High polarization antiferroelectric ceramic material, capacitor and preparation method thereof

Abstract

The present invention provides a high-polarization antiferroelectric ceramic material, a capacitor, and a preparation method thereof. The high-polarization antiferroelectric ceramic material is formed by solid-dissolving two antiferroelectric materials of different crystalline phases in a molar ratio of (1-x):x, wherein x=0.02 to 0.20, and the high-polarization antiferroelectric ceramic material has a quasi-modular phase boundary structure of a relaxor ferroelectric. The antiferroelectric ceramic material proposed by the present invention cleverly introduces the quasi-modular phase boundary structure of a relaxor ferroelectric by precisely controlling the solid-dissolve ratio of the ferroelectric materials of different crystalline phases, thereby significantly improving the polarization performance and dielectric properties of the material and achieving a comprehensive improvement in its stability performance. The high-polarization antiferroelectric ceramic capacitor proposed by the present invention has an extremely high energy storage density due to its unique antiferroelectric properties. The antiferroelectric ceramic capacitor has an excellent power density and can quickly release stored energy in a short period of time. The antiferroelectric ceramic capacitor can maintain stable performance over a wide temperature range and can operate reliably under various environmental conditions.

Description

Technical Field

[0001] The present invention relates to the field of ceramic materials, in particular to a high-polarization antiferroelectric ceramic material, a capacitor and a preparation method thereof. Background Art

[0002] Antiferroelectric materials, due to their unique electrical properties and potential applications, have attracted considerable attention in electronics, capacitors, sensors, storage devices, and other fields. These materials exhibit polarization behavior similar to ferroelectrics under an external electric field, but in the absence of a zero electric field, they exhibit a unique non-polarized state, known as the antiferroelectric phase. This property gives antiferroelectric materials unique advantages in certain applications, such as increased stability and lower power consumption.

[0003] However, the types of antiferroelectric materials currently available are relatively limited, mainly including traditional typical antiferroelectric materials such as PbZrO3 (lead zirconate), PbHfO3 (lead hafnium oxide) and AgNbO3 (silver niobate). The spontaneous polarization of these materials is usually low, generally around 40uC cm -2 In some applications, higher spontaneous polarization is required to achieve better performance, but existing materials often sacrifice antiferroelectric stability while improving polarization, which limits their application in high-performance electronic devices. For example, Pb(Zr,Ti)O3 (lead zirconium titanate) is a typical antiferroelectric material. By adjusting the ratio of Zr and Ti, the polarization properties of the material can be adjusted to a certain extent. However, when attempts are made to increase the polarization by increasing the Ti content, the antiferroelectric stability of the material is affected, resulting in reduced reliability in certain applications.

[0004] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art.

[0005] In view of the above, there is an urgent need to provide a high-polarization antiferroelectric ceramic material, a capacitor and a preparation method thereof to solve the above problems. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a high-polarization antiferroelectric ceramic material, a capacitor and a preparation method thereof, which are used to solve the problem of poor performance and stability of antiferroelectric materials in the prior art when improving spontaneous polarization.

[0007] To achieve the above-mentioned and other related purposes, the present invention provides a high-polarization antiferroelectric ceramic material, which is formed by solid solution of two antiferroelectric materials with different crystal phases in a molar ratio of (1-x):x, wherein x=0.02~0.20, and the high-polarization antiferroelectric ceramic material has a quasi-isomorphic phase boundary structure of a relaxor ferroelectric.

[0008] Optionally, the two antiferroelectric materials of different crystal phases are respectively selected from any one of PbZrO 3 , PbHfO 3 , AgNbO 3 and NaNbO 3 .

[0009] Optionally, the general chemical formula of the high polarization antiferroelectric ceramic material is: (1-x)PbZrO3-xPbHfO3, or (1-x)PbZrO3-xAgNbO3, or (1-x)AgNbO3-xNaNbO3.

[0010] Optional, x = 0.025 ~ 0.100.

[0011] The present invention provides a method for preparing a high-polarization antiferroelectric ceramic material, which comprises:

[0012] S1: weighing oxides and / or carbonates according to a stoichiometric ratio, mixing, and then performing a first grinding to obtain a first powder;

[0013] S2: performing a first heat treatment on the first powder;

[0014] S3: Grinding the first powder for a second time to obtain a second powder;

[0015] S4: bonding and pressing the second powder to obtain a ceramic material of a preset shape;

[0016] S5: performing a second heat treatment on the ceramic material to obtain a high-polarization antiferroelectric ceramic material.

