CN109354492B

CN109354492B - Bismuth-based lead-free high-energy-density ceramic material and preparation method thereof

Info

Publication number: CN109354492B
Application number: CN201811180655.6A
Authority: CN
Inventors: 周佳骏; 童兴野; 宋岷蔚; 刘红; 方敬忠
Original assignee: Institute of Optics and Electronics of CAS
Current assignee: Institute of Optics and Electronics of CAS
Priority date: 2018-10-09
Filing date: 2018-10-09
Publication date: 2021-08-13
Anticipated expiration: 2038-10-09
Also published as: CN109354492A

Abstract

The invention discloses a bismuth-based lead-free high-energy-storage-density ceramic material and a preparation method thereof, relating to the technical field of electronic ceramics and components and being used in the related field of energy storage capacitor application. The chemical components of the material conform to the general formula: (1-x) Bi_0.5Na_0.5TiO₃+x SrTiO₃+ywt％Nb₂O₅The ceramic is synthesized by adopting the traditional ceramic preparation process. By adding Nb, the grain size of the ceramic is refined, and the breakdown field strength is improved. The ceramic element prepared by the invention can obtain W under the direct current field of E-13 kV/mm_rec～1.8J/cm³The energy storage density and the energy efficiency eta can reach 80 percent; meanwhile, the material has good temperature stability of energy storage performance.

Description

Bismuth-based lead-free high-energy-density ceramic material and preparation method thereof

Technical Field

The invention relates to a ceramic material for energy storage electronic components, in particular to a bismuth-based lead-free high-energy-storage-density ceramic material and a preparation method thereof.

Background

The high energy storage density pulse power capacitor becomes a basic energy storage element of a pulse power technology by the characteristics of high power density, high working voltage, large discharge current and the like, and is widely applied to occasions such as igniters, high-power microwave weapons, electromagnetic ejection, high-energy lasers, particle accelerators and the like.

Currently, in the field of application of the components, energy storage capacitor elements are mainly divided into two types according to the used dielectric materials: organic thin film capacitors and laminated dielectric ceramic capacitors. The film capacitor uses a polymer plastic film as a middle dielectric material, and a metal electrode on the film is formed by sputtering deposition. The capacitor has self-healing capacity, and has the advantages of high voltage, long service life and the like, but the energy density is lower. Three inorganic dielectric ceramic materials commonly used are: the ceramic material comprises three ceramic materials, namely a class I dielectric ceramic (linear medium), a class II ferroelectric ceramic and an antiferroelectric ceramic. Class I materials with TiO₂Is represented by the following formula, the dielectric constant is 100, and the energy storage density is 1.0J/cm³. Class II materials with BaTiO₃A base material, typically punctureLower field strength E_b35kV/mm and 1.5J/cm of energy storage density³. The antiferroelectric ceramic represented by PZST has the highest energy storage density of 10J/cm³Moderate dielectric constant and high breakdown field strength E_b35kV/mm, and is very suitable for the application requirement of the pulse power capacitor.

The antiferroelectric energy storage ceramic raw materials used in the current market generally contain lead element, and the lead content is over 60 wt%. When the ceramic is produced or exposed to an acid environment, Pb can be liberated to cause environmental damage. In 2002, the european union has enacted RoHS laws restricting the use of 6 harmful elements, including Pb, in electronic products. China also implemented a method for preventing and controlling pollution of electronic information products in 2007. Based on the situation, the development and the development of the environment-friendly antiferroelectric energy storage ceramic material become a task with environmental and economic significance.

Bi_0.5Na_0.5TiO₃The (BNT) piezoelectric ceramic has a three-phase structure at room temperature and has high remanent polarization (P)_r＝38μC/cm²) And a higher Curie temperature (T)_c320 ℃) and a depolarization temperature (T) of around 230 ℃_d). Adding SrTiO into BNT ceramic₃Can be combined with T_dMoving the temperature to be near room temperature. At this time, reversible transition between the relaxation phase and the ferroelectric phase occurs under the driving of the electric field, and the P-E curve shows the antiferroelectric property, so that a higher energy storage density can be obtained. In 2016, Ning Xu et al (J Mater Sci: Mater Electron (2016)27:12479-³The energy storage density of (1). In the same year, WP Cao et al (J Eur ceramic Soc (2016)36: 593-600) achieved a storage density of 0.65J/cm in 0.70BNT-0.30ST material³And the efficiency is 73.6 percent. The studies above have the condition that the energy storage density and efficiency are low, and the energy storage performance of the BNT-ST material needs to be further improved.

