CN110372371B

CN110372371B - Ferroelectric material based on metal cation doping and preparation method thereof

Info

Publication number: CN110372371B
Application number: CN201910564399.9A
Authority: CN
Inventors: 罗来慧; 祝泽林; 杜鹏
Original assignee: Ningbo University
Current assignee: Shenzhen Dragon Totem Technology Achievement Transformation Co ltd
Priority date: 2019-06-27
Filing date: 2019-06-27
Publication date: 2022-05-24
Anticipated expiration: 2039-06-27
Also published as: CN110372371A

Abstract

A ferroelectric material based on metal cation doping in (1-x) Na_0.5Bi_0.5TiO₃‑xBaTiO₃The ferroelectric material is prepared by doping metal cations, and is characterized in that the chemical formula of the ferroelectric material is as follows: na (Na)_0.5‑0.5xBi_0.5‑0.5xBa_xM_yTi_1‑yO₃Wherein x is more than or equal to 0 and less than or equal to 0.07, y is more than or equal to 0.005 and less than or equal to 0.04, M is a metal cation with a valence lower than +4, and Ti is replaced by the metal cation⁴⁺Thereby increasing the depolarization temperature of the ferroelectric material. The invention also discloses a preparation method of the ferroelectric material. Compared with the prior art, the invention can effectively improve the depolarization temperature of the ferroelectric material, and the preparation methodIt is simple.

Description

Ferroelectric material based on metal cation doping and preparation method thereof

Technical Field

The invention belongs to the technical field of lead-free piezoelectric materials, and particularly relates to a ferroelectric material based on metal cation doping and a preparation method thereof.

Background

An important characteristic of ferroelectric materials is that they have excellent piezoelectric effect, which plays an important role in some applications of electrical devices, such as: piezoelectric transducers, piezoelectric buzzers, piezoelectric sensors, accelerators, piezoelectric actuators, piezoelectric igniters, piezoelectric microphones, piezoelectric transformers, piezoelectric filters, microelectromechanical systems (MEMS), and the like. The most widely used PbTiO containing lead₃-PbZrO₃(PZT) piezoelectric ceramics, but the traditional lead-based piezoelectric ceramics contain a large amount of lead oxide, and the lead-containing piezoelectric ceramics can release a large amount of lead to the environment in the processes of preparation, use and waste post-treatment, thereby bringing great damage to the environment and human health. In recent years, many countries are studying legislation that prohibits the use of piezoelectric ferroelectric materials containing lead. Since 2002, the european parliament and the european union council, japan, the united states, and other countries have put forward regulations on lead-free electronic products, effectively restricting the use of some harmful substances in electric and electronic products. The fundamental research and development of lead-free piezoelectric ceramics in the united states, japan, and the like have been continuously increased, and the development of lead-free piezoelectric ceramics with excellent performance has become one of the frontiers and hot spots of international research at present.

Piezoelectric ceramic products have a market of several billion dollars each year in the world, and are growing at a high rate of 8.9% on average, and if production companies are continuously moving to china in consideration of the beauty, the day and the europe, the growth rate of the market in China is much higher than that of the average, and the market is urgently in need of a mature lead-free piezoelectric ceramic material. In conclusion, partial replacement or complete replacement of the lead-containing piezoelectric ceramic device is an item with important scientific significance and huge social and economic benefits.

