阅读说明：本技术 铁电陶瓷材料、压电传感器及制备方法 (Ferroelectric ceramic material, piezoelectric sensor and preparation method ) 是由 高景晖 刘泳斌 吴明 钟力生 于 2020-06-19 设计创作，主要内容包括：公开了一种铁电陶瓷材料、压电传感器及制备方法,铁电陶瓷材料具有多层级铁电畴结构,制备方法包括,将称取的原料混合后放入球磨罐中球磨形成混合料,再将混合料放入烘箱内烘干,再放入研钵中研磨过筛形成粉料；粉料放入坩埚内在马弗炉中于1350℃预烧,预烧的粉料在研钵中研磨成细粉,加入预定质量分数的聚乙烯醇树脂混合均匀,过筛选出粒径为0.15mm至0.28mm的二次粉料；二次粉料倒入不锈钢模具中,在预定压力下保压第三预定时间成型为胚件；胚件放入马弗炉中,温度升至预定温度,保温第四预定时间,排出聚乙烯醇树脂形成样品,样品放入坩埚中,用相同材料的粉料做埋料埋烧,在1425-1475℃中烧结形成陶瓷片。(The preparation method comprises the steps of mixing weighed raw materials, putting the mixture into a ball milling tank for ball milling to form a mixture, putting the mixture into an oven for drying, and putting the mixture into a mortar for grinding and sieving to form powder; pre-burning the powder in a crucible at 1350 ℃ in a muffle furnace, grinding the pre-burned powder in a mortar into fine powder, adding polyvinyl alcohol resin with a predetermined mass fraction, uniformly mixing, and sieving to obtain secondary powder with the particle size of 0.15-0.28 mm; pouring the secondary powder into a stainless steel mold, and maintaining the pressure for a third preset time under a preset pressure to form a blank; and (3) placing the blank into a muffle furnace, raising the temperature to a preset temperature, preserving the heat for a fourth preset time, discharging polyvinyl alcohol resin to form a sample, placing the sample into a crucible, burying and burning the sample by using powder of the same material as an embedding material, and sintering the sample at the temperature of 1425 and 1475 ℃ to form a ceramic chip.)

1. A ferroelectric ceramic material, characterized in that the ferroelectric ceramic material consists of:

(1-x)(Ba(Zr_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃the ferroelectric ceramic material has a multi-level ferroelectric domain structure, the size of x of the ferroelectric ceramic material is adjusted to adjust the multi-level ferroelectric domain structure, and the ferroelectric ceramic material has a first predetermined range of switching amplitude and a second predetermined range of switching barrier under an external applied force field.

2. The ferroelectric ceramic material of claim 1, wherein preferably the multilevel ferroelectric domain structure comprises a nested structure of first ferroelectric domains with dimensions in the micrometer scale and second ferroelectric domains with dimensions in the tens of nanometers.

3. The ferroelectric ceramic material of claim 1, wherein the first predetermined range is greater than the second predetermined range.

4. A ferroelectric ceramic material according to claim 1, characterized in that: the piezoelectric coefficient of the ferroelectric ceramic material is 590 pC/N.

5. A piezoelectric sensor, characterized by: made via the ferroelectric ceramic material of any one of claims 1 to 4.

6. A method of preparing a ferroelectric ceramic material according to any one of claims 1 to 4, characterized in that: the method comprises the following steps of,

based on the chemical formula (1-x) (Ba (Zr)_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃The raw material BaCO is weighed according to the proportion of the elements₃、CaTiO₃、ZrO₂And TiO₂Wherein x is 0.40, 0.45, 0.50, 0.55, 0.60;

mixing the weighed raw materials, putting the mixture into a ball milling tank for ball milling to form a mixture, putting the mixture into an oven for drying, and putting the mixture into a mortar for grinding and sieving to form powder;

putting the powder into a crucible and pre-sintering in a muffle furnace at 1350 ℃, preserving heat for first preset time, naturally cooling to room temperature, and discharging;

grinding the presintered powder into fine powder in a mortar, filling the fine powder into a ball milling tank for secondary ball milling to form a secondary mixture, putting the secondary mixture into an oven for drying, grinding the secondary mixture in the mortar, adding polyvinyl alcohol resin with a predetermined mass fraction, uniformly mixing, and sieving to obtain secondary powder with the particle size of 0.15-0.28 mm;

putting the secondary powder into an oven for drying for a second preset time, pouring the secondary powder into a stainless steel mold, and maintaining the pressure at a preset pressure for a third preset time to form a blank;

putting the blank into a muffle furnace, heating to a preset temperature, preserving heat for a fourth preset time, discharging polyvinyl alcohol resin to form a sample,

and putting the sample into a crucible, burying and burning the sample by using powder made of the same material as the buried material, sintering the sample at the temperature of 1425-1475 ℃ to form a ceramic wafer, preserving the temperature for fifth preset time, and naturally cooling the ceramic wafer to the room temperature.

