Energy storage ceramic materials, their preparation methods, and preparation methods for dielectrics of high energy storage density ceramic capacitors

Abstract

The present invention discloses an energy storage ceramic material, a preparation method thereof, and a preparation method of a dielectric of a high energy storage density ceramic capacitor. Among them, the general formula of the energy storage ceramic material is (1−y)(Bi 0.5 Na 0.5 ) (1‑x) A x DE3−yG; wherein, D is Ti element, and E is O element; ADE3 is a general formula of a modifier that can improve the stability of Bi 0.5 Na 0.5 TiO3 to obtain (Bi 0.5 Na 0.5 ) (1‑x) A x DE3 with a morphotropic phase boundary; G is a general formula of a relaxor that can be introduced at the morphotropic phase boundary; the value range of x is 0.06≤x≤0.25, and the value range of y is 0<y≤0.18. Since Bi 0.5 Na 0.5 TiO3 has a more stable structure after being modified by the modifier and also has a morphotropic phase boundary, the performance of the material can be improved by introducing a relaxor at the morphotropic phase boundary.

Description

Technical Field

[0001] The invention relates to the technical field of energy storage ceramic materials, and in particular to an energy storage ceramic material and a preparation method thereof, and a high energy storage density ceramic capacitor dielectric. Background Art

[0002] At present, the main commercial energy storage materials are PbTiO 3 (PT) based, BiFeO 3 (BF) based, BaTiO 3 (BT) based energy storage ceramics, etc. However, these commonly used energy storage materials have more or less the following problems in actual use: for example, although pure PT ceramics have a high Curie temperature (Tc = 490 ° C), they are difficult to sinter, prone to cracks and poor performance. Moreover, since the lead (Pb) in PT-based materials is volatile, it will not only pollute the environment, but also endanger human health; for example, since BF-based materials have high requirements for synthesis temperature, Fe will exist in the preparation process of BF-based materials. 3+ Fe 2+ The transformation situation makes the preparation process of BF-based antiferroelectric ceramics relatively difficult; for example, although BT-based ceramics have excellent ferroelectric properties, their low Curie temperature limits their application at high temperatures.

[0003] Although sodium bismuth titanate (Bi 0.5 Na 0.5 TiO 3 BNT (Boundary Tolerance, BNT for short)-based ceramics have broad application prospects in the field of dielectric energy storage because of their environmental friendliness, cheap raw materials, large saturation polarization value, high Curie temperature and low dielectric loss. However, pure BNT has a large residual polarization and a small breakdown field strength, which leads to a large energy loss, and the energy storage density and energy storage efficiency are relatively low. Therefore, it still needs to be further optimized. Moreover, since BNT is a ferroelectric material with a high spontaneous polarization, it will lead to a large coercive field, and after the external electric field disappears, it can still maintain a high polarization intensity, thereby showing strong coercivity; in addition, due to the presence of lattice defects in BNT-based materials and vacancies caused by the volatilization of Bi ions, the electrical properties of BNT-based materials are affected, resulting in an increase in leakage current. All these make it difficult to directly apply BNT ceramics.

[0004] Therefore, it is necessary to provide a BNT-based ceramic energy storage material that is environmentally friendly, has small grain size, large saturation polarization value, low residual polarization, high energy density and energy storage efficiency, low production cost, and high stability. Summary of the invention

[0005] Generally, to improve the performance of the ceramic matrix, the following methods can be used: 1) Control the sintering process: Through a reasonable sintering process, the grain size and distribution of the ceramic can be regulated, thereby improving its mechanical properties and density. 2) Optimize the design structure: When designing ceramic samples, you can consider adopting a reasonable structural design, such as adding a supporting structure, changing the shape, etc., to improve its overall performance. 3) Element doping: Carefully select appropriate element doping methods, design the introduction of metal ions to replace the A and B position cations respectively, and perform reasonable regulation, which can effectively improve the energy storage performance of the ceramic matrix and make it have a wider application prospect in the field of energy storage.

[0006] In the process of developing energy storage ceramic materials, the inventors found that doping ADE in the BNT matrix 3 type ferroelectric, BNT matrix after ADE 3 The solid solution obtained after the modification of the ferroelectric type not only has a more stable structure, but also has a quasi-modular phase boundary (MPB). The inventors further found that by adjusting the ADE 3 The doping amount of the type ferroelectric is (1-x)Bi 0.5 Na 0.5 BO 3 -xADE 3 When x is in the range of 0.06≤x≤0.25, it exhibits excellent electrical properties near the MPB, with a higher maximum polarization intensity Pm and a lower coercive field Ec than BNT; at the same time, the inventors also found that the introduction of a relaxation agent at the quasi-isotropic phase boundary and ion doping can increase the polarization difference. Therefore, in order to solve at least one of the above problems. According to one aspect of the present invention, an energy storage ceramic material is provided.

[0007] The general formula of the energy storage ceramic material is (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yG 3 ; Where D is Ti element, E is O element; ADE 3 In order to improve Bi 0.5 Na 0.5 TiO 3 (BNT) to obtain a quasi-isotropic phase boundary (Bi 0.5 Na 0.5 ) (1-x) A x DE 3 ; G is the general formula of the relaxation agent that can be introduced at the quasi-isotropic phase boundary; the value range of x is 0.06≤x≤0.25, and the value range of y is 0<y≤0.18.

[0008] Because Bi 0.5 Na 0.5 TiO 3 After modification by the modifier, the structure becomes more stable and also has a quasi-isotropic phase boundary, so that the performance of the material can be improved by introducing a relaxation agent into the quasi-isotropic phase boundary.

[0009] In some embodiments, G is of the general formula H(J 0.7 L 0.3 )E 3 , or general formula M 0.7 Bi 0.2 DE 3 , or the general formula BiQ 2 / 3 R 1 / 3 E 3 , or general formula S 2 E 3 .

[0010] In some embodiments, H is used to make (1-y)(Bi 0.5 Na 0.5 ) 0.93 A 0.07 BO 3 -yL(M 0.7 N 0.3 ) 3 The ferroelectric domains are transformed into polar nanodomains; H and / or J are used to refine (1-y)(Bi 0.5 Na 0.5 ) 0.93 A 0.07 DE 3 -yG 3 The grain size of L is used to improve (1-y)(Bi 0.5 Na 0.5 ) 0.93 A 0.07 DE 3 -yG 3 cubic equilibrium and destroys (1-y)(Bi 0.5 Na 0.5 ) 0.93 A 0.07 DE 3 -yG 3 Long-range order (long-range ferroelectric nanodomains), induced (1-y)(Bi 0.5 Na 0.5 ) 0.93 A 0.07 DE 3 -yG 3 Polar nanoregions (PNRs) are produced.

[0011] Using G as a relaxant, (1-y)(Bi 0.5 Na 0.5 ) 0.93 A 0.07 DE 3 Doping can increase the polarization difference of the material, which is beneficial to improving the energy storage performance.