Bi_0.5Na_0.5TiO₃The piezoelectric ceramic, which is currently the lead-free piezoelectric ceramic with the most application prospect, is sodium bismuth titanate Bi_0.5Na_0.5TiO₃Has the advantages of strong ferroelectricity, low sintering temperature and the like. Sodium bismuth titanate of cubic phase and titanic acid of tetragonal phaseBarium being dissolved in a solid to form (1-x) Na_0.5Bi_0.5TiO₃-xBaTiO₃Ferroelectric ceramics, wherein x is the molar content. I know (1-x) Na_0.5Bi_0.5TiO₃-xBaTiO₃Ferroelectric ceramics at 0.06<x<0.07 has the best piezoelectric performance, but has an important constraint factor of depolarization temperature, that is, when the environmental temperature is close to the temperature, the piezoelectric performance of the ceramic is greatly reduced, and the use of the ceramic is greatly limited. According to (1-x) Na_0.5Bi_0.5TiO₃-xBaTiO₃The depolarization of ferroelectric ceramics is a long-range ferroelectric sequence-relaxation weak polar phase transition [ Journal of Applied Physics 110,074106(2011) ]]. According to the Landau theory, the electric field is beneficial to the stabilization of the ferroelectric phase, but the external electric field will greatly increase the complexity of the device when in use.

Therefore, a reasonable method is found, and the method has positive significance for improving the stability of the ferroelectric material.

To this end, the invention patent application No. CN200810223964.7, a ternary system sodium bismuth titanate-based lead-free piezoceramic material and a preparation method thereof (application publication No. CN101381231A) discloses a lead-free piezoceramic material, the composition of which is (100-x) Bi_0.5Na_0.5TiO₃-4xBi_0.5K_0.5TiO₃-xBaTiO₃-yCo₂O₃Wherein x is more than or equal to 2 and less than or equal to 4, and y is more than or equal to 0.25 and less than or equal to 2.0. The ceramic material is prepared by taking anhydrous sodium carbonate, anhydrous potassium carbonate, bismuth oxide, titanium dioxide, barium carbonate and cobaltous oxide as raw materials and carrying out pre-synthesis, rolling film, sintering and polarization on the raw materials. The ceramic material has higher depolarization temperature and mechanical quality factor, but mainly aims at Bi_0.5Na_0.5TiO₃-Bi_0.5K_0.5TiO₃-BaTiO₃A ternary system.

Disclosure of Invention

The first technical problem to be solved by the present invention is to provide a ferroelectric material based on metal cation doping, which can increase depolarization temperature and further improve material stability, in view of the current situation of the prior art.

The second technical problem to be solved by the present invention is to provide a method for preparing the ferroelectric material in view of the current state of the prior art.

The technical scheme adopted by the invention for solving the first technical problem is as follows: a ferroelectric material based on metal cation doping is prepared from Na (1-x)_0.5Bi_0.5TiO₃-xBaTiO₃The ferroelectric material is prepared by doping metal cations, and is characterized in that the chemical formula of the ferroelectric material is as follows: na (Na)_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Wherein x is more than or equal to 0 and less than or equal to 0.07, y is more than or equal to 0.005 and less than or equal to 0.04, M is a metal cation with a valence lower than +4, and Ti is replaced by the metal cation⁴⁺Thereby improving the depolarization temperature of the ferroelectric material.

Radius of the metal cation and Ti⁴⁺Are close. Preferably, the metal cation comprises Co³ ⁺、 Fe³⁺、Ni²⁺、Mn²⁺、Mn³⁺At least one of (1).

In the above scheme, the Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃After polarization, the ferroelectric material has a depolarization temperature higher than that of (1-x) Na not doped with metal cations_0.5Bi_0.5TiO₃-xBaTiO₃The depolarization temperature of the material is higher than 5 ℃.

Preferably, the Na is_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃After polarization, the ferroelectric material has a depolarization temperature higher than that of (1-x) Na not doped with metal cations_0.5Bi_0.5TiO₃-xBaTiO₃The depolarization temperature of the material is higher than 20 ℃.

