JPH0132167B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a compositionally controlled multi-component inorganic fine powder that is a raw material for inorganic materials such as glass and ceramics.

(Prior art) For inorganic materials such as glass and ceramics, the composition is generally the most important factor that determines their properties, and whether or not the composition can be completely controlled is the deciding factor for the development of excellent inorganic materials. .

For example, some types of ceramics are required to have a strict stoichiometric composition in order to maximize their properties, while other ceramics only achieve their properties by intentionally shifting the composition from the stoichiometric composition. Sometimes it is demonstrated. Furthermore, in other ceramics, functions may only be imparted by introducing trace amounts of additives.

On the other hand, controlling the composition of raw materials is also important for glass, and strict composition control is required to control the refractive index of optical glasses and optical fibers.

Furthermore, the inventors have developed a glass laser with excellent characteristics by doping silica glass with a combination of active ions such as Nd ³⁺ and co-dopants such as Al ₂ O ₃ or ₂ O ₅ . However, even in this case, the relative ratio of active ions and co-dopants is extremely sensitively reflected in the laser characteristics (Japanese Patent Laid-Open No. 60-11245). For example, if Nd ³⁺ is used as an active ion,
The optimal value when using Al ₂ O ₃ as a co-dopant is
Al ₂ O ₃ /Nd ₂ O ₃ ~ 10, below which the luminous efficiency cannot be made sufficiently high, and on the other hand, when it is above that, the base glass will deteriorate its laser properties such as a decline in heat load resistance and induction of optical damage. Something bad happens to you. Therefore, in this case as well, the composition ratio of trace amounts of additives must be strictly controlled.

Until now, inorganic materials have often been produced by physically mixing the raw material powders of each component in a predetermined ratio, and then repeating the calcining-pulverization or melting-pulverization process to promote uniform dispersion of the components, followed by sintering. Materials with desired compositions have been synthesized by freezing or melting them.

(Problems to be Solved by the Invention) However, such a method is very time consuming and it is also difficult to avoid the contamination of impurities during the process. In particular, it is almost impossible to uniformly disperse trace amounts of additives using this method.

In order to avoid such problems, a method has recently been developed to synthesize fine powder with a controlled composition by hydrolyzing a metal alkoxide solution prepared to a predetermined composition. It has the disadvantage of being expensive.

Furthermore, a method is known in which fine powder is synthesized by preparing a predetermined composition by a gas phase method. In this case, uniform dispersion of the components is guaranteed, but in order to strictly control the composition, advanced technology is required to control the vapor pressure, flow rate, etc. of the component gases. In particular, when controlling the amount of doping of two or more trace components, the technical difficulties increase dramatically.

On the other hand, in a solution state, it is generally technically easier to prepare a predetermined composition ratio than in a solid or gaseous state. Therefore, if such a solution is physically aerosolized using ultrasonic waves and reacted to form the desired compound, fine powder of the compound that maintains the composition ratio of the metals contained in the solution can be created. You should be able to get it.

This invention was completed as a result of intensive research based on the above findings with the aim of developing a method for obtaining fine powder with a controlled composition without requiring sophisticated control technology.

(Means for Solving the Problems) In order to solve the above problems, the first invention of the present application includes one or more other inorganic cation salts in a predetermined ratio in a liquid inorganic cation salt. A non-aqueous solution is prepared by dissolving the non-aqueous solution, and the non-aqueous solution is aerosolized and introduced into a reaction system, and the cations in the non-aqueous solution are reacted to produce inorganic fine powders made of various cationic compounds.

Here, the liquid inorganic cation salt is SiCl ₄ ,
Those that are liquid at room temperature such as TiCl ₄ , BBr ₃ , GeCl ₄ are used, and other inorganic cation salts can be dissolved in any ratio in the above liquid inorganic cation salts.
POCl ₃ etc. and Nd which has high solubility in the coexistence of POCl 3 etc.
Rare earth perchlorates such as (ClO ₄ ) ₃ can be used.

Further, in the reaction system, reactions such as oxidation and hydrolysis are carried out to produce inorganic fine powders made of oxides of various cations.

However, as in the first invention of the present application, the type and amount of the inorganic cation salt that can be dissolved in the liquid inorganic cation salt is extremely limited.

