A high energy density composite ceramic material with an intracrystalline structure and a preparation method thereof

Abstract

The application relates to a high-energy-density complex ceramic material with an inner crystal structure and a preparation method thereof, and belongs to the field of electronic ceramic materials. The chemical composition of the ceramic material is 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3. BaCO3, CaCO3, TiO2 and ZrO2 are used as raw materials, corresponding raw materials are weighed according to the stoichiometric ratio, and then wet grinding, drying, calcination, granulation, compression molding and sintering are sequentially carried out. The dielectric energy storage material provided by the application has a large polarization difference and a high breakdown field strength, thereby having a high energy storage density and energy storage efficiency, has a high application potential in the field of pulse energy storage ceramic capacitors, and has significant social significance and application value.

Description

Technical Field

[0001] This invention belongs to the field of electronic ceramic materials, specifically relating to a multiphase ceramic material with an internal crystal structure and high energy storage density that can be used for dielectric energy storage in ceramic capacitors, and its preparation method. Background Technology

[0002] The efficient utilization of various energy sources in today's society relies on the development of advanced energy storage technologies. Compared with common electrochemical energy storage technologies, electrostatic energy storage technology, with dielectric capacitors as its core component, has many advantages such as ultra-fast charging and discharging speeds, high power density, and excellent cycle life. Although electrostatic energy storage capacitors have been partially applied in pulse power electronic devices in military, medical, and nuclear energy fields, the energy storage density of dielectric capacitors is relatively low. In practical applications, they often require a large mass and volume, which cannot meet the requirements of miniaturization, integration, and lightweighting of electronic devices. Therefore, optimizing the energy storage performance of dielectric capacitors is an essential path for the development of next-generation electronic component materials.

[0003] For dielectric materials, their energy storage function is achieved through dielectric polarization (P) in an external electric field (E). That is, the dielectric energy storage material stores energy through dielectric polarization and the separation of positive and negative charges under an applied electric field. For dielectric energy storage materials, the total energy storage density... Effective energy storage density Energy storage efficiency The basic performance requirement for the dielectric material of a pulse capacitor is that it simultaneously possesses a high effective energy storage density W. rec And high energy storage efficiency η. In the above formula, P max and P r These represent the maximum polarization during charging and the residual polarization during discharging, respectively, with E being the applied electric field. The formula shows that the dielectric material exhibits a large polarization difference ΔP(P...). max -P r ), delayed saturation polarization and high breakdown electric field strength (E b This is beneficial for capacitors to achieve excellent energy storage performance.

[0004] BaTiO3, due to its stable perovskite structure and intrinsically high dielectric constant, has become the world's most widely used commercial ferroelectric capacitor ceramic. Through doping or forming solid solutions with other components, it is commonly used to manufacture Electronic Industries Alliance (EIA) Class II X7R or X8R type multilayer ceramic capacitors (MLCCs). However, BaTiO3 is prone to saturation polarization under low electric fields and suffers from low breakdown electric field strength and high remanent polarization, limiting its energy storage density and efficiency, thus making it difficult to apply to pulse energy storage capacitors. Constructing 0-3 type multiphase ceramics, i.e., introducing low-dielectric, high-insulating materials such as alumina, aluminum nitride, and magnesium oxide into a perovskite ferroelectric matrix, has been proven to effectively enhance the breakdown strength (E0) of multiphase materials. b This reduces residual polarization. However, the formation of the 0-3 type multiphase structure in existing materials requires the addition of a large amount of low-dielectric, high-insulating material as a second phase. These second phases mainly exist at the ceramic grain boundaries, significantly weakening the material's dielectric constant and polarization difference ΔP, thus limiting the effect on improving the material's energy storage density. Therefore, to enhance the energy storage characteristics of multiphase ceramics, new material design methods are needed to control the content and location of the second phase, ensuring the enhancement of the breakdown electric field strength (E). b While maintaining a high dielectric constant and polarization difference ΔP, it can still maintain a high dielectric constant.

