared by the invention has relatively high breakdown-resistant field strength, relatively high dielectric property, energy storage density and good discharge efficiency, the breakdown-resistant field strength reaches 850kV / cm, and the maximum energy storage density reaches 8.23 J / cm < 3 >.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic materials, and particularly relates to a high energy storage density composite ceramic. Background Art

[0002] High energy density capacitors play a key role in power supply, electronic devices, and pulse power systems due to their excellent discharge power, high energy utilization efficiency, rapid charge and discharge speed, and stable performance. They are widely used in modern industrial and national defense fields such as hybrid electric vehicles, pulse power systems, electromagnetic guns, and electromagnetic launch platforms. With the development trend of electronic devices towards miniaturization, integration, and high speed, higher energy storage, smaller volume, lighter weight, lower cost, and higher reliability requirements are put forward for capacitor components. However, current capacitor components face problems such as low energy storage density, small discharge current, and short service life, resulting in large-sized energy storage capacitors and limiting their application scope. To achieve the development of capacitor components towards higher energy storage capabilities, the key lies in improving the energy storage density of the material itself.

[0003] Strontium barium niobate dielectric ceramics are favored due to their high dielectric constant, adjustable properties, broad working temperature range, and long cycle life. For example, in the patent publication number CN117623773A, a non-full type strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material and its preparation method, its structural formula is (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 M 0.5 O 6 , where M is Ta 1 / 3 Sb 1 / 3 Hf 1 / 3 、Ta 0.25 Sb 0.25 Ti 0.25 Zr 0.25 、Ta 0.2 Sb 0.2 Ti 0.2 Zr 0.2 Hf 0.2 、Ta 0.2 Sb 0.2 Sn 0.2 Zr 0.2 Hf 0.2One of them. This patent discloses that the high-entropy ferroelectric energy storage ceramic material is not broken down under the action of an external electric field of 550 kV / cm, has a high energy storage density and energy storage efficiency, and meets the requirements of advanced pulsed power capacitors. However, in actual use, due to the influence of factors such as grain boundaries, pores, impurities, surface defects, and chemical corrosion, this material often breaks down at a lower electric field. In particular, the samples prepared by the traditional solid-state reaction sintering method usually contain pores and microcracks, thus reducing their breakdown strength. Summary of the Invention

[0004] Aiming at the technical problems of low breakdown field strength and low energy storage density of energy storage ceramics, the present invention proposes a high-energy storage density strontium barium calcium niobate / CaAl 2 Si 2 O 8 dielectric composite ceramic and its preparation method. The prepared strontium barium calcium niobate / CaAl 2 Si 2 O 8 dielectric composite ceramic has high dielectric properties, high breakdown field strength, and high energy storage performance.

[0005] In order to achieve the above object, the technical solution of the present invention is realized as follows:

[0006] A preparation method of a high-energy storage density strontium barium calcium niobate / CaAl 2 Si 2 O 8 dielectric composite ceramic, comprising the following steps:

[0007] (1) Prepare Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowders, 0.02 ≤ x ≤ 0.15;

[0008] (2) Mix the Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowders and CaAl 2 Si 2 O 8The nano-powders are mixed and ball-milled, and then tableted to obtain ceramic sheets;

[0009] (3) The ceramic sheets are subjected to spark plasma sintering to prepare Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 / CaAl 2 Si 2 O 8 composite dielectric ceramics.

[0010] CaAl 2 Si 2 O 8 Although CaAl 2 Si 2 O 8 ceramics have a relatively high breakdown strength, their dielectric constant is relatively low. By combining the high dielectric constant characteristics of strontium barium niobate ceramics with the advantages of CaAl

[0011] Preferably, the steps for preparing the Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nano-powders are as follows: According to the stoichiometric ratio, the raw material powders Sr(OH) 2 , Ba(OH) 2 , Ca(OH) 2 Nb 2 O 5 , ZrO 2 , MgO, TiO 2 , HfO 2 , Ta 2 O 5, is dispersed and dissolved in a solvent together with a complexing agent and a dispersant, and the reaction is carried out under microwave assistance. After the reaction is completed, it is dried, ground and sintered to obtain Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowder.