[0017] Optionally, in step S1: the oxides include lead oxide, zirconium oxide, hafnium oxide and niobium oxide, and the carbonates include silver carbonate and sodium carbonate.

[0018] Optionally, in step S1: if a high-polarization antiferroelectric ceramic material with a chemical formula of (1-x)PbZrO3-xPbHfO3 is prepared, lead oxide, zirconium oxide and hafnium oxide are weighed; if a high-polarization antiferroelectric ceramic material with a chemical formula of (1-x)PbZrO3-xAgNbO3 is prepared, lead oxide, zirconium oxide, silver carbonate and niobium oxide are weighed; if a high-polarization antiferroelectric ceramic material with a chemical formula of (1-x)AgNbO3-xNaNbO3 is prepared, silver carbonate, sodium carbonate and niobium oxide are weighed.

[0019] Optionally, the first grinding and the second grinding are both performed by ball milling.

[0020] Optionally, in step S2: the first heat treatment is a calcination treatment, the calcination treatment temperature range is 800°C to 950°C, and the calcination treatment time range is 2h to 4h.

[0021] Optionally, the first powder needs to be pressed before the first heat treatment in step S2.

[0022] Optionally, in step S4, the specific steps of bonding and pressing the second powder are as follows: adding a binder to the second powder for granulation to form a fluid powder, taking an appropriate amount of the fluid powder for tableting and pressing to obtain a ceramic material of a preset shape.

[0023] Optionally, in step S5: the second heat treatment is a sintering treatment, the sintering treatment temperature range is 1100° C. to 1250° C., and the sintering treatment time range is 2 h to 4 h.

[0024] The present invention also provides a high-polarization antiferroelectric ceramic capacitor, which includes a ceramic dielectric layer and metal layers on the upper and lower surfaces of the ceramic dielectric layer. The ceramic dielectric layer is made of any one of the above-mentioned antiferroelectric ceramic materials.

[0025] The present invention also provides a method for preparing a high polarization antiferroelectric ceramic capacitor, the method for preparing a high polarization antiferroelectric ceramic capacitor comprising: preparing a high polarization antiferroelectric ceramic material as described in any one of the above and

[0026] S6: coating metal on the upper and lower surfaces of the high-polarization antiferroelectric ceramic material to form a metal layer;

[0027] S7: Perform a third heat treatment to form a high polarization antiferroelectric ceramic capacitor.

[0028] Optionally, in step S7: the third heat treatment is a sintering treatment, the sintering treatment temperature range is 750° C. to 850° C., and the sintering treatment time range is 15 min to 60 min.

[0029] Optionally, in step S7: the third heat treatment is performed in a nitrogen atmosphere.

[0030] As described above, the high polarization antiferroelectric ceramic material, capacitor and preparation method thereof of the present invention have the following beneficial effects:

[0031] The high-polarization antiferroelectric ceramic material and its preparation method proposed in the present invention cleverly introduce the quasi-isomorphic phase boundary structure of the relaxor ferroelectric by precisely controlling the solid solution ratio of ferroelectric materials with different crystalline phases, which not only significantly improves the polarization performance and dielectric properties of the material, but also achieves a comprehensive improvement in its stability performance, opening up a new path for the research and application of antiferroelectric materials; the high-polarization antiferroelectric ceramic capacitor and its preparation method proposed in the present invention have extremely high energy storage density due to their unique antiferroelectric properties. Under the action of an electric field, antiferroelectric ceramics can undergo a phase transition between an antiferroelectric state and a ferroelectric state. This process is accompanied by a large amount of energy conversion, allowing the capacitor to store and release more energy. The antiferroelectric ceramic capacitor has excellent power density and can quickly release the stored energy in a short time. The antiferroelectric ceramic capacitor can maintain stable performance within a wide temperature range, which enables them to work reliably under various environmental conditions. Antiferroelectric ceramic capacitors are expected to play an important role in more fields and promote the progress and development of related technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Shown is a polarization change curve of the high polarization antiferroelectric ceramic material of the present invention.

[0033] Figure 2 Shown is a graph showing the frequency dependence of the dielectric constant and loss of the high polarization antiferroelectric ceramic material of the present invention.