[0005] In summary, this invention proposes a novel design method for high-energy-density multiphase ceramic materials with an internal crystal structure, achieving excellent comprehensive energy storage characteristics in a BaTiO3-BaZrO3-CaTiO3 ternary multiphase system (abbreviated as BCZT). Unlike the conventional 0-3 type multiphase ceramic design approach that forms a grain boundary second phase by adding an external second component, the formation of the second phase in this invention originates from the intracrystalline self-precipitation behavior of the designed system. Because CaTiO3 has limited solid solubility in the BaTiO3 matrix, this facilitates precise compositional adjustment to control the intracrystalline precipitation behavior of an appropriate amount of CaTiO3 second phase, thereby enhancing the breakdown electric field strength and maintaining a high dielectric constant. Simultaneously, BaZrO3 can form an infinite solid solution with BaTiO3; due to the difference in ion radius and ferroelectric activity at the perovskite B site, this enhances the material's relaxation characteristics and polarization difference ΔP. Among them, the best sample with an internal crystal structure, 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3, not only has a high breakdown electric field strength (E b =553.9kV / cm), and also has a high polarization difference ΔP (30.77μC / cm). 2 ), and obtained W rec =5.86Jcm -3 With its excellent performance of η=86.7%, it has great application potential in the field of dielectric capacitor energy storage. Summary of the Invention

[0006] The key feature of this invention is the design of an internally crystallized second-phase BCZT high-energy-density multiphase ceramic material. Considering the abundant multi-scale design factors in the BaTiO3-BaZrO3-CaTiO3 system—namely, the combination of BaTiO3 and BaZrO3 enhancing dielectric relaxation behavior, and the limited solid solubility of CaTiO3 in the BaTiO3 matrix facilitating control of second-phase precipitation—a BCZT multiphase material with an internally crystallized second-phase structure exhibiting appropriate CaTiO3 precipitation is constructed through precise compositional control. This achieves enhanced energy density (E) while maintaining a high polarization difference ΔP. b The goal.

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

[0008] A high-energy-density multiphase ceramic material with an internal crystal structure, characterized by its component design: The value of x ranges from 0.21 to 0.9. Through compositional refinement and process exploration, the optimal composition is x = 0.65, namely 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3. This sample has a special internal crystal structure, and its performance can achieve an effective energy storage density W. rec =5.86J cm -3 The energy storage efficiency η = 86.7%.

[0009] The energy storage multiphase ceramic material with an internal crystal structure described above in this invention is characterized by being synthesized by a conventional solid-state sintering method. Specifically, the following steps are included:

[0010] (1) According to Four raw materials, namely BaCO3, CaCO3, TiO2 and ZrO2, were weighed according to their element stoichiometric ratios in the ceramic material. The weighed raw materials were placed in a ball mill jar and ball milled in a planetary ball mill for 12 hours with anhydrous ethanol as the medium. The resulting mixture was then dried in an oven at 100°C.

[0011] (2) The dried mixture was ground and placed in an alumina crucible, then calcined at 1250℃ for 4 hours and cooled to room temperature in the furnace.

[0012] (3) Pour the calcined powder into a ball mill jar and add anhydrous ethanol for secondary ball milling. The ball milling time is 12 hours.

[0013] (4) Add binder to the powder obtained from the second ball mill, granulate, sieve, press into ceramic blank under pressure, and heat to remove the binder.

[0014] If 10 wt.% polyvinyl alcohol (PVB) binder is added, the ceramic blank is pressed under a uniaxial pressure of 500 MPa for 2 minutes, and then debinding is performed at 650℃ for 3 hours, followed by furnace cooling to room temperature.

[0015] (5) The unglazed body after debinding was sintered at 1400℃ and held for 4 hours, then cooled to room temperature in the furnace. The sintered ceramic sample, after polishing to a thickness of 0.1 mm, had a sputtering area of ​​0.003 cm². 2 Au electrodes were used to test the electrical properties of ceramic samples.

[0016] The optimal ceramic sample composition was found to be 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3, exhibiting a unique structure with the CaTiO3 second phase segregated within the grain boundaries. Hysteresis loop testing revealed its breakdown electric field strength E... b = 553.9 kV / cm, maximum polarization P max =35.21μC / cm 2 Residual polarization P r =4.44μC / cm 2 The polarization difference ΔP = 30.77 μC / cm 2 The effective energy storage density W was calculated. rec =5.86J cm -3 The energy storage efficiency η = 86.7%. It has good potential for energy storage applications.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) By controlling the CaTiO3 content and intracrystalline precipitation behavior, this invention can construct a novel intracrystalline BCZT multiphase structure that is different from the conventional grain boundary second phase multiphase structure.

[0019] (2) This invention achieves enhanced E while maintaining a high polarization difference ΔP in the 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3 multiphase ceramic system through internal crystal structure design. b Ultimately, a high effective energy storage density W was achieved. rec =5.86J cm -3 With an energy storage efficiency η = 86.7%, it can be applied to dielectric energy storage in ceramic capacitors, and further to dielectric energy storage in pulse ceramic capacitors. Attached Figure Description

[0020] Figure 1 The image shows the XRD pattern of the 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3 ceramic material in a specific embodiment of the present invention.

[0021] Figure 2 The image shows a SEM image of the 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3 ceramic material in a specific embodiment of the present invention, where the dark particles are the second phase of CaTiO3.

