JPS63201003A - Plate shaped-compound oxide, fine crystalline particle of solid solution thereof, and its production - Google Patents

Abstract

PURPOSE:To produce the title plate-shaped compound oxide and fine particles having fine and uniform particle size by mixing a coprecipitate produced from solns. of compds. of each compositional elements and a precipitating agent with a soln. of a water-soluble flux material, then separating deposit from the mixture. CONSTITUTION:A coprecipitate is formed by mixing a soln. of compds. of each compositional element constituting a compound oxide and its solid soln. with a precipitating agent. A liquid mixture of the obtd. precipitate with a soln. of a water-soluble flux material is dried. Then, the mixture is heated at above the m.p. of the flux material, and deposited crystal particles of the solid soln. of the oxide are removed after separating from the flux material. Suitable compds. of each compositional element to be used for the production of the compound oxide and crystal particles of its solid soln. are zirconium oxychloride, yttrium chloride, aluminium trichloride, etc., and suitable precipitating agents to be used for the coprecipitation of these compds. are lithium hydroxide, sodium hydroxide, ammonium carbonate, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a complex oxide having a plate-like shape with a fine and uniform particle size, solid solution crystal fine particles thereof, and a method for producing the same.

(Prior Art) Composite oxides and solid solution powders thereof are used as raw materials for structural materials such as processing tools and bearings, or as raw materials for functional materials such as ferrite, dielectrics, and piezoelectrics. In order to improve the properties of these materials, methods are being used to reduce the particle size of composite oxides and solid solution powders thereof. For example, the solid phase method involves repeatedly heating and heating the oxides of each component element that makes up the composite oxide and its solid solution, and then finely pulverizes it using a crusher; A liquid phase method is known in which a fine powder is obtained by co-precipitating a solution of an oxide dissolved in a solvent such as water with a precipitant and drying the resulting precipitate.

(Problems to be Solved by the Invention) However, in the conventional solid-phase method, the production efficiency is extremely low because the composite oxide and its solid solution are produced by repeatedly mixing the oxides of each component element and heat treatment. Moreover, since it is finely pulverized using a pulverizer, it is extremely difficult to pulverize it into uniform, fine particles. In addition, in the case of the liquid phase method, the obtained precipitate is likely to be amorphous, so heat treatment is required to crystallize it, but the powder may aggregate or grain growth may occur during the heat treatment. This has disadvantages such as

The present invention provides plate-like composite oxides and solid solutions thereof, which have a uniform crystal structure that can be uniformly mixed with other raw materials without agglomeration, and can improve the properties of materials when used as structural materials or functional materials. The object of the present invention is to provide crystalline fine particles and a method for producing the same.

(Means for Solving the Problems) The present invention was developed as a result of intensive studies on a method for producing a plate-like composite oxide and its solid solution crystal fine particles that achieve the above-mentioned objects. A composite oxide having a plate-like shape and a solid solution thereof can be obtained by mixing a precipitate obtained by mixing a solution of a compound of a component element with a precipitant and an aqueous solution of a fluxing agent, and heating the mixture after drying. We obtained the knowledge that fine particles can be obtained.

The present invention has been made based on such knowledge, and the first invention is a plate-shaped composite oxide and solid solution crystal fine particles thereof as a composite oxide and its solid solution.

The second invention is a method for producing the plate-like composite oxide and its solid solution crystal fine particles of the first invention, which comprises mixing a solution of a compound of each component element constituting the composite oxide and its solid solution with a precipitating agent to co-precipitate. The mixed solution of the obtained precipitate and the water-soluble fluxing agent solution is dried, the obtained mixture is heated above the melting point of the fluxing agent, and the precipitated composite oxide and its solid solution crystal particles are mixed with the fluxing agent. It is characterized by separating and removing from.

