CN113716956A

CN113716956A - Strontium zirconate titanate solid solution modified sodium bismuth titanate-based ceramic material and preparation method thereof

Info

Publication number: CN113716956A
Application number: CN202111012570.9A
Authority: CN
Inventors: 王之恒; 戴中华; 张凡博; 狄紫依; 刘卫国
Original assignee: Xian Technological University
Current assignee: Xian Technological University
Priority date: 2021-08-31
Filing date: 2021-08-31
Publication date: 2021-11-30

Abstract

The invention relates to a preparation method of a strontium zirconate titanate solid solution modified sodium bismuth titanate-based ceramic material, which comprises the following chemical components: (1-x) (Bi)_0.5Na_0.5)TiO₃‑xSr(Ti_0.5Zr_0.5)O₃(where 0 ≦ x ≦ 0.25). The method comprises the following steps: preparing materials, ball milling, presintering, secondary ball milling, cold isostatic pressing, tabletting and sintering, wherein in the cold isostatic pressing, the prepared raw material powder is pressed into small slices, and the strontium zirconate titanate solid solution modified ferroelectric energy storage ceramic is prepared. The method can effectively reduce the residual polarization strength of the sodium bismuth titanate-based ceramic on the premise of maintaining larger maximum polarization strength, so that the electric hysteresis loop becomes thin, and further the sodium bismuth titanate-based ferroelectric ceramic material with high energy storage density is prepared. Prepared energy storage potteryThe porcelain can obtain 1.85J/cm at higher breakdown field strength (150kV/cm)³The recoverable energy storage density of (1). In particular, the samples showed excellent frequency stability and temperature stability (W) under an electric field of 100kV/cm over a wide frequency range (1-500Hz) and temperature range (40-160 ℃ C.)_recLess than ± 6%).

Description

Strontium zirconate titanate solid solution modified sodium bismuth titanate-based ceramic material and preparation method thereof

Technical Field

The invention relates to the field of energy storage ceramic capacitors, in particular to a strontium zirconate titanate solid solution modified sodium bismuth titanate-based ceramic material and a preparation method thereof.

Background

With the rapid development of modern industry and electronic information technology, how to overcome the increasingly severe environmental problems and energy crisis, finding clean and sustainable energy resources has become a global problem. Compared with batteries, electrochemical capacitors and lead-based dielectric capacitors, lead-free dielectric materials are receiving more and more attention due to the advantages of high power density, no toxicity, environmental protection and the like. The energy density of lead-free dielectric materials is lower than batteries, electrochemical capacitors and lead-based dielectric capacitors, which limits their further applications. Therefore, how to improve the energy storage performance of the lead-free dielectric material becomes a key problem. At present, the dielectric materials of the dielectric energy storage capacitor mainly include five major categories of ceramic state ferroelectric energy storage materials, glass ceramic state energy storage materials, thick film state ferroelectric energy storage materials, epitaxial thin film state ferroelectric energy storage materials and polymer state and ceramic polymer composite ferroelectric energy storage materials. Compared with other energy storage dielectric materials, the ferroelectric ceramic has medium breakdown field strength, lower dielectric loss, excellent temperature stability and anti-fatigue property, and can better meet the requirements of the fields of aerospace, new energy power generation, power automobiles, electromagnetic pulse weapons and the like on energy storage capacitors. Thus, the ferroelectric energy storage material in ceramic state is considered to be the preferable material for preparing the high temperature resistant dielectric pulse power device.

Wherein, Bi_0.5Na_0.5TiO₃(BNT) is a traditional perovskite ceramic system that has been extensively studied since its discovery in the 60's of the 20 th century. The BNT group has higher Curie temperature (320 ℃), larger residual polarization (-32 uC/cm)²) It is a ferroelectric material with diamond symmetry at room temperature. When the temperature rises to about 200 ℃ (T), the BNT group begins to come outThe ferroelectric phase is now reversed. However, the coercive field of the BNT-based ceramic material is large (73 kV/cm), so that the BNT-based ceramic material is difficult to be polarized, and has good electrical properties, and the application of the BNT-based ceramic material in the aspect of energy storage is limited.