[0022] Figure 3 This refers to the PE hysteresis loop of the 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3 ceramic material near the breakdown field in a specific embodiment of the present invention. Detailed Implementation

[0023] The present invention will be described in detail below through embodiments. These embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0024] This invention provides a high energy density ceramic material with an internal crystal structure and its preparation method, characterized in that its chemical composition is 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3. The constituent raw materials include: BaCO3, CaCO3, TiO2, and ZrO2. The specific preparation method is as follows: First, the raw materials are weighed according to the stoichiometric ratio of each component, then placed in a ball mill jar and ball-milled for 12 hours using anhydrous ethanol as the medium. The resulting mixture is then dried in a 100℃ oven. After drying, the mixture is ground and placed in a sealed alumina crucible for calcination at 1250℃ for 4 hours, followed by furnace cooling to room temperature. The calcined product is then ball-milled a second time with anhydrous ethanol as the ball milling medium in a ball mill jar for 12 hours, followed by drying the ball milling slurry at 100℃. Approximately 10 wt.% binder is added to the dried powder, followed by granulation, sieving, and pressing into ceramic blanks. After debinding, the blanks are sintered at 1400℃ for 4 hours and then furnace cooled to room temperature. The sintered ceramic sample, after polishing to a thickness of 0.1 mm, has a sputtering area of ​​0.003 cm². 2 Au electrodes were used to test the electrical properties of ceramic samples.

[0025] The essential features and significant advantages of the present invention are further illustrated below through examples. It should be noted that the present invention is by no means limited to the embodiments described.

[0026] Example 1:

[0027] BaCO3, CaCO3, TiO2, and ZrO2 were weighed according to the chemical formula 0.9BaTiO3-0.05BaZrO3-0.05CaTiO3, and ball-milled for 12 hours using anhydrous ethanol as the medium. The mixture was dried at 100℃ and calcined at 1250℃ for 4 hours; then, anhydrous ethanol was added for a second ball milling for 12 hours. Approximately 10 wt.% binder was added to the dried powder, followed by granulation, sieving, and pressing into ceramic green bodies. After debinding, the green bodies were sintered at 1400℃ for 4 hours and then cooled to room temperature in the furnace. The sintered ceramic samples were polished to a thickness of 0.1 mm, resulting in a sputtering area of ​​0.003 cm². 2 Au electrodes were used to test the electrical properties of ceramic samples.

[0028] Example 2:

[0029] The preparation of the 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3 ceramic material is the same as in Example 1.

[0030] Example 3:

[0031] The preparation of the 0.21BaTiO3-0.395BaZrO3-0.395CaTiO3 ceramic material is the same as in Example 1.

[0032] Table 1 Performance Comparison of the Above Embodiments

[0033]

Claims

1. A high-energy-density multiphase ceramic material with an internal crystal structure, characterized in that, The matrix chemical composition of this ceramic material is 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3, and it has a special structure in which the CaTiO3 second phase segregates within the grain boundaries.

2. A high energy density multiphase ceramic material with an internal crystal structure according to claim 1, characterized in that, The matrix chemical composition is 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3, and its effective energy storage density W rec = 5.86 Jcm -3 The energy storage efficiency η = 86.7%.

3. A method for preparing the high energy density multiphase ceramic material with an internal crystal structure as described in any one of claims 1-2, characterized in that, The preparation method using the traditional solid-state method specifically includes the following steps: (1) Weigh out the raw materials BaCO3, CaCO3, ZrO2 and TiO2 according to the molar ratio of each element in the chemical formula 0.65BaTiO3-0.175BaZrO3-0.175CaTiO3; (2) Place the weighed raw material into a ball mill jar, and ball mill it in a ball mill with anhydrous ethanol as the medium. Then dry it and calcine the dried powder at 1250℃ for 4 h, and cool it with the furnace. (3) The powder cooled in step (2) is ball-milled twice and dried. The dried powder is then ground and granulated. (4) After the powder obtained by granulation in step (3) is left to stand, it is pressed into shape to obtain a green body. Then, the glue is removed and finally sintered at 1400℃ for 4 hours. The material is then cooled to room temperature in the furnace to obtain the target material.

4. The method according to claim 3, characterized in that, Step (3) involves granulation using PVB, and step (4) involves debinding the green body at 650°C.

5. The application of the high energy density multiphase ceramic material with an internal crystal structure as described in claim 1 or 2, wherein the high energy density multiphase ceramic material is used for energy storage in energy storage ceramic capacitors.

6. The application according to claim 5, wherein the high energy density multiphase ceramic material is used for dielectric energy storage in a pulse ceramic capacitor.

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