[0012] The mass ratio of the raw material powder, complexing agent, dispersant and solvent is 1:(1 - 2.8):(0.8 - 1.5):(7 - 11.8).

[0013] The complexing agent is ethylenediaminetetraacetic acid or / and citric acid; the dispersant is polyvinyl alcohol; the solvent is water or / and ethanol.

[0014] The mass ratio of the raw material powder, ethylenediaminetetraacetic acid, polyvinyl alcohol, citric acid, water, ethanol is 1:(0.5 - 1.2):(0.8 - 1.5):(0.5 - 1.6):(4 - 6.8):(3 - 5).

[0015] The temperature of the reaction carried out under microwave assistance is 65 - 80 °C, and the reaction time is 120 - 300 min.

[0016] The temperature of the sintering is 850 - 960 °C, and the heat preservation time is 6 - 10 h.

[0017] The Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The nanopowder accounts for 90 - 98% of the sum of the masses of the Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowder and CaAl 2 Si 2 O 8 nanopowder.

[0018] The process of the spark plasma sintering is as follows: Place the ceramic sheet into the spark plasma sintering furnace. When the temperature in the furnace is lower than 480 °C, the pressure in the furnace is 15 - 20 MPa, the heating rate is 50 - 80 °C per minute, and keep it at 480 °C for 5 - 10 min; then raise the temperature to 1020 - 1120 °C, the pressure in the furnace is 25 - 35 MPa, the heating rate is 30 - 70 °C per minute, and keep it for 5 - 10 min; after cooling, high energy storage density Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 / CaAl 2 Si 2 O 8 composite dielectric ceramics.

[0019] The beneficial effects of the present invention: Through effective dispersion and composite technologies, the present invention makes the heterogeneous phase nanoparticles evenly distributed in the ceramic matrix to form a composite material. Utilize the high entropy ceramic combined with the second phase composite technology to enhance the energy storage characteristics of the strontium barium calcium niobate dielectric ceramics, combine the high dielectric constant characteristics of the strontium barium niobate ceramics with the advantages of CaAl 2 Si 2 O 8 ceramics, and at the same time form high entropy ceramics by doping with Zr, Mg, Ti, Hf, Ta and other ions to improve the dielectric properties of the strontium barium niobate ceramic materials. On the other hand, introduce the low dielectric constant CaAl 2 Si 2 O 8 ceramics to improve the internal electric field distribution in the composite ceramics, and use the spark plasma sintering process to prepare a composite ceramic material with both high density and excellent comprehensive properties, realizing high dielectric constant and breakdown field strength, thereby improving the energy storage density of the material. The dielectric composite material has a breakdown field strength of up to 850 kV / cm and a maximum energy storage density of up to 8.23 J / cm 3 . The Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 / CaAl 2 Si 2 O 8The composite dielectric ceramic can be applied to pulse power energy storage capacitors. Brief Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 SEM cross-sectional view of the composite ceramic prepared for Example 3.

[0022] Figure 2 Comparison of the breakdown field strengths of the composite ceramics prepared for Examples 1, 2, 3, 4, and 5.

[0023] Figure 3 Dielectric constant diagram of the composite ceramics prepared for Examples 1, 2, 3, 4, and 5 at room temperature and a test frequency of 1 kHz.

[0024] Figure 4 Energy storage density diagram of the composite ceramics prepared for Examples 1, 2, 3, 4, and 5. Detailed Embodiments

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0026] Example 1

[0027] A high energy storage density strontium barium calcium niobate / CaAl 2 Si 2 O 8 Dielectric composite ceramic, the composite ceramic is composed of CaAl 2 Si 2 O 8 and Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowders (x = 0.02), Sr 1 / 3 Ba1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The mass percentage of the nano-powder (x = 0.02) is 90%, and the CaAl 2 Si 2 O 8 The mass percentage is 10%.