Disclosure of Invention

The invention provides a bismuth-based lead-free electronic ceramic with high energy storage density and efficiency, which is applied to the field of energy storage capacitors and aims at solving the problem that the existing bismuth-based lead-free ceramic material has low energy storage density and efficiency.

The chemical composition of the bismuth-based lead-free high-energy-storage ceramic material conforms to the following general formula:

(1-x)Bi_0.5Na_0.5TiO₃+xSrTiO₃+ywt％Nb₂O₅wherein x is more than or equal to 0.35 and less than or equal to 0.5; y is more than or equal to 1.0 and less than or equal to 5.0;

the material is in a relaxation phase due to the higher ST content and the addition of Nb, has higher density (99.5%), smaller grain size (1 micron) and higher energy storage efficiency (>80%) of the characteristic; the energy storage ceramic has the following properties: under the direct current electric field of E ═ 13kV/mm, W can be obtained_rec～1.8J/cm³The energy storage density and the energy efficiency eta can reach 80 percent; in addition, the material has good energy storage performance and temperature stability, and the change rate of the energy storage density is 15 percent and eta is measured when the temperature is raised from room temperature to 120 ℃ under the electric field of E ═ 5kV/mm>90％。

The preparation method of the bismuth-based lead-free energy storage ceramic material comprises the following steps:

step S1: (1-x) Bi_0.5Na_0.5TiO₃+xSrTiO₃+ywt％Nb₂O₅And (4) primarily synthesizing powder. Will analytically pure Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂、Nb₂O₅Raw materials, alcohol is used as a medium, ZrO is adopted₂Grinding balls, performing ball milling and mixing, drying, sieving by a 80-mesh sieve, tabletting, and sintering at 800-900 ℃ for 2h to obtain the synthetic powder.

Step S2: and (5) forming the ceramic plate. And (5) crushing, ball-milling and drying the raw material blocks obtained in the step (S1), sieving by a 120-mesh sieve, adding a certain amount of PVA aqueous solution for granulation, and carrying out compression molding to obtain green sheets.

Step S3: and degreasing and sintering the ceramic wafer. Degreasing the green sheet obtained in the step S2 at 600 ℃, covering the green sheet with the raw powder obtained in the step S1, and sintering the green sheet at about 1200-1300 ℃ for 2h to obtain the ceramic sheet.

Step S4: and manufacturing a ceramic wafer electrode. And (5) polishing the ceramic wafer sintered in the step (S3), coating silver on the surface of the ceramic wafer, and sintering the silver.

The invention has the beneficial effects that: the composition of the BNT-ST material is studied in detail, and the material with high polarization strength P and high energy storage efficiency is obtained. And further adding Nb on the basis, the grain size of the alloy is refined, and the breakdown field strength and the energy storage density are improved. The ceramic material of the invention can obtain W under the direct current electric field of E ═ 13kV/mm_rec～1.8J/cm³The energy storage density and the energy efficiency eta can reach 80 percent. In addition, the material has good energy storage performance and temperature stability, and the change rate of the energy storage density is 15% when the temperature is raised from room temperature to 120 ℃ under an electric field of E ═ 5 kV/mm.

Drawings

FIG. 1 shows 0.6Bi_0.5Na_0.5TiO₃+0.4SrTiO₃+2.5wt％Nb₂O₅P-E plot of (a);

FIG. 2 shows 0.6Bi_0.5Na_0.5TiO₃+0.4SrTiO₃+2.5wt％Nb₂O₅XRD pattern of (a);

FIG. 3 shows 0.6Bi_0.5Na_0.5TiO₃+0.4SrTiO₃SEM picture of (1);

FIG. 4 shows 0.6Bi_0.5Na_0.5TiO₃+0.4SrTiO₃+2.5wt％Nb₂O₅SEM picture of (1);

FIG. 5 shows 0.6Bi_0.5Na_0.5TiO₃+0.4SrTiO₃+2.5wt％Nb₂O₅Variable temperature W at 5kV/mm_rFigure (a).

The specific implementation mode is as follows:

the invention is further described with reference to the following figures and detailed description.

