CN109279890B

CN109279890B - Preparation method of magnetoelectric composite material

Info

Publication number: CN109279890B
Application number: CN201811110033.6A
Authority: CN
Inventors: 高洪伟; 俞胜平; 张丹阳
Original assignee: Goertek Optical Technology Co Ltd
Current assignee: Goertek Microelectronics Inc
Priority date: 2018-09-21
Filing date: 2018-09-21
Publication date: 2021-05-14
Anticipated expiration: 2038-09-21
Also published as: CN109279890A

Abstract

The invention discloses a preparation method of a magnetoelectric composite material. The preparation method comprises the following steps: the following piezoelectric ceramic raw materials are mixed according to parts by weight, are subjected to solid-phase reaction, and are prepared into first powder: fe₂O₃: 15-20 parts of Bi₂O₃: 52-58 parts of BaCO₃: 15-18 parts of TiO₂: 5-8 parts of ZnO: 0.2-0.7 part of MnO₂: 0.1-0.3 part; the following magnetic materials are mixed according to the parts by weight, and are subjected to solid-phase reaction to prepare second powder: fe₂O₃: 61-66 parts, NiO: 8-20 parts; CuO: 4.5-6.5 parts of ZnO: 4-20 parts of Bi₂O₃: 0.5-2 parts of Co₃O₄: 0.1-0.5 part; preparing a first slurry into a first membrane, preparing a second slurry into a second membrane, and pressing the first membrane and the second membrane together along the thickness direction to form a composite membrane; carrying out glue discharging treatment on the composite membrane; and sintering the composite membrane to form the magnetoelectric composite material.

Description

Preparation method of magnetoelectric composite material

Technical Field

The invention relates to the technical field of material preparation, in particular to a preparation method of a magnetoelectric composite material.

Background

With the demand of people for electronic products, electronic components are developing towards miniaturization, multifunction and high stability. The implementation of multiple functions in one element has become a new direction of development. Such elements are typically composite materials. For example, the material has capacitance, inductance dual property or composite dual property materials such as ferroelectric-ferromagnetic, piezoelectric-ferromagnetic, etc. The composite material is used for preparing a chip filter, an electromagnetic sensor, a piezoelectric sensor and the like.

However, the problem of mismatching of sintering shrinkage and densification rate exists between different dielectric layers, so that materials with different functions cannot be co-fired. Generally, materials with various functions are required to be prepared and molded respectively, and then materials with different functions are combined together, so that the preparation process of the composite material is complex, and the yield is low.

Therefore, a new technical solution is needed to solve the above technical problems.

Disclosure of Invention

An object of the present invention is to provide a new technical solution for a method for preparing a magnetoelectric composite material.

According to a first aspect of the present invention, a method for preparing a magnetoelectric composite material is provided. The preparation method comprises the following steps: the following piezoelectric ceramic raw materials are mixed according to parts by weight, are subjected to solid-phase reaction, and are prepared into first powder: fe₂O₃: 15-20 parts of Bi₂O₃: 52-58 parts of BaCO₃: 15-18 parts of TiO₂: 5-8 parts of ZnO: 0.2-0.7 part of MnO₂: 0.1-0.3 part; the following magnetic materials are mixed according to the parts by weight, and are subjected to solid-phase reaction to prepare second powder: fe₂O₃: 61-66 parts, NiO: 8-20 parts; CuO: 4.5-6.5 parts of ZnO: 4-20 parts of Bi₂O₃: 0.5-2 parts of Co₃O₄: 0.1-0.5 part; adding a liquid additive to prepare the first powder into first slurry, and preparing the second powder into second slurry; preparing a first slurry into a first membrane, preparing a second slurry into a second membrane, and pressing the first membrane and the second membrane together along the thickness direction to form a composite membrane, wherein two surfaces of the first membrane parallel to the extending direction are respectively provided with an electrode layer; carrying out glue discharging treatment on the composite membrane; and sintering the composite membrane to form the magnetoelectric composite material.

Alternatively, the temperature of the solid phase reaction in preparing the first powder is 880-930 ℃.

Alternatively, the temperature of the solid phase reaction in preparing the second powder is 880-920 ℃.

Optionally, preparing the first slurry into a first film belt by means of tape casting, and pressing a plurality of layers of the first film belt into the first membrane by means of isostatic pressing; and/or

Preparing the second slurry into a second film belt by adopting a tape casting mode, and pressing a plurality of layers of the second film belt into the second membrane by adopting an isostatic pressing mode.