Therefore, in the second invention of the present application, an aqueous solution is prepared by dissolving a predetermined amount of one or more inorganic cation salts, and on the other hand, the aerosolized aqueous solution and another gasified inorganic cation salt are added to the reaction system. A fine powder consisting of oxides of various cations is produced by introducing the ions and causing a hydrolysis reaction.

Here, the one or more inorganic cation salts are not limited to the salt form as long as they form an aqueous solution, and may be nitrates or the like.

In addition, any other inorganic cation salt to be gasified may be used as long as it is easily hydrolyzed, and in addition to SiCl ₄ , TiCl ₄ , BBr ₃ , Si(OC ₂ H ₅ ) ₄ , etc. can be used. can.

(Function) According to the first invention of the present application, a non-aqueous solution is prepared by dissolving one or more other inorganic cation salts in a predetermined ratio into a liquid inorganic cation salt, and this non-aqueous solution is used as an aerosol. into the reaction system,
Here, since the cations in the non-aqueous solution undergo reactions such as hydrolysis, it is possible to obtain a compositionally controlled inorganic fine powder containing a predetermined amount of various cationic compounds.

However, as mentioned above, the type and amount of the inorganic cation salt that can be dissolved in the liquid inorganic cation salt is extremely limited, but according to the second invention of the present application, there is no such limitation and moreover, Fine powder with controlled composition can be obtained without the need for control technology.

This is obtained by aerosolizing an aqueous solution containing a predetermined amount of one or more inorganic cation salts and introducing it into a reaction system, where it is hydrolyzed together with other gasified inorganic cation salts. This method utilizes the fact that the amount of oxide produced from the inorganic cation salt is determined by the concentration of the aqueous solution.

This method was applied to co-doped Nd ³⁺ and Al ₂ O ₃
An example of synthesis of SiO ₂ fine powder will be explained.

In this case, SiCl ₄ , NdCl ₃ , and AlCl ₃ are used as raw materials, but in general, NdCl ₃ and AlCl ₃ are more difficult to hydrolyze than SiCl ₄ , and the following procedure is required because it is necessary to obtain fine powder. becomes.

First, an aqueous solution containing a predetermined amount of NdCl ₃ and AlCl ₃ is prepared, this aqueous solution is aerosolized using an appropriate method such as an ultrasonic nebulizer, and passed through a temperature of 1000°C or higher together with an inert gas such as Ar. ₃ and AlCl ₃ to hydrolyze Nd ₂ O ₃ ,
After generating a gas mixture of ultrafine particles of Al ₂ O ₃ or a mixture thereof and water vapor, this gas mixture is
React the SiCl ₄ gas.

As a result, SiCl ₄ is immediately hydrolyzed by the water vapor, and ultrafine SiO ₂ particles are generated.

At this time, if the amount of SiCl ₄ is sufficient, the amount of SiO ₂ ultrafine particles produced is determined by the amount of water vapor in the mixed gas, and excess SiCl ₄ leaves the system. As a result,
The amount of Nd ₂ O ₃ and Al ₂ O ₃ introduced into SiO _{2 is}
It is uniquely determined by the concentration of the aqueous solution of AlCl ₃ .

Now, an aqueous solution of the molar ratio xNdCl ₃ + yAlCl ₃ + (100−x−y)H ₂ O (1) is aerosolized at a temperature sufficient for NdCl ₃ and AlCl ₃ to form oxides by hydrolysis. When reacted, xNdCl ₃ +3/2xH ₂ O →x/2Nd ₂ O ₃ +3HCl↑ (2) yAlCl ₃ +3/2yH ₂ O →y/2Al ₂ O ₃ +3HCl↑ (3), and the remaining H ₂ The amount of O is (100-x-y-3/2x-3/2y) _H2O = (100-5/2x-5/2y) _H2O (4).

When this H ₂ O reacts with a sufficient amount of SiCl ₄ (100-5/2x-5/2y) H ₂ O + 1/2 (100-
5/2x-5/2y) SiCl ₄ → 1/2 (100-5/2x-5/2y) SiO ₂ +
2(100-5/2x-5/2y)HCl↑(5) As a result, from (2), (3), and (5), xNd ₂ O ₃・yAl ₂ O ₃・(100-5/2x-5 /2y)SiO ₂ (6) A fine powder with the composition will be formed.

Now, starting from an aqueous solution with x=0.3 and y=3, a fine powder of 0.3Nd ₂ O ₃・3.2Al ₂ O ₃・96.5SiO ₂ (7) is formed.