7. The method of claim 6, wherein: polishing the ceramic wafer smoothly, coating silver paste on the upper surface and the lower surface, putting the ceramic wafer into a furnace, heating to 800 ℃, preserving heat for 20 minutes, and naturally cooling to room temperature.

8. The method of claim 6, wherein: adding a ball-milling solvent and agate balls into a ball-milling tank, ball-milling for 4 hours at the ball-milling rotating speed of 45 r/min, drying the mixture in an oven at 80 ℃ for 3 hours, grinding the mixture in a mortar, and sieving the mixture by a 60-mesh sieve.

9. The method of claim 6, wherein: the predetermined mass fraction is 8%, the first predetermined time is 4 hours, the second predetermined time is 5 to 10 minutes, the third predetermined time is 90 seconds, the fourth predetermined time is 2 hours, the fifth predetermined time is 4 hours, the predetermined pressure is 30MPa, the predetermined temperature is 600 ℃ and the temperature is raised at a rate of 5 ℃/min.

10. The method of claim 6, wherein: chemical formula is 0.50(Ba (Zr)_0.2Ti_0.8)O₃-0.50(Ba_0.7Ca_0.3)TiO₃The sample was sintered at 1450 ℃ to form a ceramic wafer, the blank being cylindrical.

Technical Field

The invention relates to the technical field of electronic ceramic materials, in particular to a ferroelectric ceramic material, a piezoelectric sensor and a preparation method.

Background

The piezoelectric material is a functional material which can stretch under the external applied voltage and generate voltage under the external applied force, and is an important sensing dielectric medium for realizing the conversion of mechanical signals and electric signals. The piezoelectric material is widely applied in the fields of modern industry and national defense, is an important perception material in a sensing system, and has an information support function which is more important for an intelligent system which develops at a high speed.

Pb (Ti, Zr) O is mostly adopted in the traditional piezoelectric material₃(PZT) the piezoelectric coefficient d33 of the lead-free piezoelectric ceramic is about 400pC/N, but lead element in the system has strong toxicity, so that the lead-free piezoelectric ceramic generates biotoxicity harm and environmental pollution in preparation and scrap links. Therefore, the development of green piezoelectric materials to replace PZT application is needed. In order to solve the problem, a great deal of research is carried out on piezoelectric materials without lead elements in recent years, but performances such as a non-lead ceramic piezoelectric coefficient and the like are far lower than those of PZT materials. The reason is that in the traditional method for modifying the piezoelectric property of the ferroelectric ceramic, the adjustment and control are only carried out by two microstructures, namely lattice deformation and micron-sized large domain inversion, wherein the amplitude of the lattice deformation is small, and the potential barrier for the micron-sized large domain inversion is high.

This information disclosed in the background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a ferroelectric ceramic material, a piezoelectric sensor and a preparation method. The piezoelectric material is based on component regulation and control, has a hierarchical nano electric domain structure, is provided with a large electric domain with a micron scale, is nested with a small electric domain with a nano scale, has high piezoelectric coefficient, is lead-free and green, is different from the traditional crystal lattice deformation and the large electric domain with the micron scale, has large overturning amplitude and small overturning potential barrier under an external force application field, and thus has a piezoelectric coefficient exceeding PZT in a macroscopic view, and d33 is up to 590 pC/N.

The purpose of the invention is realized by the following technical scheme.

In one aspect of the present invention, a ferroelectric ceramic material is composed of: (1-x) (Ba (Zr)_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃The ferroelectric ceramic material has a multi-level ferroelectric domain structure, the size of x of the ferroelectric ceramic material is adjusted to adjust the multi-level ferroelectric domain structure, and the ferroelectric ceramic material has a first predetermined range of switching amplitude and a second predetermined range of switching barrier under an external applied force field.

In the ferroelectric ceramic material, the multilevel ferroelectric domain structure comprises a nested structure of a first ferroelectric domain with the micron scale and a second ferroelectric domain with the scale of tens of nanometers.

Said ferroelectric ceramic material wherein said first predetermined range is greater than said second predetermined range.

