阅读说明：本技术 稀土元素Tm掺杂的铌酸银反铁电陶瓷材料及其制备方法 (Rare earth element Tm doped silver niobate antiferroelectric ceramic material and preparation method thereof ) 是由 毛朝梁 马江雷 王根水 闫世光 董显林 于 2019-04-16 设计创作，主要内容包括：本发明涉及稀土元素Tm掺杂的铌酸银反铁电陶瓷材料及其制备方法,所述稀土元素Tm掺杂的铌酸银反铁电陶瓷材料为单一钙钛矿结构,其组成通式为Ag<Sub>1-3x</Sub>Tm<Sub>x</Sub>NbO<Sub>3</Sub>,其中,0.01≤x≤0.08。(The invention relates to a rare earth element Tm doped silver niobate antiferroelectric ceramic material and a preparation method thereof 1‑3x Tm x NbO 3 Wherein x is more than or equal to 0.01 and less than or equal to 0.08.)

1. The rare earth element Tm doped silver niobate antiferroelectric ceramic material is characterized by being of a single perovskite structure and having a general formula of Ag_1-3xTm_xNbO₃Wherein x is more than or equal to 0.01 and less than or equal to 0.08.

2. The rare earth element Tm doped silver niobate antiferroelectric ceramic material according to claim 1, wherein x is 0.02. ltoreq. x.ltoreq.0.04.

3. The rare earth element Tm doped silver niobate antiferroelectric ceramic material according to claim 1 or 2, wherein the positive breakover electric field of the rare earth element Tm doped silver niobate antiferroelectric ceramic material is 14 to 28kV/mm and the negative breakover electric field is 5 to 14kV/mm at room temperature.

4. The rare earth element Tm doped silver niobate antiferroelectric ceramic material according to any one of claims 1 to 3, wherein the rare earth element Tm doped silver niobate antiferroelectric ceramic material has a storage density of 2.6 to 4.3J/cm at room temperature³And the energy storage efficiency is 38-77%.

5. A method for preparing a rare earth element Tm doped silver niobate antiferroelectric ceramic material according to any one of claims 1 to 4, comprising:

(1) selecting Ag₂O powder and Nb₂O₅Powder and Tm₂O₃The powder is used as raw material powder and has the composition formula of Ag_1-3xTm_xNbO₃Preparing materials and mixing to obtain mixed powder;

(2 calcining the obtained mixed powder in an oxygen-containing atmosphere at 850-900 ℃ to obtain Ag_1-3xTm_xNbO₃Powder;

(3) mixing the obtained Ag_1-3xTm_xNbO₃Mixing the powder and the binder, granulating, and performing compression molding to obtain a ceramic biscuit;

(4) and (3) after the obtained ceramic biscuit is subjected to plastic removal, sintering the ceramic biscuit in an oxygen-containing atmosphere at 1000-1250 ℃ to obtain the rare earth element Tm doped silver niobate antiferroelectric ceramic material.

6. The method for producing according to claim 5, which isCharacterized in that the binder is at least one of polyvinyl alcohol and polyvinyl butyral; the addition amount of the binder is Ag_1-3xTm_xNbO₃3-8 wt% of the powder.

7. The production method according to claim 5 or 6, wherein the oxygen-containing atmosphere is an air atmosphere or an oxygen atmosphere.

8. The preparation method according to any one of claims 5 to 7, wherein the temperature of the plastic discharge is 700 ℃ to 900 ℃ and the time is 2 to 3 hours; preferably, the temperature rise rate of the plastic discharge is 1-3 ℃/min.

9. The method according to any one of claims 5 to 8, wherein the calcination is carried out for 2 to 3 hours; the sintering time is 2-3 hours; the temperature rise rate of the sintering is 1-3 ℃/min.

10. The production method according to any one of claims 5 to 9, characterized in that the obtained rare earth element Tm doped silver niobate antiferroelectric ceramic material is polished to a prescribed thickness and then coated with a silver electrode on the surface; preferably, the predetermined thickness is 0.15 to 0.20 mm.

Technical Field

The invention relates to a silver niobate-based antiferroelectric ceramic material and a preparation method thereof, in particular to a rare earth element Tm doped silver niobate antiferroelectric ceramic material and a preparation method thereof and application of the silver niobate antiferroelectric ceramic material in an energy storage dielectric capacitor, belonging to the technical field of functional ceramic materials.