Example 1

The invention analyzes pure Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂And Nb₂O₅As raw material, 0.65Bi according to chemical formula_0.5Na_0.5TiO₃+0.35SrTiO₃+5.0wt％Nb₂O₅Weighing raw materials, putting the raw materials into a ball milling tank, taking absolute ethyl alcohol as a medium,after ball milling for 24h, putting the obtained slurry into an oven for drying, sieving with a 80-mesh sieve, and presintering for 4h at 850 ℃. And crushing the powder obtained by pre-sintering, ball-milling, drying, sieving by a 120-mesh sieve, adding a certain amount of 3 wt% PVA aqueous solution for granulation, carrying out compression molding, staying at 600 ℃ for 2h for gel removal, and sintering at 1200-1300 ℃ for 2 h. Polishing the sintered ceramic wafer, standing for 24 hours after silver electrode sintering, and finally performing electrical performance.

Example 2

The invention analyzes pure Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂And Nb₂O₅As raw material, 0.50Bi according to chemical formula_0.5Na_0.5TiO₃+0.50SrTiO₃+1.0wt％Nb₂O₅Weighing raw materials, putting the raw materials into a ball milling tank, ball milling the raw materials for 24 hours by using absolute ethyl alcohol as a medium, putting the obtained slurry into an oven for drying, sieving the dried slurry by using a 80-mesh sieve, and presintering the dried slurry for 4 hours at 850 ℃. And crushing the powder obtained by pre-sintering, ball-milling, drying, sieving by a 120-mesh sieve, adding a certain amount of 3 wt% PVA aqueous solution for granulation, carrying out compression molding, staying at 600 ℃ for 2h for gel removal, and sintering at 1200-1300 ℃ for 2 h. Polishing the sintered ceramic wafer, standing for 24 hours after silver electrode sintering, and finally performing electrical performance.

Example 3

The invention analyzes pure Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂And Nb₂O₅As raw material, 0.60Bi according to chemical formula_0.5Na_0.5TiO₃+0.40SrTiO₃+2.5wt％Nb₂O₅Weighing raw materials, putting the raw materials into a ball milling tank, ball milling the raw materials for 24 hours by using absolute ethyl alcohol as a medium, putting the obtained slurry into an oven for drying, sieving the dried slurry by using a 80-mesh sieve, and presintering the dried slurry for 4 hours at 850 ℃. And crushing the powder obtained by pre-sintering, ball-milling, drying, sieving by a 120-mesh sieve, adding a certain amount of 3 wt% PVA aqueous solution for granulation, carrying out compression molding, staying at 600 ℃ for 2h for gel removal, and sintering at 1200-1300 ℃ for 2 h. Polishing the sintered ceramic wafer, standing for 24 hours after silver electrode sintering, and finally performing electrical performance.

Example 4

The invention analyzes pure Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂And Nb₂O₅As raw material, 0.60Bi according to chemical formula_0.5Na_0.5TiO₃+0.40SrTiO₃+5.0wt％Nb₂O₅Weighing raw materials, putting the raw materials into a ball milling tank, ball milling the raw materials for 24 hours by using absolute ethyl alcohol as a medium, putting the obtained slurry into an oven for drying, sieving the dried slurry by using a 80-mesh sieve, and presintering the dried slurry for 4 hours at 850 ℃. And crushing the powder obtained by pre-sintering, ball-milling, drying, sieving by a 120-mesh sieve, adding a certain amount of 3 wt% PVA aqueous solution for granulation, carrying out compression molding, staying at 600 ℃ for 2h for gel removal, and sintering at 1200-1300 ℃ for 2 h. Polishing the sintered ceramic wafer, standing for 24 hours after silver electrode sintering, and finally performing electrical performance.

Comparative example 1

The invention analyzes pure Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂And Nb₂O₅As raw material, according to the chemical formula 0.70Bi_0.5Na_0.5TiO₃+0.30SrTiO₃+5.0wt％Nb₂O₅Weighing raw materials, putting the raw materials into a ball milling tank, ball milling the raw materials for 24 hours by using absolute ethyl alcohol as a medium, putting the obtained slurry into an oven for drying, sieving the dried slurry by using a 80-mesh sieve, and presintering the dried slurry for 4 hours at 850 ℃. And crushing the powder obtained by pre-sintering, ball-milling, drying, sieving by a 120-mesh sieve, adding a certain amount of 3 wt% PVA aqueous solution for granulation, carrying out compression molding, staying at 600 ℃ for 2h for gel removal, and sintering at 1200-1300 ℃ for 2 h. Polishing the sintered ceramic wafer, standing for 24 hours after silver electrode sintering, and finally performing electrical performance.

