MnO-coated "core-shell" structure fine-crystal energy storage dielectric ceramic material, preparation method and application thereof

Abstract

This invention belongs to the technical field of electronic ceramic energy storage capacitor materials, specifically relating to a fine-grained energy storage dielectric ceramic material with a MnO-coated "core-shell" structure, its preparation method, and its applications. The dielectric ceramic material BBT of this invention, due to its excellent dielectric properties, selects micro-nano BBT powder particles as the "core" material, while MnO... 2+ and Ti 4+ The ionic radii of manganese and barium titanate are similar, making it easier for manganese to occupy titanium sites in barium titanate during substitution. When low-valence manganese replaces high-valence titanium, defects are formed in the ceramic crystal, thus reducing the dielectric constant; while Mn... 3+ and Mn 4+ It can effectively capture electrons, thereby reducing the carrier concentration in dielectric ceramic materials, resulting in low dielectric loss and increased resistivity. Based on this microstructure design, the ceramic micromorphology can be optimized, dielectric loss reduced, and energy storage density increased.

Description

Technical Field

[0001] This invention belongs to the technical field of electronic ceramic energy storage capacitor materials, specifically relating to a fine-grained energy storage dielectric ceramic material with a MnO-coated "core-shell" structure, its preparation method, and its application. Background Technology

[0002] Barium titanate (BaTiO3) has been proven to be an excellent ferroelectric ceramic. The ferroelectricity of BaTiO3 originates from the spontaneous polarization of the crystal below its transformation temperature. Due to its advantages such as high dielectric constant, extremely low dielectric loss, low leakage current, and low electro-optic coefficient, it has potential applications in various electronic devices, including multilayer ceramic capacitors, positive temperature coefficient (PTC) resistors, optoelectronic devices, piezoelectric sensors, and energy storage systems. Bi-containing compounds, due to their low melting point and easy volatilization during high-temperature sintering, can promote ceramic sintering without deteriorating the dielectric properties of the ceramic, and are therefore highly favored by researchers.

[0003] Ur et al. prepared 0.94BT-0.06BMC+xwt.%SiO2 ceramics using a solid-state sintering method; while the 0.94BT-0.06BMC+1wt.%SiO2 ceramic sample exhibited good storage density (W). rec =1.035J / cm -3 ) and high dielectric breakdown strength (BDS = 285 kV / cm) -1 This indicates that an appropriate amount of SiO2 doping in BT-BMC ceramics can improve the insulation performance and BDS of the ceramics, enabling their application in capacitors. (Ur, Manan A, Khan MA, et al. The effects of SiO2 addition on the phase, microstructure, dielectric, and energy storage properties of BaTiO3-based ceramics[J]. Materials Science & Engineering, B. Solid-State Materials for Advanced Technology, 2023.). Lai et al. prepared MgO-coated BT powder using a chemical precipitation method, obtaining BaTiO3@xMgO (x=0-7mol%) ceramics with a "core-shell" structure. Compared to solid-state methods, wet chemical methods can more effectively modify the powder surface, easily forming a "core-shell" structure, which is beneficial for forming fine-grained ceramics with good stability at high temperatures. Because Mg... 2+ Ion-substituted Ti 4+ ions, Mg 2+The solid solubility limit of ions is 0.8 mol%; when x ≥ 0.8 mol%, Mg 2+ Ions remain at the grain boundaries, forming a secondary phase, and a core-shell structure is obtained through the Mg gradient distribution, indicating that the formed "core-shell" structure has stable dielectric properties. (Lai X, Hao H, Liu Z, et al. Structure and dielectric properties of MgO-coated BaTiO3 ceramics[J]. Journal of Materials Science: Materials in Electronics, 2020, 31(11).). Shalu et al. synthesized lead-free, environmentally friendly polycrystalline BSMT nanoparticles using the sol-gel method, doping BaTiO3 with different amounts of Mn. 0.7 Sr 0.3 In TiO3, doping with an appropriate amount of Mn can promote the mass transfer process, but at higher solution concentrations, Mn ions hinder the diffusion of other ions, leading to a reduction in grain size; moreover, the 2% Mn-doped sample exhibits the highest dielectric constant and excellent ferroelectric properties. (Shalu S, Roy S, Mukherjee A. Effect of Mn-doping on the morphological and electrical properties of (Ba 0.7 Sr 0.3 )(Mn x Ti1 -x )O3 materials for energy storage application[J]. Ceramics International, 2022(18):48.).

