WO2022231020A1

WO2022231020A1 - High-purity piezoelectric ceramic nanopowder for low-temperature calcination and preparation method therefor

Info

Publication number: WO2022231020A1
Application number: PCT/KR2021/005329
Authority: WO
Inventors: 구창영; 우도현
Original assignee: (주)퀸테스
Priority date: 2021-04-27
Filing date: 2021-04-27
Publication date: 2022-11-03
Also published as: KR102297718B1

Abstract

Disclosed are high-purity piezoelectric ceramic nanopowder for low-temperature calcination, and a preparation method therefor. The high-purity piezoelectric ceramic nanopowder can have a high-quality and uniform composition ratio by completely removing an organic polymer component through pyrolysis by calcination after separating and extracting only a liquid-phase organic solvent component from a piezoelectric precursor solution prepared by a chemical solution synthesis method. According to the high-purity piezoelectric ceramic nanopowder for low-temperature calcination and the preparation method therefor according to the present invention, each component may be completely dissolved by the chemical solution synthesis method to carry out the synthesis, and thus, the adjustment of the composition ratio may be easy, and high-purity piezoelectric ceramic nanopowder having a uniform composition ratio can be prepared.

Description

High-purity piezoelectric ceramic nanopowder for low-temperature firing and manufacturing method thereof

The present invention relates to a high-purity piezoelectric ceramic nanopowder for low-temperature firing and a method for manufacturing the same, and more particularly, only a liquid organic solvent component is separated and extracted from a piezoelectric precursor solution prepared by a chemical solution synthesis method, and then pyrolyzed by calcination heat treatment to organically The present invention relates to a high-purity piezoelectric ceramic nanopowder for low-temperature firing, which can have a high-quality and uniform composition ratio by completely removing the polymer component, and a method for manufacturing the same.

As of 2020, Pb(Zr _, Ti)O ₃ (PZT)-based and lead-free materials, which are the main raw materials for Piezoelectric Micro-Electro-Mechanical System (P-MEMS) and piezoelectric sensors, occupying a market of over 30 trillion won as of 2020 Metal oxide materials such as (lead-free) composition, (K,Na)NbO ₃ (KNN), Bi(Na,K)TiO ₃ (BNKT), BaTiO ₃ (BT), etc. , an actuator using piezoelectricity, a gyro, an acceleration sensor, and an infrared sensor using pyroelectricity.

Currently, in the case of piezoelectric ceramic raw materials in powder form, powders of each component are generally mixed according to the composition ratio of the piezoelectric material, and then synthesized through a high-temperature calcination process and then manufactured using a solid-state synthesis method of pulverization. However, the non-uniformity of the multi-component composition may occur depending on the particle size and mixing degree of each powder material in the initial stage. Therefore, it is possible to manufacture nanopowders by reducing the particle size only by performing several steps of grinding process using expensive grinding equipment.

In addition, Pb-based and Bi-based piezoelectric ceramic materials usually have excellent dielectric and piezoelectric properties when sintered at a high temperature of 1100°C or higher. Therefore, it may cause a change in the composition of the ceramic element component, which may result in deterioration or change in performance. Therefore, it is necessary to use piezoelectric nanopowders for low-temperature sintering capable of lowering the sintering temperature in order to manufacture lead-free and lead-free ceramics having stable characteristics.

For this reason, in the field of ceramic raw material powder manufacturing technology, various research and development have been carried out to increase production efficiency due to the possibility of non-uniformity in composition and control of particle size. have. The hydrothermal synthesis method is one of the liquid phase synthesis methods. It is a process method for synthesizing substances using water or a thermal solution or fluid under high temperature and high pressure. It can be considered similar to the solution synthesis method. However, unlike the hydrothermal synthesis method in which the raw materials are not completely dissolved and are mixed in particle units, in this technology, as in the example of the solution prepared by the sol-gel method, the raw materials of each component are completely dissolved in the solvent, There is a big difference in that it is a synthesis of a uniform composition ratio.

Co-precipitation (CO-PRECIPITATION) refers to a method of simultaneously precipitating various different ions in an aqueous or non-aqueous solution. In this case, the insoluble oxalate, carbonate, or oxalate is finely mixed and dispersed and precipitated together, which is not suitable for the production of multi-component ceramic powder, since non-uniformity in composition and purity control problems occur.

Therefore, in the present invention, the multi-component composition is synthesized in a complete liquid phase through the sol-gel method, the MOD method, or the use of an acid-based solvent, only the solvent is separated and extracted, and only the organic polymer component is pyrolyzed again to obtain pure metal ion oxide. By synthesizing with ceramic nanopowder, it is a technology for producing piezoelectric ceramic nanopowders for low-temperature firing with accurate composition ratio and uniform particle distribution unlike other powder manufacturing methods. (semiconducting) and other ceramic material parts will make a significant contribution to the development of the industry.