[0034] Figure 3 Shown is a curve diagram of the dielectric constant change of the high polarization antiferroelectric ceramic material of the present invention.

[0035] Figure 4 Shown is a flow chart of the method for preparing the high polarization antiferroelectric ceramic material of the present invention.

[0036] Figure 5 Shown is a flow chart of a method for preparing a high polarization antiferroelectric ceramic capacitor according to the present invention. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0038] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional views showing the device structures will not be partially enlarged according to the general scale, and the schematic views are only examples and should not limit the scope of protection of the present invention.

[0039] For ease of description, spatially relative terms such as "under," "below," "below," "below," "above," and "on" may be used herein to describe the relationship of one structure or feature shown in the drawings to other structures or features. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings. Additionally, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. As used herein, "between" is inclusive of both endpoints.

[0040] In the context of the present application, a structure described as a first feature being "above" a second feature may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where an additional feature is formed between the first and second features, such that the first and second features may not be in direct contact.

[0041] See also Figures 1 to 5 It should be noted that the diagrams provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0042] Example 1

[0043] This embodiment provides a high-polarization antiferroelectric ceramic material, which is formed by solid solution of two antiferroelectric materials with different crystal phases in a molar ratio of (1-x):x, wherein x=0.02~0.20, including 0.02 and 0.20, for example, x=0.025, 0.050, 0.075, 0.10, 0.125, 0.150, 0.175, 0.20, and the high-polarization antiferroelectric ceramic material has a morphotropic phase boundary (MPB) structure of a relaxor ferroelectric, that is, antiferroelectric phases and ferroelectric phases with different symmetries exist simultaneously in the MPB system structure.

[0044] The coexistence of the antiferroelectric and ferroelectric phases greatly promotes the flipping process between the antiferroelectric and ferroelectric phases, allowing the antiferroelectric phase to quickly and efficiently transform into the ferroelectric phase under the action of an external electric field, thereby releasing a huge polarization charge. Compared with single-phase antiferroelectric materials, this composite structure significantly improves the material's polarization strength.

[0045] The presence of the MPB structure allows the material to exhibit more complex dielectric behavior near the phase boundary, including an increase in the dielectric constant, a decrease in dielectric loss, and an acceleration of the dielectric response. These excellent dielectric properties not only improve the signal transmission efficiency of electronic devices but also enable higher energy conversion efficiency in energy storage devices. Furthermore, by adjusting the x value, the dielectric properties of the material can be further fine-tuned to meet the specific needs of different application scenarios.

[0046] Traditional antiferroelectric materials are prone to performance degradation under temperature fluctuations or mechanical stress, limiting their application in extreme environments. High-polarization antiferroelectric ceramics, however, form a more stable crystal structure by solid-solutionizing two different crystalline phases of antiferroelectric materials. This structural stability not only improves the material's thermal stability, enabling it to maintain stable electrical properties over a wide temperature range, but also enhances its mechanical strength, reducing the risk of cracking or breakage due to external forces. Therefore, this material has broad application prospects in high-temperature, high-stress environments such as aerospace and automotive electronics.

[0047] In one specific embodiment, the two antiferroelectric materials of different crystalline phases are selected from any one of PbZrO3, PbHfO3, AgNbO3, and NaNbO3. Specifically, the general chemical formula of the high-polarization antiferroelectric ceramic material is: (1-x)PbZrO3-xPbHfO3, or (1-x)PbZrO3-xAgNbO3, or (1-x)AgNbO3-xNaNbO3.

[0048] like Figures 1 to 3 As shown, taking the (1-x)PbZrO3-xPbHfO3 system as an example, when deeply studying this system, a series of different x values were selected within the set numerical range of x. Through precise experimental design and rigorous testing methods, the polarization and dielectric properties of the system were comprehensively and systematically analyzed. The specific test results are as follows:

[0049] In order to compare the high polarization antiferroelectric ceramic material of the present application with the traditional single-phase antiferroelectric ceramic material, the value of x is selected to be 0-0.10, specifically 0, 0.025, 0.050, 0.075, and 0.100.