[0004] To further meet the demands for high energy density and miniaturization of core-shell structure materials, there is an urgent need for a fine-grained MnO-coated core-shell structure energy storage dielectric ceramic material to optimize its dielectric and energy storage properties. Furthermore, there is an urgent need for a method to prepare this MnO-coated core-shell structure fine-grained energy storage dielectric ceramic material, thereby laying the foundation for the fabrication of multilayer ceramic capacitors.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a fine-grained energy storage dielectric ceramic material with a MnO-coated "core-shell" structure, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] On one hand, this invention provides a fine-grained energy storage dielectric ceramic material with a MnO-coated "core-shell" structure, employing materials including Ba... 0.99 Bi 0.01 The material is made of TiO3@xMnO micro / nano powder, and the Ba 0.99 Bi 0.01 TiO3@xMnO micro / nano powder comprises a "core" and a "shell," wherein the "core" material is Ba. 0.99 B i0.01 TiO3, wherein the shell material is MnO;

[0009] Wherein, 0≤x≤1, and x can be adaptively adjusted according to actual preparation needs. Optional values ​​are 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%, etc., which will not be listed one by one.

[0010] On the other hand, this invention provides a method for preparing a fine-grained energy storage dielectric ceramic material with a MnO-coated "core-shell" structure, firstly by preparing monodisperse Ba through a chemical precipitation method. 0.99 B i0.01 TiO3 micro / nano powders were then used to prepare monodisperse MnO-coated Ba2O3 using a liquid-phase coating method. 0.99 B i0.01 TiO3@xMnO micro / nano powder was finally sintered to prepare Ba 0.99 Bi 0.01 TiO3@xMnO dielectric ceramic material.

[0011] The specific steps are as follows:

[0012] Step 1: Add TiCl4 solution dropwise to 4-8 mol / L NaOH solution, and simultaneously place in a water bath at 10-40℃ and stir thoroughly for 0.5-2 hours;

[0013] Step 2: Prepare aqueous solutions of bismuth compound and barium compound according to the stoichiometric ratio, and then slowly add the solutions to each solution while stirring continuously. The reaction temperature is 10-40℃ and the stirring reaction time is 0.5-2h.

[0014] Step 3: Place the obtained solution in a water bath at 80-100℃ and stir continuously for 4-6 hours. Then filter and dry in an oven at 80-100℃ to obtain Ba. 0.99 Bi 0.01 TiO3 powder;

[0015] Step 4, Ba 0.99 Bi 0.01TiO3 powder was ultrasonically dispersed in deionized water and ethanol to obtain Ba 0.99 Bi 0.01 TiO3 suspension was prepared, and then a 30% ammonia solution was added, and the pH was adjusted to 9-11; the mass ratio of deionized water to ethanol was (2:3);

[0016] Step 5: Prepare a manganese acetate solution using the stoichiometric ratio, then add it dropwise to the above solution while simultaneously stirring mechanically at a speed of 60-80 rpm to ensure uniform mixing and promote the uniform coating of Ba with the generated MnO. 0.99 Bi 0.01 TiO3 particle surface;

[0017] Step 6: After complete precipitation, age the solution for a certain period of time, then filter the suspension and wash it multiple times. Dry the solution in an oven at 80-100℃ to obtain micro / nano powder. Calcine the obtained micro / nano powder in air at 700-900℃ for 1-2 hours, and then cool to obtain Ba. 0.99 Bi 0.01 TiO3@xMnO micro / nano media powder;

[0018] Step 7, for Ba 0.99 Bi 0.01 TiO3@xMnO micro / nano dielectric powder was granulated using PVA and glycerol grinding. After granulation, it was pressed into sheets using a mold at 8-10 MPa and sintered at 1220-1260℃ for 2-4 hours to prepare Ba. 0.99 Bi 0.01 TiO3@xMnO dielectric ceramic material.

[0019] Specifically, the Ba obtained in step 3 0.99 Bi 0.01 TiO3 powder is a monodisperse micro-nano powder with a particle size of 50-500 nm.

[0020] Specifically, the Ba obtained in step 6 0.99 Bi 0.01 The ceramic grains of TiO3@xMnO micro / nano dielectric powder are approximately 100-500 nm.

[0021] Specifically, the MnO is coated with monodisperse Ba. 0.99 Bi 0.01 Surface of TiO3 particles.

[0022] Specifically, in step 7, the Ba 0.99 Bi 0.01 TiO3@xMnO micro / nano powder is pressed and then sintered at 1220-1260℃ for 2-6 hours to produce dielectric ceramic materials.

[0023] Specifically, the Ba prepared in step 7 0.99 Bi 0.01 The discharge energy storage density of TiO3@xMnO dielectric ceramic materials is 0.09-0.26 J / cm³. 3 .

[0024] On the other hand, the present invention provides Ba prepared by the method described above. 0.99 Bi 0.01 Applications of TiO3@xMnO dielectric ceramic materials, the Ba 0.99 Bi 0.01 TiO3@xMnO dielectric ceramic materials are used in applications including, but not limited to, the fabrication of multilayer ceramic capacitors, positive temperature coefficient (PTC) resistors, optoelectronic devices, piezoelectric sensors, and energy storage systems.

