CN109111222B

CN109111222B - Co-doped multiferroic ceramic with Olivies structure and preparation method thereof

Info

Publication number: CN109111222B
Application number: CN201811156346.5A
Authority: CN
Inventors: 蒲永平; 师裕; 张倩雯; 王雯; 李经纬; 彭鑫; 张磊
Original assignee: Shaanxi University of Science and Technology
Current assignee: Shaanxi University of Science and Technology
Priority date: 2018-09-30
Filing date: 2018-09-30
Publication date: 2022-03-01
Anticipated expiration: 2038-09-30
Also published as: CN109111222A

Abstract

The present invention providesNovel Co-doped SrBi₂Nb_1.8Fe_0.2O_8.8Multiferroic ceramic materials. The invention also provides a preparation method of the ceramic material, which comprises the following steps: respectively adopt SrCO₃、Bi₂O₃、Nb₂O₅、Fe₂O₃And Co₂O₃Preparing raw materials; ball milling the powder at 750-^oPre-burning for 3-5 hours, sieving and molding, and finally sintering at 995-1080 ℃ for 2-4 hours to obtain single-phase SrBi with an Olympus structure₂Nb_1.8‑ _xFe_0.2Co_xO_8.8‑xMultiferroic ceramic materials. The single-phase multiferroic Oriviris compound ceramic material prepared by the invention has the advantages of simple preparation process, cheap raw materials and low production cost. After doping by Co ions, the material is transformed from a weak antiferromagnetic at room temperature to a material that is ferromagnetic due to the introduction of more double exchange interactions.

Description

Co-doped multiferroic ceramic with Olivies structure and preparation method thereof

Technical Field

The invention belongs to the technical field of multiferroic ceramic materials, and relates to a novel Co-doped SrBi₂Nb_1.8Fe_0.2O_8.8Multiferroic ceramic materials having an Olivies structure and methods for making the same.

Background

In recent years, along with the rapid rise and rapid development of the electronic information industry, higher requirements on integration and multi-functionalization of devices are put forward; meanwhile, due to the explosive growth of data information, information storage media with high speed and large capacity are becoming hot areas for research and exploration in the industry. The multiferroic material is a multifunctional material that can be applied to the field of high-density storage, and generally has two or more properties of ferroelectricity, ferromagnetism, ferroelasticity and the like, and can realize mutual coupling and mutual regulation between a ferroelectric sequence and a ferromagnetic sequence or a ferroelastic sequence. Multiferroic materials contribute to miniaturization and multifunctionalization of sensors and magnetic memory devices, and offer the possibility of developing new multifunctional devices, thus becoming one of the key fields of materials science research.

SrBi₂Nb₂O₉The ceramic material is one representative of Oliviz compounds, and has Curie temperature of 440^oC is about, the material has higher resistivity and smaller loss, has excellent anti-fatigue property and temperature stability, the dielectric constant at the Curie temperature can reach 1432, and the piezoelectric coefficient is 16 pC/N. In the orivelis compound, the difficulty of pure phase synthesis of the material is increased along with the increase of the number of layers, and the SrBi with the number of layers being 2₂Nb₂O₉The ceramic pure phase material can be synthesized easily and has high repeatability, and the characteristic also provides a foundation for future application and mass production.

In previous work, we have found that Fe will be present³⁺Introduction of SrBi₂Nb₂O₉In ceramics, Ti is substituted⁴⁺The position (2) is such that the material is transformed from a purely ferroelectric material to a multiferroic material. However, such doping also brings disadvantages, such as limited solid solubility, excessive doping can produce a hetero-phase, and single transition metal doping is not significant in improving magnetic properties. So we pass through Co³⁺The introduction of (a) allows a plurality of double exchange interactions to occur in the material, thereby allowing the material to exhibit ferromagnetic properties, which also provides the possibility for further applications of the material.

Disclosure of Invention

The invention aims to provide a novel Co-doped SrBi₂Nb_1.8Fe_0.2O_8.8Multiferroic ceramic material with Olivies structure and preparation method thereof, and the multiferroic ceramic material has excellent ferroelectric property and weak antiferromagnetismSrBi₂Nb_1.8Fe_0.2O_8.8In the material, the material is converted from weak antiferromagnetic property to ferromagnetic property at room temperature by doping transition metal Co ions.