As a related prior document, there is Republic of Korea Patent Publication No. 10-2020-0017847 (published on February 19, 2020), which describes a method for manufacturing a piezoelectric thin film and a piezoelectric sensor using the piezoelectric thin film.

An object of the present invention is to selectively remove only the organic polymer by thermally decomposing the solid piezoelectric precursor polymer prepared by selectively separating and extracting only the organic solvent in the piezoelectric precursor solution by the reduced pressure distillation method through calcination heat treatment, thereby providing pure perovskide crystalline metal. An object of the present invention is to provide a high-purity piezoelectric ceramic nanopowder for low-temperature sintering capable of having an accurate composition ratio and uniform particle distribution by forming a piezoelectric ceramic nanopowder made of an oxide, and a method for manufacturing the same.

A method for producing high-purity piezoelectric ceramic nanopowder for low-temperature firing according to a first embodiment of the present invention for achieving the above object includes the steps of: (a) preparing a piezoelectric precursor solution synthesized by a chemical solution synthesis method; (b) reducing and heating the piezoelectric precursor solution by vacuum distillation to separate and extract an organic solvent in the piezoelectric precursor solution to obtain a solid piezoelectric precursor polymer; (c) pyrolyzing the solid piezoelectric precursor polymer by calcination heat treatment to remove the organic polymer, thereby forming a piezoelectric ceramic powder made of a metal oxide; and (d) pulverizing the piezoelectric ceramic powder to obtain a piezoelectric ceramic nanopowder.

In the step (b), when the organic solvent in the piezoelectric precursor solution is reduced pressure and heated by vacuum distillation, the organic solvent in the piezoelectric precursor solution is selectively volatilized, so that the organic solvent separated and extracted in the extraction vessel is are kept

In step (b), the pressure reduction and heating is carried out at a pressure of 6 mbar or less at 120 ~ 200 ℃ conditions.

In step (c), the calcination heat treatment comprises the steps of primary heat treatment at 400 ~ 500 ℃ for 0.5 ~ 2 hours; and secondary heat treatment at 600 to 800° C. for 1 to 5 hours.

Each of the first and second heat treatment is heated at a rate of 3 ~ 7 ℃ / min.

In step (d), the pulverization is performed by ball milling at a speed of 50 to 200 rpm for 20 to 30 hours.

A method for producing high-purity piezoelectric ceramic nanopowder for low-temperature firing according to a second embodiment of the present invention for achieving the above object includes the steps of: (a) preparing a piezoelectric precursor solution synthesized by a chemical solution synthesis method; (b) reducing and heating the piezoelectric precursor solution by vacuum distillation to separate and extract an organic solvent in the piezoelectric precursor solution to obtain a solid piezoelectric precursor polymer; (c) low-temperature heat treatment of the solid piezoelectric precursor polymer; (d) pyrolyzing the low-temperature heat-treated solid piezoelectric precursor polymer through calcination heat treatment to remove the organic polymer, thereby forming a piezoelectric ceramic powder made of a metal oxide; and (e) pulverizing the piezoelectric ceramic powder to obtain a piezoelectric ceramic nanopowder.

Here, the low-temperature heat treatment is preferably carried out at 120 ~ 200 ℃ conditions.

The high-purity piezoelectric ceramic nanopowder for low-temperature firing according to an embodiment of the present invention for achieving the above object is made of pure metal oxide, and has an average diameter of 150 nm or less.

Here, the pure metal oxide has a perovskite crystal phase.

The high-purity piezoelectric ceramic nanopowder for low-temperature firing according to the present invention and a method for producing the same according to the present invention selectively separate and extract only the organic solvent in the piezoelectric precursor solution by vacuum distillation. By removing it as a piezoelectric ceramic nanopowder made of pure perovskite crystal phase metal oxide, it is possible to have an accurate composition ratio and uniform particle distribution.

As described above, the high-purity piezoelectric ceramic nanopowder for low-temperature firing and the method for manufacturing the same according to the present invention are synthesized by completely dissolving each component by a chemical solution synthesis method, thereby making it easy to control the composition ratio and to produce a high-purity piezoelectric ceramic nanopowder having a uniform composition ratio. It may be possible to manufacture

In addition, the high-purity piezoelectric ceramic nanopowder for low-temperature firing and the method for manufacturing the same according to the present invention can reuse the organic solvent separated and extracted in the extraction vessel through the vacuum distillation method as a solvent for synthesizing the piezoelectric precursor solution by the chemical solution synthesis method. do.