[0025] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0026] This invention designs a fine-grained energy storage dielectric ceramic material, BBT, with controllable microstructure. Due to BBT's excellent dielectric properties, we selected micro / nano BBT powder particles as the "core" material, while Mn... 2+ and Ti 4+ The ionic radii of manganese and barium titanate are similar, making it easier for manganese to occupy titanium sites in barium titanate during substitution. When low-valence manganese replaces high-valence titanium, defects are formed in the ceramic crystal, thus reducing the dielectric constant; while Mn... 3+ and Mn 4+ It can effectively capture electrons, thereby reducing the carrier concentration in dielectric ceramic materials, resulting in low dielectric loss and increased resistivity. Based on this microstructure design, the ceramic micromorphology can be optimized, dielectric loss reduced, and energy storage density increased.

[0027] Furthermore, the Ba prepared by this invention 0.99 Bi 0.01 TiO3 micro / nano powder materials have the characteristics of particle size of 50-500nm and good dispersibility.

[0028] Furthermore, the fine-grained energy storage dielectric ceramic material prepared by this invention achieves a discharge energy storage density of 0.26 J / cm². 3 It has a dielectric constant of 3610 and low dielectric loss.

[0029] Furthermore, the ceramic grains prepared by this invention have a size of approximately 100-500 nm, uniform particle size, and high reliability, making them suitable for producing ceramic energy storage capacitors with large capacity and ultra-thin dielectric layers. Attached Figure Description

[0030] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 For example, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6Ba in Example 1 0.99 Bi 0.01 SEM image of TiO3@xMnO media powder sample;

[0033] Figure 2 For example #1-3Ba in Example 1 0.99 Bi 0.01 TEM image of TiO3@0.4mol%MnO media powder sample;

[0034] Figure 3 For example, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6Ba in Example 1 0.99 Bi 0.01 SEM image of TiO3@xMnO dielectric ceramic sample;

[0035] Figure 4 For example, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6Ba in Example 1 0.99 Bi 0.01 XRD pattern of TiO3@xMnO media powder;

[0036] Figure 5 For example, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6Ba in Example 1 0.99 Bi 0.01 XRD pattern of TiO3@xMnO dielectric ceramic sample;

[0037] Figure 6 For example, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6Ba in Example 1 0.99 Bi 0.01 Dielectric constant diagram of TiO3@xMnO dielectric ceramic sample;

[0038] Figure 7For example, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6Ba in Example 1 0.99 Bi 0.01 The characteristic curve of dielectric loss as a function of temperature for TiO3@xMnO dielectric ceramic samples.

[0039] Figure 8 For example, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6Ba in Example 1 0.99 Bi 0.01 Hysteresis loop diagram of TiO3@xMnO dielectric ceramic sample before breakdown;

[0040] Figure 9 For example, #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6Ba in Example 2 0.99 Bi 0.01 SEM image of TiO3@xMnO dielectric ceramic sample;

[0041] Figure 10 For example, #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6Ba in Example 2 0.99 Bi 0.01 XRD pattern of TiO3@xMnO dielectric ceramic sample;

[0042] Figure 11 For example, #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6Ba in Example 2 0.99 Bi 0.01 Dielectric constant diagram of TiO3@xMnO dielectric ceramic sample;

[0043] Figure 12 For example, #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6Ba in Example 2 0.99 Bi 0.01 The characteristic curve of dielectric loss as a function of temperature for TiO3@xMnO dielectric ceramic samples.

[0044] Figure 13 For example, #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6Ba in Example 2 0.99 Bi 0.01 Hysteresis loop of TiO3@xMnO dielectric ceramic sample before breakdown. Detailed Implementation

[0045] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. The embodiments described below do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0046] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0047] This invention provides a fine-grained energy storage dielectric ceramic material with a MnO-coated "core-shell" structure, employing materials including Ba... 0.99 Bi 0.01 It is made of TiO3@xMnO micro / nano powder, and the Ba 0.99 Bi 0.01 TiO3@xMnO micro / nano powder comprises a "core" and a "shell," wherein the "core" material is Ba. 0.99 B i0.01 TiO3, wherein the shell material is MnO;

[0048] Wherein, 0≤x≤1, and x can be adaptively adjusted according to actual preparation needs. Optional values ​​are 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%, etc., which will not be listed one by one.

