JP2005162562A - Method for manufacturing crystalline ceramic particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a crystalline ceramic particle useful for a catalyst, a photocatalyst and the like without high temperature firing and a crushing step from the amorphous particle of a compound or a composite compound containing each element among Ti, Zr, Zn, Sn, In and Si. <P>SOLUTION: A crystalline TiO<SB>2</SB>or SiO<SB>2</SB>-TiO<SB>2</SB>particle is manufactured by applying impulse force, for example with ball milling, to the amorphous particle of the compound, for example a TiO<SB>2</SB>or SiO<SB>2</SB>-TiO<SB>2</SB>particle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing crystalline ceramic particles. More specifically, the present invention relates to a method for producing crystalline ceramic particles without the need for high temperature firing. The crystalline ceramic particles obtained by the method of the present invention are useful as, for example, oxide-based catalyst particles, photocatalyst particles, and transparent conductive ceramic particles for electronic and electrical materials.

  Conventionally, as a method for producing highly functional crystalline ceramic fine particles used as a catalyst, a photocatalyst, and a conductive oxide, a raw material salt is dissolved in water, an alkali solution is added thereto, and amorphous hydration oxidation is performed. The most common method is to form a precipitate of the product, wash, dry and pulverize it into a raw material powder, calcinate at a temperature of several hundred to several thousand degrees, crystallize, pulverize and atomize again. is there.

  However, according to this method, many steps are required, the crystal is coarsened by high-temperature firing, and it is necessary to pulverize again for a long time in order to obtain a fine crystal, and the crystal grain size becomes uneven. There was a problem such as.

  On the other hand, in the case of oxide particles that are relatively easy to crystallize, such as titanium oxide, titanium hydrate compound raw material is placed in an autoclave reaction vessel in Japanese Patent Application Laid-Open No. 5-163022. , A method of hydrolyzing at a temperature of 170 ° C. or higher is disclosed, and according to crystallization by such a hydrothermal synthesis reaction, oxide fine particles having relatively good crystallinity undergo a firing and pulverization step. It is known that it can be synthesized without any problems.

However, it is difficult to crystallize by SiO ₂ -TiO ₂ -based amorphous composite oxide, hydrated composite oxide, ZrO ₂ , SnO _2, etc. because of hydrothermal reaction. In order to produce, the high temperature baking process and the grinding | pulverization process were indispensable.

  In contrast to these conventional manufacturing methods, Japanese Patent Application Laid-Open No. 2003-73125 (Patent Document 2) discloses a technique for synthesizing an optical material yttrium / aluminum / iron-based oxide at a low temperature while applying a mechanical impact force in a ball mill. ). However, the possibility of synthesizing compound particles containing Ti, Zr, Zn, Sn, In, and Si, and catalyst / photocatalyst materials and conductive materials by this method is disclosed in Patent Document 2. Absent. In addition, Patent Document 2 has no description or suggestion about converting amorphous particles synthesized in advance into crystalline particles by mechanical milling treatment.

  Also, in published patent publication 2003-507300 (Patent Document 3), a raw material solution obtained by adding a chemical control agent to a titanium chloride solution is hydrolyzed at a temperature lower than the crystallization temperature, and then the product is baked to produce crystals. Although a method for obtaining titanium oxide crystal powder particles by milling this is disclosed, crystallization in this method is performed by firing at 450 ° C. or higher, so that the crystal is prevented from being coarsened by heating. Was difficult.

JP-A-5-163022 “Spherical anatase type titanium dioxide and method for producing the same” JP 2003-73125 A “Method for Producing Yttrium / Aluminum / Iron Composite Oxide” Japanese Patent Publication No. 2003-507300 “Method for producing ultrafine titanium dioxide from aqueous titanium chloride solution”

  In the present invention, particles of a compound containing Ti, Zr, Zn, Sn, In, and Si, which have been difficult to crystallize unless fired at a high temperature, and crystalline ceramic particles of a catalyst / photocatalyst material and a conductive material, It is an object of the present invention to provide a method for manufacturing in a room temperature environment without requiring a complicated and long manufacturing process or special equipment.