[0028] Its preparation method includes the following steps:

[0029] (1) Preparation of Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The process of the nano-powder (x = 0.02) is as follows: Calculate and weigh Sr(OH) according to the stoichiometric ratio 2 , Ba(OH) 2 , Ca(OH) 2 , Nb 2 O 5 , ZrO 2 , MgO, TiO 2 and HfO 2 , Ta 2 O 5 , then mix the raw material powder, ethylenediaminetetraacetic acid, polyvinyl alcohol, citric acid, water, and alcohol in a mass ratio of 1:0.5:0.8:0.5:4:3, and stir magnetically at 30 °C for 3 hours; then react in a microwave reactor at a reaction temperature of 80 °C for a reaction time of 120 min to obtain a sol, dry and grind it at 90 °C, and sinter it at 850 °C for 8 h to obtain Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 (x = 0.02) nano-powder.

[0030] (2) Mix the above nano-powders using a ball mill, Sr1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The mass percentage of the nano-powder (x = 0.02) is 90%, and the mass percentage of the said CaAl 2 Si 2 O 8 is 10%. When ball milling, anhydrous ethanol and ZrO 2 are used as ball milling media, the rotation speed is 350 r / min, the running direction is adjusted every half an hour, the ball milling time is 6 h, and the traditional ceramic pressing process is used for pressing and forming.

[0031] (3) Using the spark plasma sintering method to prepare Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2 x O 3 / CaAl 2 Si 2 O 8 composite ceramics. The ceramic sheet is placed in a spark plasma sintering furnace. When the temperature in the furnace is lower than 480 °C, the pressure in the furnace is 15 MPa, the heating rate is 50 °C per minute, and it is kept warm at 480 °C for 5 min; then the temperature is raised to 1020 °C, the pressure in the furnace is 25 MPa, the heating rate is 30 °C per minute, and it is kept warm for 5 min; after cooling, high energy storage density Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 / CaAl 2 Si 2 O 8 composite dielectric ceramics.

[0032] Example 2

[0033] A kind of strontium barium calcium niobate / CaAl 2 Si2 O 8 Dielectric composite ceramics, the composite ceramics are composed of CaAl 2 Si 2 O 8 and Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowders (x = 0.13), the mass percentage of Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowders (x = 0.13) is 93%, and the mass percentage of the said CaAl 2 Si 2 O 8 is 7%.

[0034] Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The preparation method of the nanopowders (x = 0.13) is as follows:

[0035] (1) The process of preparing Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowders (x = 0.13) is as follows: Weigh Sr(OH) 2 、Ba(OH) 2 、Ca(OH) 2 Nb 2 O 5 、ZrO2 , MgO, TiO 2 and HfO 2 , Ta 2 O 5 , then mix the raw material powder, ethylenediaminetetraacetic acid, polyvinyl alcohol, citric acid, water, and alcohol in a mass ratio of 1:1.1:1.2:1.3:4.7:4.5, and magnetically stir at 38 °C for 4 hours; then react in a microwave reactor at a reaction temperature of 65 °C for a reaction time of 300 min to obtain a sol. After drying at 96 °C and grinding, sinter at 960 °C for 8 h to obtain Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowder (x = 0.13).

[0036] (2) Mix the above nanopowder using a ball mill. The mass percentage of Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowder (x = 0.13) is 93%, and the mass percentage of the said CaAl 2 Si 2 O 8 is 7%. Use absolute ethanol and ZrO 2 as the ball milling medium, with a rotation speed of 470 r / min. Adjust the rotation direction every half hour, and the ball milling time is 7 h. Use the traditional ceramic pressing process for pressing and forming.