In order to achieve the above mentioned performance, the invention adopts the following technical scheme:

novel Co-doped SrBi₂Nb_1.8Fe_0.2O_8.8A multiferroic ceramic material having an orivivis structure, the single-phase multiferroic material having the formula: SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xWherein x is the doping amount of Co ions, x is more than or equal to 0 and less than or equal to 0.4, and x represents the mole percentage.

Novel Co-doped SrBi₂Nb_1.8Fe_0.2O_8.8The preparation method of the multiferroic ceramic material with an Olivies structure comprises the following steps:

(1) SrBi according to chemical equation₂Nb_1.8-xFe_0.2Co_xO_8.8-xMixing SrCO₃、Bi₂O₃、Nb₂O₅、Fe₂O₃And Co₂O₃After preparation, ball milling and mixing are carried out uniformly, and then drying, sieving and presintering are carried out to obtain a massive solid;

(2) SrBi according to chemical equation₂Nb_1.8-xFe_0.2Co_xO_8.8-xMixing SrCO₃、Bi₂O₃、Nb₂O₅、Fe₂O₃And Co₂O₃After preparation, ball milling and mixing are carried out uniformly, and then drying, sieving and presintering are carried out to obtain a massive solid;

(3) the obtained SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xWeighing 0.4g of powder by mass, pouring the powder into a mold, applying a force in the vertical direction of 500-700N, and demolding the molded wafer to obtain a sample with a perfect shape.

(4) And placing the wafer in the rubber sleeve, discharging air in the rubber sleeve by using a vacuumizing device, sealing a rubber sleeve opening, and placing the rubber sleeve into a cold isostatic pressing mold.

(5) Taking the obtained sample out of the rubber sleeve, sintering the sample in a box type furnace to form porcelain, and obtaining SrBi with an Oliviss structure₂Nb_1.8-xFe_0.2Co_xO_8.8-xMultiferroic ceramic material samples.

(6) Polishing and cleaning the pattern sintered in the step (5), uniformly coating silver electrode slurry on the front and back surfaces of the pattern, and performing heat treatment to obtain SrBi with an Olympus structure₂Nb_1.8-xFe_0.2Co_xO_8.8-xMultiferroic ceramic materials.

The ball milling time in the step (1) and the step (2) is 5-7 hours.

And (3) mixing the mixed oxide, the zircon and the deionized water in the step (1) and the step (2), ball-milling and drying to form a dry material.

The pre-sintering conditions in the step (1) are as follows: heating to 750 deg.C and 850 deg.C at 5 deg.C/min, maintaining for 3-5 hr, cooling to 500 deg.C at 5 deg.C/min, and cooling to room temperature.

In the step (2), the block is crushed and then sieved by a 200-300-mesh sieve to obtain powder with uniform size.

In the step (4), the cold isostatic pressing is performed by applying a pressure of 200-250MPa in a press, and the pressure holding time is 180-300 s.

The sintering conditions in the step (5) are as follows: raising the temperature to 995-1080 ℃ at the speed of 5 ℃/min, preserving the heat for 2-4 hours, then reducing the temperature to 500 ℃ at the speed of 5 ℃/min, and cooling to room temperature along with the furnace.

The temperature of the heat treatment in the step (6) is 800-850 ℃, and the heat preservation time is 15-20 min.

Compared with the prior art, the invention has the following beneficial effects: the invention introduces Co ions into the multiferroic material SrBi₂Nb_1.8Fe_0.2O_8.8In place of the Nb ions, different double exchange interactions with the Fe ions in the material occur, further enhancing the magnetic properties of the material. Introduction by double exchange interactionIn addition, the material can generate considerable ferromagnetic performance under the condition of low doping concentration. Compared with the prior art, the material prepared by the invention has obvious room temperature ferromagnetic characteristic, and in the preparation process of the sample, a more advanced cold isostatic pressing technology is adopted, so that the waste of the sample and the addition of the binder are avoided, the manufacturing cost is saved, the production period is accelerated, and the possibility of sample pollution caused by the binder is avoided. The material prepared by the invention has good compactness, no obvious air holes and uniform grain size, and also provides a foundation for excellent performance of the material.

Drawings

FIG. 1 shows SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xXRD pattern of ceramic material powder;

FIG. 2 shows SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xSEM photo of polishing hot corrosion of ceramic material;

FIG. 3 shows SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xHysteresis loop of ceramic material:

FIG. 4 shows SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xHysteresis loops of ceramic material.

Detailed Description

The present invention will be described in detail below with reference to the drawings and examples, but the present invention is not limited to the following examples.