In addition, the high-purity piezoelectric ceramic nanopowder for low-temperature firing and the method for manufacturing the same according to the present invention separate the organic solvent accounting for approximately 50 to 90 wt% of the piezoelectric precursor solution through vacuum distillation, and only 600 remaining solid piezoelectric precursor polymer components Since the calcination heat treatment is carried out at a low temperature of ~800°C, it is possible to not only increase the production efficiency, but also to minimize environmental pollution.

In addition, the high-purity piezoelectric ceramic nanopowder for low-temperature firing according to the present invention and a method for manufacturing the same according to the present invention are calcined heat treatment at a low temperature of 600-800°C, which is 300-500°C lower than other powder manufacturing methods, thus reducing energy consumption and providing high-quality, high-purity It is possible to prepare piezoelectric ceramic nanopowders.

1 is a process flow chart showing a method for manufacturing high-purity piezoelectric ceramic nanopowder for low-temperature sintering according to a first embodiment of the present invention.

Figure 2 is a schematic diagram for explaining the vacuum distillation apparatus used during the separation and extraction process of Figure 1;

Figure 3 is a schematic diagram for explaining the calcination heat treatment process of Figure 1;

4 is a process flow chart showing a method for manufacturing high-purity piezoelectric ceramic nanopowder for low-temperature firing according to a second embodiment of the present invention.

5 is a schematic diagram for explaining a low-temperature heat treatment apparatus used during the low-temperature heat treatment process of FIG.

6 is a graph showing the XRD measurement results of the KNN-based piezoelectric ceramic nanopowder.

7 is a graph showing the XRD measurement results of the BNKT-based piezoelectric ceramic nanopowder.

8 and 9 are SEM photographs showing KNN-based piezoelectric ceramic nanopowders taken.

10 and 11 are SEM photographs showing BNKT-based piezoelectric ceramic nanopowders taken.

Advantages and features of the present invention, and methods for achieving them, will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be embodied in various different forms, only this embodiment allows the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, with reference to the accompanying drawings, a high-purity piezoelectric ceramic nanopowder for low-temperature firing and a method for manufacturing the same according to a preferred embodiment of the present invention will be described in detail as follows.

1 is a process flow chart showing a method for manufacturing high-purity piezoelectric ceramic nanopowder for low-temperature firing according to a first embodiment of the present invention.

As shown in FIG. 1, the method for manufacturing high-purity piezoelectric ceramic nanopowder for low-temperature firing according to the first embodiment of the present invention includes a synthesis step (S110), a separation and extraction step (S120), a calcination heat treatment step (S130), and pulverization. Step S140 is included.

synthesis

In the synthesis step (S110), a piezoelectric precursor solution synthesized by a chemical solution synthesis method is prepared.

Here, the piezoelectric precursor solution is methanol (Methyl alcohol), ethanol (Ethyl alcohol), butanol (Butyl alcohol), propanol (Propyl alcohol) methoxyethanol (2-methoxiethanol), propanediol (2,4-Propandiol), xyl An organic solvent containing xylene, etc., an organic complexing agent containing acetylacetone, ethanolamine (1,2,3-Ethanolamine), etc., acetic acid, nitric acid, etc. The catalyst and other additives may be a solution for manufacturing a perovskite piezoelectric material prepared by a chemical solution synthesis method such as a sol-gel method and an organic chemical synthesis method (MOD), but is not limited thereto.

That is, in the present invention, the piezoelectric precursor solution is not limited to one material property such as dielectric, piezoelectric, conductive, and semiconducting properties. That is, the piezoelectric precursor solution includes a solution for manufacturing a conductive material such as Indium Tin Oxide (ITO) and Indium Zinc Oxide (IZO), a solution for manufacturing a semiconducting material such as Indium Gallium Zinc Oxide (IGZO), etc., as well as a chemical solution synthesis method It may include a solution for manufacturing all high-purity ceramic materials manufactured by .

Separation and extraction

In the separation and extraction step ( S120 ), the piezoelectric precursor solution is reduced pressure and heated by vacuum distillation to separate and extract the organic solvent in the piezoelectric precursor solution to obtain a solid piezoelectric precursor polymer.

FIG. 2 is a schematic diagram for explaining a vacuum distillation apparatus used during the separation and extraction process of FIG. 1 , and will be described in more detail with reference to this.

1 and 2, the vacuum distillation apparatus 100 includes a reaction vessel 110, a heating body 120, a heating panel 130, a thermometer 140, a reduced pressure distillation tube 150, a condenser ( 160 ) and an extraction vessel 170 .