The compounds of each component element used in the production of the composite oxide and its solid solution crystal particles of the present invention include zirconium oxychloride,
Yttrium chloride, titanium tetrachloride, aluminum trichloride, niobium pentachloride, tantalum pentachloride, zinc chloride, etc. are optional. Precipitating agents used for coprecipitation of these compounds include lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia. Water, ammonium carbonate, etc. are optional.

In addition, there is no particular limitation on the method of mixing a solution of the compound of each component element constituting the composite oxide and its solid solution with a precipitant and co-precipitating it to produce a precipitate. Either the coprecipitation method or the alkoxide method, which has been carried out since 1999, may be used. Further, the precipitate produced by coprecipitation may be in either a non-quality state or a crystalline state. In particular, if it is desired to obtain highly pure and uniform plate-shaped crystalline fine particles, the primary particle diameter of the precipitated particles produced by coprecipitation may be made as small as possible. When a solution of a compound of each component element constituting a complex oxide and its solid solution is mixed with a precipitant to produce a precipitate by co-precipitation, a salt is produced along with the precipitate. If it is used as a water-soluble fluxing agent in the production method of the invention, the process of separating and removing formed salts during the production process of crystalline fine particles becomes unnecessary and production can be carried out efficiently. The water-soluble fluxing agent is not particularly limited, and must have extremely low reactivity with the resulting composite oxide and its solid solution, be inert, have a low melting point that melts at least at a temperature of 1000°C or lower, and have a temperature higher than the melting point. The vapor pressure during process 111 is 1#ll
It is preferable to consider a low pressure of 11 Hg or less, and for example, chlorides such as lithium chloride and sodium chloride, and sulfates such as lithium sulfate and sodium sulfate are used. Any method such as a spray dryer method may be used to dry the mixed solution of the precipitate and the aqueous solution of the water-soluble fluxing agent, especially when it is desired to obtain a highly pure and uniform plate-shaped composite oxide and its solid solution crystal fine particles. In this case, it is preferable to use a drying method that uniformly coats the primary particles of the precipitate with the fluxing agent.

The reason why the heat treatment temperature of the mixture of the precipitate and the fluxing agent is set above the melting point of the 7lux agent is to ensure that the precipitate is sufficiently dissolved in the 7lux agent. The higher the heat treatment temperature is, the more oxide solid solution crystal particles with higher crystallinity and larger particle size will be precipitated. Although there is no particular limitation on the temperature increase rate, the diameter of the precipitated oxide solid solution crystal particles will increase if the temperature decrease rate is slowed down; This will reduce the diameter of the precipitated particles, so it should be adjusted as appropriate depending on the use of the obtained plate-shaped oxide solid solution crystal particles.

(Example) Next, specific examples of the method for producing the plate-like composite oxide and solid solution crystal fine particles of the present invention will be described together with comparative examples.

Example 1 Zirconium oxychloride (ZrOCj!28)+20
1st Rare Element @, purity 99.0%) 0.1iol
and zirconium oxide in zirconium oxychloride (Z
Yttrium oxide (1.0iol, 2.01110 in terms of Yz(h)) per Omol
1.3.0nol, 4. O+aol, 5, Omo1
% yttrium chloride (YCj!3, manufactured by Shin-Etsu Chemical,
(purity: 9%, 9%) and 200% pure water were added to prepare respective aqueous solutions. Next, add a reagent-grade lithium hydroxide aqueous solution (Limit H2O, manufactured by Kanto Kagaku ■, purity 9) to each aqueous solution.
5.0% 0.2m01) 1000- was added and coprecipitated to obtain each precipitate. The pH value measured at this time was 9.
．． It was 0. Furthermore, 0% of reagent grade lithium chloride (L i C1, manufactured by Kanto Kagaku ■, purity 99.0%) was added to each precipitate.
．． After adding and dissolving 2s+ol and thoroughly stirring and mixing, the mixtures were dried by a spray dryer method to obtain respective powder mixtures. Next, 5 g of each dry mixed powder was placed in separate aluminum crucibles, heated in an electric furnace at a temperature of 800° C. for 1 hour, and then cooled to room temperature. Note that the temperature increase rate and temperature decrease rate before and after this heat treatment were each 300° C./hour. Subsequently, pure water was added to each heat-treated product cooled to room temperature to elute only the fluxing agent (LiCj), and the precipitated oxide solid solution crystal particles were separated using a centrifuge.