Disclosure of Invention

The invention aims to provide a strontium zirconate titanate solid solution modified sodium bismuth titanate-based ceramic material and a preparation method thereof, which aim to overcome the problems of high residual polarization strength and poor temperature stability in the prior art, so that the electrical properties are not ideal enough, and simultaneously overcome the problems of more complex preparation method and easy generation of impurities.

In order to achieve the purpose, the invention adopts the following technical scheme: a strontium zirconate titanate solid solution modified sodium bismuth titanate-based ceramic material comprises the following components in percentage by weight: (1-x) (Bi)_0.5Na_0.5)TiO₃-xSr(Ti_0.5Zr_0.5)O₃Wherein 0 ≦ x ≦ 0.25.

The preparation method of the strontium zirconate titanate solid solution modified sodium bismuth titanate based energy storage ceramic comprises the following steps:

(1) material mixing and ball milling: according to (1-x) (Bi)_0.5Na_0.5)TiO₃-xSr(Ti_0.5Zr_0.5)O₃Respectively weighing high-purity chemical Bi₂O₃(≥99.9％)，Na₂CO₃(≥99.8％)，TiO₂(≥99.9％)，SrCO₃(not less than 99.0%) and ZrO₂(more than or equal to 99.0%) mixing, ball milling, drying the raw material mixture at 85-100 ℃ for 2-4 h, and sieving to obtain mixed powder;

(2) pre-burning: placing the powder obtained in the step (1) in an alumina crucible, pre-burning at 830-870 ℃, and then naturally cooling to room temperature;

(3) secondary ball milling: performing secondary ball milling on the pre-sintered mixed powder, drying the fully-mixed ball-milled pre-sintered powder at 85-100 ℃ for 2-4 h, and sieving to obtain powder;

(4) tabletting: filling the powder obtained in the step (3) into a die for manual prepressing and forming, and then putting the powder into a cold isostatic press for pressing into tablets under the pressure of 200-300 MPa to obtain a ceramic material green body;

(5) and (3) sintering: mixing the (1-x) (Bi)_0.5Na_0.5)TiO₃-xSr(Ti_0.5Zr_0.5)O₃And (3) preserving the heat of the green body at 1140-1220 ℃, and naturally cooling to room temperature to obtain the sodium bismuth titanate-based energy storage ceramic material.

In the preparation method, the tabletting and pressure maintaining time in the step (5) is 1-3 min, the size of the obtained green body is 11-15 mm, and the thickness is 1-1.4 mm.

Compared with the prior art, the invention has the following beneficial technical effects:

1. the second component SrTi is introduced into the composition_0.5Zr_0.5O₃For sodium bismuth titanate-based energy storage ceramics, Sr is considered²⁺Can disturb the long-range order structure of the ferroelectric and generate polar nano-regions (PNRs) in the matrix while maintaining large P_maxAnd inhibition of P_rAbility of Ti⁴⁺The introduction of the elements can be distributed at the grain boundary of the material to improve the insulation of the material, so that a stronger effect is generated.

The energy storage ceramic prepared by the method can obtain 1.85J/cm³High energy storage density of (2); in particular, the samples showed excellent frequency stability and temperature stability (W) under an electric field of 100kV/cm over a wide frequency range (1-500Hz) and temperature range (40-160 ℃ C.)_recLess than ± 6%);

2. the preparation process comprises the following steps: by adopting the cold isostatic pressing forming method, impurities are not easy to be mixed in the preparation process, the glue adding and discharging processes are avoided, the process flow is simplified, and the compactness of the ceramic is improved.

3. By doping strontium zirconate titanate into the modified sodium bismuth titanate-based energy storage ceramic, along with the increase of the doping amount of the second component, the crystal lattice generates distortion, the ceramic breakdown field strength is improved, and the polarization difference (P)_max-P_r) And the micro-domain structure is reduced, so that the micro-domain structure can be more easily turned over under an applied electric field to obtain higher energy storage density.

Drawings

FIG. 1 shows (1-x) Bi produced by the present invention_0.5Na_0.5TiO₃-xSrTi_0.5Zr_0.5O₃An XRD pattern of the ceramic sample, wherein x is less than or equal to 0 and less than or equal to 0.25.