Background

Due to the increasing attention on energy, economy and social sustainable development, energy storage materials have received great attention and research interest, which are also the core of efficient energy storage devices. In the currently used electric energy storage devices, the pulse power capacitor has the advantages of fast charge and discharge capacity and high power density, and is increasingly widely applied in the pulse power technology. Such as electromagnetic pulse guns, particle accelerators, geological exploration, medical instruments, electrostatic precipitation, and the like. But the energy density is lower, typically an order of magnitude lower than electrochemical capacitors, batteries. In addition, capacitors are large in pulsed power devices. Pulsed power capacitors are reported to account for more than 25% of the volume and weight of the power electronics. Therefore, development of a pulse power device having high energy storage performance and high power density with miniaturization, weight reduction, and integration is moving forward in the future.

The dielectric materials used as capacitors are generally classified into organic and inorganic materials. The inorganic ceramic capacitor has the advantages of wide use temperature range, low loss, high discharge speed and the like, and is widely applied to pulse capacitors. It is mainly classified into linear dielectric ceramics, ferroelectric dielectric ceramics and antiferroelectric dielectric ceramics. The antiferroelectric ceramic material has higher energy storage density and faster discharge speed compared with linear ceramics and ferroelectric ceramics because of having electric field induced antiferroelectric-ferroelectric phase transition and being capable of returning to antiferroelectric phase in a very short time after the electric field is removed, thereby releasing a large amount of energy.

The most studied antiferroelectric ceramics are currently lead-containing material systems. Mainly comprises the following steps: pb (La, Zr, Ti) O₃Base ceramic and Pb (La, Zr, Sn, Ti) O₃A base ceramic. However, because of the environmental pollution and the harm to the health of human life caused by lead, researchers are looking for an alternative lead-free antiferroelectric material, in which silver niobate (AgNbO) having a perovskite structure is used₃) Ceramics, as a class of antiferroelectric materials, which have high saturation polarization and high energy storage density, are considered to be very promisingOne of the antiferroelectric energy storage materials of (1). In fact, AgNbO₃Materials have been widely studied as microwave ceramics and photocatalytic materials. Until recently, silver niobate (AgNbO)₃) The material is focused as an energy storage material and becomes a research hotspot in the field of energy storage.

2016 Tian et al first treated AgNbO₃Ceramic materials are used in the field of energy storage. Reports pure AgNbO under the electric field condition of 175kV/cm₃Energy storage density W of ceramic_recUp to 2.1J/cm³. But pure AgNbO₃The ceramic has a ferrielectric phase (M) at room temperature₁) The improvement of the energy storage performance is influenced, and the bending electric field and the breakdown field strength are to be improved. In the prior art, AgNbO is generally realized by doping and modifying components₃The energy storage characteristic of the ceramic is greatly improved, which shows that AgNbO₃The ceramic has wide application prospect in the field of energy storage.

Disclosure of Invention

Aiming at AgNbO in the prior art₃The invention aims to provide a silver niobate antiferroelectric ceramic material doped with a rare earth element Tm and a preparation method thereof, which are designed from the multi-angle consideration of tolerance factors, high polarizability and grain size influencing antiferroelectric performance and solve the problems of low energy storage density, improved energy storage efficiency, ferroelectricity at room temperature and the like in antiferroelectric energy storage ceramic materials.

On one hand, the invention provides a rare earth element Tm doped silver niobate antiferroelectric ceramic material which is of a single perovskite structure and has a general formula of Ag_1-3xTm_xNbO₃Wherein x is more than or equal to 0.01 and less than or equal to 0.08.

In the invention, AgNbO is realized by doping rare earth elements Tm (introducing A-site small ions and vacancies) with smaller ionic radius₃Suppression of the ferroelectrics phase (FIE) at room temperature in ceramic materials, in particular M₁-M₂The phase transition temperature of the phase, namely the ferrielectric phase-the antiferroelectric phase, is reduced to be below room temperature, so that the room temperature presents the antiferroelectric phase, namely the antiferroelectric is enhanced. And alsoThe introduction of the rare earth element Tm is also beneficial to refining grains (the granularity of the solid solution can be reduced by doping refractory metal oxide into a matrix with a low melting point), the compactness of the ceramic is improved, the forward turning electric field is improved, and the AgNbO is further enhanced₃The energy storage performance of the antiferroelectric energy storage ceramic.

Preferably, x is more than or equal to 0.02 and less than or equal to 0.04. For example, when x is 0.03, the energy density of the rare earth element Tm doped silver niobate antiferroelectric ceramic is 4.3J/cm³The energy storage efficiency is 64%.