[0037] (3) Prepare Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2 x O 3 / CaAl 2 Si 2 O 8Composite ceramics. Place the ceramic pieces into a spark plasma sintering furnace. When the temperature in the furnace is lower than 480 °C, the pressure in the furnace is 18 MPa, the heating rate is 60 °C per minute, and keep it at 480 °C for 7 minutes; then raise the temperature to 1110 °C, the pressure in the furnace is 32 MPa, the heating rate is 50 °C per minute, and keep it for 8 minutes; after cooling, high energy storage density Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 / CaAl 2 Si 2 O 8 Composite dielectric ceramics.

[0038] Example 3

[0039] A high energy storage density strontium barium calcium niobate / CaAl 2 Si 2 O 8 dielectric composite ceramic and its preparation method: The composite ceramic is composed of CaAl 2 Si 2 O 8 and Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowders (x = 0.05). The mass percentage of Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowders (x = 0.05) is 95%, and the mass percentage of the said CaAl 2 Si 2 O 8 is 5%.

[0040] Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 Nano powder (x = 0.05), the steps are as follows:

[0041] (1) Preparation of Sr by microwave sol-gel method 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The process of nanopowder (x = 0.05) is as follows: Calculate and weigh Sr(OH) according to the stoichiometric ratio 2 、Ba(OH) 2 , Ca(OH) 2 Nb 2 O 5 、ZrO 2 ,MgO,TiO 2 and HfO 2 、 2 O 5 Then, the raw material powder I, ethylenediaminetetraacetic acid, polyvinyl alcohol, citric acid, water and alcohol were mixed in a mass ratio of 1:0.7:1.2:1.3:5.2:4, and magnetically stirred at 40°C for 4 hours; then a microwave sol-gel reaction was carried out, the reaction temperature of the microwave reactor was 70°C, the reaction time was 150min, and a sol was obtained. After drying and grinding at 95°C, Sr was obtained by sintering at 930°C for 6h. 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 Nanopowder (x=0.05).

[0042] (2) Use a ball mill to mix the above nanopowders, Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3The mass percentage of the nano-powder (x = 0.05) is 95%, and the mass percentage of CaAl 2 Si 2 O 8 is 5%. During ball milling, absolute ethanol and ZrO 2 are used as the ball milling medium, the rotation speed is 450 r / min, the rotation direction is adjusted every half hour, the ball milling time is 7 h, and the traditional ceramic pressing process is used for pressing and forming.

[0043] (3) Preparation of Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2 x O 3 / CaAl 2 Si 2 O 8 composite ceramics. The ceramic sheet is placed in a spark plasma sintering furnace. When the temperature in the furnace is lower than 480 °C, the pressure in the furnace is 17 MPa, the heating rate is 60 °C per minute, and it is kept at 480 °C for 7 min; then the temperature is raised to 1100 °C, the pressure in the furnace is 30 MPa, the heating rate is 60 °C per minute, and it is kept at the temperature for 8 min; after cooling, high energy storage density Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 / CaAl 2 Si 2 O 8 composite dielectric ceramics.

[0044] Example 4

[0045] A high energy storage density strontium barium calcium niobate / CaAl 2 Si 2 O 8 dielectric composite ceramic and its preparation method: The composite ceramic is composed of CaA l 2 Si 2 O 8 and Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2xZr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanometer powder (x = 0.10), Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The mass percentage of the nanometer powder (x = 0.10) is 96%, and the CaAl 2 Si 2 O 8 The mass percentage is 4%.