Furthermore, the separated oxide solid solution crystal particles were washed several times with pure water to remove the fluxing agent remaining on the surface of the crystal particles. Next, the washed crystal particles were dried at a temperature of 100° C. for 3 hours.

Analysis of the obtained crystal particles by X-ray diffraction revealed that a solid solution (Z) consisting of zirconium oxide and yttrium oxide
rY205) was confirmed to be crystal fine particles. In addition, in the diffraction pattern of the X-ray diffraction method, the diffraction surface (11T) of monoclinic zirconia (which shows the crystal structure when there are few yttrium oxide-containing holes in the siliconium oxide particles)
Compare the diffraction peak intensity of the diffraction peak intensity of 111 with that of the diffraction plane (111) of tetragonal or cubic zirconia (which shows the crystal structure when the yttrium oxide content is high in the silicon oxide particles). The tetragonal content was investigated for each amount of yttrium oxide added.

The results are shown in FIG.

In addition, these crystal particles were examined using a transmission electron microscope (magnification: so, o
As shown in the second figure, the particle size is 0.1~
It was confirmed that uniform plate-like crystal fine particles of 0.2 μm were obtained.

Comparative Example: 0.1 iol of zirconium oxide (ZrO2, manufactured by rare element@J, purity 99.9%) and 1.0 iol of zirconium oxide (Zr02), Omo
1%, 2. Omo1%, 3. Omo1%, 4. Omo
1%, 5, Ono 1% yttrium oxide (Yz
(h, manufactured by Shin-Etsu Chemical @, purity 999%) and reagent-grade lithium chloride (LiCj!.

(manufactured by Kanto Kagaku ■, purity 99.0%)) were mixed in a ball mill using water as a medium, and then the mixture was dried at a temperature of 120° C. for 24 hours. The heat treatment and subsequent treatments of each of the obtained dry mixture powders were performed in the same manner as in Example 1 to obtain crystal particles of a solid solution consisting of zirconium oxide and yttrium oxide.

The obtained crystal particles were subjected to X-ray diffraction, and based on the diffraction pattern, the content of yttrium oxide to zirconium oxide as in Example 1 was determined. The results are shown in FIG.

When this crystal grain was observed with a transmission type electron Wl mirror, the grain size was approximately 13 μm.

As shown in Figure 1, in Example 1, even if the amount of yttrium oxide added to zirconium oxide is small compared to the comparative example, both oxides can dissolve and form a solid solution with a uniform crystal structure. This was confirmed.

Therefore, the oxide solid solution of the present invention is a fine particle made of high-purity crystals, and each particle is separated and independent without agglomeration, so it can be used as a raw material for structural materials such as processing tools and bearings, or as a raw material for ferrite, When used as a raw material for functional materials such as dielectrics and piezoelectric materials, it can be easily dispersed and mixed with other raw materials to obtain a mixed material, and can improve properties such as mechanical strength. Furthermore, since the particles have a plate-like shape, particle orientation is possible, and the piezoelectric properties of materials such as piezoelectric bodies that have axial anisotropy can be significantly improved.

Example 2 Using the same materials as in Example 1, the heat treatment conditions were set to a temperature of 10
Zirconium oxide and yttrium oxide were treated in the same manner as in Example 1, except that heating was carried out at 0°C for 1 hour, and the temperature increase rate before and after the heat treatment was 300°C/hour, and the temperature cooling rate was 700°C/hour. A solid solution of plate-like crystal fine particles was obtained.

The obtained crystalline fine particles were subjected to a transmission electron microscope (magnification: IOO,
As shown in the third diagram, the particle size was 100
There was a uniformity of ~200 people.