[0049] On the other hand, this invention provides a method for preparing a fine-grained energy storage dielectric ceramic material with a MnO-coated "core-shell" structure, firstly by preparing monodisperse Ba through a chemical precipitation method. 0.99 B i0.01 TiO3 micro / nano powders were then used to prepare monodisperse MnO-coated Ba2O3 using a liquid-phase coating method. 0.99 B i0.01 TiO3@xMnO micro / nano powder was finally sintered to prepare Ba 0.99 Bi 0.01 TiO3@xMnO dielectric ceramic material.

[0050] The specific steps are as follows:

[0051] Step 1: Add TiCl4 solution dropwise to 4-8 mol / L NaOH solution, and simultaneously place in a water bath at 10-40℃ and stir thoroughly for 0.5-2 hours;

[0052] Step 2: Prepare aqueous solutions of bismuth compound and barium compound according to the stoichiometric ratio, and then slowly add the solutions to each solution while stirring continuously. The reaction temperature is 10-40℃ and the stirring reaction time is 0.5-2h.

[0053] Step 3: Place the obtained solution in a water bath at 80-100℃ and stir continuously for 4-6 hours. Then filter and dry in an oven at 80-100℃ to obtain Ba. 0.99 Bi 0.01 TiO3 powder;

[0054] Step 4, Ba 0.99 Bi 0.01 TiO3 powder was ultrasonically dispersed in deionized water and ethanol to obtain Ba 0.99 Bi 0.01 TiO3 suspension was prepared, and then a 30% ammonia solution was added to adjust the pH to 9-11; the mass ratio of deionized water to ethanol was 2:3.

[0055] Step 5: Prepare a manganese acetate solution using the stoichiometric ratio, then add it dropwise to the above solution while simultaneously stirring mechanically at a speed of 60-80 rpm to ensure uniform mixing and promote the uniform coating of Ba with the generated MnO. 0.99 Bi 0.01 TiO3 particle surface;

[0056] Step 6: After complete precipitation, age the solution for a certain period of time, then filter the suspension and wash it multiple times. Dry the solution in an oven at 80-100℃ to obtain micro / nano powder. Calcine the obtained micro / nano powder in air at 700-900℃ for 1-2 hours, and then cool to obtain Ba. 0.99 Bi 0.01 TiO3@xMnO micro / nano media powder;

[0057] Step 7, for Ba 0.99 Bi 0.01 TiO3@xMnO micro / nano dielectric powder was granulated using PVA and glycerol grinding. After granulation, it was pressed into sheets using a mold at 8 MPa and sintered at 1220-1260℃ for 2-4 h to prepare Ba. 0.99 Bi 0.01 TiO3@xMnO dielectric ceramic material.

[0058] Specifically, the Ba obtained in step 3 0.99 Bi 0.01 TiO3 powder is a monodisperse micro-nano powder with a particle size of 50-500 nm.

[0059] Specifically, the Ba obtained in step 6 0.99 Bi 0.01 The ceramic grains of TiO3@xMnO micro / nano dielectric powder are approximately 100-500 nm.

[0060] Specifically, the MnO is coated with monodisperse Ba.0.99 Bi 0.01 Surface of TiO3 particles.

[0061] Specifically, in step 7, the Ba 0.99 Bi 0.01 TiO3@xMnO micro / nano powder is pressed and then sintered at 1220-1260℃ for 2-6 hours to produce dielectric ceramic materials.

[0062] Specifically, the Ba prepared in step 7 0.99 Bi 0.01 The discharge energy storage density of TiO3@xMnO dielectric ceramic materials is 0.04-0.25 J / cm³. 3 .

[0063] To further verify the preparation method of MnO-coated "core-shell" structured fine-grained energy storage dielectric ceramic materials, Ba was prepared. 0.99 Bi 0.01 Regarding the properties of TiO3@xMnO dielectric ceramic materials, the present invention also provides the following embodiments:

[0064] Example 1

[0065] Preparation of Ba 0.99 Bi 0.01 TiO3@xMnO powder and its dielectric ceramic materials, wherein x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%, and the corresponding sample numbers are denoted as #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6, respectively; Ba was prepared in this embodiment. 0.99 Bi 0.01 The specific steps for producing TiO3@xMnO powder and its dielectric ceramic materials are as follows:

[0066] Step 1: At a water bath temperature of 30℃, TiCl4 solution was slowly added dropwise to a 6 mol / L NaOH solution, and stirred thoroughly for 0.5 h. Bismuth and barium compounds were then slowly added according to their stoichiometric ratios, with continuous stirring. The reaction temperature was 30℃, and the reaction time was 0.5 h. The solution was then stirred for another 4 h at a water bath temperature of 90℃, washed, and dried in an oven at 80℃ to obtain Ba. 0.99 Bi 0.01 TiO3 powder;

[0067] Step 2: Weigh 3.000g Ba 0.99 Bi 0.01 TiO3 powder was ultrasonically dispersed in 300 mL of deionized water for 30 min to obtain Ba. 0.99 Bi 0.01TiO3 suspension, its pH was adjusted to above 9 with 30% ammonia solution;

[0068] Step 3, Ba 0.99 Bi 0.01 The TiO3 suspension was transferred into a three-necked flask and stirred at room temperature at a speed of 60 rpm. The pH was then adjusted to above 10 with ammonia.