Co-doped SrBi is prepared in the invention₂Nb_1.8Fe_0.2O_8.8A ferrous ceramic material.

Example one

The chemical formula of the single-phase multiferroic ceramic material is as follows: SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xWherein x represents a mole percentage and x =0.

The Co-doped SrBi₂Nb_1.8Fe_0.2O_8.8The preparation method of the iron ceramic material comprises the following steps:

(1) SrBi according to chemical equation₂Nb_1.8Fe_0.2O_8.8SrCO₃、Bi₂O₃、Nb₂O₅、Fe₂O₃And Co₂O₃After preparation, the raw materials are ball-milled and mixed evenly, and then are dried, sieved and processed by 800^oC, pre-burning for 4 hours to obtain a blocky solid;

(2) crushing the blocky solid, ball-milling again, and sieving the product to obtain SrBi with uniform size₂Nb_1.8Fe_0.2O_8.8A body;

(3) the obtained SrBi₂Nb_1.8Fe_0.2O_8.8Weighing 0.4g of the mass of each part, pouring the weighed parts into a mold, applying 600N force, and demolding the molded wafer to obtain a sample with a perfect shape;

(4) and placing the wafer in the rubber sleeve, discharging air in the rubber sleeve by using a vacuumizing device, sealing the rubber sleeve opening, placing the rubber sleeve opening into a cold isostatic pressing mold, and maintaining the pressure at 200Mpa for 300 s. (ii) a

(5) Taking the obtained sample out of the rubber sleeve, sintering the sample in a box type furnace at 1080 ℃ for 2 hours to form porcelain, and obtaining SrBi₂Nb_1.8Fe_0.2O_8.8A ferrous ceramic material;

(6) polishing and cleaning the pattern sintered once in the step (5), uniformly coating silver electrode slurry on the front and back surfaces of the pattern, and carrying out heat treatment at 850 ℃ for 15min to obtain SrBi₂Nb_1.8Fe_0.2O_8.8Samples of ferrous ceramic materials.

Referring to fig. 1, the x =0 curve in fig. 1 is the XRD curve of the sample prepared in this example, and it can be seen from fig. 1 that a single-phase multiferroic SrBi having an orivivis structure in a pure phase is synthesized₂Nb_1.8Fe_0.2O_8.8A ceramic material.

Referring to fig. 2, the x =0 curve in fig. 2 is an SEM photograph of the sample prepared in this example, and from fig. 2, it can be seen that the single-phase multiferroic material ceramic material SrBi₂Nb_1.8Fe_0.2O_8.8The ceramic particles take the shape of elliptical platelets.

Referring to fig. 3, the curve x =0 in fig. 3 is the hysteresis loop of the sample prepared in this example, and the maximum polarization P_m=0.6348μC/cm²Residual polarization P_r=0.0159μC/cm²Coercive field strength E_c=0.2995kV/cm。

Referring to fig. 4, the curve x =0 in fig. 4 represents the hysteresis loop of the sample prepared in this example, and the remanent magnetization Mr =5.4736 × 10^-7emu/g。

Example two

The chemical formula of the single-phase multiferroic ceramic material is as follows: SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xWherein x represents a mole percentage and x = 0.1.

(1) SrBi according to chemical equation₂Nb_1.7Fe_0.2Co_0.1O_8.7SrCO₃、Bi₂O₃、Nb₂O₅、Fe₂O₃And Co₂O₃After preparation, the raw materials are ball-milled and mixed evenly, and then are dried, sieved and processed by 800^oC, pre-burning for 4 hours to obtain a blocky solid;

(2) crushing the blocky solid, ball-milling again, and sieving the product to obtain SrBi with uniform size₂Nb_1.7Fe_0.2Co_0.1O_8.7A body;

(3) the obtained SrBi₂Nb_1.7Fe_0.2Co_0.1O_8.7Weighing 0.4g of the mass of each part, pouring the weighed parts into a mold, applying 600N force, and demolding the molded wafer to obtain a sample with a perfect shape;

(5) Taking the obtained sample out of the rubber sleeve and placing the sample in a boxSintering the mixture for 2 hours in a furnace at 1060 ℃ to obtain SrBi₂Nb_1.7Fe_0.2Co_0.1O_8.7A ferrous ceramic material;

(6) polishing and cleaning the pattern sintered once in the step (5), uniformly coating silver electrode slurry on the front and back surfaces of the pattern, and carrying out heat treatment at 850 ℃ for 15min to obtain SrBi₂Nb_1.7Fe_0.2Co_0.1O_8.7Samples of ferrous ceramic materials.