[0012] In some embodiments, the general formula is ADE 3 The modifier is a ferroelectric material. This is to make the modified material have a higher saturation polarization intensity, which is conducive to obtaining higher energy storage characteristics.

[0013] In some embodiments, A is a Ba element, and the general formula of the material is (1-y)(Bi 0.5 Na 0.5 ) (1-x) Ba x DE 3 -yG, the value range of x is 0.06≤x≤0.08; preferably, the value of x is 0.07. 3 (referred to as BT) to modify BNT, not only can a more stable structure (Bi 0.5 Na 0.5 ) (1-x) Ba x TiO 3 , referred to as BNBT; and the obtained BNBT has a quasi-modular phase boundary. In some embodiments, A is a general formula Bi 0.5 K 0.5 The general formula of the material is (1-y)(Bi 0.5 Na 0.5 ) (1-x) (Bi 0.5 K 0.5 ) x DE 3 -yG, the value range of x is 0.06≤x≤0.25; preferably, the value of x is 0.2. 0.5 K 0.5 TiO 3 (BKT for short) can modify BNT to obtain a more stable structure (Bi 0.5 Na 0.5 ) (1-x) (Bi 0.5 K 0.5 ) x TiO 3 , referred to as BNBKT; it can also obtain a more stable structure with a quasi-isotropic phase boundary (Bi 0.5 Na 0.5 ) (1-x) (Bi0.5 K 0.5 ) x TiO 3 .

[0014] In some embodiments, H is Ca; and / or J is Hf; and / or L is Zr; and / or M is Sr; and / or Q is Mg; and / or R is Nb; and / or S is La. Since Ca has a small volume and a low polarization degree, it can promote the transformation of ferroelectric domains into polar nanodomains; for example, when the relaxant is Ca(Hf 0.7 Zr 0.3 ) 3 When BNBT is ion doped, the obtained (1-y)(Bi 0.5 Na 0.5 ) (1-x) Ba x TiO 3 -yCa(Hf 0.7 Zr 0.3 ) 3 The polarization difference △P of (1-y)BNBT-yCHZ) is reduced, and the residual polarization of (1-y)BNBT-yCHZ) is reduced, which greatly improves its electrical insulation performance, reduces its leakage current, greatly improves the energy storage density and energy storage efficiency of the capacitor, improves its breakdown field strength, and reduces energy loss; moreover, since the raw materials do not contain volatile components, it is not easy to pollute the environment; when the modifier is BKT, or when the relaxation agent is Sr 0.7 Bi 0.2 TiO 3 、BiMg 2 / 3 Nb 1 / 3 O 3 ,La 2 O 3 When the modifier is BT and the relaxant is Ca(Hf 0.7 Zr 0.3 ) 3 The role played is the same as that played by the , so I will not go into details here.

[0015] In some embodiments, y has a value of 0.10, 0.12, 0.14, 0.16 or 0.18.

[0016] According to one aspect of the present invention, there is provided a method for preparing the aforementioned energy storage ceramic material, which comprises the following steps:

[0017] S10: Bi 0.5 Na 0.5 TiO 3A first matrix is ​​modified by a modifier to stabilize the structure of the first matrix to obtain a second matrix having a morphotropic phase boundary;

[0018] S20: introducing a relaxation agent at the quasi-isotropic phase boundary of the second matrix to perform ion doping to obtain a front energy storage ceramic material.

[0019] Because Bi 0.5 Na 0.5 TiO 3 After modification by the modifier, the structure becomes more stable and also has a quasi-isotropic phase boundary, so that the performance of the material can be improved by introducing a relaxation agent into the quasi-isotropic phase boundary.

[0020] According to one aspect of the present invention, another method for preparing the aforementioned energy storage ceramic material is provided, comprising the following steps:

[0021] S100: According to the general formula (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yG weigh the raw materials, A is Ba element; or the general formula Bi 0.5 K 0.5 ;

[0022] G is the general formula H(J 0.7 L 0.3 )E 3 , raw materials include: Bi 2 E 3 、Na 2 CE 3 、BaCE 3 ,DE 2 、HCE 3 , JE 2 and LE 2 , or raw materials include: Bi 2 E 3 、Na 2 CE 3 ,DE 2 、HCE 3 , JE 2 LE 2 and KCE 3 ;

[0023] Or G is the general formula M 0.7 Bi 0.2 DE 3 , raw materials include: Bi 2 E 3 、Na 2 CE 3 、BaCE3 ,DE 2 and MCE 3 , or raw materials include: Bi 2 E 3 、Na 2 CE 3 ,DE 2 、MCE 3 and KCE 3 ;

[0024] Or G is the general formula BiQ 2 / 3 R 1 / 3 E 3 , raw materials include: Bi 2 E 3 、Na 2 CE 3 、BaCE 3 ,DE 2 , QE and R 2 E 5 , or raw materials include: Bi 2 E 3 、Na 2 CE 3 ,DE 2 , QE, R 2 E 5 and KCE 3 ;

[0025] Or G is the general formula S 2 E 3 , raw materials include: Bi 2 E 3 、Na 2 CE 3 、BaCE 3 ,DE 2 and S 2 E 3 , or raw materials include: Bi 2 E 3 、Na 2 CE 3 ,DE 2 , S 2 E 3 and KCE 3 ;

[0026] Wherein, D is Ti element, E is O element, x and y are both mole percentages, the value range of x is 0.06≤x≤0.25, and the value range of y is 0<y≤0.18.

[0027] S200: preparing the raw material into powder;

[0028] S300: granulating the prepared powder;

[0029] S400: forming and tableting the granulated raw materials to form a ceramic embryo;

[0030] S500: Sintering the ceramic body to obtain (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yG ceramics.

[0031] Because Bi 0.5 Na 0.5 TiO 3 After being modified by the modifier, the structure is more stable and has a quasi-isotropic phase boundary, so that the performance of the material can be improved by introducing a relaxation agent into the quasi-isotropic phase boundary; moreover, the present invention adopts a solid phase sintering method for preparation, so that the production cost is low.

[0032] In some embodiments, HCE 3 H in which is Ca element; and / or JE 2 Where J is Hf element; and / or LE 2 Where L is Zr element; and / or MCE 3 M in QE is Sr; and / or Q in QE is Mg; and / or R 2 E 5 R is Nb element; and / or S 2 E 3 The S in the formula is La. Thus, the obtained (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yG polarization difference △P, reduce (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 The residual polarization of -yG greatly improves its electrical insulation properties, reduces its leakage current, greatly increases the energy storage density and energy storage efficiency of the capacitor, increases its breakdown field strength, reduces energy loss, and reduces pollution to the environment.

[0033] According to one aspect of the present invention, a method for preparing a high energy storage density ceramic capacitor dielectric is provided, which comprises the following steps:

[0034] S1000: grinding and polishing the ceramic material, which is the aforementioned energy storage ceramic material, to obtain a ceramic sheet;

[0035] S2000: Preparation of electrodes on ceramic sheets;

[0036] Or based on the above preparation method, the method further comprises the following steps:

[0037] S600: grinding and polishing the sintered ceramic to obtain a ceramic slice;

[0038] S700: Preparation of electrodes on ceramic wafers.