FIG. 2 shows (1-x) Bi produced by the present invention_0.5Na_0.5TiO₃-xSrTi_0.5Zr_0.5O₃The original surface morphology of the ceramic sample, wherein x is 0 ≦ 0.25.

FIG. 3 shows (1-x) Bi produced by the present invention_0.5Na_0.5TiO₃-xSrTi_0.5Zr_0.5O₃A hysteresis loop at room temperature for the ceramic sample, wherein x is 0 ≦ 0.25.

FIG. 4 shows 0.80Bi obtained by the present invention_0.5Na_0.5TiO₃-0.20SrTi_0.5Zr_0.5O₃P-E curve of ceramic sample under 100kV/cm electric field at 40-160 deg.C.

FIG. 5 shows 0.80Bi obtained by the present invention_0.5Na_0.5TiO₃-0.20SrTi_0.5Zr_0.5O₃P-E curves of ceramic samples at 1-500Hz in a 100kV/cm electric field.

Detailed Description

Embodiments of the invention are described in further detail below:

example 1

This example is a sodium bismuth titanate-based energy storage ceramic modified by solid solution of strontium zirconate titanate, whose chemical composition is 0.80Bi_0.5Na_0.5TiO₃-0.20SrTi_0.5Zr_0.5O₃The preparation method comprises the following steps:

(1) weighing Bi according to the proportion of a stoichiometric formula₂O₃、Na₂CO₃、TiO₂、SrCO₃And ZrO₂Mixing and carrying out ball milling for 12 hours at the rotating speed of 350 r/min. After the ball milling is finished, drying the mixture for 2h at the drying temperature of 85 ℃ and sieving to obtain 0.80Bi_0.5Na_0.5TiO₃-0.20SrTi_0.5Zr_0.5O₃And (3) powder.

(2) Adding the mixture into a crucible, placing the crucible into a sintering furnace, heating to 850 ℃, preserving heat for 2 hours, and naturally cooling to room temperature, wherein the pre-sintering heating rate is 3 ℃/min.

(3) Ball milling is carried out on the pre-sintered mixed powder, the rotating speed of the ball milling is 350r/min, the ball milling time is 24 hours, and after the ball milling is finished, the mixed material is dried at 85 ℃ for 2 hours and is sieved.

(4) Filling the powder into a mold, pre-pressing for molding, putting into a cold isostatic press, pressing the granules into a green body with the thickness of 1.2mm under the pressure of 300MPa, and keeping the pressure for 2min to obtain the green body with the size of 13 mm.

(5) Putting the green body into an alumina crucible, heating to 1200 ℃ at a speed of 3 ℃/min, and preserving heat for 4 h; and naturally cooling to room temperature to obtain the sodium bismuth titanate-based ceramic material.

The prepared 0.80Bi_0.5Na_0.5TiO₃-0.20SrTi_0.5Zr_0.5O₃XRD testing of the energy storage ceramic sample, as shown in figure 1(a), showed that the sample was a uniform perovskite structure without any secondary phase, indicating Sr²⁺、Ti⁴⁺And Zr⁴⁺Fully diffused into the BNT lattice to form a solid solution. Further, as can be seen from fig. 1(b), the increase in the amount of STZ introduction causes a tendency of the characteristic peak of the ceramic material to shift toward a low angle, because Zr having a larger radius is introduced with the STZ introduction⁴⁺Ion(s)

Replacing the smaller radius Ti in the unit cell⁴⁺Ion(s)

Resulting in distortion of the crystal lattice.

For 0.80Bi obtained in example 1_0.5Na_0.5TiO₃-0.20SrTi_0.5Zr_0.5O₃The original shape of the energy storage ceramic sample is characterized, as shown in fig. 2, and all the ceramics are observed to show a uniform and compact microstructure, the boundaries between crystal grains are clear, and no defects such as obvious pores exist. And with the continuous increase of the addition amount of the STZ, the grain size of the ceramic is obviously reduced and is shown to be firstly reduced and then increasedThe tendency is that the crystal grain size is smallest when x is 0.20.