Preferably, at room temperature (20-25 ℃), the positive bending electric field of the rare earth element Tm doped silver niobate antiferroelectric ceramic material is 14-28 kV/mm, and the reverse bending electric field is 5-14 kV/mm.

Preferably, the energy storage density of the rare earth element Tm doped silver niobate antiferroelectric ceramic material is 2.6-4.3J/cm at room temperature (20-25 ℃)³And the energy storage efficiency is 38-77%.

In another aspect, the present invention provides a method for preparing a rare earth element Tm doped silver niobate antiferroelectric ceramic material, comprising:

(1) selecting Ag₂O powder and Nb₂O₅Powder and Tm₂O₃The powder is used as raw material powder and has the composition formula of Ag_1-3xTm_xNbO₃Preparing materials and mixing to obtain mixed powder;

(2 calcining the obtained mixed powder in an oxygen-containing atmosphere at 850-900 ℃ to obtain Ag_1-3xTm_xNbO₃Powder;

(3) mixing the obtained Ag_1-3xTm_xNbO₃Mixing the powder and the binder, granulating, and performing compression molding to obtain a ceramic biscuit;

(4) and (3) after the obtained ceramic biscuit is subjected to plastic removal, sintering the ceramic biscuit in an oxygen-containing atmosphere at 1000-1250 ℃ to obtain the rare earth element Tm doped silver niobate antiferroelectric ceramic material.

In the present invention, Ag is selected₂O powder and Nb₂O₅Powder and Tm₂O₃Using the powder as raw materialPowder of Tm by addition³⁺Doping modification, and then preserving heat for 2-3 hours at 850-900 ℃ in an oxygen-containing atmosphere, wherein Tm is in the process³⁺Regulate and control M thereof₁，M₂Phase, which is made to present an antiferroelectric phase at room temperature, namely inhibiting the ferroelectricicity, enhancing the antiferroelectricity and reducing the residual polarization strength, and then grinding and drying are carried out to obtain the Ag with the perovskite structure_1-3xTm_xNbO₃And (3) powder. Mixing the obtained Ag_1-3xTm_xNbO₃Adding binder into the powder, granulating, molding, removing plastic and sintering. Due to addition of Tm³⁺And crystal grains can be refined in the process of re-sintering, and the density of the ceramic is improved.

Preferably, the binder is at least one of polyvinyl alcohol and polyvinyl butyral; the addition amount of the binder is Ag_1-3xTm_xNbO₃3-8 wt% of the powder.

Preferably, the oxygen-containing atmosphere is an air atmosphere or an oxygen atmosphere.

Preferably, the temperature of the plastic discharge is 700-900 ℃, and the time is 2-3 hours; preferably, the temperature rise rate of the plastic discharge is 1-3 ℃/min.

Preferably, the calcining time is 2-3 hours; the sintering time is 2-3 hours; the temperature rise rate of the sintering is 1-3 ℃/min.

Preferably, after the obtained rare earth element Tm doped silver niobate antiferroelectric ceramic material is polished to a specified thickness, a silver electrode is coated on the surface of the rare earth element Tm doped silver niobate antiferroelectric ceramic material; preferably, the predetermined thickness is 0.15 to 0.20 mm.

Preferably, the pressing and forming mode is dry pressing and forming, and the pressure of the dry pressing and forming is 150-200 MPa.

The invention has the beneficial effects that:

in the invention, a novel AgNbO is developed through component design by considering from multiple angles of tolerance factors, high polarizability and grain size which influence the antiferroelectric performance₃A base antiferroelectric ceramic. Rare earth elements Tm (introducing A-site small ions and vacancies) with smaller ionic radius are adopted to ensure that the tolerance factor of the rare earth elements Tm is as high as possibleSmall possibility (reduction of tolerance factor helps to stabilize antiferroelectric phase), makes AgNbO₃The ferroelectrics phase (FIE) of the ceramic is reduced to below room temperature, so that the ferroelectrics phase is presented at room temperature, and the antiferroelectricity phase area is enlarged. Moreover, the introduction of the rare earth element Tm can also refine grains (the granularity of the solid solution can be reduced by doping refractory metal oxide into a matrix with a low melting point), so that the compactness is improved, the forward turning electric field is improved, and the AgNbO of the composite material is enhanced₃Energy storage density and energy storage efficiency of the ceramic. Thus, Ag of the present invention_1-3xTm_xNbO₃The ceramic has high energy storage performance. The energy storage ceramic of the invention has energy storage density W_recUp to 4.3J/cm³The energy storage efficiency can reach 64 percent. The energy storage ceramic of the invention also discloses rare earth element Tm doped AgNbO with smaller ionic radius₃Ceramics hold great promise in applications of dielectric energy storage capacitors.