[0039] Compared with the prior art, the high energy storage density ceramic capacitor dielectric of the present invention is made of ferroelectric material ADE 3 and Bi 0.5 Na 0.5 TiO 3 Made by solid phase sintering with G doping. 3 Compare 0.5 Na 0.5 TiO 3 Modification to obtain a quasi-modular phase boundary (Bi 0.5 Na 0.5 ) (1-x) A x DE 3 , and modified by doping (Bi 0.5 Na 0.5 ) (1-x) A x DE 3 With the increase of doping content, the relaxation characteristics are gradually enhanced, and polar nanoregions (PNRs) are induced and the grain size is refined, which significantly increases the maximum breakdown field strength and effectively improves the pure Bi 0.5 Na 0.5 TiO 3 The disadvantages of large residual polarization difference and large leakage current greatly improve the energy storage density and energy storage efficiency of capacitor dielectrics. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flow chart of a method for preparing an energy storage ceramic material according to an embodiment of the present invention;

[0041] Figure 2 A flow chart of a method for preparing an energy storage ceramic material according to another embodiment of the present invention;

[0042] Figure 3 An XRD spectrum of an energy storage ceramic material according to an embodiment of the present invention;

[0043] Figure 4 This is a SEM microscopic characterization image of an energy storage ceramic material according to one embodiment of the present invention;

[0044] Figure 5This is a test diagram of the dielectric properties of an energy storage ceramic material according to one embodiment of the present invention;

[0045] Figure 6 An energy storage performance analysis diagram of an energy storage ceramic material according to one embodiment of the present invention;

[0046] Figure 7 This is a stability analysis test diagram of an energy storage ceramic material according to one embodiment of the present invention;

[0047] Figure 8 A flow chart of a method for preparing a high energy storage density ceramic capacitor dielectric according to an embodiment of the present invention;

[0048] Fig. 9 The present invention is a flowchart of a method for preparing a high energy storage density ceramic capacitor dielectric according to another embodiment of the present invention. DETAILED DESCRIPTION

[0049] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0050] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include" and "comprise" include not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such processes, methods, articles or equipment. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the existence of other identical elements in the process, method, article or equipment that includes the elements. The terms used in this article are generally commonly used terms by those skilled in the art. If they are inconsistent with commonly used terms, the terms in this article shall prevail.

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] According to one embodiment of the present invention, there is provided an energy storage ceramic material, the general formula of which is (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3-yG; where D is Ti element; ADE 3 In order to improve Bi 0.5 Na 0.5 TiO 3 The stability modifier formula is to obtain a (Bi 0.5 Na 0.5 ) (1-x) A x DE 3 ; G is the general formula of the relaxation agent that can be introduced at the quasi-isotropic phase boundary; the value range of x is 0.06≤x≤0.25, and the value range of y is 0<y≤0.18.

[0053] Because Bi 0.5 Na 0.5 TiO 3 After ADE 3 The modified structure of the modifier is more stable and also has a quasi-isotropic phase boundary, so that the performance of the material can be improved by introducing a relaxation agent in the quasi-isotropic phase boundary.

[0054] In some preferred embodiments, G is of the general formula H(J 0.7 L 0.3 )E 3 , or general formula M 0.7 Bi 0.2 DE 3 , or the general formula BiQ 2 / 3 R 1 / 3 E 3 , or general formula S 2 E 3 .

[0055] In some preferred embodiments, H is used to make (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yG 3 The ferroelectric domains are transformed into polar nanodomains; M is used to refine (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yG grain size; N is used to improve (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yG 3 cubic equilibrium and destroys (1-y)(Bi 0.5 Na 0.5 )(1-x) A x DE 3 -yG 3 The long-range order of (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yG 3 Polar nanoregions (PNRs) are generated. In the field of ceramic energy storage, high energy storage density usually requires high breakdown field strength. However, high voltage places more stringent requirements on the reliability of ceramic capacitors. At the same time, long-term high-voltage operation will also cause more equipment losses and lead to more production costs. This product is tested by ADE 3 Bi 0.5 Na 0.5 TiO 3 Modification, so that the obtained (Bi 0.5 Na 0.5 ) (1-x) A x DE 3 Not only is the stability improved, but also has a quasi-isotropic phase boundary, and this product also has 0.5 Na 0.5 ) (1-x) A x DE 3 The relaxation agent H(J 0.7 L 0.3 )E 3 , which improves the general formula to (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yH(J 0.7 L 0.3 )E 3 The performance of energy storage ceramic materials. For example, H is Ca; and / or J is Hf; and / or L is Zr; A is Ba; and / or D is Ti; and / or E is O. Since Ca has a small volume and low polarization degree, it can promote the transformation of ferroelectric domains to polar nanodomains; when the modifier is BT and the relaxant is Ca(Hf 0.7 Zr 0.3 ) 3 When BNBT is ion doped, the obtained (1-y)(Bi 0.5 Na 0.5 ) (1-x) Ba x TiO 3 -yCa(Hf 0.7 Zr 0.3 )3 The polarization difference of (1-y)BNBT-yCHZ (abbreviated as (1-y)BNBT-yCHZ) is reduced, the residual polarization of (1-y)BNBT-yCHZ) is reduced, and its electrical insulation performance is greatly improved, the leakage current is reduced, the energy storage density and energy storage efficiency of the capacitor are greatly improved, the breakdown field strength is increased, and the energy loss is reduced; moreover, since the raw materials do not contain volatile components, it is not easy to pollute the environment.

[0056] In other preferred embodiments, M is the element Sr; and / or Q is the element Mg; and / or R is the element Nb; and / or S is the element La. 0.7 Bi 0.2 TiO 3 、BiMg 2 / 3 Nb 1 / 3 O 3 or La 2 O 3 These relaxants adjust the ceramic material (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yG's relaxation properties.

[0057] In some preferred embodiments, the general formula is ADE 3 The modifier is a ferroelectric material. For example, A is Ba, D is Ti, and E is O. Thus, by using the modifier BaTiO 3 Compare 0.5 Na 0.5 TiO 3 Modification can obtain a more stable structure (Bi 0.5 Na 0.5 ) (1-x) A x TiO 3 (BNBT for short).

[0058] In other preferred embodiments, the general formula is ADE 3 A in Bi 0.5 K 0.5 , D is Ti, and E is O. Thus, by the modifier Bi 0.5 K 0.5 TiO 3 Compare 0.5 Na 0.5 TiO 3 Modification can obtain a more stable structure (Bi 0.5 Na 0.5 ) (1-x) A x TiO 3 .