Example 3 Zirconium oxychloride (ZrOC1281120, manufactured by Rare Element ■, purity 99.0%) 0.1 mol and titanium tetrachloride (TiC, manufactured by Osaka Titanium ■, purity 99)
, 9%) 0.1101 and 200 m of pure water were added to prepare an aqueous solution. This aqueous solution contains reagent grade lithium hydroxide aqueous solution (LtOt) lhO, manufactured by Kanto Kagaku H, purity 99.0%,
0.6 mol) 100G- was added thereto for coprecipitation to obtain a precipitate. The 011 value measured at this time was 1.0.

To this precipitate, 0.4 mol of reagent special grade lithium chloride (LiC1!, manufactured by Kanto Kagaku ■, purity 99.0%) was added and dissolved, thoroughly stirred and mixed, and then dried by a spray dryer method to obtain a powder mixture. Ta. Next, put this dry mixed powder into an aluminum crucible and heat it in an electric furnace at a temperature of 700℃ for 1 hour.
It was cooled to normal temperature after being subjected to heat treatment for an hour. The temperature increase rate and temperature decrease rate before and after this heat treatment were each 300℃.
/ time. Next, pure water is added to the heat-treated product that has been cooled to room temperature to elute only the fluxing agent (LiCj), and the precipitated oxide solid solution crystal particles are separated using a centrifuge. Washing was repeated several times to remove the fluxing agent remaining on the surface of the crystal particles. The washed crystal particles were then dried at a temperature of 100° C. for 3 hours. Analysis of the obtained crystal particles by X-ray diffraction revealed that they were a solid solution of zirconium oxide and titanium oxide (ZrTiO
*) was confirmed to be crystal fine particles. Furthermore, when the crystal fine particles were observed using a transmission electron microscope 111 (magnification 10G, 0.00x), the particle size was 200 to 300, as shown in Figure 4.
The people were uniform.

(Effects of the Invention) According to the present invention, the first invention is a plate-shaped composite oxide and its solid solution crystal fine particles. Therefore, when used as a raw material for structural materials or functional materials, it can be uniformly dispersed and mixed with other raw materials without agglomeration, and because the particles have a uniform crystal structure, it has the effect of improving the characteristic values of the material. .

Further, the method for producing a plate-shaped composite oxide and its solid solution crystal fine particles according to the second invention includes mixing a solution of a compound of each component element constituting the oxide solid solution and a precipitating agent to co-precipitate the resulting precipitate. A mixed solution of the fluxing agent and a water-soluble fluxing agent solution is dried, the resulting mixture is heated above the melting point of the fluxing agent, and the precipitated oxide solid solution crystal particles are separated and removed from the fluxing agent. This method has the advantage that it has a uniform crystal structure that could not be obtained by conventional methods, and that plate-shaped composite oxides and solid solution crystal fine particles thereof can be produced with high purity and extremely easily.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the amount of yttrium oxide added to zirconium oxide and the content of tetragonal or cubic crystals, and FIG. 2 is a diagram showing the relationship between the amount of yttrium oxide added to zirconium oxide and the content of tetragonal or cubic crystals. FIG. Transmission electron micrographs of crystalline fine particles, FIGS. 3 and 4 are transmission electron micrographs of plate-shaped oxide solid solution crystalline fine particles obtained by another implementation of the production method of the present invention. Outer figure 1

Claims (1)

[Claims] 1. A plate-like composite oxide and its solid solution crystal fine particles. 2. A solution of the compound of each component element constituting the composite oxide and its solid solution is mixed with a precipitant to cause coprecipitation, and a mixed solution of the obtained precipitate and a water-soluble fluxing agent solution is dried. A method for producing a plate-shaped composite oxide and solid solution crystal fine particles thereof, which comprises heating the obtained mixture above the melting point of the flux agent, and separating and removing precipitated oxide solid solution crystal particles from the flux agent.