[0046] Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanometer powder (x = 0.10), the steps are as follows:

[0047] (1) Preparation of Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The process of the nanometer powder (x = 0.10) is as follows: Calculate and weigh Sr(OH) 2 , Ba(OH) 2 , Ca(OH) 2 Nb 2 O 5 , ZrO 2 , MgO, TiO 2 and HfO 2 , Ta 2 O 5, then the raw material powder I, ethylenediaminetetraacetic acid, polyvinyl alcohol, citric acid, water, and alcohol are mixed at a mass ratio of 1:0.8:1.4:1.2:6.3:4.5 and magnetically stirred at 42 °C for 4.5 hours; then a microwave sol-gel reaction is carried out. The reaction temperature of the microwave reactor is 75 °C and the reaction time is 200 min to obtain a sol. After drying at 98 °C and grinding, it is sintered at 910 °C for 10 h to obtain Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowder (x = 0.10).

[0048] (2) Mix the above nanopowders using a ball mill. The mass percentage content of Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowder (x = 0.10) is 96%, and the mass percentage content of the said CaAl 2 Si 2 O 8 is 4%. During ball milling, absolute ethanol and ZrO 2 are used as ball milling media, the rotation speed is 480 r / min, the rotation direction is adjusted every half hour, the ball milling time is 8.5 h, and a tablet is formed using the traditional ceramic tablet pressing process.

[0049] (3) Prepare Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2 x O 3 / CaAl 2 Si 2 O 8Composite ceramics. Place the ceramic pieces into a spark plasma sintering furnace. When the temperature in the furnace is lower than 480 °C, the pressure in the furnace is 19 MPa, the heating rate is 75 °C per minute, and hold at 480 °C for 9 minutes; then raise the temperature to 1080 °C, the pressure in the furnace is 34 MPa, the heating rate is 68 °C per minute, and hold for 9 minutes; after cooling, high energy storage density Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 / CaAl 2 Si 2 O 8 Composite dielectric ceramics.

[0050] Example 5

[0051] A strontium barium calcium niobate / CaAl 2 Si 2 O 8 Dielectric composite ceramics and its preparation method: The composite ceramics are composed of CaAl 2 Si 2 O 8 and Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowders (x = 0.15). The mass percentage of Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanopowders (x = 0.15) is 98%, and the mass percentage of the said CaAl 2 Si 2 O 8 is 2%.

[0052] Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanometer powder (x = 0.15), the steps are as follows:

[0053] (1) Preparation of Sr by microwave sol-gel method 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The process of the nanometer powder is as follows: Calculate and weigh Sr(OH) according to the stoichiometric ratio 2 , Ba(OH) 2 , Ca(OH) 2 Nb 2 O 5 , ZrO 2 , MgO, TiO 2 and HfO 2 , Ta 2 O 5 , then mix the raw material powder I, ethylenediaminetetraacetic acid, polyvinyl alcohol, citric acid, water, and alcohol in a mass ratio of 1:1.2:1.5:1.6:6.8:5, and stir magnetically at 45 °C for 5 hours; then carry out microwave sol-gel reaction. The reaction temperature of the microwave reactor is 78 °C, and the reaction time is 150 min to obtain a sol. After drying at 100 °C and grinding, sinter at 950 °C for 8 h to obtain Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nanometer powder (x = 0.15).

[0054] (2) Mix the above nanometer powders using a ball mill, Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3The mass percentage of the nano powder is 98%, and the mass percentage of CaAl 2 Si 2 O 8 is 2%. During ball milling, absolute ethanol and ZrO 2 are used as the ball milling media, the rotation speed is 500 r / min, the rotation direction is adjusted every half hour, the ball milling time is 9 h, and the traditional ceramic pressing process is used for pressing and forming.

[0055] (3) Prepare the Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2 x O 3 / CaAl 2 Si 2 O 8 composite ceramic. Place the ceramic sheet into a spark plasma sintering furnace. When the temperature in the furnace is lower than 480 °C, the pressure in the furnace is 20 MPa, the heating rate is 80 °C per minute, and it is held at 480 °C for 10 min; then the temperature is raised to 1120 °C, the pressure in the furnace is 35 MPa, the heating rate is 70 °C per minute, and it is held for 10 min; after cooling, a high energy storage density Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 / CaAl 2 Si 2 O 8 composite dielectric ceramic.