[0059] In some embodiments, y is 0.10, 0.12, 0.14, 0.16 or 0.18. Preferably, y is 0.14, whereby at a low field strength of 283 kV / cm, 0.86BNBT-0.14CHZ ceramic has a value of 5.09 J / cm 3 The optimal recoverable energy storage density (Wrec) and the optimal energy storage efficiency (η) of 77% were obtained, and the value of 42.5μC / cm 2 The ultra-high polarization difference, when the energy storage ceramic material is used for capacitor dielectrics, can greatly improve the energy storage density and energy storage efficiency of capacitor dielectrics, and its performance is better than other lead-free bismuth titanate-based energy storage materials; and in actual applications, 0.86BNBT-0.14CHZ ceramics also have excellent frequency stability, temperature stability and fatigue stability.

[0060] Although some progress has been made in NBT-based ceramics in previous studies, it is still difficult to obtain a large W rec All of them need to be obtained under ultra-high electric fields (>500kV / cm); under relatively low electric fields (<300kV / cm), it is still difficult to obtain a large W rec (>5J / cm 3 ) and large η (>70%). In practical applications, high E will limit the conditions of long-term operation environment, and long-term operation under high field strength will also cause greater loss to the device. Therefore, under relatively low electric fields, it is necessary to explore the excellent W rec The new lead-free ceramic capacitor is urgently needed. The 0.86BNBT-0.14CHZ ceramic of the present invention can obtain 5.09J / cm at a field strength of 283kV / cm 3 W rec and 77% of η.

[0061] Figure 1 The preparation method of the energy storage ceramic material according to one embodiment of the present invention is shown as an example. Figure 1 As shown, the preparation method of the energy storage ceramic material comprises the following steps:

[0062] S10: Bi 0.5 Na 0.5 TiO 3 A first matrix is ​​modified by a modifier to stabilize the structure of the first matrix to obtain a second matrix having a morphotropic phase boundary;

[0063] S20: introducing a relaxation agent at the quasi-isotropic phase boundary of the second matrix to perform ion doping to obtain a front energy storage ceramic material.

[0064] Because Bi 0.5 Na 0.5 TiO 3 After modification by the modifier, the structure becomes more stable and also has a quasi-isotropic phase boundary, so that the performance of the material can be improved by introducing a relaxation agent into the quasi-isotropic phase boundary.

[0065] Figure 2 The preparation method of the energy storage ceramic material according to another embodiment of the present invention is shown as an example. Figure 2 As shown, the preparation method of the energy storage ceramic material comprises the following steps:

[0066] S100: According to the general formula (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE 3 -yG weigh the raw materials, A is Ba element; or the general formula Bi 0.5 K 0.5 ;

[0067] G is the general formula H(J 0.7 L 0.3 )E 3 , raw materials include: Bi 2 E 3 、Na 2 CE 3 、BaCE 3 ,DE 2 、HCE 3 , JE 2 and LE 2 , or raw materials include: Bi 2 E 3 、Na 2 CE 3 ,DE 2 、HCE 3 , JE 2 LE 2 and KCE 3 ;

[0068] Or G is the general formula M 0.7 Bi 0.2 DE 3 , raw materials include: Bi 2 E 3 、Na 2 CE 3 、BaCE 3 ,DE 2 and MCE 3 , or raw materials include: Bi 2 E 3 、Na 2CE 3 ,DE 2 、MCE 3 and KCE 3 ;

[0069] Or G is the general formula BiQ 2 / 3 R 1 / 3 E 3 , raw materials include: Bi 2 E 3 、Na 2 CE 3 、BaCE 3 ,DE 2 , QE and R 2 E 5 , or raw materials include: Bi 2 E 3 、Na 2 CE 3 ,DE 2 , QE, R 2 E 5 and KCE 3 ;

[0070] Or G is the general formula S 2 E 3 , raw materials include: Bi 2 E 3 、Na 2 CE 3 、BaCE 3 ,DE 2 and S 2 E 3 , or raw materials include: Bi 2 E 3 、Na 2 CE 3 ,DE 2 , S 2 E 3 and KCE 3 ;

[0071] Wherein, D is Ti element, E is O element, x and y are both mole percentages, and the value range of x is 0.06≤x≤0.25, and the value range of y is 0<y≤0.18.

[0072] S200: preparing the raw material into powder;

[0073] S300: granulating the prepared powder;

[0074] S400: forming and tableting the granulated raw materials to form a ceramic embryo;

[0075] S500: Sintering the ceramic body to obtain (1-y)(Bi0.5 Na 0.5 ) (1-x) A x DE 3 -yG ceramics.

[0076] At present, the main molding methods of ceramics include cold isostatic pressing, ultra-high pressure molding, dry pressing, etc. Cold isostatic pressing is to use liquid as the pressure transmission medium in a high-pressure container to obtain a ceramic embryo with high density and good uniformity. Ultra-high pressure molding is a rapidly developing molding method. Due to the uneven force caused by high pressure, the obtained sample is small. Dry pressing is simple to operate and low in cost. It is suitable for embryos with simple shapes and small sizes. This embodiment adopts dry pressing.

[0077] Because Bi 0.5 Na 0.5 TiO 3 After being modified by the modifier, the structure is more stable and has a quasi-isotropic phase boundary, so that the performance of the material can be improved by introducing a relaxation agent into the quasi-isotropic phase boundary; moreover, the present invention adopts a solid phase sintering method for preparation, so that the production cost is low.

[0078] In some preferred embodiments, HCE 3 H in which is Ca element; and / or JE 2 Where J is Hf element; and / or LE 2 Where L is Zr element; and / or MCE 3 M in QE is Sr; and / or Q in QE is Mg; and / or R 2 E 5 R is Nb element; and / or S 2 E 3 The S in the figure is La, that is, the ceramic that can be prepared is (1-y)(Bi 0.5 Na 0.5 ) (1-x) Ba x TiO 3 -yCa(Hf 0.7 Zr 0.3 ) 3 , Ca(Hf 0.7 Zr 0.3 ) 3 Abbreviated as CHZ, abbreviated as (1-y)BNBT-yCHZ, or the general formula is (1-y)(Bi 0.5 Na 0.5 ) (1-x) Ba x TiO 3 -ySr 0.7 Bi 0.2 TiO 3Ceramic of the general formula (1-y)(Bi 0.5 Na 0.5 ) (1-x) Ba x TiO 3 -yBiMg 2 / 3 Nb 1 / 3 O 3 Ceramic of the general formula (1-y)(Bi 0.5 Na 0.5 ) (1-x) Ba x TiO 3 -yLa 2 O 3 Ceramic of the general formula (1-y)(Bi 0.5 Na 0.5 ) (1-x) (Bi 0.5 K 0.5 ) x TiO 3 -yCa(Hf 0.7 Zr 0.3 ) 3 Ceramic of the general formula (1-y)(Bi 0.5 Na 0.5 ) (1-x) (Bi 0.5 K 0.5 ) x TiO 3 -ySr 0.7 Bi 0.2 TiO 3 Ceramic of the general formula (1-y)(Bi 0.5 Na 0.5 ) (1-x) (Bi 0.5 K 0.5 ) x TiO 3 -yBiMg 2 / 3 Nb 1 / 3 O 3 Ceramic of the general formula (1-y)(Bi 0.5 Na 0.5 ) (1-x) (Bi 0.5 K 0.5 ) x TiO 3 -yLa 2 O 3 of ceramics.