[0050] Figure 1 The polarization change curve is shown in Figure 1.5 MV cm -1 In an electric field environment, the polarization of the (1-x)PbZrO3-xPbHfO3 system changes with different x values. When x is in the range of 0 to 0.10, the polarization performance of the system shows a trend of first increasing and then decreasing as the x value increases. When x = 0.075, the polarization strength of the system reaches a maximum of 75uC cm -2It can be seen that the quasi-morphological phase boundary is at x = 0.075, the interaction between the antiferroelectric phase and the ferroelectric phase in the system is the strongest, and the phase transition process is the fastest and most efficient.

[0051] Figure 2 The graph below shows the frequency dependence of the dielectric constant and loss. The upper curve group shows the change of the dielectric constant at different frequencies. It can be seen that the dielectric constant also shows a trend of first increasing and then decreasing with the change of x value. At x = 0.075, that is, near the quasi-morphological phase boundary, the dielectric constant reaches its peak. The lower curve group shows the change of energy loss at different frequencies. It can be seen that the energy loss shows a trend of first decreasing and then increasing with the change of x value. At x = 0.075, that is, near the quasi-morphological phase boundary, the energy loss value is the smallest. This indicates that at this x value, the system has better charge storage capacity and lower energy loss.

[0052] Further, Figure 3 The dielectric constant change curve shows that under the environment of 10kHz, as the x value increases, the dielectric constant of the system shows a trend of first increasing and then decreasing. At x=0.075, that is, near the quasi-isomorphic phase boundary, the dielectric constant reaches its peak.

[0053] From the above, it can be seen that when x = 0.075, the (1-x)PbZrO3-xPbHfO3 system has the best polarization performance, charge storage capacity and lower energy loss. Preferably, x = 0.025 to 0.100. In the range of x = 0 to 0.20, the polarization performance of the system shows a trend of first increasing and then decreasing, the dielectric constant also shows a trend of first increasing and then decreasing, and the energy loss shows a trend of first decreasing and then increasing. Because the changes in their trends are more obvious in the range of 0 to 0.10, the figure of this embodiment is not shown in the range of x = 0.10 to 0.20.

[0054] Example 2

[0055] like Figure 4 As shown, this embodiment provides a method for preparing a high-polarization antiferroelectric ceramic material, which is prepared by a solid-phase method. The method for preparing a high-polarization antiferroelectric ceramic material includes the following steps:

[0056] S1: weighing oxide and / or carbonate powders according to a stoichiometric ratio, mixing, and then performing a first grinding to obtain a first powder;

[0057] S2: performing a first heat treatment on the first powder;

[0058] S3: Grinding the first powder for a second time to obtain a second powder;

[0059] S4: bonding and pressing the second powder to obtain a ceramic material of a preset shape;

[0060] S5: performing a second heat treatment on the ceramic material to obtain a high-polarization antiferroelectric ceramic material.

[0061] The specific steps of the preparation method of high polarization antiferroelectric ceramic material are as follows:

[0062] Step S1: Obtain oxides and / or carbonates, including lead oxide, zirconium oxide, hafnium oxide, and niobium oxide, and carbonates including silver carbonate and sodium carbonate, and pack them separately into wide-mouth bottles. These raw materials are then placed in an oven for baking to obtain dry oxides and carbonates with a purity exceeding 98%. The baking temperature is 100°C to 150°C, and the baking time is at least 10 hours. The wide-mouth bottles are sealed with weighing paper during the baking process. The purpose of baking is to dry the materials and increase their purity. The actual baking temperature and baking time can also be set according to actual needs. The required oxides and carbonates are weighed according to the stoichiometric ratios in the general chemical formula of the high-polarization antiferroelectric ceramic material. It should be noted that the preparation of antiferroelectric materials generally requires the use of oxides containing the required elements. Although carbonates are not the primary raw material used directly in the preparation of antiferroelectric materials, they may be used as auxiliary raw materials or precursors in certain situations. In this embodiment, the corresponding oxides, or oxides and carbonates, can be obtained as needed to prepare the antiferroelectric material.

[0063] For example, if (1-x)PbZrO3-xPbHfO3 is prepared, lead oxide, zirconium oxide and hafnium oxide are weighed separately; if (1-x)PbZrO3-xAgNbO3 is prepared, lead oxide, zirconium oxide, silver carbonate and niobium oxide are weighed separately; if (1-x)AgNbO3-xNaNbO3 is prepared, silver carbonate, sodium carbonate and niobium oxide are weighed separately.