In the ferroelectric ceramic material, the piezoelectric coefficient of the ferroelectric ceramic material is 590 pC/N.

According to another aspect of the present invention, a piezoelectric sensor is made via the ferroelectric ceramic material.

According to still another aspect of the present invention, a method for preparing the ferroelectric ceramic material comprises,

based on the chemical formula (1-x) (Ba (Zr)_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃The raw material BaCO is weighed according to the proportion of the elements₃、CaTiO₃、ZrO₂And TiO₂Wherein x is 0.40, 0.45, 0.50, 0.55, 0.60;

mixing the weighed raw materials, putting the mixture into a ball milling tank for ball milling to form a mixture, putting the mixture into an oven for drying, and putting the mixture into a mortar for grinding and sieving to form powder;

putting the powder into a crucible and pre-sintering in a muffle furnace at 1350 ℃, preserving heat for first preset time, naturally cooling to room temperature, and discharging;

grinding the presintered powder into fine powder in a mortar, filling the fine powder into a ball milling tank for secondary ball milling to form a secondary mixture, putting the secondary mixture into an oven for drying, grinding the secondary mixture in the mortar, adding polyvinyl alcohol resin with a predetermined mass fraction, uniformly mixing, and sieving to obtain secondary powder with the particle size of 0.15-0.28 mm;

putting the secondary powder into an oven for drying for a second preset time, pouring the secondary powder into a stainless steel mold, and maintaining the pressure at a preset pressure for a third preset time to form a blank;

putting the blank into a muffle furnace, heating to a preset temperature, preserving heat for a fourth preset time, discharging polyvinyl alcohol resin to form a sample,

and putting the sample into a crucible, burying and burning the sample by using powder made of the same material as the buried material, sintering the sample at the temperature of 1425-1475 ℃ to form a ceramic wafer, preserving the temperature for fifth preset time, and naturally cooling the ceramic wafer to the room temperature.

In the method, the ceramic wafer is polished smoothly, silver paste is coated on the upper surface and the lower surface, the ceramic wafer is placed in a furnace to be heated to 800 ℃, the temperature is kept for 20 minutes, and the ceramic wafer is naturally cooled to room temperature.

In the method, a ball milling solvent and agate balls are added into a ball milling tank, the ball milling solvent comprises absolute ethyl alcohol, ball milling is carried out for 4 hours, the ball milling rotating speed is 45 r/min, the mixture is put into an oven and dried for 3 hours at the temperature of 80 ℃, then the mixture is put into a mortar and ground, and the mixture is sieved by a 60-mesh sieve.

In the method, the preset mass fraction is 8%, the first preset time is 4 hours, the second preset time is 5-10 minutes, the third preset time is 90 seconds, the fourth preset time is 2 hours, the fifth preset time is 4 hours, the preset pressure is 30MPa, the preset temperature is 600 ℃ and the temperature is raised at the temperature raising speed of 5 ℃/min.

In the method, the chemical formula is 0.50(Ba (Zr)_0.2Ti_0.8)O₃-0.50(Ba_0.7Ca_0.3)TiO₃The sample was sintered at 1450 ℃ to form a ceramic wafer, the blank being cylindrical.

The description is only an outline of the technical solution of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention is implemented by those skilled in the art according to the content of the description, and in order to make the description and other objects, features and advantages of the present invention more obvious, the following is exemplified by the specific embodiments of the present invention.

Drawings

Various other advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. It is obvious that the drawings described below are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. Also, like parts are designated by like reference numerals throughout the drawings.

In the drawings:

FIG. 1 is a schematic transmission electron microscopy bright field image of a ferroelectric ceramic material according to one embodiment of the present invention;

FIG. 2 is a graph showing the variation of piezoelectric coefficient with BCT composition of a ferroelectric ceramic material according to an embodiment of the present invention.

The invention is further explained below with reference to the figures and examples.

Detailed Description

Specific embodiments of the present invention will be described in more detail below with reference to fig. 1 to 2. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

It should be noted that certain terms are used throughout the description and claims to refer to particular components. As one skilled in the art will appreciate, various names may be used to refer to a component. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description which follows is a preferred embodiment of the invention, but is made for the purpose of illustrating the general principles of the invention and not for the purpose of limiting the scope of the invention. The scope of the present invention is defined by the appended claims.

For the purpose of facilitating an understanding of the embodiments of the present invention, the following description will be made in terms of several specific embodiments with reference to the accompanying drawings, and the drawings are not intended to limit the embodiments of the present invention.