Drawings

FIG. 1 is an XRD diffractogram of ceramic samples prepared according to comparative example 1 and examples 1-3 of the present invention;

FIG. 2 is a surface SEM image of a ceramic sample prepared according to comparative example 1 of the present invention;

FIG. 3 is a surface SEM image of a ceramic sample prepared according to example 1 of the present invention;

FIG. 4 is a surface SEM image of a ceramic sample prepared according to example 2 of the present invention;

FIG. 5 is a surface SEM image of a ceramic sample prepared according to example 3 of the present invention;

FIG. 6 is a graph showing a dielectric thermogram and a dielectric spectrogram of ceramic samples prepared in comparative example 1 and examples 1 to 3 according to the present invention;

FIG. 7 is a hysteresis loop of ceramic samples prepared in comparative example and examples 1-3 of the present invention;

FIG. 8 is a graph of turning electric fields of ceramic samples prepared in comparative example and examples 1-3 according to the present invention;

FIG. 9 is a graph of the energy storage density and efficiency of ceramic samples prepared according to comparative examples and examples 1-3 of the present invention.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

In the present disclosure, the chemical formula of the rare earth element Tm doped silver niobate antiferroelectric ceramic material with high energy storage density can be represented as: ag_1-3xTm_xNbO₃Wherein x is more than or equal to 0.01 and less than or equal to 0.08. The x is the molar weight, so that the energy storage performance of the catalyst is further improved. Wherein, the doping of the rare earth element Tm can inhibit AgNbO₃The ferroelectricity in the ceramic material is enhanced, the antiferroelectricity is enhanced, and the AgNbO is improved₃The electric field is positively turned in the ceramic material, so that the silver niobate-based antiferroelectric energy storage ceramic material with high energy storage density and energy storage efficiency is obtained. The invention can also lead the silver niobate antiferroelectric ceramic material doped with the rare earth element Tm to be an antiferroelectric phase at room temperature by adjusting the doping content of Tm to be more than or equal to 0.01 and less than or equal to 0.08. Meanwhile, the remanent polarization is reduced, the forward turning electric field is improved, and the energy storage ceramic material with high energy storage density and energy storage efficiency is obtained, so that the energy storage ceramic material has a good application prospect.

In an alternative embodiment, at room temperature, the positive bending electric field of the rare earth element Tm doped silver niobate antiferroelectric ceramic material can be 14-28 kV/mm, and the reverse bending electric field can be 5-14 kV/mm.

In an optional embodiment, at room temperature, the energy storage density of the rare earth element Tm doped silver niobate antiferroelectric ceramic material can be 2.6-4.3J/cm³And the energy storage efficiency is 38-77%. For example, the rare earth element Tm doped silver niobate antiferroelectric energy storage ceramic material has the energy storage density W under the condition that x is 0.03mol_recHeight of 4.6J/cm³The energy storage efficiency is as high as 69%.

In the disclosure, the rare earth element Tm doped silver niobate antiferroelectric ceramic material is prepared by a solid phase reaction method. Specifically, the synthesis of Ag by passing oxygen_1-3xTm_xNbO₃Powder (x is more than or equal to 0.01 and less than or equal to 0.08). Mixing Ag with water_1-3xTm_xNbO₃The powder is then granulated, pressed, molded and discharged, and sintered and compacted at a certain temperature to obtain Ag_1-3xTm_xNbO₃Ceramic material (rare earth Tm doped niobiumSilver acid antiferroelectric ceramics).

Hereinafter, the method of preparing the rare earth element Tm doped silver niobate antiferroelectric ceramic of the present invention is exemplarily described.