[0064] Specifically, the first grinding method is ball milling, and the weighed oxides and carbonates are mixed and added to a ball mill for the first grinding. During the grinding process, the material in the ball mill is directly milled with a ball mill. The ball milling speed and the ball milling time can be set according to actual needs and are not specifically limited here. Alternatively, anhydrous ethanol is used as the ball milling medium. The specific gravity of the material, ball mill, and anhydrous ethanol, the ball milling speed and the ball milling time can be set according to actual needs and are not specifically limited here, thereby obtaining the first powder. It should be noted here that when using a ball milling medium, the mixed slurry after the ball milling process needs to be dried to remove the ethanol in the mixed slurry. The baking temperature and the drying time can be set according to actual needs and are not specifically limited here.

[0065] Preferably, the first powder is passed through a sieve with a preset mesh size to refine the powder, so that the powder is fully mixed and evenly mixed, thereby increasing its contact surface area and improving the reaction activity or mixing efficiency.

[0066] Step S2: Perform a first heat treatment on the first powder. Before the first heat treatment, the first powder can be pressed into blocks to facilitate placing the block-shaped first powder into a muffle furnace for the first heat treatment. In a specific example that can be implemented, the first heat treatment is a calcination treatment, and the calcination treatment temperature range is 800°C to 950°C, and the calcination treatment time range is 2h to 4h. The specific calcination treatment temperature and calcination treatment time can be set according to actual needs and are not limited here.

[0067] Step S3: The bulk first powder is placed in a grinding body for grinding, and then placed in a ball mill for a second grinding to obtain a second powder. The second grinding method can also be ball milling. The specific ball milling method is the same as the first grinding method and is not described here. It should be noted that the second grinding is finer than the first grinding, which facilitates the subsequent acquisition of ceramic materials.

[0068] Step S4: Bonding and pressing the second powder, i.e., granulating and pressing the second powder into a mold. Specifically, a binder is added to the second powder for granulation to obtain a fluid powder with good fluidity. The fluid powder is ground and sieved to ensure that the binder and the second powder are fully mixed. The fluid powder with good fluidity has good uniformity and flowability. The binder is preferably polyvinyl alcohol (PVA). The mass fraction and amount of polyvinyl alcohol added, as well as the mesh size of the fluid powder, can be set according to actual needs and are not specifically limited here.

[0069] The fluid powder is allowed to stand for at least 24 hours to obtain a fluid powder with stable properties. An appropriate amount of the fluid powder is then placed in a tablet press and compressed to obtain a dense and uniform ceramic material. The tableting pressure range and holding time, as well as the weight, shape, and size of the ceramic material, can be adjusted according to actual needs. In this embodiment, the ceramic material is in the shape of a disc. Furthermore, the ceramic material can be subjected to a secondary compression to obtain an even denser and more uniform ceramic material.

[0070] In this step, the ceramic material also needs to be debonded. The temperature is quickly raised in a short period of time and kept warm for a certain period of time. The debonding temperature and holding time can be set according to actual needs and are not specifically shown here. It is only necessary to remove the adhesive from the ceramic material.

[0071] Step S5: Perform a second heat treatment on the ceramic material. The second heat treatment is a sintering treatment. The ceramic material is placed in a sintering furnace for sintering treatment. The sintering treatment temperature range is 1100℃~1250℃, and the calcination treatment time range is 2h~4h. The specific heating time, sintering treatment temperature and sintering treatment time can be set according to actual needs and are not limited here.

[0072] Three groups of ceramic material preparation experiments are conducted as follows:

[0073] Comparative example: PbZrO3

[0074] Obtain lead oxide and zirconium oxide and pack them separately in wide-mouth bottles, and seal the wide-mouth bottles. Place the lead oxide and zirconium oxide in the wide-mouth bottles in an oven for baking and drying to obtain lead oxide and zirconium oxide with a purity higher than 98%. According to the stoichiometric ratio in the chemical formula of PbZrO3, weigh the required lead oxide and zirconium oxide respectively. Mix the weighed lead oxide and zirconium oxide and add them to a ball mill for the first ball milling to obtain a first powder. Calcine the first powder at 850°C and then ball mill it for a second time to obtain a second powder. Add polyvinyl alcohol to the second powder for granulation to obtain a flowing powder with good fluidity, and grind and sieve the flowing powder. Leave the powder with good fluidity for more than 24 hours to obtain a flowing powder with stable performance. Take an appropriate amount of the flowing powder and put it into a tablet press for tablet pressing to obtain a dense and uniform disc-shaped ceramic material. The disc-shaped ceramic material was subjected to debinding treatment and sintered at 1200°C to obtain the antiferroelectric material PbZrO3. After testing, the dielectric constant of the obtained antiferroelectric material PbZrO3 was 230 and the maximum polarization was 57uC cm -2 .