As shown in fig. 1 to 2, a ferroelectric ceramic material is composed of:

(1-x)(Ba(Zr_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃wherein x is 42% -56%, and the ferroelectric ceramic material has a multi-level ferroelectric domain structure.

Preferably, the ferroelectric ceramic material consists of: (1-x) (Ba (Zr)_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃Wherein x is 42% -48%, and the formed multi-level ferroelectric domain structure has a nested structure of a first ferroelectric domain with micron scale and a second ferroelectric domain with 1-10 nm scale, so that the piezoelectric coefficient is maximized.

In a preferred embodiment of the ferroelectric ceramic material, the multilevel ferroelectric domain structure includes a nested structure of a first ferroelectric domain with a micron scale and a second ferroelectric domain with a tens of nanometers, and the ferroelectric ceramic material adjusts the multilevel ferroelectric domain structure by adjusting the size of x.

In a preferred embodiment of the ferroelectric ceramic material, the ferroelectric ceramic material has a first predetermined range of the switching amplitude and a second predetermined range of the switching barrier under an applied force field.

In a preferred embodiment of the ferroelectric ceramic material, the piezoelectric coefficient of the ferroelectric ceramic material is 590 pC/N.

The invention obtains a novel hierarchical nano ferroelectric domain structure by regulating and controlling components in barium titanate-based ceramics, and prepares a green piezoelectric material with ultrahigh piezoelectric coefficient.

In the preferred embodiment of the ferroelectric ceramic material, the raw material components and the mole percentage content of the ferroelectric ceramic material are (1-x) (Ba (Zr)_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃And (x is 42% -56%), and the multi-level ferroelectric domain structure is realized by adjusting the size of x, so that the piezoelectric coefficient is maximized.

In the preferred embodiment of the ferroelectric ceramic material, the raw material components and the mol percentage content thereof of the ferroelectric ceramic material are 0.50(Ba (Zr)_0.2Ti_0.8)O₃-0.50(Ba_0.7Ca_0.3)TiO_3，Abbreviated as BZT-50 BCT.

In the preferred embodiment of the ferroelectric ceramic material, the piezoelectric material BZT-50BCT has a multi-level ferroelectric domain structure. FIG. 1 is a transmission electron microscopy bright field image of a BZT-50BCT piezoelectric material of an embodiment of the invention. The graph shows that the piezoelectric material has a nested structure of a large ferroelectric domain with the scale of micron and a small ferroelectric domain with the scale of tens of nanometers, which is called a hierarchical nano ferroelectric domain structure.

In a preferred embodiment of the ferroelectric ceramic material, the first predetermined range is greater in value than the second predetermined range.

A piezoelectric sensor is made via the ferroelectric ceramic material.

In one embodiment, the piezoelectric sensor is a dynamic cable vibration detection piezoelectric sensor for marine use.

A method for preparing the ferroelectric ceramic material comprises the following steps,

based on the chemical formula (1-x) (Ba (Zr)_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃The raw material BaCO is weighed according to the proportion of the elements₃、CaTiO₃、ZrO₂And TiO₂Wherein x is 0.40, 0.45, 0.50, 0.55, 0.60;

mixing the weighed raw materials, putting the mixture into a ball milling tank for ball milling to form a mixture, putting the mixture into an oven for drying, and putting the mixture into a mortar for grinding and sieving to form powder;

putting the powder into a crucible and pre-sintering in a muffle furnace at 1350 ℃, preserving heat for first preset time, naturally cooling to room temperature, and discharging;

grinding the presintered powder into fine powder in a mortar, filling the fine powder into a ball milling tank for secondary ball milling to form a secondary mixture, putting the secondary mixture into an oven for drying, grinding the secondary mixture in the mortar, adding polyvinyl alcohol resin with a predetermined mass fraction, uniformly mixing, and sieving to obtain secondary powder with the particle size of 0.15-0.28 mm;

putting the secondary powder into an oven for drying for a second preset time, pouring the secondary powder into a stainless steel mold, and maintaining the pressure at a preset pressure for a third preset time to form a blank;

putting the blank into a muffle furnace, heating to a preset temperature, preserving heat for a fourth preset time, discharging polyvinyl alcohol resin to form a sample,

and putting the sample into a crucible, burying and burning the sample by using powder made of the same material as the buried material, sintering the sample at the temperature of 1425-1475 ℃ to form a ceramic wafer, preserving the temperature for fifth preset time, and naturally cooling the ceramic wafer to the room temperature.