The technical scheme adopted by the invention for solving the second technical problem is as follows: the preparation method of the ferroelectric material based on metal cation doping is characterized by comprising the following steps:

adopts Bi₂O₃，Na₂CO₃，BaCO₃，TiO₂The metal cation M is a raw material according to the chemical formula Na_0.5- _0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Weighing and proportioning the stoichiometric ratio of Bi, Na, Ba, Ti and M elements; then ball milling and mixing are carried out, the raw materials after 2-15 hours of ball milling are dried and tabletted, and the pressure of tabletting is 5-80 Mpa; keeping the temperature of the pressed green blank at 750-850 ℃ for 1-3 hours to synthesize Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃A blank body;

② Na prepared in the step I_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Grinding and ball-milling the blank for 5-12 hours, and drying after ball-milling to obtain Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Drying the powder;

thirdly, Na prepared by the step two_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Adding a polyvinyl alcohol aqueous solution into the dried powder to be used as a binder for granulation, and tabletting and molding the granulated powder under 100-200 MPa; after tabletting, the binder is decomposed by heat preservation for 0.5 to 3 hours at the temperature of 600 to 700 ℃; then preserving heat for 2-4 hours at 1050-1200 ℃, and finally obtaining the ceramic wafer Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃A ferroelectric material.

Preferably, the volume of the raw materials in the ball milling mixing of step (i): agate sphere volume: the volume ratio of the ball milling meson absolute ethyl alcohol is 1: 1-1.2: 1 to 1.5.

In the step (c), the mass concentration of the polyvinyl alcohol is preferably 3-5%, and each 10g of Na_0.5-0.5xBi_0.5- _0.5xBa_xM_yTi_1-yO₃The volume of the polyvinyl alcohol dropped into the dried powder is preferably 1-2 mL.

Granulating the binder in the step III to obtain Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Baking powderThe body and polyvinyl alcohol are fully mixed in a mortar and then are sieved by a 40-200 mesh sieve.

Compared with the prior art, the invention has the advantages that: by reacting at (1-x) Na_0.5Bi_0.5TiO₃-xBaTiO₃The metal cation is doped in the solution so that the metal cation in a lower valence state replaces the Ti in a higher valence state⁴⁺Forming a defective dipole in the ferroelectric material, and further constructing a built-in electric field in the ferroelectric material through the directional arrangement of the defective dipole, thereby improving the depolarization temperature of the ferroelectric material; and because x is more than or equal to 0 and less than or equal to 0.07, Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃The ferroelectric material is a three-phase or three-phase four-phase coexisting, the non-polarized ferroelectric material is a polar nano domain, and the long-range ferroelectric sequence is converted after polarization; meanwhile, the preparation method is simple, and all chemical reactions are carried out in the air; the cost of the required raw materials is low, and the prepared ferroelectric material has good stability.

Drawings

FIG. 1 shows the increase of (1-x) Na in the present invention_0.5Bi_0.5TiO₃-xBaTiO₃Schematic diagram of material depolarization temperature;

FIG. 2 shows Na in example 1 of the present invention_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃An X-ray diffraction pattern of the ferroelectric material;

FIG. 3 shows Na in example 1 of the present invention_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃A thermal current curve of the ferroelectric material;

FIG. 4 shows Na in example 1 of the present invention_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃A graph of the relationship between the heat treatment temperature and the piezoelectric coefficient of the ferroelectric material.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

As shown in fig. 1, the principle of increasing the depolarization temperature of the ferroelectric material according to the present invention is as follows: by in (1-x)Na_0.5Bi_0.5TiO₃-xBaTiO₃The metal cation is doped in the solution, so that the metal cation in a lower valence state replaces the Ti in a higher valence state⁴⁺In order to maintain the electrovalence balance, the ceramic causes oxygen vacancies in the crystal lattice during sintering, and thus forms

Defective dipoles, orientation of the defective dipoles and Na under the action of a polarizing electric field_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃The spontaneous polarization direction of the middle domain is consistent, and Na is favored due to the built-in electric field formed by the defect dipole_0.5-0.5xBi_0.5- _0.5xBa_xM_yTi_1-yO₃The stability of the long-range order phase of the medium ferroelectric domain is improved, and then (1-x) Na is increased_0.5Bi_0.5TiO₃-xBaTiO₃The depolarization temperature of (a).