[0075] Example 2-1: 0.95PbZrO3-0.05PbHfO3

[0076] Obtain lead oxide, zirconium oxide, and hafnium oxide and package them separately in wide-mouth bottles, which are sealed. Place the lead oxide, zirconium oxide, and hafnium oxide in the wide-mouth bottles in an oven to dry them, thereby obtaining lead oxide, zirconium oxide, and hafnium oxide with a purity greater than 98%. According to the stoichiometric ratio in the chemical formula of 0.95PbZrO3-0.05PbHfO3, the required lead oxide, zirconium oxide, and hafnium oxide are weighed respectively. The weighed lead oxide, zirconium oxide, and hafnium oxide are mixed and added to a ball mill for a first ball milling to obtain a first powder. The first powder is calcined at 850°C and then ball milled a second time to obtain a second powder. Polyvinyl alcohol is added to the second powder for granulation to obtain a fluid powder with good fluidity, which is then ground and sieved. The powder, which has good fluidity, was allowed to stand for at least 24 hours to obtain a stable, flowing powder. An appropriate amount of this flowing powder was then placed in a tablet press and pressed to form a dense and uniform disc-shaped ceramic material. The disc-shaped ceramic material was subjected to a binder removal process and sintered at 1200°C to obtain the antiferroelectric material 0.95PbZrO3-0.05PbHfO3. Testing revealed that the resulting antiferroelectric material, 0.95PbZrO3-0.05PbHfO3, had a dielectric constant of 245 and a maximum polarization of 62uC cm. -2 .

[0077] Example 2-2: 0.95PbZrO3-0.05PbHfO3

[0078] Obtain lead oxide, zirconium oxide, and hafnium oxide and package them separately in wide-mouth bottles, which are sealed. Place the lead oxide, zirconium oxide, and hafnium oxide in the wide-mouth bottles in an oven to dry them, thereby obtaining lead oxide, zirconium oxide, and hafnium oxide with a purity greater than 98%. According to the stoichiometric ratio in the chemical formula of 0.95PbZrO3-0.05PbHfO3, the required lead oxide, zirconium oxide, and hafnium oxide are weighed respectively. The weighed lead oxide, zirconium oxide, and hafnium oxide are mixed and added to a ball mill for a first ball milling to obtain a first powder. The first powder is calcined at 850°C and then ball milled a second time to obtain a second powder. Polyvinyl alcohol is added to the second powder for granulation to obtain a fluid powder with good fluidity, which is then ground and sieved. The powder with good fluidity was allowed to stand for at least 24 hours to obtain a stable, flowing powder. An appropriate amount of the flowing powder was then placed in a tablet press and pressed to obtain a dense and uniform disc-shaped ceramic material. The disc-shaped ceramic material was subjected to a binder removal process and sintered at 1150°C to obtain the antiferroelectric material 0.95PbZrO3-0.05PbHfO3. Testing showed that the dielectric constant of the antiferroelectric material 0.95PbZrO3-0.05PbHfO3 was 260 and the maximum polarization was 65uC cm -2 .

[0079] From the comparative experiments, it can be seen that the dielectric constant and polarization values of the antiferroelectric ceramic material formed by the solid solution of two antiferroelectric materials with different crystal phases are improved compared with the single-phase antiferroelectric material.

[0080] The interaction between quasi-morphous phase boundaries and the interface effect promote the redistribution of charge and the diversification of polarization mechanisms, thereby significantly improving the dielectric constant of ceramic materials. Specifically, the charge accumulation at the quasi-morphous phase boundaries, the increase in space charge limited current, and the possible dipole orientation effect act together on the composite system, allowing the ceramic material to store more charge under the action of the electric field, thereby exhibiting a higher dielectric constant. At the same time, the stress coupling between different crystal phases and the possible formation of microdomain structures. The lattice constant difference and strain state between different crystal phases induce the formation of microdomains, which can more easily undergo orientation changes under the action of the electric field, thereby contributing to a greater polarization strength. In addition, the charge accumulation at the quasi-morphous interface may also form an additional polarization mechanism, further improving the polarization value of the material.