[0079] The obtained ceramic material is (1-y)(Bi 0.5 Na 0.5 )(1-x) Ba x TiO 3 -yCa(Hf 0.7 Zr 0.3 ) 3 , and BaTiO 3 Taking the doping amount as 0.07 as an example, the prepared (1-y)(Bi 0.5 Na 0.5 ) 0.93 Ba 0.07 TiO 3 -yCa(Hf 0.7 Zr 0.3 ) 3 The performance of the test was tested and the test results are as follows:

[0080] The (1-y)BNBT-yCHZ ceramics were tested by a Y-ray diffractometer (model: Y'Pert PRO, PANalyticalY), and the obtained YRD spectrum was as follows: Figure 3 As shown, according to Figure 3 It can be seen that the relaxation agent Ca(Hf 0.7 Zr 0.3 ) 3 The doping amount y was selected as 0.00, 0.10, 0.12, 0.14, 0.16 or 0.18, and the prepared (1-y)BNBT-yCHZ showed a standard cubic perovskite structure without any impurity peaks. Moreover, with the increase of CHZ doping amount y, the (200) diffraction peak moved to a lower level, which indicated that the lattice expanded after doping (the reason was that Ti at the B site 4+ (CN6, ) is replaced by Hf with a larger ionic radius 4+ (CN6, ) and Zr 4+ (CN4, ) substitution causes lattice expansion, and the YRD spectrum also shows that the relaxation agent unit CHZ forms a perfect solid solution with BNBT ceramics, and a sample with a standard perovskite structure is synthesized). It can be seen that after the introduction of CHZ, (1-y)BNBT-yCHZ ceramics produce more disordered lattices, which is beneficial to the enhancement of relaxation behavior.

[0081] At the same time, the relaxation agent Ca(Hf 0.7 Zr 0.3 ) 3 The (1-y)BNBT-yCHZ obtained by selecting the doping amount y of 0.00, 0.10, 0.12, 0.14, 0.16 or 0.18 was tested to obtain the particle size distribution of the ceramic. Figure 4The SEM microscopic characterization diagram shown is as follows: Figure 4 As shown in Figure (a), the grain size of (1-y)BNBT-yCHZ ceramics with a relaxation agent doping amount of 0.00 is 2.44 μm. Figure 4 As shown in Figure (b), the grain size of the (1-y)BNBT-yCHZ ceramic with a relaxation agent doping amount of 0.10 is 1.59 μm. Figure 4 As shown in Figure (c), the grain size of (1-y)BNBT-yCHZ ceramics with a relaxation agent doping amount of 0.12 is 1.53 μm. Figure 4 As shown in Figure (d), the grain size of (1-y)BNBT-yCHZ with a relaxant doping amount of 0.14 is 0.62 μm. Figure 4 As shown in Figure (e), the grain size of (1-y)BNBT-yCHZ ceramics with a relaxation agent doping amount of 0.16 is 1.20 μm. Figure 4 As shown in Figure (f), the grain size of (1-y)BNBT-yCHZ with a relaxant doping amount of 0.18 is 1.27 μm; it can be seen that the grain size of (1-y)BNBT-yCHZ ceramics with a relaxant doping amount of 0.14 is the smallest. Small grain size is usually beneficial to obtain higher dielectric breakdown field strength (BDS). Figure 4 It can be seen that the prepared (1-y)BNBT-yCHZ ceramics have the advantages of clear grain boundaries, dense morphology and low porosity.

[0082] The relaxation agent Ca(Hf 0.7 Zr 0.3 ) 3 The (1-y)BNBT-yCHZ ceramics obtained by selecting the doping amount y of 0.00, 0.10, 0.12, 0.14, 0.16 or 0.18 were tested, and the dielectric properties test diagram obtained is shown in Figure 5 As shown, Figure 5 Figures (a), (b), (c), (d), (e), and (f) represent doping levels of 0.00, 0.10, 0.12, 0.14, 0.16, and 0.18, respectively. Figure 5 It can be seen that with the relaxation agent Ca(Hf 0.7 Zr 0.3 ) 3 With the increase of the doping amount, the relatively sharp dielectric peak is gradually suppressed and widened; at the same time, the temperature corresponding to the maximum dielectric constant gradually decreases, indicating that the relaxation behavior is enhanced; moreover, it can be seen that its dielectric loss is small and the insulation is good.

[0083] The prepared (1-y)BNBT-yCHZ ceramics were tested by a ferroelectric tester (Radiant Technology), and the energy storage performance analysis diagram was obtained as shown in the figure below. Figure 6 As shown, Figure 6 Figure (a) shows the PE test results of (1-y)BNBT-yCHZ ceramics (P is the polarization vector and E is the electric field). According to the test results, as the doping amount increases, the PE ring gradually becomes thinner, which indicates that the (1-y)BNBT-yCHZ ceramics transform from macroscopic ferroelectric domains to relaxor ferroelectric domains; moreover, when the doping amount of the relaxant is 0.14, the polarization difference △P of (1-y)BNBT-yCHZ ceramics can be as high as 42.5μC / cm 2 That is, after doping BNBT with a relaxant, the recyclable energy storage density of the obtained material is significantly improved compared with that of the material without the relaxant. Moreover, according to Figure 6 As shown in Figure (b), when the doping amount of the relaxant is 0.14, the (1-y)BNBT-yCHZ ceramic has a high thermal conductivity of 5.09 J / cm 3 The recoverable energy storage density (Wrec) and the optimal energy storage efficiency (η) of up to 77% are achieved according to Figure 6 It can also be seen from Figure (b) that after doping BNBT with a relaxant, the energy storage efficiency of the obtained material is significantly improved compared with the material without a relaxant. At the same time, the stability (including frequency stability (such as Figure 7 As shown in Figure (a) and Figure (b), Figure 7 Figure (b) corresponds to Figure 7 The recoverable energy storage density value of the frequency value in (a)), temperature stability (such as Figure 7 As shown in Figure (c) and Figure (d), Figure 7 Figure (d) corresponds to Figure 7 The recoverable energy density value of the temperature value in Figure (c)) and fatigue stability (such as Figure 7 As shown in Figure (e) and Figure (f), Figure 7 Figure (f) corresponds to Figure 7 The recoverable energy density value of the fatigue value of Figure (e)) is tested, such as Figure 7As shown, in the frequency stability, temperature stability and fatigue stability tests, the change values ​​of Wrec are 3.7%, 14.3% and 5.1%, respectively, indicating that the 0.86BNBT-0.14CHZ ceramic sample of the present invention has excellent frequency stability, temperature stability and fatigue stability, and also shows that BNBT-0.14CHZ ceramics have excellent stability in practical applications.