According to the method for producing crystalline ceramic particles of the present invention, at least one of a compound containing at least one element selected from Ti, Zr, Zn, Sn, In, and Si and an amorphous particle of a composite compound is applied with an impact force. The amorphous particles are converted into crystalline ceramic particles by subjecting to an additional treatment.
In the method for producing crystalline ceramic particles of the present invention, the compound is preferably selected from an oxide containing at least one of the elements and a hydrated oxide.
In the method for producing crystalline ceramic particles of the present invention, it is preferable that each of the oxide and the hydrated oxide is synthesized by a liquid phase reaction method.
In the method for producing crystalline ceramic particles of the present invention, the treatment for applying the impact force is preferably performed by a mechanical milling method.
In the method for producing crystalline ceramic particles of the present invention, the treatment for applying the impact force is preferably performed in the air or in a non-oxidizing atmosphere.
In the method for producing crystalline ceramic particles of the present invention, the crystalline ceramic particles are at least one selected from titanium oxide, zirconium oxide, zinc oxide, tin oxide, indium oxide, silicon oxide, and indium-tin mixed oxide. It is preferable to contain.

  The method for producing crystalline ceramic particles of the present invention can produce ceramic particles having a high crystallinity and a uniform particle size without the need for a high-temperature firing step and a pulverizing step, and is produced by the method of the present invention. The crystalline ceramic particles are practically useful as chemical reaction catalysts, photocatalysts, visible light responsive catalysts, transparent conductive particles, and the like.

  The raw material used in the method of the present invention is an amorphous particle of a compound and / or a composite compound containing at least one element selected from the element group consisting of Ti, Zr, Zn, Sn, In and Si. The compound constituting the particle may be a compound containing one of the above elements, or a composite compound containing two or more thereof, and at least one of the above elements and the element It may be a complex compound containing at least one kind of different elements. The above compounds and composite compounds may be used alone or as a mixture of two or more thereof. The complex compound may be a complex compound, or may be a doped compound doped with one of the elements, an element different from the element, or a compound thereof.

The compound or composite compound used as a raw material for the method of the present invention includes oxides, hydrated oxides, nitrides, borides and the like, and among these, it is preferable to be selected from oxides and hydrated oxides.
For example, one or more alkoxides of the above element group, for example, titanium butoxide, zirconium isopropoxide, tetraethylorthosilicate, etc. are hydrolyzed at a low temperature (for example, 0 to 80 ° C.) to form amorphous hydrated titanium dioxide. Hydrated zirconium oxide or hydrated silicon dioxide particles formed and dried at a temperature not crystallizing (eg 50 to 300 ° C.), or titanium chloride, zirconium nitrate, zinc nitrate, stannous chloride For example, an aqueous solution of a metal salt such as indium chloride is added with an alkaline aqueous solution such as aqueous ammonia, and the resulting amorphous precipitated particles of the hydrated oxide are separated and washed.

The amorphous particles of the compound or composite compound used as the raw material of the method of the present invention are preferably dried in advance at a temperature at which they do not crystallize, but they are in a gel or slurry containing water. It may be a thing.
The particle size and particle shape of the amorphous particles are not limited. In general, the particle size of the amorphous particles is preferably in the range of 1 to 1000 μm, more preferably 10 to 100 μm.

In the method of the present invention, the amorphous particles of the compound or composite compound of the element group used as a raw material are subjected to a treatment for applying a mechanical impact force. In this impact force addition treatment, the acceleration of the impact force applied to the amorphous particles is preferably 9.8 to 9.8 × 10 ² m / s ² (1 to 100 G), more preferably 49. It is -490m / s < ² > (5-50G). When the acceleration of the impact force exceeds 9.8 × 10 ² m / s ² , a part of the impact imparting material may be mixed (contaminated) in the impacted material. On the other hand, if it is less than 9.8 m / s ² , the desired amorphous to crystalline conversion may be insufficient.
In the method of the present invention, means for applying a mechanical impact force to the amorphous particles is not limited, but a mechanical milling method and production, or an impact press method and apparatus can be used. Among these, it is preferable to use a mechanical milling method and production, for example, a ball mill or a bead mill, and the milling balls and beads are preferably formed of a hard material such as glass, zirconia, titania, alumina, and stainless steel.