Here, the piezoelectric precursor solution 10 is filled in the reaction vessel 110 , and the heating panel 130 is mounted on the heating body 120 . The heating body 120 receives power from the power wiring 125 and heats the piezoelectric precursor solution 10 inside the reaction vessel 110 through the heating panel 130 mounted on the heating body 120 . . Here, the heating panel 130 may be a hot plate or a heating mantle, but is not limited thereto.

The reduced pressure distillation tube 150 is mounted on the upper side so as to be coupled to the reaction vessel 110, and is mounted to be inclined in the form of an oblique line. In addition, the thermometer 140 is mounted on the reduced pressure distillation tube 150 to measure the temperature inside the reaction vessel 110 and the reduced pressure distillation tube 150 .

At this time, as the piezoelectric precursor solution 10 is heated by the heating panel 130 into the vacuum distillation tube 150 , the organic solvent in the piezoelectric precursor solution 10 is volatilized and introduced into the vacuum distillation tube 150 . The organic solvent 20 cooled by the condenser 160 disposed to surround the separated and extracted organic solvent 20 is filled in the extraction vessel 170 . Here, the condenser 160 receives cooling water from the outside through the cooling water supply port 162 disposed on one side, and discharges the cooling water through the cooling water discharge port 164 disposed on the other side. In addition, during the process of decompression and heating by the reduced pressure distillation method, the vacuum is discharged through the vacuum outlet 166 and the pressure is reduced.

As described above, in the present invention, when the organic solvent in the piezoelectric precursor solution 10 is pressure-reduced and heated by a reduced pressure distillation method, the organic solvent in the piezoelectric precursor solution 10 is selectively volatilized, thereby separating into the extraction vessel 170 . and the extracted organic solvent 20 is stored. Here, the organic solvent 20 separated and extracted in the extraction vessel 170 through the reduced pressure distillation method is reused as a solvent for synthesizing the piezoelectric precursor solution by the chemical solution synthesis method.

In the present invention, the higher the concentration of the components constituting the metal oxide in the piezoelectric precursor solution 10 is, the better, this is in order to increase the production efficiency of the piezoelectric ceramic nanopowder made of the metal oxide. In addition, in the present invention, the concentration of the piezoelectric precursor solution 10 does not need to be precisely controlled. However, it is necessary to control so that precipitation or precipitation of the second phase does not occur, since it may be difficult to manufacture the piezoelectric ceramic nanopowder with the desired composition of the metal oxide.

To this end, reduced pressure and heating are carried out at a pressure of 6 mbar or less and at 120 ~ 200 ° C. it is preferable As such, when the pressure is lowered to 6 mbar or less at a temperature of 120 to 200° C., extraction and separation of the organic solvent occupying approximately 50 to 90 wt% of the piezoelectric precursor solution 10 can be efficiently performed.

In addition, in this step, only the heating body 120 and the heating panel 130 may be used to prepare a solid piezoelectric precursor polymer, but the volatilized organic solvent cannot be distilled or the boiling point of the organic solvent cannot be lowered at normal pressure. The extraction and separation process may take a lot of time. Therefore, it should be noted that precipitation or gelation of the piezoelectric precursor solution 10 may proceed due to additional hydrolysis, condensation and polymerization reaction between moisture in the atmosphere and the piezoelectric precursor solution 10 .

Therefore, in this step, the piezoelectric precursor solution 10 is transferred to a dedicated glass for the vacuum distillation apparatus 100, and the process of transferring the manufactured solid piezoelectric precursor polymer to a glass bottle is omitted to increase stability and process efficiency. , a method of preparing a solid piezoelectric precursor polymer by directly attaching a glass bottle, not a flask-shaped glass bottle, to the vacuum distillation apparatus 100 is also applicable.

That is, in this step, the piezoelectric precursor solution 10 is filled in the reaction vessel 110 , and the organic solvent in the piezoelectric precursor solution 10 is completely removed under reduced pressure using the heating body 120 and the heating panel 130 . In order to promote removal and thermal decomposition of some organic polymer components, the solid piezoelectric precursor polymer is prepared by heating to 120 to 200° C. to remove the liquid organic solvent component and some organic polymer components.

Here, when extracting only the piezoelectric precursor polymer by volatilizing and distilling the organic solvent, an inert gas such as Ar or N ₂ is injected so as not to be exposed to external air, so that the chemical synthesis solution does not react with the external atmosphere (oxygen and moisture) or deteriorate. should avoid

As described above, in the present invention, an organic solvent including an alcohol solvent (2-methoxyethanol, Butanol, Isopropylalcohol), a complexing agent (Acetylacetone, Ethanolamine), and an additive/accelerator (Acetic acid, Polyethylene glycol) is used to form a sol-gel (Sol) -From a piezoelectric precursor solution of lead (Pb-based) and lead-free (Non-Pb-based) composition prepared by chemical solution synthesis methods such as -Gel) method or MOD (metal organic decomposition) method, toxic and explosive alcohol and other organic solvents The components are separated and extracted to form a solid piezoelectric precursor polymer.

calcination heat treatment

In the calcination heat treatment step ( S130 ), the solid piezoelectric precursor polymer is pyrolyzed by calcination heat treatment to remove the organic polymer, thereby forming a piezoelectric ceramic powder made of a metal oxide.