Example 1:

na with the purity of 99.8 percent is adopted₂CO₃99.9% of Bi₂O₃99.8% of TiO₂99.5% of BaCO₃99.5% CoFe₂O₄(in this embodiment, metal oxide is used as the raw material, and metal salt can be used as the raw material) according to the chemical formula Na_0.47Bi_0.47Ba_0.06M_yTi_1-yO₃(CoFe₂O₄The molar content ratio of Ti to (b) is y: 1, wherein M is Co and Fe, y is 0, 0.005, 0.02, 0.05), and the stoichiometric ratio of Bi, Na, Ba, Ti and M elements are respectively weighed and put into a ball milling tank for ball milling and mixing, and the ball milling conditions are the volume of the raw materials: agate sphere volume: the volume ratio of the ball milling medium absolute ethyl alcohol is equal to 1: 1: 1.5, putting the raw materials subjected to ball milling for 12 hours into an oven, and drying for 4 hours at 80 ℃. Then pressing the dried raw materials into raw material blanks with the diameter of 40mm by a tablet press under the pressure of 20Mpa, then putting the pressed raw material blanks into a KBF1400 box furnace for pre-sintering, preserving the heat for 2 hours under the pre-sintering condition of 850 ℃, and synthesizing Na_0.47Bi_0.47Ba_0.06M_yTi_1-yO₃A embryo body. Then pre-burning the block-shaped Na_0.47Bi_0.47Ba_0.06M_yTi_1-yO₃Grinding the blank, grinding into powder, sieving, ball milling for 12 hr, oven drying at 80 deg.C for 4 hr to obtain Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃And (5) drying the powder. Finally, grinding the dried powder according to the proportion that 1mL of PVA adhesive (the mass concentration of polyvinyl alcohol is 3%) is added into every 10g of the dried powder, granulating, sieving for 3 times by using a 80-mesh sieve, pressing the granulated powder into small pieces with the diameter of 11mm under the pressure of 200MPa, and then preserving the temperature for 2 hours at 650 ℃ to decompose the adhesive PVA and Al₂O₃Laying mother powder on the gasket, covering the pressed small pieces with the mother powder, putting the small pieces into a box-type furnace for sintering under the sintering condition of 1150 ℃ for 2 hours, and finally obtaining the ceramic piece which is Na_0.47Bi_0.47Ba_0.06M_yTi_1-yO₃A ferroelectric material.

And (4) grinding the sintered ceramic plate to be flat, and carrying out related tests. The test results are shown in FIGS. 2 to 4. From FIG. 3, Na can be seen_0.47Bi_0.47Ba_0.06M_yTi_1-yO₃The peak of thermal current of ferroelectric material is associated with CoFe₂O₄The increase in content increases the temperature of its thermal excitation peak. To further prove the addition of CoFe₂O₄The depolarization temperature of the ceramic sheet was increased, and the piezoelectric coefficient of the prepared ceramic was measured after the ceramic was thermally insulated at different temperatures for 30 minutes, as shown in fig. 4, in which CoFe was added as shown in fig. 4₂O₄The depolarization temperature of the ceramic sheet was increased, which confirmed that the temperature stability of the prepared ceramic sheet was greatly improved, and we found that CoFe was greatly improved₂O₄The content (e.g., y ═ 0.05) deteriorates the piezoelectric performance of the ceramic sheet.

Example 2:

na with the purity of 99.8 percent is adopted₂CO₃99.9% of Bi₂O₃99.8% of TiO₂98% of MnCO₃Is taken as a raw material and is expressed by a chemical formula Na_0.5Bi_0.5Mn_yTi_1-yO₃And (y is more than or equal to 0 and less than or equal to 0.05), weighing the stoichiometric ratios of Bi, Na, Ba, Ti and Mn respectively, putting the weighed materials into a ball milling tank, and carrying out ball milling and mixing, wherein the ball milling conditions are the volume of the raw materials: volume of agate ball: the volume ratio of the ball milling medium absolute ethyl alcohol is equal to 1: 1: 1.5, putting the raw materials subjected to ball milling for 12 hours into an oven to be dried for 4 hours at the temperature of 80 ℃. Then, tabletting the dried raw materials into raw material blanks with the diameter of 40mm under the pressure of 20Mpa by using a tablet press, putting the pressed raw material blanks into a KBF1400 box type furnace for presintering, preserving the heat for 2 hours under the presintering condition of 850 ℃, and synthesizing Na_0.5Bi_0.5Mn_yTi_1-yO₃A embryo body. Then pre-burning the block-shaped Na_0.5Bi_0.5Mn_yTi_1-yO₃Grinding the blank, grinding into powder, sieving, ball milling for 12 hr, oven drying at 80 deg.C for 4 hr to obtain Na_0.5Bi_0.5Mn_yTi_1-yO₃And (5) drying the powder. Finally, grinding the dried powder according to the proportion that 1mL of PVA adhesive (the mass concentration of polyvinyl alcohol is 3%) is added into every 10g of the dried powder, granulating, sieving for 3 times by using a 80-mesh sieve, pressing the granulated powder into small pieces with the diameter of 11mm under the pressure of 200MPa, and then preserving the temperature for 2 hours at 650 ℃ to decompose the PVA adhesive and Al₂O₃Laying mother powder on the gasket, covering the pressed small pieces with the mother powder, putting the small pieces into a box-type furnace for sintering under the condition of 1120 ℃ heat preservation for 2 hours, and finally obtaining the ceramic piece which is Na_0.5Bi_0.5Mn_yTi_1-yO₃A ferroelectric material.

And (3) grinding the sintered ceramic wafer, and performing related tests to obtain the optimal value of y which is more than or equal to 0.005 and less than or equal to 0.03.

Example 3:

na with the purity of 99.8 percent is adopted₂CO₃99.9% of Bi₂O₃99.8% of TiO₂99.5% of BaCO₃99.9 percent of NiO is used as raw material according to the chemical formula of Na_0.47Bi_0.47Ba_0.06Ni_yTi_1-yO₃And (y is more than or equal to 0 and less than or equal to 0.05), weighing the stoichiometric ratios of Bi, Na, Ba, Ti and Ni elements respectively, putting the weighed materials into a ball milling tank for mixing and ball milling, wherein the ball milling conditions are the volumes of the raw materials: volume of agate ball: the volume ratio of the ball milling medium absolute ethyl alcohol is equal to 1: 1: 1.5, putting the raw materials subjected to ball milling for 12 hours into an oven, and baking for 4 hours at 80 ℃. Then, tabletting the dried raw materials into raw material blanks with the diameter of 40mm under the pressure of 20Mpa by using a tabletting machine, putting the pressed raw material blanks into a KBF1400 box type furnace for presintering, preserving the heat for 2 hours under the presintering condition of 850 ℃, and synthesizing Na_0.47Bi_0.47Ba_0.06Ni_yTi_1-yO₃A embryo body. Then pre-burning the pre-sintered block Na_0.47Bi_0.47Ba_0.06Ni_yTi_1-yO₃Grinding the blank into powder, sieving, ball milling for 12 hr, oven drying at 80 deg.C for 4 hr to obtain Na_0.47Bi_0.47Ba_0.06Ni_yTi_1-yO₃And (5) drying the powder. Finally, grinding the dried powder according to the proportion that 1mL of PVA adhesive (the mass concentration of polyvinyl alcohol is 3%) is added into 10g of dried powder, granulating, sieving for 3 times by using a 80-mesh sieve, pressing the granulated powder with the weighed mass of 0.495-0.500 g into small pieces with the diameter of 11mm under 200MPa, and then preserving the heat at 650 ℃ for 2 hours to decompose the adhesive PVA in Al₂O₃Laying mother powder on the gasket, covering the pressed small pieces with the mother powder, putting the small pieces into a box-type furnace for sintering under the sintering condition of 1150 ℃ for 2 hours, and finally obtaining the ceramic piece which is Na_0.47Bi_0.47Ba_0.06Ni_yTi_1-yO₃A ferroelectric material.