[0069] Step 4: Weigh out 0.0063g, 0.0125g, 0.0188g, 0.0251g, and 0.0314g of manganese acetate respectively, add the manganese acetate solution to a three-necked flask, and stir mechanically at room temperature at a speed of 60 RPM for 1 hour.

[0070] Step 5: After complete precipitation, age for 24 hours, then filter and wash repeatedly. Dry in an oven at 90℃, then calcine at 800℃ for 2 hours to obtain six Ba compounds. 0.99 Bi 0.01 TiO3@xMnO media powder (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%);

[0071] Step 6: Obtain Ba 0.99 Bi 0.01 TiO3@xMnO dielectric powders (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%) were granulated and pressed into blank discs with a diameter of 10 mm and a thickness of 1.5 mm under a pressure of 8 MPa. These discs were then sintered at 1250 °C for 2 h to obtain six different BaO content. 0.99 Bi 0.01 TiO3@xMnO dielectric ceramic samples (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%).

[0072] See Figure 1 As shown in the figure, there are six types of Ba: #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6. 0.99 Bi 0.01 SEM images of TiO3@xMnO media powder (SEM images are used to analyze the microstructure of the powder; all powders were photographed at 25000x magnification; the images show Ba...) 0.99 Bi 0.01 The TiO3@xMnO dielectric powder consists of uniform and well-dispersed spherical particles with average particle sizes of approximately 358, 382, ​​435, 402, 472, and 492 nm, which is beneficial for preparing fine-grained dielectric ceramics.

[0073] See Figure 2 As shown in the figure, it is #1-3Ba 0.99Bi 0.01 TEM image of TiO3@0.4mol%MnO dielectric powder sample (TEM shows fine structures smaller than 0.2µm that are not visible under an optical microscope). A uniform coating with a thickness of 19nm is present on the surface of the BBT powder; a red manganese oxide outer shell is also visible in the image; however, the diffusion of Mn into the BBT "core" is very obvious, which is mainly related to the calcination process during the preparation of BBT@MnO powder, as increased temperature affects manganese diffusion. EDS analysis shows that the inner layer is mainly composed of Ba. 2+ Bi 3+ Ti 4+ O 2- The composition is ionic, with the outer layer mainly containing Mn, indicating that MnO is uniformly coated on the surface of the BBT ceramic powder.

[0074] See Figure 3 As shown in the figure, there are six types of Ba: #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6. 0.99 Bi 0.01 SEM images of TiO3@xMnO dielectric ceramic samples (SEM images are used to analyze the microstructure of the ceramic surface; all Ba...) 0.99 Bi 0.01 All TiO3@xMnO dielectric ceramic samples were photographed at 13000x magnification. In the images, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6 are MnO dielectric ceramic samples with concentrations of 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol%, respectively. The images show a dense ceramic structure with clear grain boundaries. After adding MnO, the ceramic grain size decreases, accompanied by a small number of voids. The fewest voids are observed when x = 0.4 mol%. The void formation can be attributed to: ① low sintering temperature, resulting in incomplete reaction within the sample; ② low diffusion rate of manganese in BaTiO3-based materials, leading to insufficient MnO doping. 2+ and Mn 3+ Ions accumulate at grain boundaries, thus suppressing grain densification during sintering; ③ Doping with polyvalent manganese ions facilitates the formation of titanium and oxygen vacancies, and the migration of oxygen vacancies reduces the density of the ceramic.

[0075] See Figure 4 As shown in the figure, there are six types of Ba: #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6. 0.99 Bi 0.01XRD patterns of TiO3@xMnO media powders (XRD patterns are used to analyze the phase structure of powders. In the figure, the horizontal axis represents the 2θ angle, and the vertical axis represents the relative intensity. In the figure, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6 are 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol% MnO media powders, respectively. All media powders are pure perovskite structures, with no second phase and no manganese oxide detected. The specific reason is that the weak diffraction peaks of a small amount of manganese oxide are covered by the diffraction curve of BBT.)