[0084] Figure 8 The method for preparing a high energy storage density ceramic capacitor dielectric according to another embodiment of the present invention is shown as an example. Figure 8 As shown, the preparation method of the high energy storage density ceramic capacitor dielectric comprises the following steps:

[0085] S1000: grinding and polishing the ceramic material, which is the aforementioned energy storage ceramic material, to obtain a ceramic sheet;

[0086] S2000: Preparation of electrodes on ceramic wafers.

[0087] Fig. 9 The method for preparing a high energy storage density ceramic capacitor dielectric according to another embodiment of the present invention is shown as an example. Fig. 9 As shown, the preparation method of the high energy storage density ceramic capacitor dielectric further includes the following steps based on the above-mentioned preparation method of the energy storage ceramic material:

[0088] S600: grinding and polishing the sintered ceramic to obtain a ceramic slice;

[0089] S700: Preparation of electrodes on ceramic wafers.

[0090] The purpose of making ceramic electrodes is to make the sample conductive. Generally, a metal layer is evenly coated on both sides of the ceramic sheet. Among them, gold (Au), silver (Ag), copper (Cu), nickel (Ni), etc. can be used as metal electrodes. In this embodiment, Au electrodes are preferred.

[0091] The upper and lower Au electrodes can be plated by ion sputtering, magnetron sputtering, electron beam evaporation, pulsed laser deposition, ion beam deposition, chemical vapor deposition, etc. Preferably, the electrode is plated by ion sputtering. In a vacuum container, under the action of a high voltage of 1500V, the residual gas molecules are ionized to form a plasma, and the cations bombard the metal target under the acceleration of the electric field, so that the metal atoms are sputtered to the surface of the sample to form a conductive film. The advantage of the ion sputtering method is that the obtained coating has a very strong adhesion to the substrate, has a high deposition rate, and has a high density of the film.

[0092] The preparation method of the energy storage ceramic material of the present invention will be exemplified below with reference to specific embodiments.

[0093] Example 1

[0094] This embodiment adopts the solid phase sintering method to prepare the energy storage ceramic material. The specific steps are as follows:

[0095] first step,

[0096] Ingredients: Bi as shown in Table 1 2 O 3 、Na 2 CO 3 、BaCO 3 、TiO 2 、CaCO 3 , HfO 2 and ZrO 2 As raw materials, according to the preparation chemical formula (1-y)(Bi 0.5 Na 0.5 ) (1-x) Ba x TiO 3 -yCa(Hf 0.7 Zr 0.3 ) 3 The stoichiometric ratio of the system is as follows: Weigh the above raw materials, where y is 0.10. Since the Bi ions in BNT are easily volatile, in order to avoid the loss of BNT in the subsequent mixing and ball milling process, the proportion of BNT is greater than the stoichiometric ratio during the batching stage. For example, Bi 2 O 3 The amount will be 1% more than the stoichiometric amount.

[0097] Table 1. Raw materials for preparation of (1-y)BNBT-yCHZ powder

[0098] Drug name (chemical symbol) Drug purity (%) Production <![CDATA[Bismuth oxide (Bi 2 O 3 )]]> 99.99 Aladdin <![CDATA[Sodium carbonate (Na 2 CO 3 )]]> 99.80 Aladdin <![CDATA[Barium carbonate (BaCO 3 )]]> 99.95 Aladdin <![CDATA[Titanium dioxide (TiO 2 )]]> 99.99 Aladdin <![CDATA[Calcium carbonate (CaCO 3 )]]> 99.99 Aladdin <![CDATA[Hafnium Oxide (HfO 2 )]]> 99.90 Aladdin <![CDATA[Zirconium oxide (ZrO 2 )]]> 99.99 Aladdin

[0099] Step 2:

[0100] (1-y) Preparation of BNBT-yCHZ powder. Specifically includes the following steps:

[0101] First, a ball milling is performed, the prepared raw materials weighed in the first step are placed in a nylon ball mill, and then ethanol and zirconium oxide grinding balls of different diameters are added to obtain a mixture, the speed of the ball mill is controlled to be 380 rpm, and the ball milling time is set to be 12-24 hours. After the ball milling, the mixture is dried at 80°C. Zirconia is used as a grinding medium, ethanol is used as a grinding solvent, the total mass of the prepared raw materials: the total mass of zirconium oxide is 1:1; the diameter range of the zirconium oxide grinding balls is 3-6 mm, and the number ratio of the zirconium oxide grinding balls is controlled to be 6 mm grinding balls: 4-5 mm grinding balls: 3 mm small grinding balls = 1:2:3.

[0102] Next, high-temperature pre-firing is carried out. The mixture that has been ball-milled and dried once is poured into an agate mortar and ground with an agate rod for 15-45 minutes. The ground mixture is then poured into an alumina crucible and calcined at 800°C for 200 minutes in an air atmosphere in a muffle furnace. The heating rate is controlled at 8°C / min. After calcination, the mixture is naturally cooled to room temperature with the furnace.

[0103] Then, secondary ball milling is performed, the mixture after high temperature pre-sintering is placed in a nylon ball mill, and then ethanol and zirconium oxide grinding balls of different diameters are added to obtain a mixture, the speed of the ball mill is controlled to be 380 rpm, the secondary ball milling time is set to be 12-24 hours, and the mixture is dried at 80°C after the ball milling. Zirconia is used as a grinding medium, ethanol is used as a grinding solvent, the total mass ratio of the prepared raw materials: the total mass of zirconium oxide is 1:1; the diameter range of the zirconium oxide grinding balls is 3-6 mm, and the number ratio of the zirconium oxide grinding balls is controlled to be 6 mm grinding balls: 4-5 mm grinding balls: 3 mm small grinding balls = 1:2:3.

[0104] Step 3.

[0105] Granulation: After the processed powder is dried, ground, sieved and other steps, the particle size is greatly reduced, and then an appropriate amount of binder PVA (3%-5% concentration) is added to grind it, and the ground powder is sieved with 100 mesh.

[0106] Step 4.

[0107] Molding and tableting: The (1-y)BNBT-yCHZ powder obtained by granulation was loaded into a tableting mold and formed by uniaxial pressure using a powder tablet press. The pressure was controlled at 9 MPa and maintained for 60 seconds to obtain a (1-y)BNBT-yCHZ ceramic embryo with a diameter of 13.5 mm and a thickness of 1.1 mm.

[0108] Step 5.

[0109] Sintering: The prepared (1-y)BNBT-yCHZ ceramic body is placed in a muffle furnace, the heating rate is controlled at 8°C / min, the temperature is slowly raised to 1200°C, and the temperature is kept for 150 minutes. After the insulation is completed, the (1-y)BNBT-yCHZ ceramic body is naturally cooled to room temperature with the furnace, and a (1-y)BNBT-yCHZ ceramic with a thickness of 1.1 mm is obtained. Since the Bi ions in BNT are easily volatilized, in order to reduce the volatilization of Bi ions, the sintering process of the (1-y)BNBT-yCHZ ceramic body needs to adopt a buried firing method, that is, the (1-y)BNBT-yCHZ ceramic body is placed in a muffle furnace, and the ceramic body is completely covered with sample powder of the same component before sintering.