The sintered ceramic plate is ground flat and relevant tests are carried out, and the result shows that the embodiment can improve (1-x) Na_0.5Bi_0.5TiO₃-xBaTiO₃The depolarization temperature of the ceramic material can be increased by 30 ℃ optimally.

Example 4:

na with the purity of 99.8 percent is adopted₂CO₃99.9% of Bi₂O₃99.8% of TiO₂99.5% of BaCO₃99.9% of MnCO₃Is taken as a raw material and is expressed by a chemical formula Na_0.465Bi_0.465Ba_0.07Mn_yTi_1-yO₃And (y is 0.04), weighing the stoichiometric ratios of Bi, Na, Ba, Ti and Mn respectively, putting the weighed materials into a ball milling tank for mixing and ball milling, wherein the ball milling conditions are the volumes of the raw materials: agate sphere volume: the volume ratio of the ball milling medium absolute ethyl alcohol is equal to 1: 1.2: 1, putting the raw materials subjected to ball milling for 2 hours into an oven to be dried for 4 hours at 80 ℃. Then, tabletting the dried raw materials into raw material blanks by a tablet machine under 5Mpa, putting the pressed raw material blanks into a KBF1400 box type furnace for presintering, and keeping the presintering condition at 750 ℃ for 3 hours to synthesize Na_0.465Bi_0.465Ba_0.07Mn_yTi_1-yO₃A embryo body. Then pre-burning the block-shaped Na_0.465Bi_0.465Ba_0.07Mn_yTi_1-yO₃Grinding the blank into powder, sieving, ball milling for 5 hr, oven drying at 80 deg.C for 4 hr to obtain Na_0.465Bi_0.465Ba_0.07Mn_yTi_1-yO₃And (5) drying the powder. Finally, grinding the dried powder according to the proportion that 2mL of PVA adhesive (the mass concentration of polyvinyl alcohol is 5%) is added into 10g of the dried powder, granulating, sieving for 3 times by a 40-mesh sieve, pressing the granulated powder with the weighed mass of 0.495-0.500 g into small pieces with the diameter of 11mm under 100MPa, and then preserving the heat for 3 hours at 600 ℃ to decompose the adhesive PVA in Al₂O₃Laying mother powder on the gasket, covering the pressed small pieces with the mother powder, sintering in a box furnace at 1050 ℃ for 4 hours to obtain the final ceramic piece Na_0.465Bi_0.465Ba_0.07Mn_yTi_1-yO₃A ferroelectric material.

Example 5:

na with the purity of 99.8 percent is adopted₂CO₃99.9% of Bi₂O₃99.8% of TiO₂99.5% of BaCO₃99.9% Fe₂O₃As a raw material, according to the chemical formula Na_0.49Bi_0.49Ba_0.02Fe_yTi_1-yO₃And (y is 0.03), weighing the stoichiometric ratios of Bi, Na, Ba, Ti and Fe, putting the weighed materials into a ball milling tank, and mixing and ball milling the materials under the ball milling conditions of the volume of the raw materials: agate sphere volume: the volume ratio of the ball milling medium absolute ethyl alcohol is equal to 1: 1.1: 1.3, putting the raw materials subjected to ball milling for 15 hours into an oven to be dried for 4 hours at the temperature of 80 ℃. Then, tabletting the dried raw materials into raw material blanks by a tabletting machine under the pressure of 80Mpa, putting the pressed raw material blanks into a KBF1400 box type furnace for presintering, preserving the heat for 1 hour under the presintering condition of 800 ℃, and synthesizing Na_0.49Bi_0.49Ba_0.02Fe_yTi_1-yO₃A embryo body. Then pre-burning the block-shaped Na_0.49Bi_0.49Ba_0.02Fe_yTi_1-yO₃Grinding the blank into powder, sieving, ball milling for 10 hr, oven drying at 80 deg.C for 4 hr to obtain Na_0.49Bi_0.49Ba_0.02Fe_yTi_1-yO₃And drying the powder. Finally, grinding the dried powder according to the proportion that 1.5mL of PVA adhesive (the mass concentration of polyvinyl alcohol is 4%) is added into every 10g of the dried powder, granulating, sieving for 3 times by using a 200-mesh sieve, pressing the granulated powder with the weighed mass of 0.495-0.500 g into small pieces with the diameter of 11mm under the pressure of 150MPa, and then preserving the heat at 700 ℃ for 2 hours to decompose the PVA adhesive and add the PVA into Al₂O₃Laying mother powder on the gasket, covering the pressed small pieces with the mother powder, sintering in a box-type furnace at 1200 ℃ for 2 hours to obtain the final ceramic plate Na_0.49Bi_0.49Ba_0.02Fe_yTi_1-yO₃A ferroelectric material.