Optionally, at least one of the first and second film strips has a thickness of 20-70 microns.

Optionally, the liquid additive comprises the following mixed together in parts by weight: PVB: 5-8 parts of a plasticizer: 2-3 parts of toluene: 30-35 parts of ethanol: 8-9 parts of isopropanol: 5-7 parts.

Optionally, the sintering temperature is 880-930 ℃, and the sintering time is 2-5 hours

Optionally, each of the first membrane sheet and the second membrane sheet is at least one, and the first membrane sheet and the second membrane sheet are arranged in a staggered manner.

Optionally, at least one of the first powder and the second powder has a particle size of 0.6 to 1.5 microns.

Optionally, in preparing at least one of the first powder and the second powder, the raw material is milled by ball milling before and after the solid-phase reaction, and the particle size of the powder obtained by ball milling after the solid-phase reaction is smaller than that of the powder obtained by ball milling before the solid-phase reaction.

According to one embodiment of the disclosure, the magnetoelectric composite material can realize low-temperature co-firing, is simple to process and manufacture, and has high yield.

Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is a flow diagram of a method of preparing a magnetoelectric composite material according to an embodiment of the present invention.

Fig. 2 is a schematic view of a magnetoelectric composite material structure according to an embodiment of the present invention.

Fig. 3 is a cross-sectional view of fig. 2.

Description of reference numerals:

11: a piezoelectric ceramic layer; 12: a magnetic material layer; 13: and an electrode layer.

Detailed Description

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

According to one embodiment of the present disclosure, a method of preparing a magnetoelectric composite material is provided. The preparation method comprises the following steps:

s1, mixing the following piezoelectric ceramic raw materials in parts by weight, carrying out solid-phase reaction, and preparing into first powder: fe₂O₃: 15-20 parts of Bi₂O₃: 52-58 parts of BaCO₃: 15-18 parts of TiO₂: 5-8 parts of ZnO: 0.2-0.7 part of MnO₂: 0.1 to 0.3 portion.

In this step, the various raw materials are powders or granules. Mixing the raw materials after proportioning. For example, the mixing is carried out by means of mechanical stirring, roller milling, planetary milling or the like to form a uniform mixed powder.

In one example, the mixing is performed using ball milling. Ball milling may be performed in a nylon ball mill tank. In order to make the obtained mixed powder finer and more uniform, absolute ethyl alcohol is added into a nylon ball milling tank. The time of ball milling can be set by those skilled in the art according to actual needs.

After the ball milling is finished, drying the mixed powder to remove absolute ethyl alcohol and the like; then the mixed powder is sieved. And carrying out solid-phase reaction on the sieved material.

In the solid phase reaction, various raw materials as reactants undergo chemical reactions at a phase interface to initially generate a perovskite structure. For example, the temperature of the solid phase reaction is 880-930 ℃ and the reaction time is 1-4 hours. Under the reaction conditions, the piezoelectric coefficient d33 of the formed piezoceramic material is 100-300.

After the solid-phase reaction, the mixed powder after the solid-phase reaction is finely ground. The purpose of the fine grinding is to obtain a first powder of suitable particle size. The granularity of the first powder is smaller than that of the powder formed in the mixing process.

For example, ball milling is used for fine milling. Adding the mixed powder after the solid phase reaction into a nylon spherical tank, and then adding absolute ethyl alcohol for ball milling. In the fine grinding process, the ball milling time is longer than the mixing time, so that powder with smaller granularity is obtained. And after the ball milling is finished, drying and sieving the powder again. The material to be sieved is first powder. For example, the first powder may have a particle size of 0.6 to 1.5. mu.m. The piezoelectric ceramic formed in the granularity range has compact surface and high structural strength.

S2, mixing the following raw materials of the magnetic material according to parts by weight, carrying out solid phase reaction, and preparing into second powder: fe₂O₃: 61-66 parts, NiO: 8-20 parts; CuO: 4.5-6.5 parts of ZnO: 4 to 20 portions of，Bi₂O₃: 0.5-2 parts of Co₃O₄: 0.1 to 0.5 portion.

In this step, the various raw materials are powders or granules. Mixing the raw materials after proportioning. For example, the various powders are mixed by mechanical stirring, roller milling, planetary milling, or the like to form a uniform mixed powder. For example, ball milling may be performed in a nylon ball mill tank. In order to make the obtained mixed powder finer and more uniform, absolute ethyl alcohol is added into a nylon ball milling tank. The time of ball milling can be set by those skilled in the art according to actual needs.