[0110] Example 2

[0111] The difference between this embodiment and embodiment 1 is that:

[0112] In the first step, the value of y is 0.12.

[0113] Example 3

[0114] The difference between this embodiment and embodiment 1 is that:

[0115] In the first step, the value of y is 0.14.

[0116] Example 4

[0117] The difference between this embodiment and embodiment 1 is that:

[0118] In the first step, the value of y is 0.16.

[0119] Example 5

[0120] The difference between this embodiment and embodiment 1 is that:

[0121] In the first step, the value of y is 0.18.

[0122] Comparative Example 1

[0123] The difference between this embodiment and embodiment 1 is that:

[0124] In the first step, the value of y is 0.00.

[0125] The preparation method of the high energy storage density ceramic capacitor dielectric of the present invention will be exemplarily described below in conjunction with specific embodiments.

[0126] Example 6

[0127] The difference between this embodiment and embodiment 3 is that:

[0128] In the first step, ingredients: Bi 2 O 3 、Na 2 CO 3 、TiO 2 、CaCO 3 , HfO 2 、ZrO 2 and KCO 3 As raw materials, according to the preparation chemical formula (1-y)(Bi 0.5 Na 0.5 ) 0.8 (Bi 0.5 K 0.5 ) 0.2 TiO 3 -yCa(Hf 0.7 Zr 0.3 ) 3The stoichiometric ratio of the system is as follows: Weigh the above raw materials, where y is 0.14. Since the Bi ions in BNT are easily volatile, in order to avoid the loss of BNT in the subsequent mixing and ball milling process, the proportion of BNT is greater than the stoichiometric ratio during the batching stage. For example, Bi 2 O 3 The amount will be 1% more than the stoichiometric amount.

[0129] In the second, third and fifth steps, the general formula (1-y)BNBT-yCHZ is replaced by (1-y)(Bi 0.5 Na 0.5 ) 0.8 (Bi 0.5 K 0.5 ) 0.2 TiO 3 -yCa(Hf 0.7 Zr 0.3 ) 3 .

[0130] Example 7

[0131] The difference between this embodiment and embodiment 3 is that:

[0132] In the first step, ingredients: Bi 2 O 3 、Na 2 CO 3 、BaCO 3 、TiO 2 , and SrCO 3 As raw materials, according to the preparation chemical formula (1-y)(Bi 0.5 Na 0.5 ) 0.93 Ba 0.07 TiO 3 -ySr 0.7 Bi 0.2 TiO 3 The stoichiometric ratio of the system is as follows: Weigh the above raw materials, where y is 0.14. Since the Bi ions in BNT are easily volatile, in order to avoid the loss of BNT in the subsequent mixing and ball milling process, the proportion of BNT is greater than the stoichiometric ratio during the batching stage. For example, Bi 2 O 3 The amount will be 1% more than the stoichiometric amount.

[0133] In the second, third and fifth steps, the general formula (1-y)BNBT-yCHZ is replaced by (1-y)(Bi 0.5 Na 0.5 ) 0.93 Ba 0.07 TiO 3 -ySr 0.7Bi 0.2 TiO 3 .

[0134] Example 8

[0135] The difference between this embodiment and embodiment 3 is that:

[0136] In the first step, ingredients: Bi 2 O 3 、Na 2 CO 3 、TiO 2 、SrCO 3 and KCO 3 As raw materials, according to the preparation chemical formula (1-y)(Bi 0.5 Na 0.5 ) 0.8 (Bi 0.5 K 0.5 ) 0.2 TiO 3 -ySr 0.7 Bi 0.2 TiO 3 The stoichiometric ratio of the system is as follows: Weigh the above raw materials, where y is 0.14. Since the Bi ions in BNT are easily volatile, in order to avoid the loss of BNT in the subsequent mixing and ball milling process, the proportion of BNT is greater than the stoichiometric ratio during the batching stage. For example, Bi 2 O 3 The amount will be 1% more than the stoichiometric amount.

[0137] In the second, third and fifth steps, the general formula (1-y)BNBT-yCHZ is replaced by (1-y)(Bi 0.5 Na 0.5 ) 0.8 (Bi 0.5 K 0.5 ) 0.2 TiO 3 -ySr 0.7 Bi 0.2 TiO 3 .

[0138] Example 9

[0139] The difference between this embodiment and embodiment 3 is that:

[0140] In the first step, ingredients: Bi 2 O 3 、Na 2 CO 3 、BaCO 3 、TiO 2 , MgO and Nb 2 O5 As raw materials, according to the preparation chemical formula (1-y)(Bi 0.5 Na 0.5 ) 0.93 Ba 0.07 TiO 3 -yBiMg 2 / 3 Nb 1 / 3 O 3 The stoichiometric ratio of the system is as follows: Weigh the above raw materials, where y is 0.14. Since the Bi ions in BNT are easily volatile, in order to avoid the loss of BNT in the subsequent mixing and ball milling process, the proportion of BNT is greater than the stoichiometric ratio during the batching stage. For example, Bi 2 O 3 The amount will be 1% more than the stoichiometric amount.

[0141] In the second, third and fifth steps, the general formula (1-y)BNBT-yCHZ is replaced by (1-y)(Bi 0.5 Na 0.5 ) 0.93 Ba 0.07 TiO 3 -yBiMg 2 / 3 Nb 1 / 3 O 3 .

[0142] Example 10

[0143] The difference between this embodiment and embodiment 3 is that:

[0144] In the first step, ingredients: Bi 2 O 3 、Na 2 CO 3 、TiO 2 ,MgO,Nb 2 O 5 and KCO 3 As raw materials, according to the preparation chemical formula (1-y)(Bi 0.5 Na 0.5 ) 0.8 (Bi 0.5 K 0.5 ) 0.2 TiO 3 -yBiMg 2 / 3 Nb 1 / 3 O 3 The stoichiometric ratio of the system is as follows: Weigh the above raw materials, where y is 0.14. Since the Bi ions in BNT are easily volatile, in order to avoid the loss of BNT in the subsequent mixing and ball milling process, the proportion of BNT is greater than the stoichiometric ratio during the batching stage. For example, Bi 2 O 3The amount will be 1% more than the stoichiometric amount.

[0145] In the second, third and fifth steps, the general formula (1-y)BNBT-yCHZ is replaced by (1-y)(Bi 0.5 Na 0.5 ) 0.8 (Bi 0.5 K 0.5 ) 0.2 TiO 3 -yBiMg 2 / 3 Nb 1 / 3 O 3 .