Claims

1. A ferroelectric material based on metal cation doping is prepared from Na (1-x)_0.5Bi_0.5TiO₃-xBaTiO₃The ferroelectric material is prepared by doping metal cations, and is characterized in that the chemical formula of the ferroelectric material is as follows: na (Na)_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Wherein x is more than 0 and less than or equal to 0.07, y is more than or equal to 0.005 and less than or equal to 0.04, M is a metal cation with valence lower than +4, and Ti is replaced by the metal cation⁴⁺Further improving the depolarization temperature of the ferroelectric material;

the metal cation comprises Fe³⁺、Ni²⁺、Mn²⁺、Mn³⁺At least one of; or, the metal cation is Co²⁺、Fe³⁺；

The Na is_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃After polarization, the ferroelectric material has a depolarization temperature higher than that of (1-x) Na not doped with metal cations_0.5Bi_0.5TiO₃-xBaTiO₃The depolarization temperature of the material is higher than 20 ℃;

the preparation method of the ferroelectric material comprises the following steps:

by using Bi₂O₃，Na₂CO₃，BaCO₃，TiO₂The metal cation M is a raw material according to the chemical formula Na_0.5- _0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Weighing and proportioning the stoichiometric ratio of Bi, Na, Ba, Ti and M elements; then ball milling and mixing are carried out, the raw materials after 2-15 hours of ball milling are dried and tabletted, and the pressure of tabletting is 5-80 MPa; keeping the temperature of the pressed green blank at 750-850 ℃ for 1-3 hours to synthesize Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃A blank body;

will be described in detail

The obtained Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Grinding and ball-milling the blank for 5-12 hours, and drying after ball-milling to obtain Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Drying the powder;

will be described in detail

The obtained Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃Adding a polyvinyl alcohol aqueous solution into the dried powder to be used as a binder for granulation, and tabletting and molding the granulated powder under 100-200 MPa; after tabletting, the binder is decomposed by heat preservation for 0.5 to 3 hours at the temperature of 600 to 700 ℃; then preserving heat for 2-4 hours at 1050-1200 ℃, and finally obtaining the ceramic wafer Na_0.5-0.5xBi_0.5- _0.5xBa_xM_yTi_1-yO₃A ferroelectric material;

said step (c) is

Volume of raw materials in ball milling mixing: agate sphere volume: the volume ratio of the ball milling meson absolute ethyl alcohol is 1: 1-1.2: 1 to 1.5;

in the step III, the mass concentration of the polyvinyl alcohol is 3-5 percent, and each 10g of Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃The volume of polyvinyl alcohol dropped into the dried powder is 1-2 mL;

granulating the binder in the step III to obtain Na_0.5-0.5xBi_0.5-0.5xBa_xM_yTi_1-yO₃And fully mixing the dried powder and polyvinyl alcohol in a mortar, and then sieving by using a 40-200-mesh sieve.