In solid phase reactions, various raw materials as reactants are chemically reacted at a phase interface. For example, the temperature of the solid phase reaction is 880-920 ℃ and the reaction time is 1-4 hours.

Similarly, in the preparation of the second powder, the raw materials are ground by ball milling both before and after the solid-phase reaction. And as mentioned before the solid phase reaction after the ball milling get the powder granularity smaller than before the solid phase reaction before the ball milling get the powder granularity, this makes subsequent sintering speed faster, sintering effect is better.

For example, the particle size of the second powder is 0.6 to 1.5. mu.m. The magnetic material formed in the particle size range has a compact surface and high structural strength.

It will be understood by those skilled in the art that the steps S1 and S2 are not sequential, and may be performed simultaneously or first in either step.

And S3, adding a liquid additive to prepare the first powder into first slurry, and preparing the second powder into second slurry.

The liquid additive is combined with the first powder and the second powder, respectively, to prepare first slurry and second slurry in a viscous state. The first slurry and the second slurry have set consistencies, so that the first slurry and the second slurry can be prepared into set shapes according to actual needs.

In one example, the liquid additive includes the following mixed together: PVB (polyvinyl butyral): 5-8 parts of a plasticizer: 2-3 parts of toluene: 30-35 parts of ethanol: 8-9 parts of isopropanol: 5-7 parts. The liquid additive can be rapidly combined with the first powder and the second powder to form the first slurry and the second slurry, and the shape retention of the first slurry and the second slurry is good.

And S4, preparing the first slurry into a first membrane sheet, preparing the second slurry into a second membrane sheet, and pressing the first membrane sheet and the second membrane sheet together along the thickness direction to form the composite membrane sheet. Wherein both surfaces of the first membrane parallel to the extension direction are provided with an electrode layer 13, respectively. The direction of extension refers to the direction of extension of the surface on which the long and wide sides of the membrane lie.

In this step, the first diaphragm and the second diaphragm may be of unitary construction; alternatively, the laminated structure may be a multilayer structure formed by laminating a plurality of layers of materials.

In one example, the composite membrane is a multi-layer structure having first and second membranes interleaved. For example, the composite diaphragm includes a first diaphragm and a second diaphragm; or

The diaphragm comprises a first diaphragm and two second diaphragms, wherein the first diaphragm is positioned between the two second diaphragms; or

The diaphragm comprises a second diaphragm and two first diaphragms, wherein the second diaphragm is positioned between the two first diaphragms; or

The composite diaphragm includes a plurality of first diaphragms and a plurality of second diaphragms. The plurality of first membrane sheets and the plurality of second membrane sheets are alternately arranged in a staggered mode.

The thickness, the number of layers and the like of the first membrane and the second membrane can be set by those skilled in the art according to actual needs.

The electrode layer 13 may be formed by silver or silver firing. For example, in this step, silver coating is performed on both surfaces. The electrode layer 13 is then formed by firing silver in a sintering process.

And S5, performing glue discharging treatment on the composite membrane.

The purpose of the binder removal is to remove high molecular compounds, such as liquid additives, from the composite membrane to avoid adversely affecting sintering. The high molecular compound contains a large amount of carbon, and when oxygen is insufficient, carbon monoxide having a strong reducibility is produced by combustion. Carbon monoxide is capable of reducing the oxides in the feedstock to metals or suboxides. The metal or suboxide affects the color, ceramic forming, platability and polarization of the ceramic.

And S6, sintering the composite membrane to form the magnetoelectric composite material. Sintering refers to the process of heating the composite membrane to a set temperature and preserving heat so as to change the powder into a compact body.

In the embodiment of the present disclosure, since the sintering temperatures of the raw materials of the piezoelectric ceramic and the magnetic material are close and the sintering temperature is low, co-firing of the two can be achieved. In the co-firing process, the first membrane and the second membrane can be well combined together due to the similar shrinkage rates and the matching densification speeds to form the magnetoelectric composite material. As shown in fig. 2 to 3, the first film sheet forms a piezoelectric ceramic layer 11 after co-firing, and the second film sheet forms a magnetic material layer 12 after co-firing. The magnetoelectric composite material has the performances of both piezoelectric ceramics and magnetic materials.

The magnetoelectric composite material has lower co-firing temperature, for example, the sintering temperature is 880-930 ℃, the sintering time is 2-5 hours, and the production difficulty is reduced.

In addition, the piezoelectric ceramic material is a lead-free piezoelectric ceramic material and has good environmental protection performance.