Referring to fig. 1, the x =0.1 curve in fig. 1 is the XRD curve of the sample prepared in this example, and it can be seen from fig. 1 that the single-phase multiferroic SrBi having an orivivis structure in a pure phase is synthesized₂Nb_1.7Fe_0.2Co_0.1O_8.7A ceramic material.

Referring to fig. 2, the x =0.1 curve in fig. 2 is an SEM photograph of the sample prepared in this example, and from fig. 2, it can be seen that the single-phase multiferroic ceramic material SrBi₂Nb_1.7Fe_0.2Co_0.1O_8.7The ceramic particles take the shape of elliptical platelets.

Referring to fig. 3, the curve x =0.1 in fig. 3 is the hysteresis loop of the sample prepared in this example, and the maximum polarization P_m=0.6513μC/cm²Residual polarization P_r=0.0343μC/cm²Coercive field strength E_c=0.9446kV/cm。

Referring to fig. 4, the curve x =0.1 in fig. 4 is a hysteresis loop of the sample prepared in this example, and the residual magnetization Mr =0.09163 emu/g.

EXAMPLE III

The chemical formula of the single-phase multiferroic ceramic material is as follows: SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xWherein x represents a mole percentage and x = 0.2.

The Co-doped SrBi₂Nb_1.6Fe_0.2O_8.8The preparation method of the ceramic material comprises the following steps:

(1) SrBi according to chemical equation₂Nb_1.6Fe_0.2Co_0.2O_8.6SrCO₃、Bi₂O₃、Nb₂O₅、Fe₂O₃And Co₂O₃After preparation, the raw materials are ball-milled and mixed evenly, and then are dried, sieved and processed by 800^oC, pre-burning for 4 hours to obtain a blocky solid;

(2) crushing the blocky solid, ball-milling again, and sieving the product to obtain SrBi with uniform size₂Nb_1.6Fe_0.2Co_0.2O_8.6A body;

(3) the obtained SrBi₂Nb_1.6Fe_0.2Co_0.2O_8.6Weighing 0.4g of the mass of each part, pouring the weighed parts into a mold, applying 600N force, and demolding the molded wafer to obtain a sample with a perfect shape;

(5) Taking the obtained sample out of the rubber sleeve, sintering the sample in a box type furnace at 1040 ℃ for 2 hours to form porcelain, and obtaining SrBi₂Nb_1.6Fe_0.2Co_0.2O_8.6A ferrous ceramic material;

(6) polishing and cleaning the pattern sintered once in the step (5), uniformly coating silver electrode slurry on the front and back surfaces of the pattern, and carrying out heat treatment at 850 ℃ for 15min to obtain SrBi₂Nb_1.6Fe_0.2Co_0.2O_8.6Samples of ferrous ceramic materials.

Referring to fig. 1, the x =0.2 curve in fig. 1 is the XRD curve of the sample prepared in this example, and it can be seen from fig. 1 that the single-phase multiferroic SrBi having an orivivis structure in a pure phase is synthesized₂Nb_1.6Fe_0.2Co_0.2O_8.6A ceramic material.

Referring to fig. 2, the x =0.2 curve in fig. 2 is an SEM photograph of the sample prepared in this example, and from fig. 2, it can be seen that the single-phase multiferroic ceramic material SrBi₂Nb_1.6Fe_0.2Co_0.2O_8.6The ceramic particles take the shape of elliptical platelets.

Referring to fig. 3, the curve x =0.2 in fig. 3 is the true pointEXAMPLES preparation of the samples the hysteresis loop, maximum polarization P_m=0.7023μC/cm²Residual polarization P_r=0.0673μC/cm²Coercive field strength E_c=1.7566kV/cm。

Referring to fig. 4, the curve x =0.2 in fig. 4 is a hysteresis loop of the sample prepared in this example, and the residual magnetization Mr =0.0909 emu/g.

Example four

The chemical formula of the single-phase multiferroic ceramic material is as follows: SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xWherein x represents a mole percentage and x = 0.3.