3 is a schematic diagram for explaining the calcination heat treatment process of FIG. 1 .

3, the calcination heat treatment step (S130) is subdivided into a process of primary heat treatment at 400 to 500 ° C. for 0.5 to 2 hours, and a process of secondary heat treatment at 600 to 800 ° C. for 1 to 5 hours. It is preferable to carry out

As such, in the present invention, organic polymers such as C, H, N, CH, NH are thermally decomposed by primary heat treatment at 400 to 500° C. for 0.5 to 2 hours, and secondary heat treatment at 600 to 800° C. for 1 to 5 hours. In this way, the process of calcination and heat treatment is performed.

Metal hydroxide of M-OH is formed by thermal decomposition through primary heat treatment, and piezoelectric ceramics composed of pure M-Ox metal oxide through secondary heat treatment at 600 ~ 800℃ powder is produced.

Here, it is preferable to raise the temperature of each of the primary and secondary heat treatment at a rate of 3 to 7°C/min. If the temperature increase rate of each of the primary and secondary heat treatment is less than 3 °C / min, the productivity may be lowered due to the temperature increase rate being too slow, thereby reducing economic efficiency. Conversely, when the temperature increase rate of each of the primary and secondary heat treatment exceeds 7° C./min, it is not preferable because there is a risk of rapid thermal decomposition of organic components.

The purpose of performing the two-step calcination heat treatment of primary heat treatment at 400 ~ 500 ° C and secondary heat treatment at 600 ~ 800 ° C is that when the thermal decomposition reaction of the organic polymer occurs rapidly at a high temperature at once, the process stability is reduced due to excessive exothermic reaction. because it could be lowered. In addition, the reason for performing the two-step calcination heat treatment is to suppress the generation of a second phase due to thermal decomposition of some volatile components, and after complete thermal decomposition of some residual components such as carbon, pure high-quality piezoelectric ceramic powder for low-temperature firing in order to manufacture

In the present invention, piezoelectric ceramic nanopowder having a pure perovskite crystal structure can be manufactured at a low temperature of 600 to 800°C, which is about 300 to 500°C lower than other methods. Therefore, it is possible to prevent volatilization of the piezoelectric composition component that can volatilize during the high-temperature calcination and sintering process, so that it is possible to manufacture high-purity piezoelectric ceramic nanopowder for low-temperature calcination with excellent compositional uniformity.

smash

In the pulverization step (S140), piezoelectric ceramic powder is pulverized to obtain piezoelectric ceramic nanopowder.

In this step, the pulverization may be performed by ball milling for 20 to 30 hours at a speed of 50 to 200 rpm, but is not limited thereto.

By such pulverization, the piezoelectric ceramic nanopowder is made of pure metal oxide in the form of spherical particles, and has an average diameter of 150 nm or less.

Here, when high-efficiency milling equipment such as a super mill is used instead of ball milling, it is possible to more easily and quickly produce uniformly nano-sized, high-purity piezoelectric ceramic nanopowders.

The pulverized piezoelectric ceramic nanopowder is sorted and separated by particle size through sieving, and then packaged in a container.

As described above, the method for manufacturing high-purity piezoelectric ceramic nanopowder for low-temperature sintering according to the first embodiment of the present invention may be completed.

Hereinafter, a method for manufacturing high-purity piezoelectric ceramic nanopowder for low-temperature firing according to a second embodiment of the present invention will be described with reference to the accompanying drawings.

4 is a process flow chart showing a method for manufacturing high-purity piezoelectric ceramic nanopowder for low-temperature sintering according to a second embodiment of the present invention.

As shown in FIG. 4 , the method for manufacturing high-purity piezoelectric ceramic nanopowder for low-temperature firing according to the second embodiment of the present invention includes a synthesis step (S210), a separation and extraction step (S220), a low-temperature heat treatment step (S230), and calcination. It includes a heat treatment step (S240) and a grinding step (S250). Here, the synthesis step (S210) and the separation and extraction step (S220) of the second embodiment of the present invention are the synthesis step (S210) and the separation and extraction step of the first embodiment of the present invention described with reference to FIGS. 1 and 2 . Since it is substantially the same as (S220), the overlapping description will be omitted and mainly the differences will be described.

low temperature heat treatment

In the low-temperature heat treatment step (S230), the solid piezoelectric precursor polymer obtained by separating and extracting the organic solvent in the piezoelectric precursor solution by vacuum distillation is subjected to low-temperature heat treatment.