In the preferred embodiment of the method, the ceramic wafer is polished smoothly, silver paste is coated on the upper surface and the lower surface, the ceramic wafer is placed in a furnace to be heated to 800 ℃, the temperature is kept for 20 minutes, and the ceramic wafer is naturally cooled to the room temperature.

In a preferred embodiment of the method, a ball-milling solvent and agate balls are added into a ball-milling tank, the ball-milling solvent comprises absolute ethyl alcohol, the ball-milling is carried out for 4 hours, the ball-milling rotation speed is 45 r/min, the mixture is put into an oven and dried for 3 hours at the temperature of 80 ℃, then the mixture is put into a mortar and ground, and the mixture is sieved by a 60-mesh sieve.

In a preferred embodiment of the method, the predetermined mass fraction is 8%, the first predetermined time is 4 hours, the second predetermined time is 5 to 10 minutes, the third predetermined time is 90 seconds, the fourth predetermined time is 2 hours, the fifth predetermined time is 4 hours, the predetermined pressure is 30MPa, the predetermined temperature is 600 ℃ and the temperature is raised at a rate of 5 ℃/min.

In a preferred embodiment of the process, the formula is 0.50(Ba (Zr)_0.2Ti_0.8)O₃-0.50(Ba_0.7Ca_0.3)TiO₃The sample was sintered at 1450 ℃ to form a ceramic wafer, the blank being cylindrical.

In one embodiment, the preparation method comprises the steps of:

weighing material

(1) According to the formula (1-x) (Ba (Zr)_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃Weighing BaCO as raw material according to the proportion of each element₃，CaTiO₃，ZrO₂And TiO₂Wherein x is 0.40, 0.45, 0.50, 0.55 and 0.60 respectively;

(2) mixing the weighed raw materials, putting the mixture into a ball milling tank, adding ball milling solvents of absolute ethyl alcohol and agate balls, carrying out ball milling for 4 hours at the ball milling rotating speed of 45 r/min, putting the mixture into an oven, drying the mixture for 3 hours at the temperature of 80 ℃, putting the mixture into a mortar, grinding the mixture, and sieving the mixture by using a 60-mesh sieve;

pre-firing

(3) Putting the powder treated in the step 2 into a crucible, compacting and covering; presintering in a muffle furnace at 1350 ℃, preserving heat for 4 hours, naturally cooling to room temperature, and discharging;

secondary ball milling

(4) Grinding the powder preburning in the step 3 into fine powder in a mortar, filling the fine powder into a ball milling tank, adding a ball milling medium, namely absolute ethyl alcohol, performing secondary ball milling at the rotating speed of 45 revolutions per minute for 8 hours, and putting the mixture into an oven to be dried at the temperature of 80 ℃;

granulating

(5) Grinding the powder dried in the step 4 in a mortar, adding PVA with the mass fraction of 8%, uniformly mixing, and sieving to obtain powder with the particle size of 0.15 mm-0.28 mm;

shaping of

(6) Drying the powder granulated in the step 5 in an oven for 5 to 10 minutes, weighing a certain amount of powder, pouring the powder into a stainless steel mold with the diameter of 10mm, and maintaining the pressure at 30MPa for 90 seconds to form a cylindrical blank;

glue discharging

(7) And (4) putting the blank in the step 6 into a muffle furnace, heating to 600 ℃, preserving the heat for 2 hours, and discharging PVA.

Sintering

(8) Putting the sample obtained in the step 7 into a crucible, burying and burning the sample by using the same powder as the buried material, sintering the sample at the temperature of 1425-1475 ℃, preserving the heat for 4 hours, and naturally cooling the sample to room temperature along with the furnace;

burning electrode

(9) Polishing the ceramic wafer fired in the step 8 to be smooth, coating silver paste on the upper surface and the lower surface, putting the ceramic wafer into a furnace, heating to 800 ℃, preserving heat for 20 minutes, and naturally cooling to room temperature;

(10) and testing the electric domain structure and the piezoelectric coefficient of the sample.

In one embodiment, the temperature rise rate of the piezoelectric material in step 7 is 5 ℃/min; the temperature rise rate in step 8 is 5 ℃/min.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the specific embodiments and the application fields, and the specific embodiments are illustrative, instructive, and not restrictive. Those skilled in the art, having the benefit of this disclosure, may effect numerous modifications thereto without departing from the scope of the invention as defined by the appended claims.