For 0.80Bi obtained in example 1_0.5Na_0.5TiO₃-0.20SrTi_0.5Zr_0.5O₃The energy storage ceramic sample is subjected to the hysteresis loop test at room temperature, as shown in FIG. 3, it can be seen that as the addition amount of STZ is increased, P is_rIs gradually decreased, P_maxThen it is maintained at a higher level and the ferroelectric hysteresis loop of the ceramic material becomes "thin" and exhibits the characteristics of typical relaxor ferroelectric materials, with ever-increasing effective energy storage density and energy storage efficiency. In particular, when x is 0.20, as in fig. 3(e), W thereof_rec＝1.85J/cm³，η＝65.92％，W_recIs 4.5 times of the effective energy storage density of pure BNT. This phenomenon can be explained by macroscopic domains and PNRs. PNRs are smaller than macroscopic domain sizes and are more easily aligned and folded under an applied electric field. The thin P-E loop with PNRs can improve energy storage density and reduce energy loss in the charging and discharging process. This embodiment is the most preferred embodiment.

Example 2

According to formula (1-x) Bi_0.5Na_0.5TiO₃-xSrTi_0.5Zr_0.5O₃The procedure was the same as in example 1 except that the value of x was changed to 0.05, 0.10, 0.15 and 0.25.

The sample prepared in this example 2 was subjected to morphology characterization and hysteresis loop testing. The test results show that the performance is all inferior to 0.20 component.

Example 3

The other conditions were the same as in example 1 except that the sintering temperature was changed to 1160 ℃.

The sample prepared in this example 3 was subjected to morphology characterization and hysteresis loop testing. The result of an electron scanning microscope shows that micropores appear in the prepared ceramic at the sintering temperature, and the relative density of the micropores is reduced. The hysteresis loop shows, although at its maximum polarization P_maxGreater, but at the same time remanent, polarization P_rAlso increased, resulting in a difference in polarization (P)_max-P_r) And the recyclable energy storage density is reduced.

Comparative example: the other conditions were the same as in example 1 except that the tabletting method was changed to the gel addition and removal method.

The sample prepared in this example 4 was tested and characterized, and compared with the cold isostatic pressing method, the ceramic sample prepared by the method had a non-compact grain microstructure and had obvious defects such as pores.

According to the invention, the lead-free ceramic with high energy storage density is successfully prepared by doping strontium zirconate titanate with the modified sodium bismuth titanate-based energy storage ceramic. The energy storage ceramic prepared by the method can obtain 1.85J/cm under higher breakdown field strength (150kV/cm)³High energy storage density of (2); in particular, the samples showed excellent frequency stability and temperature stability (W) under an electric field of 100kV/cm over a wide frequency range (1-500Hz) and temperature range (40-160 ℃ C.)_recLess than ± 6%), as shown in fig. 4 and 5;

the above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims

1. A strontium zirconate titanate solid solution modified sodium bismuth titanate-based ceramic material is characterized in that: the components and the contents thereof are as follows: (1-x) (Bi)_0.5Na_0.5)TiO₃-xSr(Ti_0.5Zr_0.5)O₃Wherein 0 ≦ x ≦ 0.25.

2. The preparation method of the strontium zirconate titanate solid solution modified sodium bismuth titanate based energy storage ceramic as claimed in claim 1, characterized by comprising the following steps:

(1) material mixing and ball milling: according to (1-x) (Bi)_0.5Na_0.5)TiO₃-xSr(Ti_0.5Zr_0.5)O₃Respectively weighing high-purity chemical Bi₂O₃(≥99.9％)，Na₂CO₃(≥99.8％)，TiO₂(≥99.9％)，SrCO₃(≧ 99.0%) and ZrO₂(more than or equal to 99.0%) mixing, ball milling, drying the raw material mixture at 85-100 ℃ for 2-4 h, and sieving to obtain mixed powder;

3. The method for preparing the strontium zirconate titanate solid solution modified sodium bismuth titanate based energy storage ceramic according to claim 2, wherein the tablet-making pressure maintaining time in the step (5) is 1-3 min, the size of the obtained green body is 11-15 mm, and the thickness is 1-1.4 mm.