[0056] Figure 1 For the Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 / CaAl 2 Si 2 O 8SEM image of the cross-section of the composite ceramic (x = 0.05). The size of the powder is between 60 - 160 nm, and the grains of the composite material are dense.

[0057] Figure 2 Diagram of the breakdown field strength of the composite ceramics prepared in Examples 1, 2, 3, 4, and 5. The breakdown field strength of the composite ceramic prepared in Example 1 reaches 850 kV / cm.

[0058] Figure 3 Diagram of the dielectric constant of the composite ceramics prepared in Examples 1, 2, 3, 4, and 5 at room temperature and a test frequency of 1 kHz. When the CaAl 2 Si 2 O 8 composite content is 10 wt%, the dielectric constant of the composite ceramic is 630.

[0059] Figure 4 Diagram of the room-temperature energy storage density of the composite ceramics prepared in Examples 1, 2, 3, 4, and 5. It can be found that when the CaAl 2 Si 2 O 8 composite content is 5 wt%, the energy storage density of the composite ceramic reaches 8.23 J / cm 3 .

[0060] Example 6

[0061] A high-energy storage density strontium barium calcium niobate / CaAl 2 Si 2 O 8 dielectric composite ceramic and its preparation method: The composite ceramic is composed of CaAl 2 Si 2 O 8 and Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nano-powders (x = 0.05). The mass percentage of Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 nano-powders (x = 0.1) is 95%, and the described CaAl 2 Si2 O 8 The mass percentage is 5%.

[0062] Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 Nano-powder (x = 0.05), the steps are as follows:

[0063] (1) Prepare Sr by microwave sol-gel method 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The process of nano-powder (x = 0.05) is as follows: Calculate and weigh Sr(OH) according to the stoichiometric ratio 2 , Ba(OH) 2 , Ca(OH) 2 Nb 2 O 5 , ZrO 2 , MgO, TiO 2 and HfO 2 , Ta 2 O 5 , then mix the raw material powder I, ethylenediaminetetraacetic acid, polyvinyl alcohol, citric acid, water, and alcohol in a mass ratio of 1:1.2:1.2:1.3:5.6:4, and stir magnetically at 40 °C for 4 hours; then carry out microwave sol-gel reaction, the reaction temperature of the microwave reactor is 80 °C, the reaction time: 150 min, to obtain a sol, after drying at 95 °C and grinding, sinter at 890 °C for 8 h to obtain Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 Nano-powder (x = 0.1).

[0064] (2) Mix the above nano-powders using a ball mill, Sr 1 / 3 Ba 1 / 3 Ca1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 The mass percentage of the nano powder (x = 0.1) is 95%, and the described CaAl 2 Si 2 O 8 has a mass percentage of 5%. During ball milling, absolute ethanol and ZrO 2 are used as the ball milling medium, the rotation speed is 450 r / min, the rotation direction is adjusted every half hour, the ball milling time is 7 h, and the traditional ceramic tablet pressing process is used for tablet pressing and forming.

[0065] (3) Prepare the Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2 x O 3 / CaAl 2 Si 2 O 8 composite ceramic. Place the ceramic sheet into a spark plasma sintering furnace. When the temperature in the furnace is lower than 480 °C, the pressure in the furnace is: 20 MPa, the heating rate is 60 °C per minute, and keep it at 480 °C for 10 min; then raise the temperature to 1100 °C, the pressure in the furnace is 35 MPa, the heating rate is 60 °C per minute, and keep it at 1100 °C for 10 min; after cooling, obtain the high energy storage density Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O 3 / CaAl 2 Si 2 O 8 composite dielectric ceramic.