[0076] See Figure 5 As shown in the figure, there are six types of Ba: #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6. 0.99 Bi 0.01 XRD patterns of TiO3@xMnO dielectric ceramic samples; (XRD patterns are used to analyze the phase structure of ceramics. The horizontal axis represents the 2θ angle, and the vertical axis represents the relative intensity. In the figure, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6 are 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol% MnO dielectric ceramic samples, respectively. The BBT particles exhibit a pure perovskite structure, and no second phase was observed. After manganese coating, MnO, MnO2, and Mn3O4 peaks appeared in the XRD pattern, which may be due to the thermal decomposition of manganese oxide, indicating that manganese oxide was successfully coated onto Ba.) 0.99 Bi 0.01 On TiO3 particles; from the magnified image, it can be seen that there are no obvious splitting peaks in the magnified diffraction peaks of the (200) crystal plane; however, there are signs of expansion and weak splitting, indicating that the ceramic may be in a state of coexistence of tetragonal and cubic phases; the diffraction pattern shows that the manganese oxide coating can cause slight changes in the phase structure of the ceramic, promoting the coexistence of multiple phases in the ceramic.

[0077] See Figure 6 As shown in the figure, there are six types of Ba: #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6. 0.99 Bi 0.01Dielectric constant graph of TiO3@xMnO dielectric ceramic samples (the horizontal axis of the dielectric constant graph is temperature, and the vertical axis is dielectric constant). In the graph, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6 are MnO dielectric ceramic samples with concentrations of 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol%, respectively. The dielectric constant initially increases and then decreases with increasing MnO coating amount. When the MnO coating amount is 0.4 mol%, the dielectric constant reaches a relatively large value of 3610. When the MnO coating amount exceeds 0.4 mol%, the dielectric constant decreases slightly. The increase in dielectric constant of the manganese-doped samples is related to the MnO content. 3+ The electronic structure of Mn is related to AB bonds. 2+ To Mn 3+ The transitions between these ions lead to orientation polarization, which is an electron exchange between them. The introduction of Mn may cause TiO6 octahedral deformation, generating oxygen vacancies, and may also weaken the AB sublattice interaction, reducing polarization resistance and thus increasing the dielectric constant. The decrease in dielectric constant is due to the substitution of high-valence titanium with low-valence manganese, which creates defects in the ceramic crystal, thereby reducing the dielectric constant.

[0078] See Figure 7 As shown in the figure, there are six types of Ba: #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6. 0.99 Bi 0.01 The characteristic curve of dielectric loss as a function of temperature for TiO3@xMnO dielectric ceramic samples is shown in the figure (the horizontal axis of the dielectric loss graph is temperature, and the vertical axis is dielectric loss). In the figure, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6 are MnO dielectric ceramic samples with coating amounts of 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol%, respectively. The dielectric loss first decreases and then increases with increasing MnO coating amount. The dielectric loss is lowest (0.01 mol%) when the MnO coating amount is 0.4 mol%. The decrease in dielectric loss is due to the MnO coating amount... 3+ and Mn 4+ It can effectively trap electrons, thereby reducing the carrier density in the material; ceramics containing 0.4 mol% MnO achieved the highest dielectric constant (3610) and the lowest dielectric loss (0.01).

[0079] See Figure 8 As shown in the figure, there are six types of Ba: #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6. 0.99 Bi 0.01The hysteresis loop diagram of TiO3@xMnO dielectric ceramic samples before breakdown (the horizontal axis represents the ratio of electric field to ceramic thickness, and the vertical axis represents polarization. In the diagram, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6 are MnO dielectric ceramic samples with 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol% polarization, respectively. As can be seen from the diagram, all ceramics exhibit a thin hysteresis loop. The maximum polarization intensity (Pmax) first increases and then decreases, reaching its maximum value when the coating x = 0.4 mol%. The energy storage density can be calculated using the hysteresis loop.)

[0080] Its main energy storage properties are shown in Table 1:

[0081] Table 1 shows the energy storage performance parameters of dielectric ceramic samples #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6.

[0082]

[0083] In the table, #1-1, #1-2, #1-3, #1-4, #1-5, and #1-6 are MnO dielectric ceramic samples with x = 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol%, respectively. The table shows that as the MnO content increases, the discharge energy density of the dielectric ceramic samples first increases and then decreases, reaching a maximum of 0.26 J / cm² when the coating layer x = 0.4 mol%. 3 It achieves a high energy storage efficiency of 76.5%.