FIG. 5 is a schematic diagram for explaining a low-temperature heat treatment apparatus used during the low-temperature heat treatment process of FIG. 4 , which will be described in more detail with reference to FIG.

4 and 5 , the low-temperature heat treatment apparatus 200 includes a reaction vessel 210 , a heating body 220 , a heating panel 230 , a thermometer 240 , a gas inlet 250 and an exhaust gas outlet. (260).

Here, the solid piezoelectric precursor polymer 30 is filled in the reaction vessel 210 , and the heating panel 230 is mounted on the heating body 220 . The heating body 220 receives power from the power wiring 225 and heats the piezoelectric precursor polymer 30 inside the reaction vessel 210 through the heating panel 230 mounted on the heating body 220 . .

In addition, the thermometer 240 is mounted on the upper side of the reaction vessel 210 to measure the temperature inside the reaction vessel 210 . Here, the organic polymer in the solid piezoelectric precursor polymer 30 filled in the reaction vessel 210 is discharged by thermal decomposition through the exhaust gas outlet 260 disposed above the thermometer 240 .

At this time, in order to increase the thermal decomposition efficiency, it is preferable to introduce one or more reactive gases of air and oxygen (O ₂ ) into the reaction vessel 210 through the gas inlet 260 .

Although not shown in detail in the drawings, the low-temperature heat treatment apparatus 200 may be equipped with a fume treatment mechanism communicating with the exhaust gas outlet 260, and after removing harmful components through the fume treatment mechanism, the discharge is made. be able to Accordingly, the harmful components can be dissolved and removed while the exhaust gas passes through the water bath of the fume treatment mechanism.

By performing low-temperature heat treatment on the solid piezoelectric precursor polymer 30 at 120 to 200° C. using the low-temperature heat treatment apparatus 200 having the above-described configuration, the residual solvent and some organic substances in the solid piezoelectric precursor polymer 30 are By thermally decomposing the polymer component, it becomes possible to manufacture a piezoelectric ceramic of higher purity than in the first embodiment.

In this way, when the low-temperature heat treatment is additionally performed, it is possible to prevent the second phase from being generated in advance during or after the separation and extraction process, and at the same time, it becomes possible to perform a more effective calcination heat treatment process.

calcination heat treatment

As shown in FIG. 4 , in the calcination heat treatment step S240 , the organic polymer is removed by thermally decomposing the low-temperature heat treated solid piezoelectric precursor polymer through calcination heat treatment to form a piezoelectric ceramic powder made of a metal oxide.

This calcination heat treatment step (S240), like the first embodiment, is subdivided into a process of primary heat treatment at 400 to 500 ° C. for 0.5 to 2 hours, and a process of secondary heat treatment at 600 to 800 ° C. for 1 to 5 hours. It is preferable to carry out

smash

In the pulverization step (S250), piezoelectric ceramic powder is pulverized to obtain piezoelectric ceramic nanopowder.

As described above, the method for manufacturing high-purity piezoelectric ceramic nanopowder for low-temperature sintering according to the second embodiment of the present invention may be completed.

The high-purity piezoelectric ceramic nanopowder for low-temperature sintering produced by the above-described process is obtained by forming a ceramic compact in the form of a thin plate by a powder molding method or a tape-casting method, and then sintering the ceramic compact at a low temperature of 900 ~ 1100 ° C. or less to manufacture a ceramic element will do

At this time, when a ceramic element is manufactured using the high-purity piezoelectric ceramic nanopowder for low-temperature firing according to the present invention, the high-temperature calcination and sintering temperature is lowered, thereby reducing the loss of volatile components and accurately controlling the composition ratio. When manufacturing a multilayer ceramic device such as , MLA, etc., it is possible to widen the selection of electrodes.

As described so far, the high-purity piezoelectric ceramic nanopowder for low-temperature firing and the method for manufacturing the same according to the present invention selectively separate and extract only the organic solvent in the piezoelectric precursor solution by vacuum distillation. By selectively removing only the organic polymer by thermal decomposition, a piezoelectric ceramic nanopowder made of a metal oxide in a pure perovskite crystal phase is formed, thereby having an accurate composition ratio and uniform particle distribution.

실시예Example

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, these are presented as preferred examples of the present invention and cannot be construed as limiting the present invention in any sense.

Content not described here will be omitted because it can be technically inferred sufficiently by those skilled in the art.