Synthesis of Ag by oxygen introduction_1-3xTm_xNbO₃Powder, wherein x is more than or equal to 0.01 and less than or equal to 0.08; x is mole percent. The rare earth element Tm doped silver niobate antiferroelectric ceramic material can adopt Ag₂O powder and Nb₂O₅Powder and Tm₂O₃The powder is used as a starting material, and the starting materials are proportioned and mixed according to a stoichiometric ratio to obtain mixed powder. Keeping the mixed powder in an oxygen-containing atmosphere at 850-900 ℃ for 2-3 hours to obtain Ag_1-3xTm_xNbO₃And (3) powder. As an example, Ag with a purity of 99.0% or more may be used₂O powder and Nb₂O₅Powder and Tm₂O₃The powder is used as raw material powder, then the materials are mixed according to the stoichiometric ratio, and the mixture is subjected to ball milling, drying and grinding, and then is subjected to heat preservation for 2-3 hours at 850-900 ℃ under the oxygen condition to synthesize the Ag with the perovskite structure_{1- 3x}Tm_xNbO₃And (3) powder. The polishing method of the present invention is not particularly limited, and known polishing methods such as wet ball milling and the like can be used. In the case of wet ball milling, the feed: ball: the mass ratio of the ethanol is (0.8-1.0): (4.0-4.5): 1.5-1.7), and the mixing time is 12 hours.

In Ag_1-3xTm_xNbO₃And adding a binder into the powder, granulating, and performing compression molding to obtain a biscuit. Specifically, the synthesized Ag_1-3xTm_xNbO₃And (3) grinding the powder, adding a binder for granulation, and performing compression molding to obtain a biscuit. The sanding may be performed by a sand mill. In this case, Ag may be used_1-3xTm_xNbO₃Powder: ball: the sanding time may be 3 hours for absolute ethyl alcohol (0.8-1.0): (4.0-4.5): 1.0-1.2). For example, iron balls, agate balls, zirconia balls, or the like can be used as the grinding balls. The binder to be added may be polyvinyl alcohol (PVA), polyvinyl butyral (PVB), or the like. The addition amount of the binder is ceramic3 to 8 percent of the mass of the powder. The pressure for the press molding may be 150 to 200 MPa. In the invention, the ball milling is carried out in a ball milling tank, the sand milling is carried out in a sand mill, and the ball milling is respectively carried out for 12 hours and 3 hours by adopting absolute ethyl alcohol as a medium. Is beneficial to the uniform dispersion of the raw materials so as to obtain the powder with uniform and refined components. Therefore, the energy storage performance of the rare earth element Tm doped silver niobate antiferroelectric ceramic material can be further improved.

And (3) performing plastic removal on the biscuit, namely removing the organic matter binder (such as PVA) at a certain temperature to obtain a green body of the raw material. Specifically, the temperature for plastic removal can be 700 ℃ -900 ℃ (preferably 850 ℃ -900 ℃), and the heat preservation time can be 2-3 hours. The temperature rise rate of the plastic discharge can be 1-3 ℃/min.

And sintering the biscuit at a certain temperature after plastic removal. Specifically, the sintering process can be carried out in oxygen, the sintering temperature can be 1000-1250 ℃, and the heat preservation time can be 2-3 hours. In the invention, the temperature rise rate of sintering can be 1-3 ℃/min. Wherein, oxygen-filling sintering is favorable for improving the density and inhibiting Ag₂The decomposition of O ensures that the exact stoichiometric ratio of the components is obtained.

In the invention, the obtained crude product of the rare earth element Tm doped silver niobate antiferroelectric ceramic material is ground to be thin to be 0.15-0.20 mm thick (grinding and polishing treatment) on the upper surface and the lower surface, so that the energy storage density of the rare earth element Tm doped silver niobate antiferroelectric ceramic material can be further improved.

In the invention, an electrode (for example, a silver electrode) is coated on the surface of the rare earth element Tm doped silver niobate antiferroelectric ceramic material, and then the energy storage ceramic element is obtained. Specifically, the surface-coated electrode includes, for example, screen-printing silver, baking, firing silver (for example, sintering at 600 ℃ for 30 minutes in air), and the like.

In the invention, a TF Analyzer 2000 ferroelectric Analyzer is adopted to measure that the forward bending electric field of the rare earth element Tm doped silver niobate antiferroelectric ceramic material is 14-28 kV/mm, and the reverse bending electric field is 5-14 kV/mm.

In the invention, the rare earth element Tm doped silver niobate antiferroelectric ceramicThe energy storage density of the material is 2.6-4.3J/cm³And the energy storage efficiency is 38-77%.

In the invention, the rare earth element Tm doped silver niobate antiferroelectric ceramic material can be used for an energy storage capacitor, such as the manufacture of an energy storage ceramic capacitor, is beneficial to promoting the application and development of a high energy storage density ceramic technology, and has good application prospect.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.