[0066] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a high energy storage density calcium strontium barium niobate / CaAl2Si2O8 dielectric composite ceramic, characterized in that: The following steps are involved: (1) Preparation of Sr by microwave sol-gel method 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O3 nanopowder, 0.02≤x≤0.15; (2) Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O3 nanopowder and CaAl2Si2O8 nanopowder are mixed and ball-milled, and then pressed into tablets to obtain ceramic sheets; (3) Spark plasma sintering of ceramic sheets to prepare Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O3 / CaAl2Si2O8 composite dielectric ceramics.

2. The method for preparing the high energy storage density calcium strontium barium niobate / CaAl2Si2O8 dielectric composite ceramic according to claim 1, characterized in that: The microwave sol-gel method for preparing Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2 x The steps of preparing O3 nano powder are as follows: dispersing and dissolving raw material powders Sr(OH)2, Ba(OH)2, Ca(OH)2, Nb2O5, ZrO2, MgO, TiO2, HfO2 and Ta2O5 in a solvent with a complexing agent and a dispersant according to a stoichiometric ratio, reacting under the assistance of microwaves, drying, grinding and sintering to obtain Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O3 nano powder.

3. The method for preparing the high energy storage density calcium strontium barium niobate / CaAl2Si2O8 dielectric composite ceramic according to claim 2, characterized in that: The mass ratio of the raw material powder, complexing agent, dispersant and solvent is 1:(1-2.8):(0.8-1.5):(7-11.8).

4. The method for preparing the high energy storage density calcium strontium barium niobate / CaAl2Si2O8 dielectric composite ceramic according to claim 3, characterized in that: The complexing agent is ethylenediaminetetraacetic acid and / or citric acid; the dispersant is polyvinyl alcohol; and the solvent is water and / or ethanol.

5. The method for preparing the high energy storage density calcium strontium barium niobate / CaAl2Si2O8 dielectric composite ceramic according to claim 4, characterized in that: The mass ratio of the raw material powder, ethylenediaminetetraacetic acid, polyvinyl alcohol, citric acid, water and ethanol is 1:(0.5-1.2):(0.8-1.5):(0.5-1.6):(4-6.8):(3-5).

6. The method for preparing the high energy storage density calcium barium strontium niobate / CaAl2Si2O8 dielectric composite ceramic according to any one of claims 1 to 5, characterized in that: The temperature for the microwave-assisted reaction is 65-80° C., and the reaction time is 120-300 min.

7. The method for preparing the high energy storage density calcium strontium barium niobate / CaAl2Si2O8 dielectric composite ceramic according to claim 6, characterized in that: The sintering temperature is 850-960° C., and the heat preservation time is 6-10 hours.

8. The method for preparing the high energy storage density calcium strontium barium niobate / CaAl2Si2O8 dielectric composite ceramic according to claim 7, characterized in that: The Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O3 nanopowder accounts for Sr 1 / 3Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x 90-98% of the sum of the mass of O3 nanopowder and CaAl2Si2O8 nanopowder.

9. The method for preparing the high energy storage density calcium strontium barium niobate / CaAl2Si2O8 dielectric composite ceramic according to claim 1, characterized in that: The spark plasma sintering process is as follows: placing the ceramic sheet in a spark plasma sintering furnace, when the temperature in the furnace is lower than 480°C, the pressure in the furnace is 15-20MPa, the heating rate is 50-80°C per minute, and the temperature is kept at 480°C for 5-10min; then the temperature is raised to 1020-1120°C, the pressure in the furnace is 25-35MPa, the heating rate is 30-70°C per minute, and the temperature is kept for 5-10min; after cooling, a high energy storage density Sr 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2 x O3 / CaAl2Si2O8 composite dielectric ceramics.

10. The high energy storage density Sr prepared by the method according to any one of claims 1 to 9 1 / 3 Ba 1 / 3 Ca 1 / 3 Nb 1-0.2x Zr 0.2x Mg 0.2x Ti 0.2x Hf 0.2x Ta 0.2x O3 / CaAl2Si2O8 composite ceramics.

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