(1) SrBi according to chemical equation₂Nb_1.5Fe_0.2Co_0.3O_8.5Mixing SrCO₃、Bi₂O₃、Nb₂O₅、Fe₂O₃And Co₂O₃After preparation, the raw materials are ball-milled and mixed evenly, and then are dried, sieved and processed by 800^oC, pre-burning for 4 hours to obtain a blocky solid;

(2) crushing the blocky solid, ball-milling again, and sieving the product to obtain SrBi with uniform size₂Nb_1.5Fe_0.2Co_0.3O_8.5Powder;

(3) the obtained SrBi₂Nb_1.5Fe_0.2Co_0.3O_8.5Weighing 0.4g of powder per part by mass, pouring the powder into a mould, applying a force of 600N, and demoulding the formed wafer to obtain a sample with a perfect shape;

(5) Taking the obtained sample out of the rubber sleeve, sintering the sample in a box furnace at 1020 ℃ for 2 hours to form porcelain, and obtaining SrBi₂Nb_1.5Fe_0.2Co_0.3O_8.5A multiferroic ceramic material;

(6) polishing and cleaning the pattern sintered once in the step (5), uniformly coating silver electrode slurry on the front and back surfaces of the pattern, and carrying out heat treatment at 850 ℃ for 15min to obtain SrBi₂Nb_1.5Fe_0.2Co_0.3O_8.5Multiferroic ceramic material samples.

Referring to fig. 1, the x =0.3 curve in fig. 1 is the XRD curve of the sample prepared in this example, and it can be seen from fig. 1 that the single-phase multiferroic SrBi having an orivivis structure in a pure phase is synthesized₂Nb_1.5Fe_0.2Co_0.3O_8.5A ceramic material.

Referring to fig. 2, the x =0.3 curve in fig. 2 is an SEM photograph of the sample prepared in this example, and from fig. 2, it can be seen that the single-phase multiferroic ceramic material SrBi₂Nb_1.5Fe_0.2Co_0.3O_8.5The ceramic particles are in a mixed shape of an elliptical plate and a sphere.

Referring to fig. 3, the curve x =0.3 in fig. 3 is the hysteresis loop of the sample prepared in this example, and the maximum polarization P_m=0.7861μC/cm²Residual polarization P_r=0.1176μC/cm²Coercive field strength E_c=3.0518kV/cm。

Referring to fig. 4, the curve x =0.3 in fig. 4 is a hysteresis loop of the sample prepared in this example, and the residual magnetization Mr =0.02473 emu/g.

EXAMPLE five

The chemical formula of the single-phase multiferroic ceramic material is as follows: SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xWherein x represents a mole percentage and x = 0.4.

The Co-doped SrBi₂Nb_1.8Fe_0.2O_8.8The preparation method of the multiferroic ceramic material comprises the following steps:

(1) SrBi according to chemical equation₂Nb_1.4Fe_0.2Co_0.4O_8.4Mixing SrCO₃、Bi₂O₃、Nb₂O₅、Fe₂O₃And Co₂O₃After preparation, the raw materials are ball-milled and mixed evenly, and then are dried, sieved and processed by 800^oC, pre-burning for 4 hours to obtain a blocky solid;

(2) crushing the blocky solid, ball-milling again, and sieving the product to obtain SrBi with uniform size₂Nb_1.4Fe_0.2Co_0.4O_8.4Powder;

(3) the obtained SrBi₂Nb_1.4Fe_0.2Co_0.4O_8.4Weighing 0.4g of powder per part by mass, pouring the powder into a mould, applying a force of 600N, and demoulding the formed wafer to obtain a sample with a perfect shape;

(5) Taking the obtained sample out of the rubber sleeve, sintering the sample in a box type furnace at 995 ℃ for 2 hours to form porcelain, and obtaining SrBi₂Nb_1.4Fe_0.2Co_0.4O_8.4A multiferroic ceramic material;

(6) polishing and cleaning the pattern sintered once in the step (5), uniformly coating silver electrode slurry on the front and back surfaces of the pattern, and carrying out heat treatment at 850 ℃ for 15min to obtain SrBi₂Nb_1.4Fe_0.2Co_0.4O_8.4Multiferroic ceramic material samples.

Referring to fig. 1, the x =0.4 curve in fig. 1 is the XRD curve of the sample prepared in this example, and it can be seen from fig. 1 that the single-phase multiferroic SrBi having an orivivis structure in a pure phase is synthesized₂Nb_1.4Fe_0.2Co_0.4O_8.4A ceramic material.