[0081] Example 3

[0082] This embodiment provides a high-polarization antiferroelectric ceramic capacitor. The high-polarization antiferroelectric ceramic capacitor includes a ceramic dielectric layer and metal layers disposed on opposite upper and lower surfaces of the ceramic dielectric layer. The ceramic dielectric layer is made of the antiferroelectric ceramic material described in any one of the first embodiments. The metal layers disposed on opposite upper and lower surfaces of the ceramic dielectric layer serve as metal electrodes of the ceramic capacitor. The metal electrodes may be any conductive metal such as silver (Ag), copper (Cu), aluminum (Al), palladium (Pd), or a nickel (Ni) alloy. In this embodiment, the metal layer is preferably a silver layer, which has good conductivity. The thickness and shape of the electrode layer can be adjusted according to actual needs and are not specifically limited herein.

[0083] In a specific embodiment, the high polarization antiferroelectric ceramic capacitor further includes a plastic encapsulation layer to encapsulate the ceramic dielectric layer, leaving only the metal leads exposed, to prevent the ceramic dielectric layer from being damp or contaminated. The plastic encapsulation layer can be made of a polymer material such as resin.

[0084] The high-polarization antiferroelectric ceramic capacitor proposed in this embodiment has an extremely high energy storage density due to its unique antiferroelectric properties. Under the action of an electric field, antiferroelectric ceramics can undergo a phase change between an antiferroelectric state and a ferroelectric state. This process is accompanied by a large amount of energy conversion, which enables the capacitor to store and release more energy. Antiferroelectric ceramic capacitors have excellent power density and can quickly release stored energy in a short time. Antiferroelectric ceramic capacitors can maintain stable performance within a wide temperature range, which enables them to work reliably under various environmental conditions. Antiferroelectric ceramic capacitors are expected to play an important role in more fields and promote the progress and development of related technologies.

[0085] Example 4

[0086] like Figure 5 As shown, this embodiment provides a method for preparing a high-polarization antiferroelectric ceramic capacitor. The method for preparing a high-polarization antiferroelectric ceramic capacitor includes the method for preparing an antiferroelectric ceramic material as described in any one of the second embodiments, and S6: coating metal on the upper and lower surfaces of the antiferroelectric ceramic material to form a metal layer; S7: performing a third heat treatment to form a high-polarization antiferroelectric ceramic capacitor.

[0087] Furthermore, before coating the upper and lower surfaces of the ceramic material with metal, the ceramic material is polished, cleaned, and dried to obtain a clean ceramic material with a preset thickness.

[0088] In a specific embodiment, the third heat treatment is a sintering treatment, the sintering temperature range is 750°C to 850°C, and the sintering time range is 15 minutes to 60 minutes. The specific heating rate, sintering temperature, and sintering time can be set according to actual needs and are not limited. Furthermore, the sintering treatment is carried out in a nitrogen atmosphere.

[0089] In a specific implementation example, the method of coating the metal layer is any one of screen printing, sintering, sputtering, electroplating, pulsed laser deposition, etc., and the metal material of the metal layer is any one of conductive metals such as silver (Ag), copper (Cu), aluminum (Al), palladium (Pd), nickel (Ni) alloy, etc. The specific preparation method of the metal layer, the selection of the metal layer material, and the thickness and shape of the metal layer can be set according to actual needs, and again no specific restrictions are made.

[0090] In one specific embodiment, the method for preparing a high-polarization antiferroelectric ceramic capacitor further includes step S8: applying a plastic encapsulation layer to the surface of the high-polarization antiferroelectric ceramic capacitor. The plastic encapsulation layer encapsulates the ceramic dielectric layer, leaving only the metal layer exposed, to protect the ceramic dielectric layer from moisture or contamination. The plastic encapsulation layer can be made of a polymer material such as a resin, and can be selected based on actual needs and is not limited herein.