1. 압전 세라믹 나노분말 제조1. Piezoelectric Ceramic Nanopowder Manufacturing

Manufacture of KNN-based piezoelectric ceramic nanopowder

A solid KNN-based piezoelectric precursor polymer was obtained by separating and extracting the organic solvent in the KNN-based piezoelectric precursor solution by reducing and heating the KNN-based piezoelectric precursor solution synthesized by the chemical solution synthesis method at a pressure of 3 mbar by vacuum distillation at 150° C. did.

Next, the solid-state KNN-based piezoelectric precursor polymer was subjected to low-temperature heat treatment at 150° C. for 2 hours.

Next, the solid KNN-based piezoelectric precursor polymer subjected to low-temperature heat treatment was thermally decomposed by calcination heat treatment to remove the organic polymer, thereby forming a KNN-based piezoelectric ceramic powder made of a metal oxide.

Next, the KNN-based piezoelectric ceramic powder was pulverized by ball milling at a speed of 100 rpm for 24 hours to prepare a KNN-based piezoelectric ceramic nanopowder.

Here, in the calcination heat treatment, after heating to 450°C at a rate of 5°C/min, primary heat treatment is performed at 450°C for 2 hours, and secondary heat treatment is performed at 500°C, 550°C, 600°C, 650°C, and 700°C for 3 hours, respectively. After performing the heat treatment, it was cooled to room temperature (10° C.).

BNKT-based piezoelectric ceramic nanopowder production

The BNKT-based piezoelectric precursor solution synthesized by the chemical solution synthesis method was decompressed and heated at a pressure of 3 mbar by a vacuum distillation method at 150° C., and the organic solvent in the BNKT-based piezoelectric precursor solution was separated and extracted to obtain a solid BNKT-based piezoelectric precursor polymer. did.

Next, the solid-state BNKT-based piezoelectric precursor polymer was subjected to low-temperature heat treatment at 150° C. for 2 hours.

Next, the solid BNKT-based piezoelectric precursor polymer subjected to low-temperature heat treatment was thermally decomposed by calcination heat treatment to remove the organic polymer, thereby forming a BNKT-based piezoelectric ceramic powder made of a metal oxide.

Next, the BNKT-based piezoelectric ceramic powder was pulverized by ball milling at a speed of 100 rpm for 24 hours to prepare a BNKT-based piezoelectric ceramic nanopowder.

Here, in the calcination heat treatment, after heating to 450°C at a rate of 5°C/min, primary heat treatment is performed at 450°C for 2 hours, and secondary heat treatment is performed at 600°C, 650°C, 700°C, 750°C, and 800°C for 4 hours, respectively. After performing the heat treatment, it was cooled to room temperature (10° C.).

2. 결정성 분석2. Crystallinity Analysis

6 is a graph showing the XRD measurement result of the KNN-based piezoelectric ceramic nanopowder, and FIG. 7 is a graph showing the XRD measurement result of the BNKT-based piezoelectric ceramic nanopowder.

As shown in FIG. 6 , the crystallinity change results for each calcination heat treatment temperature (secondary heat treatment) of the KNN-based piezoelectric ceramic nanopowder are shown.

In the case of this KNN-based piezoelectric ceramic nanopowder, crystallinity appeared from 500 °C, and it was confirmed that the perovskite crystal phase was clearly displayed even at a relatively low calcination heat treatment temperature of 650 to 700 °C.

In addition, as shown in FIG. 7, the crystallinity change results for each calcination heat treatment temperature (secondary heat treatment) of the BNKT-based piezoelectric ceramic nanopowder are shown.

In the case of such a BNKT-based piezoelectric ceramic nanopowder, it can be seen that the piezoelectric perovskite crystal phase clearly appeared at 600° C. or higher.

3. 미세조직 관찰3. Microstructure observation

8 and 9 are SEM pictures taken by taking a KNN-based piezoelectric ceramic nanopowder, and FIGS. 10 and 11 are SEM pictures taken by taking a BNKT-based piezoelectric ceramic nanopowder. Here, FIG. 8 shows that the calcination heat treatment temperature (secondary heat treatment) was carried out at 650°C, and FIG. 9 shows that the calcination heat treatment temperature (secondary heat treatment) was performed at 700°C. In addition, FIG. 10 shows that the calcination heat treatment temperature (secondary heat treatment) was performed at 700°C, and FIG. 11 shows that the calcination heat treatment temperature (secondary heat treatment) was performed at 750°C.

8 and 9, all of the KNN-based piezoelectric ceramic nanopowders have a spherical shape with an average diameter of about 100 nm, and it can be confirmed that they are uniformly dispersed.