[0084] Example 2

[0085] Preparation of Ba 0.99 Bi 0.01 TiO3@xMnO powder and its dielectric ceramic materials, wherein x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%, and the corresponding sample numbers are denoted as #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6, respectively; Ba was prepared in this embodiment. 0.99 Bi 0.01 The specific steps for producing TiO3@xMnO powder and its dielectric ceramic materials are as follows:

[0086] Step 1: At a water bath temperature of 30℃, TiCl4 solution was slowly added dropwise to a 6 mol / L NaOH solution, and stirred thoroughly for 0.5 h. Bismuth and barium compounds were then slowly added according to their stoichiometric ratios, with continuous stirring. The reaction temperature was 40℃, and the reaction time was 1 h. The solution was then stirred for another 5 h at a water bath temperature of 100℃, washed, and dried in an oven at 90℃ to obtain Ba. 0.99 Bi 0.01 TiO3 powder;

[0087] Step 2: Weigh 3.000g Ba 0.99 Bi 0.01 TiO3 powder was ultrasonically dispersed in 300 mL of deionized water for 30 min to obtain Ba. 0.99 Bi 0.01 TiO3 suspension was adjusted to pH 9 or higher with 30% ammonia solution, and five parallel groups were formed.

[0088] Step 3, Ba 0.99 Bi 0.01 The TiO3 suspension was transferred into a three-necked flask and mechanically stirred at room temperature at a speed of 80 RPM. The pH was adjusted to above 10 with ammonia.

[0089] Step 4: Weigh out 0.0063g, 0.0125g, 0.0188g, 0.0251g, and 0.0314g of manganese acetate respectively, add the manganese acetate solution to a three-necked flask, and stir mechanically at room temperature at a speed of 60 RPM for 1 hour.

[0090] Step 5: After complete precipitation, age for 12 hours, filter, wash repeatedly, dry in an oven at 80℃, and then calcine at 800℃ for 2 hours to obtain Ba. 0.99 Bi 0.01 TiO3@xMnO media powder (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%);

[0091] Step 6: Obtain the six types of Ba 0.99 Bi 0.01 TiO3@xMnO dielectric powders (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%) were granulated and pressed into blank discs with a diameter of 10 mm and a thickness of 1.5 mm under a pressure of 8 MPa. These discs were then sintered at 1220 °C for 2 h to obtain six types of Ba. 0.99 Bi 0.01 TiO3@xMnO dielectric ceramic samples (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol%).

[0092] See Figure 9 As shown in the figure, there are six types of Ba: #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6. 0.99 Bi 0.01 SEM images of TiO3@xMnO dielectric ceramic samples (SEM images are used to analyze the microstructure of the ceramic surface. All dielectric ceramic samples were photographed at 13000x magnification. In the image, #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6 are MnO dielectric ceramic samples with contents of 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol%, respectively. As the MnO content increases, the grain size of the ceramic first increases and then decreases. All dielectric ceramic samples have clear grain boundaries and small grain sizes, with x = 0.4 mol% being the optimal value.)

[0093] See Figure 10 As shown, the figures are #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6Ba. 0.99 Bi 0.01 XRD patterns of TiO3@xMnO dielectric ceramic samples (the horizontal axis of the XRD pattern is the 2θ angle, and the vertical axis is the relative intensity. In the figure, #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6 are MnO dielectric ceramic samples with concentrations of 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol%, respectively. All samples show a pure perovskite structure without a second phase, possibly due to the low sintering temperature and absence of manganese oxide. The splitting of the diffraction peak at approximately 45° in pure BBT indicates the coexistence of tetragonal and cubic phases. As the MnO content increases, the peak gradually transforms into a single peak, indicating an increase in the tetragonal phase content. The diffraction patterns suggest that the manganese oxide coating can slightly alter the phase structure of the ceramic, promoting multiphase coexistence.)

[0094] See Figure 11 As shown in the figure, there are six types of Ba: #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6. 0.99 Bi 0.01 Dielectric constant plot of TiO3@xMnO dielectric ceramic samples (the horizontal axis of the dielectric constant plot is temperature, and the vertical axis is dielectric constant. In the plot, #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6 are MnO dielectric ceramic samples with values ​​of 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol%, respectively. At x = 0.8 mol%, two peaks are observed, possibly one representing the "core" BBT and the other the "shell" MnO, indicating the formation of a core-shell structure and successful coating of MnO onto the BBT ceramic.)

[0095] See Figure 12 As shown in the figure, there are six types of Ba: #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6. 0.99 Bi 0.01 The dielectric loss characteristic curve of TiO3@xMnO dielectric ceramic samples as a function of temperature is shown in the figure (the horizontal axis of the dielectric loss curve is temperature, and the vertical axis is dielectric loss). In the figure, #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6 are MnO dielectric ceramic samples with values ​​of 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol%, respectively. It can be seen from the figure that the dielectric loss is lowest when x = 0.4 mol%.

[0096] See Figure 13 As shown in the figure, there are six types of Ba: #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6. 0.99 Bi 0.01 The hysteresis loop diagram of TiO3@xMnO dielectric ceramic samples before breakdown (the horizontal axis of the hysteresis loop diagram is the ratio of electric field to ceramic thickness, and the vertical axis is polarization. In the figure, #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6 are MnO dielectric ceramic samples with 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol% concentrations, respectively. It can be seen from the figure that the pure BBT ceramic has the smallest maximum polarization and the smallest PE loop; the maximum polarization increases after the addition of MnO, and the storage density reaches its maximum value at x = 0.4 mol%.)