Comparative example 2

The invention analyzes pure Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂And Nb₂O₅As raw material, 0.45Bi according to chemical formula_0.5Na_0.5TiO₃+0.55SrTiO₃+1.0wt％Nb₂O₅Weighing raw materials, putting the raw materials into a ball milling tank, ball milling the raw materials for 24 hours by using absolute ethyl alcohol as a medium to obtain slurryDrying in an oven, sieving with 80 mesh sieve, and presintering at 850 deg.C for 4 hr. And crushing the powder obtained by pre-sintering, ball-milling, drying, sieving by a 120-mesh sieve, adding a certain amount of 3 wt% PVA aqueous solution for granulation, carrying out compression molding, staying at 600 ℃ for 2h for gel removal, and sintering at 1200-1300 ℃ for 2 h. Polishing the sintered ceramic wafer, standing for 24 hours after silver electrode sintering, and finally performing electrical performance.

Comparative example 3

The invention analyzes pure Bi₂O₃、Na₂CO₃、SrCO₃And TiO₂As raw material, 0.60Bi according to chemical formula_0.5Na_0.5TiO₃+0.40SrTiO₃Weighing raw materials, putting the raw materials into a ball milling tank, ball milling the raw materials for 24 hours by using absolute ethyl alcohol as a medium, putting the obtained slurry into an oven for drying, sieving the dried slurry by using a 80-mesh sieve, and presintering the dried slurry for 4 hours at 850 ℃. And crushing the powder obtained by pre-sintering, ball-milling, drying, sieving by a 120-mesh sieve, adding a certain amount of 3 wt% PVA aqueous solution for granulation, carrying out compression molding, staying at 600 ℃ for 2h for gel removal, and sintering at 1200-1300 ℃ for 2 h. Polishing the sintered ceramic wafer, standing for 24 hours after silver electrode sintering, and finally performing electrical performance.

Table 1: energy storage performance of the ceramic material of the invention

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can readily modify the above examples and apply the general principles to other examples without inventive faculty. Therefore, it is well within the protection scope of the present invention to modify and improve the present invention by those skilled in the art according to the teachings of the present invention.

Claims

1. A bismuth-based lead-free high energy storage density ceramic material is characterized in that: the component is (1-x)Bi_0.5Na_0.5TiO₃+xSrTiO₃+ywt%Nb₂O₅Which is0.35 inx≤0.5，1.0≤y≤5.0；

The material is in a relaxation phase due to the high ST content and the addition of Nb, and has the following characteristics: the density is high and is 99.5%, the grain size is small and is 1 micron, the energy storage efficiency is high,>80 percent; the energy storage ceramic has the following properties: in thatEUnder the direct current field of =13kV/mm, the product can be obtainedW _rec ~ 1.8J/cm³The energy storage density and the energy efficiency eta can reach 80 percent; in addition, the material has good energy storage performance and temperature stabilityEHeating to 120 kV/mm electric field from room temperature^oAt C, the change rate of the energy storage density is 15 percent, eta>90%。

2. The method for preparing a ceramic material according to claim 1, comprising the steps of:

step S1: (1-x)Bi_0.5Na_0.5TiO₃+xSrTiO₃+ywt%Nb₂O₅Preliminary synthesis of powder, analytically pure Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂、Nb₂O₅The raw materials are ball-milled and mixed by taking alcohol as a medium, dried, sieved by a 80-mesh sieve, tabletted and processed in 800-900 percent solution^oC, sintering for 2 hours to obtain synthetic powder;

step S2: forming the ceramic chip: crushing, ball-milling, drying and sieving the raw material blocks obtained in the step S1, adding a certain amount of PVA aqueous solution for granulation, and carrying out compression molding to obtain green sheets;

step S3: degreasing and sintering the ceramic wafer: the green sheet obtained in step S2 is first processed at 600^oC degreasing, then covering the raw powder obtained in S1 at 1200-^oC, sintering for 2 hours to obtain a ceramic wafer;

step S4: manufacturing a ceramic chip electrode: and (5) polishing the ceramic wafer sintered in the step (S3), coating silver on the surface, burning the silver, and waiting for an electrical test.