In addition, as shown in FIGS. 10 and 11 , it can be confirmed that all of the BNKT-based piezoelectric ceramic nanopowders also have a spherical shape with an average diameter of about 100 nm, and are uniformly dispersed.

As can be seen from the above experimental results, it was confirmed that it is possible to manufacture piezoelectric ceramic nanopowders with a diameter of about 100 nm, despite simple ball milling at a speed of 100 rpm for 24 hours.

In addition, in the present invention, it was confirmed that a high-purity piezoelectric ceramic nanopowder having a pure perovskite crystal phase can be prepared at a lower calcination heat treatment temperature compared to the solid-phase synthesis method generally used for ceramic powder synthesis.

In the above, the embodiments of the present invention have been mainly described, but various changes or modifications can be made at the level of those skilled in the art to which the present invention pertains. Such changes and modifications can be said to belong to the present invention without departing from the scope of the technical spirit provided by the present invention. Accordingly, the scope of the present invention should be judged by the claims described below.

[Explanation of code]

S110: synthesis step

S120: separation and extraction step

S130: calcination heat treatment step

S140: crushing step

S210: synthesis step

S220: Separation and extraction step

S230: low temperature heat treatment step

S240: calcination heat treatment step

S250: crushing step

Claims

(a) preparing a piezoelectric precursor solution synthesized by a chemical solution synthesis method;

(b) reducing and heating the piezoelectric precursor solution by vacuum distillation to separate and extract an organic solvent in the piezoelectric precursor solution to obtain a solid piezoelectric precursor polymer;

(c) pyrolyzing the solid piezoelectric precursor polymer by calcination heat treatment to remove the organic polymer, thereby forming a piezoelectric ceramic powder made of a metal oxide; and

(d) pulverizing the piezoelectric ceramic powder to obtain a piezoelectric ceramic nanopowder;

High-purity piezoelectric ceramic nanopowder manufacturing method for low-temperature firing, characterized in that it comprises a.
According to claim 1,

In step (b),

In the process of depressurizing and heating the organic solvent in the piezoelectric precursor solution by vacuum distillation, the organic solvent in the piezoelectric precursor solution is selectively volatilized, and the separated and extracted organic solvent is stored in the extraction container. Method for producing high-purity piezoelectric ceramic nanopowder for firing.
According to claim 1,

In step (b),

The decompression and heating

A method for producing high-purity piezoelectric ceramic nanopowder for low-temperature firing, characterized in that it is carried out at a pressure of 6 mbar or less at 120 ~ 200 °C.
According to claim 1,

In step (c),

The calcination heat treatment

First heat treatment at 400 ~ 500 ℃ for 0.5 ~ 2 hours; and

Secondary heat treatment at 600 ~ 800 ℃ for 1 ~ 5 hours;

High-purity piezoelectric ceramic nanopowder manufacturing method for low-temperature firing, characterized in that it comprises a.
5. The method of claim 4,

Each of the first and second heat treatment is

A method for producing high-purity piezoelectric ceramic nanopowder for low-temperature firing, characterized in that the temperature is raised at a rate of 3 to 7°C/min.
According to claim 1,

In step (d),

the crushing

A method for producing high-purity piezoelectric ceramic nanopowder for low-temperature firing, characterized in that ball milling is performed for 20 to 30 hours at a speed of 50 to 200 rpm.
(a) preparing a piezoelectric precursor solution synthesized by a chemical solution synthesis method;

(b) reducing and heating the piezoelectric precursor solution by vacuum distillation to separate and extract an organic solvent in the piezoelectric precursor solution to obtain a solid piezoelectric precursor polymer;

(c) low-temperature heat treatment of the solid piezoelectric precursor polymer;

(d) pyrolyzing the low-temperature heat-treated solid piezoelectric precursor polymer through calcination heat treatment to remove the organic polymer, thereby forming a piezoelectric ceramic powder made of a metal oxide; and

(e) pulverizing the piezoelectric ceramic powder to obtain a piezoelectric ceramic nanopowder;

High-purity piezoelectric ceramic nanopowder manufacturing method for low-temperature firing, characterized in that it comprises a.
8. The method of claim 7,

The low-temperature heat treatment

High-purity piezoelectric ceramic nanopowder manufacturing method for low-temperature firing, characterized in that carried out at 120 ~ 200 ℃ conditions.
It is manufactured by the method for producing high-purity piezoelectric ceramic nanopowder for low-temperature firing according to any one of claims 1 to 8,

High-purity piezoelectric ceramic nanopowder for low-temperature firing, characterized in that it is made of pure metal oxide and has an average diameter of 150 nm or less.
10. The method of claim 9,

The pure metal oxide is

A high-purity piezoelectric ceramic nanopowder for low-temperature firing, characterized in that it has a perovskite crystal phase.