[0146] Embodiment 11

[0147] The difference between this embodiment and embodiment 3 is that:

[0148] In the first step, ingredients: Bi 2 O 3 、Na 2 CO 3 、BaCO 3 、TiO 2 and La 2 O 3 As raw materials, according to the preparation chemical formula (1-y)(Bi 0.5 Na 0.5 ) 0.93 Ba 0.07 TiO 3 -yLa 2 O 3 The stoichiometric ratio of the system is as follows: Weigh the above raw materials, where y is 0.14. Since the Bi ions in BNT are easily volatile, in order to avoid the loss of BNT in the subsequent mixing and ball milling process, the proportion of BNT is greater than the stoichiometric ratio during the batching stage. For example, Bi 2 O 3 The amount will be 1% more than the stoichiometric amount.

[0149] In the second, third and fifth steps, the general formula (1-y)BNBT-yCHZ is replaced by (1-y)(Bi 0.5 Na 0.5 ) 0.93 Ba 0.07 TiO 3 -yLa 2 O 3 .

[0150] Example 12

[0151] The difference between this embodiment and embodiment 3 is that:

[0152] In the first step, ingredients: Bi2 O 3 、Na 2 CO 3 、TiO 2 ,La 2 O 3 and KCO 3 As raw materials, according to the preparation chemical formula (1-y)(Bi 0.5 Na 0.5 ) 0.8 (Bi 0.5 K 0.5 ) 0.2 TiO 3 -yLa 2 O 3 The stoichiometric ratio of the system is as follows: Weigh the above raw materials, where y is 0.14. Since the Bi ions in BNT are easily volatile, in order to avoid the loss of BNT in the subsequent mixing and ball milling process, the proportion of BNT is greater than the stoichiometric ratio during the batching stage. For example, Bi 2 O 3 The amount will be 1% more than the stoichiometric amount.

[0153] In the second, third and fifth steps, the general formula (1-y)BNBT-yCHZ is replaced by (1-y)(Bi 0.5 Na 0.5 ) 0.8 (Bi 0.5 K 0.5 ) 0.2 TiO 3 -yLa 2 O 3 .

[0154] Example 13

[0155] This embodiment further includes, based on any one of Embodiments 1 to 5

[0156] Step 6.

[0157] Grinding and polishing: The (1-y)BNBT-yCHZ ceramics prepared in the fifth step were ground and polished with 800-mesh green silicon carbide abrasive sand to a (1-y)BNBT-yCHZ ceramic sheet of about 0.1 mm.

[0158] Step 7

[0159] Electrode plating:

[0160] First, the bottom electrode was plated: the (1-y)BNBT-yCHZ ceramic wafer was placed in a small ion sputtering instrument, and Au was used as the target at 2×10 -3The Au electrode film was grown under a vacuum of 1.5 Å / min. Pa, the sputtering current was controlled to be 8-10 mA, the target material was sputtered in an argon (Ar) atmosphere, the sputtering time was 50 seconds, and the above sputtering operation was repeated 3 times.

[0161] Next, the top electrode was plated: a mask with holes was placed on the non-electrode side of the (1-y)BNBT-yCHZ ceramic wafer, and the (1-y)BNBT-yCHZ ceramic wafer was placed in a small ion sputtering instrument. Au was used as the target material at 2×10 -3 The Au electrode was grown in a vacuum of 1.50 Pa, the sputtering current was controlled to be 8-10 mA, the target was sputtered in an argon (Ar) atmosphere, the sputtering time was 50 seconds, and the above sputtering operation was repeated 3 times. The diameter of the hole on the mask was 1.5 mm.

[0162] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. Energy storage ceramic material, characterized in that: The general formula of the material is (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE3-yG; wherein D is Ti element and E is O element; ADE3 is able to improve Bi 0.5 Na 0.5 The general formula of the modifier of the stability of TiO3 is to obtain a (Bi 0.5 Na 0.5 ) (1-x) A x DE3; G is the general formula of a relaxation agent that can be introduced at the morphotropic phase boundary; The value range of x is 0.06≤x≤0.25, and the value range of y is 0<y≤0.18; G is the general formula H(J 0.7 L 0.3 )E3, H is Ca, J is Hf element, and L is Zr element.

2. The energy storage ceramic material according to claim 1, characterized in that: H is used to make (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x The ferroelectric domains of DE3-yG transform into polar nanodomains; J is used to refine (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x The grain size of DE3-yG; L is used to improve (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x The cubic equilibrium of DE3-yG and the destruction of (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x The long-range order of DE3-yG induces (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE3-yG produces polar nanodomains.

3. The energy storage ceramic material according to any one of claims 1 to 2, characterized in that: The modifier of the general formula ADE3 is a ferroelectric material.

4. The energy storage ceramic material according to claim 3, characterized in that: A is Ba element, and the general formula of the material is (1-y)(Bi 0.5 Na 0.5 ) (1-x) Ba x DE3-yG, the value range of x is 0.06≤x≤0.08; or A is the general formula Bi 0.5 K 0.5 The general formula of the material is (1-y)(Bi 0.5 Na 0.5 ) (1-x) Bi 0.5 K 0.5x DE3-yG, the value range of x is 0.06≤x≤0.

25.

5. The energy storage ceramic material according to any one of claims 1 to 2, characterized in that: The value of y is 0.10, 0.12, 0.14, 0.16 or 0.

18.

6. The method for preparing the energy storage ceramic material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S10: Bi 0.5 Na 0.5 TiO3 is a first matrix, and the first matrix is ​​modified by a modifier to stabilize the structure of the first matrix to obtain a second matrix with a morphotropic phase boundary; S20: introducing a relaxation agent at the morphotropic phase boundary of the second matrix to perform ion doping to obtain the energy storage ceramic material.

7. The method for preparing the energy storage ceramic material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S100: According to the general formula (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE3-yG weigh the raw materials, A is Ba element; or the general formula Bi 0.5 K 0.5 ; G is the general formula H(J 0.7 L 0.3 )E3, raw materials Includes: Bi2E3, Na2CE3, BaCE3, DE2, HCE3, JE2 and LE2, or raw materials include: Bi2E3, Na2CE3, DE2, HCE3, JE2, LE2 and KCE3; Wherein, D is Ti element, E is O element, x and y are mole percentages, and the value range of x is 0.06≤x≤0.25, and the value range of y is 0<y≤0.18; S200: preparing the raw material into powder; S300: granulating the prepared powder; S400: forming and tableting the granulated raw materials to form a ceramic embryo; S500: Sintering the ceramic body to obtain (1-y)(Bi 0.5 Na 0.5 ) (1-x) A x DE3-yG ceramic.

8. The method for preparing the energy storage ceramic material according to claim 7, characterized in that: The H in the HCE3 is Ca element; and / or J in the JE2 is an Hf element; and / or L in the LE2 is a Zr element.

9. A method for preparing a high energy storage density ceramic capacitor dielectric, characterized in that: The following steps are involved: S1000: grinding and polishing the ceramic material, which is the energy storage ceramic material according to any one of claims 1 to 5, to obtain a ceramic sheet; S2000: preparing an electrode on the ceramic sheet; Or based on the preparation method described in claim 7 or 8, the method further comprises the following steps: S600: grinding and polishing the sintered ceramic to obtain a ceramic slice; S700: preparing an electrode on the ceramic sheet.

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