In one example, the piezoelectric ceramic layer 11 is polarized by two electrode layers 13 so that it obtains piezoelectric performance. For example, the piezoelectric ceramic layer 11 is polarized at a set polarization voltage.

For example, the polarization is performed under an inert gas atmosphere. The polarization temperature is 70-150 ℃, and the polarization voltage is 3-5 kV/mm.

In other examples, the piezoelectric ceramic layer 11 is directly polarized in the atmospheric environment, and the piezoelectric ceramic layer 11 can also have piezoelectric properties.

In one example, the first slurry is prepared into a first film tape by tape casting. And pressing the multiple layers of the first films into the first film sheet in an isostatic pressing mode. And/or

Preparing the second slurry into a second film belt by adopting a tape casting mode. And pressing the multiple layers of second films into a second film sheet in an isostatic pressing mode.

In this example, the first film strip and the second film strip may be cut into a set shape according to actual needs. For example, a long strip, a square, etc., of a set size.

The thickness of the film belt formed by the tape casting mode is uniform. In one example, at least one of the first and second film strips has a thickness of 20-70 microns. The thickness range can meet the use requirements of membranes with different thicknesses.

Isostatic pressing is a pressure processing method in which a plurality of film layers are placed in a closed container filled with liquid, and pressure is gradually applied by a pressurizing system to apply equal pressure to the surfaces of the film layers, so that the distance between molecules is reduced and the density is increased without changing the appearance and shape of the film layers, thereby improving the physical properties of the film layers.

In the example, the pressure is 30-60MPa, the pressing time is 5-15 minutes, and the processing temperature is 20-70 ℃ in the isostatic pressing process. Under the processing condition, the formed first membrane and the second membrane have good compactness, and the subsequent sintering is facilitated.

Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for preparing a magnetoelectric composite material, comprising:

the following piezoelectric ceramic raw materials are mixed according to parts by weight, are subjected to solid-phase reaction, and are prepared into first powder: fe₂O₃: 15-20 parts of Bi₂O₃: 52-58 parts of BaCO₃: 15-18 parts of TiO₂: 5-8 parts of ZnO: 0.2-0.7 part of MnO₂: 0.1-0.3 part;

the following magnetic materials are mixed according to the parts by weight, and are subjected to solid-phase reaction to prepare second powder: fe₂O₃: 61-66 parts, NiO: 8-20 parts; CuO: 4.5-6.5 parts of ZnO: 4-20 parts of Bi₂O₃: 0.5-2 parts of Co₃O₄: 0.1-0.5 part;

adding a liquid additive to prepare the first powder into first slurry, and preparing the second powder into second slurry;

preparing a first slurry into a first membrane, preparing a second slurry into a second membrane, and pressing the first membrane and the second membrane together along the thickness direction to form a composite membrane, wherein two surfaces of the first membrane parallel to the extending direction are respectively provided with an electrode layer;

carrying out glue discharging treatment on the composite membrane;

and sintering the composite membrane to form the magnetoelectric composite material.

2. The preparation method according to claim 1, wherein the temperature of the solid phase reaction at the time of preparing the first powder is 880-930 ℃.

3. The preparation method according to claim 1, wherein the temperature of the solid phase reaction at the time of preparing the second powder is 880-920 ℃.

4. The production method according to claim 1, wherein the first slurry is produced into a first film tape by tape casting, and a plurality of the first film tapes are laminated into the first film sheet by isostatic pressing; and/or

5. The production method according to claim 4, wherein at least one of the first film tape and the second film tape has a thickness of 20 to 70 μm.

6. The method of claim 1, wherein the liquid additive comprises the following mixed together in parts by weight: PVB: 5-8 parts of a plasticizer: 2-3 parts of toluene: 30-35 parts of ethanol: 8-9 parts of isopropanol: 5-7 parts.

7. The method as claimed in claim 1, wherein the sintering temperature is 880-930 ℃ and the sintering time is 2-5 hours.

8. The production method according to claim 1, wherein each of the first membrane sheet and the second membrane sheet is at least one, and the first membrane sheet and the second membrane sheet are alternately arranged.

9. The method according to claim 1, wherein at least one of the first powder and the second powder has a particle size of 0.6 to 1.5 μm.

10. The production method according to claim 1, wherein in the production of at least one of the first powder and the second powder, the raw material is ground by ball milling both before and after the solid-phase reaction, and the particle size of the powder obtained by ball milling after the solid-phase reaction is smaller than the particle size of the powder obtained by ball milling before the solid-phase reaction.