[0097] Its main energy storage properties are shown in Table 2:

[0098] Table 2 shows the energy storage performance parameters of dielectric ceramic samples #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6.

[0099]

[0100] Table #2-1, #2-2, #2-3, #2-4, #2-5, and #2-6 represent MnO dielectric ceramic samples with x = 0, 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, and 1.0 mol%, respectively. The table shows that as the MnO content increases, the discharge energy density of the dielectric ceramic samples first increases and then decreases, reaching a maximum of 0.25 J / cm² when the coating layer x = 0.4 mol%. 3 It achieves a high energy storage efficiency of 71.4%.

[0101] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0102] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A fine-grained energy storage dielectric ceramic material with a MnO-coated "core-shell" structure, characterized in that, Using Ba 0.99 Bi 0.01 The material is made of TiO3@xMnO micro / nano powder, and the Ba 0.99 Bi 0.01 TiO3@xMnO micro / nano powder comprises a "core" and a "shell," wherein the "core" material is Ba. 0.99 Bi 0.01 TiO3, wherein the "shell" material is MnO; Among them, 0.2 mol% ≤ x ≤ 0.4 mol%.

2. A method for preparing a fine-grained energy storage dielectric ceramic material with a MnO-coated "core-shell" structure as described in claim 1, characterized in that, Monodisperse Ba was first prepared by chemical precipitation. 0.99 Bi 0.01 TiO3 micro / nano powders were then used to prepare monodisperse MnO-coated Ba2O3 using a liquid-phase coating method. 0.99 Bi 0.01 TiO3@xMnO micro / nano powder was finally sintered to prepare Ba 0.99 Bi 0.01 TiO3@xMnO dielectric ceramic material; specific steps are as follows: Step 1: Add TiCl4 solution dropwise to NaOH solution, while simultaneously bathing in a water bath at a certain temperature and stirring thoroughly for a certain period of time; Step 2: Prepare aqueous solutions of bismuth compound and barium compound according to the stoichiometric ratio, then slowly add them to the solutions and stir until homogeneous; Step 3: Place the obtained solution in a water bath at a certain temperature with continuous stirring, then filter, dry, and obtain Ba. 0.99 Bi 0.01 TiO3 powder; the Ba 0.99 Bi 0.01 TiO3 powder is a monodisperse micro-nano powder with a particle size of 50-500 nm; Step 4, Ba 0.99 Bi 0.01 TiO3 powder was ultrasonically dispersed in deionized water and ethanol to obtain Ba 0.99 Bi 0.01 TiO3 suspension was prepared, then an ammonia solution was added, and the pH was adjusted to an alkaline environment. Step 5: Prepare a manganese acetate solution using the stoichiometric ratio, then add it dropwise to the above solution while stirring to ensure thorough mixing; Step 6: Then, the suspension is filtered and dried to obtain micro / nano powders, which are then calcined in air at a certain temperature to obtain Ba. 0.99 Bi 0.01 TiO3@xMnO micro / nano dielectric powder; the Ba 0.99 Bi 0.01 The ceramic grains of TiO3@xMnO micro / nano dielectric powder are 100-500nm; Step 7, for Ba 0.99 Bi 0.01 TiO3@xMnO micro / nano dielectric powder was granulated, and after granulation, it was pressed into shape using a mold and sintered at a certain temperature to prepare Ba. 0.99 Bi 0.01 TiO3@xMnO dielectric ceramic material.

3. The method for preparing dielectric ceramic material according to claim 2, characterized in that, In step 4, the pH is adjusted to 9-11.

4. The method for preparing dielectric ceramic material according to claim 2, characterized in that, In step 7, the Ba 0.99 Bi 0.01 TiO3@xMnO micro / nano powder is pressed and then sintered at 1220-1260℃ for 2-6 hours to produce dielectric ceramic materials.

5. The method for preparing dielectric ceramic material according to claim 2, characterized in that, Ba prepared in step 7 0.99 Bi 0.01 The discharge energy storage density of TiO3@xMnO dielectric ceramic materials is 0.10-0.26 J / cm³. 3 .

6. Ba prepared by the method according to any one of claims 2-5 0.99 Bi 0.01 The application of TiO3@xMnO dielectric ceramic materials is characterized by... The Ba 0.99 Bi 0.01 TiO3@xMnO dielectric ceramic materials are used in the fabrication of multilayer ceramic capacitors, positive temperature coefficient resistors, optoelectronic devices, piezoelectric sensors, and energy storage systems.

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