In the method of the present invention, the impact force addition treatment is preferably performed at a temperature of 200 ° C. or lower, more preferably a treatment temperature of 0 to 80 ° C., more preferably a normal temperature. Further, the impact force addition treatment may be performed in the air, or may be performed in a non-oxidizing atmosphere. When the impact force of the method of the present invention is to produce conductive crystalline particles or catalyst particles by giving defects of constituent atoms, for example, oxygen atom defects, to the amorphous particles in the addition step, the impact force addition treatment is performed as follows: It is preferably applied in a non-oxidizing atmosphere. This non-oxidizing atmosphere may contain oxygen scavengers (such as ammonia and methyl ethyl ketoxime) and / or reducing agents (such as hydrazine and hydroxylamine sulfate), or nitrogen gas or argon gas, etc. A gas that is unreactive with the raw material particles and the product particles may be used.
There is no particular limitation on the atmospheric pressure during the impact force addition treatment of the method of the present invention, and it is generally preferably carried out within the range of atmospheric pressure ± 500 hPa, more preferably atmospheric pressure.

  The crystalline ceramic particles obtained by the method of the present invention are crystalline ceramic particles such as crystalline titanium oxide, zirconium oxide, zinc oxide, tin oxide, indium oxide, ITO (cindium-tin, composite oxide), and silicon oxide. Is included.

  The titanium oxide includes crystalline anatase-type titanium dioxide, crystalline rutile-type titanium dioxide, crystalline brookite-type titanium dioxide, oxygen atom-deficient (defect) -type crystalline titanium dioxide (including both anatase-type rutile type), and Includes crystalline visible light reactive titanium dioxide such as nitrogen doped crystalline titanium dioxide.

The zinc oxide includes crystalline ZnO, oxygen-deficient crystalline zinc oxide, heterogeneous element doped crystalline zinc oxide (eg, Al-doped crystalline conductive zinc oxide),
In the method of the present invention, when amorphous particles of a composite compound containing two or more of Ti, Zr, Zn, Sn, In and Si elements are used as raw materials, the crystalline particles or doped crystallinity of these composite compounds Particles can be obtained. For example, in the method of the present invention, when a mixture of Sn amorphous compound particles and In amorphous compound particles is used as a starting material, Sn-doped In compound (ITO) crystalline particles can be obtained. .

Examples The process of the present invention is further illustrated by the following examples.

17.9 g Si (OC ₂ H ₅ ) ₄ was dissolved in 19.8 g ethanol and dilute hydrochloric acid (3.9%, 6.4 g) was added to this solution. After the solution is thoroughly stirred, 9.74 g Ti (OC ₄ H ₉ ) ₄ and 26.4 g ethanol are mixed with it, and the mixture is stirred in an oven at a temperature of 50 ° C. Gelled.
2 g of the obtained Si—Ti hydrated oxide mixed gel was placed in a planetary ball mill (ball diameter: 10 nm, number of balls: 10, ball material: agate, number of revolutions: 720 rpm). In the atmosphere, ball milling was performed for 0 hour and 1 to 20 hours to cause gelation. The obtained gel (mixture in the case of processing time: 0) was subjected to an X-ray diffractometer to measure the crystallinity of the particles. The measured crystal is shown in FIG.
In Figure 1, a ball mill processing time in the case of 0, although not observed formation of crystalline grains, as the processing time increases, observed generation of the crystal structure of titanium dioxide, in the previous period, SiO ₂ from -TiO ₂ gels, generation of anatase TiO ₂ crystal grains was observed, in the latter, formation of rutile TiO ₂ crystal grains were observed.

Crystalline particles were produced in the same manner as in Example 1. However, Si (OC ₂ H ₅ ) ₄ was not used as a raw material. FIG. 2 shows the results of X-ray diffraction in which the ball milling time was changed within the range of 0 to 1 to 5 hours.
In FIG. 2, the generation of rutile TiO ₂ crystal particles was confirmed.