[0091] In summary, the present invention proposes a high-polarization antiferroelectric ceramic material, a capacitor and a preparation method thereof. The high-polarization antiferroelectric ceramic material is formed by solid solution of two antiferroelectric materials with different crystal phases in a molar ratio of (1-x):x, where x=0.02~0.20. The high-polarization antiferroelectric ceramic material has a quasi-isomorphic phase boundary structure of a relaxor ferroelectric. The high polarization antiferroelectric ceramic material and its preparation method proposed in the present invention, by precisely controlling the solid solution ratio of different crystalline phase-contrast ferroelectric materials, cleverly introduces the quasi-morphous phase boundary structure of the relaxor ferroelectric, which not only significantly improves the polarization performance and dielectric properties of the material, but also achieves a comprehensive improvement in its stability performance, opening up a new path for the research and application of antiferroelectric materials; the high polarization antiferroelectric ceramic capacitor and its preparation method proposed in the present invention have extremely high energy storage density due to their unique antiferroelectric properties. Under the action of an electric field, antiferroelectric ceramics can undergo a phase transition between an antiferroelectric state and a ferroelectric state. This process is accompanied by a large amount of energy conversion, allowing the capacitor to store and release more energy. The antiferroelectric ceramic capacitor has excellent power density and can quickly release the stored energy in a short time. The antiferroelectric ceramic capacitor can maintain stable performance in a wide temperature range, which enables them to work reliably under various environmental conditions. Antiferroelectric ceramic capacitors are expected to play an important role in more fields and promote the progress and development of related technologies. Therefore, the present invention effectively overcomes certain shortcomings in the prior art and has high industrial utilization value.

[0092] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing a high polarization antiferroelectric ceramic capacitor, characterized in that: The preparation method of the high-polarization antiferroelectric ceramic capacitor comprises: S1: weighing oxides and / or carbonates according to a stoichiometric ratio, mixing, and then performing a first grinding to obtain a first powder; S2: performing a first heat treatment on the first powder, wherein the first heat treatment is a calcination treatment, the calcination treatment temperature range is 800° C. to 950° C., and the calcination treatment time range is 2 h to 4 h; S3: Grinding the first powder for a second time to obtain a second powder; S4: bonding and pressing the second powder to obtain a ceramic material of a preset shape; S5: performing a second heat treatment on the ceramic material to obtain a high-polarization antiferroelectric ceramic material, wherein the second heat treatment is a sintering treatment, the sintering treatment temperature range is 1100° C. to 1250° C., and the sintering treatment time range is 2 hours to 4 hours; S6: coating metal on the upper and lower surfaces of the high-polarization antiferroelectric ceramic material to form a metal layer; S7: performing a third heat treatment to form a high-polarization antiferroelectric ceramic capacitor, wherein the third heat treatment is a sintering treatment, the sintering treatment temperature range is 750° C. to 850° C., and the sintering treatment time range is 15 min to 60 min; The chemical formula of the high-polarization antiferroelectric ceramic material is: (1-x)PbZrO3-xPbHfO3, wherein x=0.

075. The high-polarization antiferroelectric ceramic material has a quasi-morphous phase boundary structure of a relaxor ferroelectric.

2. The method for preparing a high polarization antiferroelectric ceramic capacitor according to claim 1, wherein: In step S1, lead oxide, zirconium oxide and hafnium oxide are weighed.

3. The method for preparing a high polarization antiferroelectric ceramic capacitor according to claim 1, wherein: The first grinding and the second grinding are both ball milling.

4. The method for preparing a high polarization antiferroelectric ceramic capacitor according to claim 1, wherein: Before the first heat treatment in step S2, the first powder needs to be pressed.

5. The method for preparing a high polarization antiferroelectric ceramic capacitor according to claim 1, wherein: In step S4, the specific steps of bonding and pressing the second powder are as follows: adding a binder to the second powder for granulation to form a fluid powder, taking an appropriate amount of the fluid powder for tableting and pressing to obtain a ceramic material of a preset shape.

6. The method for preparing a high polarization antiferroelectric ceramic capacitor according to claim 1, wherein: In step S7: the third heat treatment is performed in a nitrogen atmosphere.

7. The high polarization antiferroelectric ceramic capacitor prepared by the method for preparing a high polarization antiferroelectric ceramic capacitor according to claim 1, characterized in that: The high-polarization antiferroelectric ceramic capacitor includes a ceramic dielectric layer and metal layers on upper and lower surfaces of the ceramic dielectric layer facing each other. The ceramic dielectric layer is made of the antiferroelectric ceramic material according to claim 1.

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