Referring to fig. 2, the x =0.4 curve in fig. 2 is an SEM photograph of the sample prepared in this example, and from fig. 2, it can be seen that the single-phase multiferroic ceramic material SrBi₂Nb_1.4Fe_0.2Co_0.4O_8.4The ceramic particles are spherical.

Referring to FIG. 3, the curve x =0.4 in FIG. 3 is for the sample prepared in this exampleHysteresis loop, maximum polarization P_m=1.1109μC/cm²Residual polarization P_r=1.40914μC/cm²Coercive field strength E_c=19.0105kV/cm。

Referring to fig. 4, the curve x =0.4 in fig. 4 represents the hysteresis loop of the sample prepared in this example, and the residual magnetization Mr =3.3 × 10^-4emu/g。

Claims

1. A Co-doped multiferroic ceramic with an Olivies structure, characterized in that the chemical formula is SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xWherein x is the doping amount of Co ions, 0<x≤0.4。

2. The method of preparing a Co-doped multiferroic ceramic having an Olivies structure according to claim 1, comprising the steps of:

SrBi according to chemical equation₂Nb_1.8-xFe_0.2Co_xO_8.8-xMixing SrCO₃、Bi₂O₃、Nb₂O₅、Fe₂O₃And Co₂O₃After preparation, the powder is ball milled, presintered, screened and formed, and the formed ceramic blank is sintered at the temperature of 995-₂Nb_1.8Fe_0.2O_8.8Multiferroic ceramic materials having an Olivies structure.

3. The method for preparing the Co-doped multiferroic ceramic with an Olivies structure according to claim 2, comprising the following specific steps:

1) SrBi according to chemical equation₂Nb_1.8-xFe_0.2Co_xO_8.8-xMixing SrCO₃、Bi₂O₃、Nb₂O₅、Fe₂O₃And Co₂O₃After preparation, ball milling and mixing are carried out uniformly, and then drying, sieving and presintering are carried out to obtain a massive solid;

2) crushing the blocky solid, ball-milling again, drying and sieving to obtain SrBi with uniform size₂Nb_1.8- _xFe_0.2Co_xO_8.8-xPowder;

3) the obtained SrBi₂Nb_1.8-xFe_0.2Co_xO_8.8-xPouring the powder into a die for compression molding, and demolding the molded blank to obtain a blank with a complete shape;

4) carrying out cold isostatic pressing on the blank prepared in the step 3);

5) sintering the blank obtained in the step 4) into porcelain to obtain Co-doped SrBi₂Nb_1.8Fe_0.2O_8.8Multiferroic ceramic materials having an Olivies structure.

4. The method for preparing a multiferroic Co-doped ceramics with an Olympus structure according to claim 3, wherein the mixed oxides obtained in the steps 1) and 2) are mixed with zircon and deionized water, ball-milled and dried to form a dry material, and the ball-milling time is 5-7 hours.

5. The method for preparing a multiferroic Co-doped ceramics with an Olympus structure according to claim 3, wherein the pre-sintering conditions in step 1) are as follows: heating to 750-850 ℃ at the speed of 5 ℃/min, preserving heat for 3-5 hours, then cooling to 500 ℃ at the speed of 5 ℃/min, and furnace-cooling to room temperature.

6. The method as claimed in claim 3, wherein the step 4) of cold isostatic pressing is performed by applying a pressure of 200-250MPa in a press and a dwell time of 180-300 s.

7. The method for preparing a multiferroic ceramic having an Olivies structure doped with Co according to claim 3, wherein the sintering conditions in the step 5) are as follows: raising the temperature to 995-1080 ℃ at the speed of 5 ℃/min, preserving the heat for 2-4 hours, then reducing the temperature to 500 ℃ at the speed of 5 ℃/min, and cooling to room temperature along with the furnace.

8. A method of surface treating a Co-doped multiferroic ceramic having an orivitis structure according to claim 1, comprising the steps of: polishing and cleaning Co-doped SrBi₂Nb_1.8Fe_0.2O_8.8The multiferroic ceramic material with an Olivies structure is prepared by uniformly coating silver electrode slurry on the front and back surfaces of ceramic, and performing heat treatment to obtain Co-doped SrBi₂Nb_1.8Fe_0.2O_8.8Multiferroic ceramic material test specimens with an oriville structure.

9. The method as claimed in claim 8, wherein the heat treatment temperature is 800-850 ℃ and the holding time is 15-20 min.

10. A Co-doped multiferroic ceramic having an orivitis structure prepared according to any of claims 8 or 9.