In Example 1, the processing rotation speed and processing time by the planetary ball mill are set to the following four stages:
None,
720 rpm x 40 hours,
720 rpm x 5 hours,
360 rpm x 80 hours,
The resulting SiO ₂ —TiO ₂ mixed gel was dispersed in an aqueous solution of a blue dye (methylene blue) and irradiated with ultraviolet light having an intensity of 1 mW / cm ² to measure the change in absorbance over time. Thus, the decomposition rate of methylene blue due to the photocatalytic action of the SiO ₂ —TiO ₂ crystal particles contained in the gel was measured. The measurement results are shown in FIG.
In FIG. 3, it was confirmed that anatase TiO ₂ crystalline particles were generated by mechanical milling of the mixed gel of SiO ₂ —TiO ₂ amorphous particles, and the crystalline particles had photocatalytic activity.

  Ammonia water (concentration: 200 g / liter) is added to an aqueous solution of titanium chloride (concentration: 50 g / liter) to neutralize it to produce a gel containing amorphous particles of hydrated titanium dioxide. Separately, it was dried at room temperature. 20 g of this dried gel was placed in a planetary ball mill and subjected to mechanical milling for 20 hours using 20 meno balls having a diameter of 10 mm at room temperature in an ammonia-containing reducing gas atmosphere. By X-ray diffraction analysis of the obtained particles, it was confirmed that titanium dioxide crystal particles were produced and doped with nitrogen.

  20 g of a 1: 9 mass ratio mixture of stannous chloride and indium chloride was dissolved in 1000 ml of water, and this aqueous solution was neutralized with aqueous ammonia to form a precipitate. The precipitated particles were separated, washed with water and dried at a temperature of 80 ° C. 10 g of this dried gel was subjected to the same ball milling treatment as in Example 4. When the obtained particles were subjected to X-ray diffraction analysis, it was confirmed that indium-tin and composite compound crystals were formed.

  The method of the present invention requires complicated and long-time processes such as a high-temperature firing process and a pulverizing process for crystalline particles containing at least one element of Ti, Zr, Zn, Sn, In, and Si having various functions. This makes it possible to manufacture easily. In addition, the method of the present invention can produce a catalyst, a photocatalyst, a visible light responsive photocatalyst, and conductive ceramic particles by appropriately setting the kind of amorphous particles used as the raw material and the treatment conditions for the impact force addition treatment. The crystalline particles produced by the method of the present invention include ceramics such as oxides, composite oxides, nitrides, borides, and sialon ceramic particles.

In Example 1, the ball milling of SiO ₂ -TiO ₂ composite compound, various ball chart showing the relationship between the change in X-ray diffraction pattern of variation between the obtained particles of milling conditions. In Example 2, the chart showing the ball milling of TiO _2, and the change of the ball milling time, the relationship between the change in X-ray diffraction pattern of the obtained particles. 3 is a chart showing a relationship between a change in ball milling treatment conditions and a change in concentration of a methylene blue aqueous solution in the ball milling treatment of the SiO ₂ —TiO ₂ composite compound in Example 1.

Explanation of symbols

R ... rutile TiO ₂
A ... anatase TiO ₂
Q ... SiO ₂ (Quartz)
R. T.A. ... rotation speed (rpm)
MB ... Methylene blue M ... mol

Claims (6)

  At least one amorphous particle of a compound containing at least one element selected from Ti, Zr, Zn, Sn, In and Si is subjected to a treatment for applying an impact force, and the amorphous particle is converted into a crystalline material. A method for producing crystalline ceramic particles, characterized by converting into ceramic particles.   The method for producing crystalline ceramic particles according to claim 1, wherein the compound is selected from an oxide containing at least one of the elements and a hydrated oxide.   The method for producing crystalline ceramic particles according to claim 2, wherein each of the oxide and the hydrated oxide is synthesized by a liquid phase reaction method.   The method for producing crystalline ceramic particles according to claim 1, wherein the treatment for applying the impact force is performed by a mechanical milling method.   The manufacturing method of the crystalline ceramic particle of Claim 1 or 4 with which the process which adds the said impact force is performed in air | atmosphere or non-oxidizing atmosphere.   The crystalline ceramic particles include at least one selected from titanium oxide, zirconium oxide, zinc oxide, tin oxide, indium oxide, silicon oxide, and indium-tin mixed oxide. The manufacturing method of the crystalline-ceramics particle | grains of description.

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