(Example) Examples of this invention will be shown below.

In order to obtain a raw material powder for laser glass that uses Nd ³⁺ as an active ion and uses silica glass as a matrix, Nd ³⁺
A powder containing 0.3 mol% of P ₂ O ₅ and co-doped with P/Nd to 10 was produced.

POCl ₃ was used as a raw material for P ₂ O ₅ and Nd(ClO ₄ ) ₃ was used as a raw material for Nd. SiCl ₄ and POCl ₃ are mixed in the entire composition range. On the other hand, Nd(ClO ₄ ) ₃ is difficult to mix with SiCl ₄ , but when POCl ₃ is added, it mixes uniformly. Therefore, a mixed non-aqueous solution containing 0.3 mol % of Nd(ClO ₄ ) ₃ , 3 mol % of POCl ₃ , and 96.7 mol % of SiCl ₄ was prepared. The mixed non-aqueous solution prepared above was aerosolized using an ultrasonic nebulizer and reacted with water vapor at 1000℃ in a furnace. A powder was obtained.

Example 2 The drawing shows an apparatus for producing inorganic fine powder used in Example 2, in which 1 has an ultrasonic vibrator 2 at the bottom.
3 is a quartz or magnetic reaction tube having an electric furnace 4 on its outer periphery; 5 is a bubbler; a transport pipe 6 is connected to the top of the ultrasonic nebulizer 1; An aerosol introduction tube 7 is connected to the tip, and the aerosol introduction tube 7 is inserted into the reaction tube 3.

In addition, a transport pipe 8 is connected to the top of the bubbler 5,
An introduction tube 9 is connected to the tip of the transport tube 8, and the introduction tube 9 is inserted into the reaction tube 3.

Note that a collection bottle 10 is provided at the bottom of the reaction tube 3.

An aqueous solution of NdCl ₃ and AlCl ₃ adjusted at a predetermined ratio is put into the ultrasonic nebulizer 1, and the bubbler 5
_Four SiCl liquids are placed inside.

The aqueous solution contained in the ultrasonic nebulizer 1 is aerosolized by the ultrasonic vibrator 2, and this aerosolized aqueous solution is transported to the argon gas introduced through the introduction tube 11 and released into the center of the reaction tube 3. Ru. On the other hand, the inside of the reaction tube 3 is heated by an electric furnace 4 to a temperature of 1000°C or higher at its center.
Therefore, NdCl ₃ and AlCl ₃ in the aerosol are hydrolyzed to become ultrafine particles of Nd ₂ O ₃ , Al ₂ O ₃ or their compounds, which are released into the reaction tube 3 together with the water vapor evaporated from the aerosol.

On the other hand, the SiCl ₄ liquid in the bubbler 5 is transported by argon gas and introduced into the reaction tube 3 from the tip of the introduction tube 9, where the SiCl ₄ is immediately hydrolyzed by the water vapor evaporated from the aerosol and converted into SiO ₂ fine particles. Become. At this time, it is expected that the SiO ₂ fine particles are formed using ultrafine particles such as Nd ₂ O ₃ and Al ₂ O ₃ as nuclei.

The fine powder 12 generated in this way is collected in the collection bottle 1.
0, unreacted SiCl ₄ and reaction product gas
HCl is exhausted from the exhaust port 13.

When the above example was carried out with an aqueous solution of 0.3NdCl ₃ 3AlCl ₃ 96.7H ₂ O housed in the ultrasonic nebulizer 1, the composition was controlled to the theoretical value of equation (7) above within analytical error. A fine powder could be obtained. Furthermore
A composition-controlled fine powder containing four components, Cr ₂ O ₃ .Nd ₂ O ₃ .Al ₂ O ₃ and SiO ₂ , can also be obtained by this method.

An important condition for obtaining fine powder with a controlled composition using this method is to introduce SiCl ₄ into the reaction tube in excess of the amount of water vapor generated from the aerosol that is hydrolyzed; however, the amount of SiCl ₄ introduced can be easily controlled by a known method of adjusting the temperature of the bubbler 5 and the flow rate of the argon gas to be transported.

On the other hand, the amount of aerosol can be easily controlled by the input to the ultrasonic nebulizer and the flow rate of argon for aerosol delivery. At this time, in order to keep the water level of the aqueous solution constant, it is necessary to replenish the aqueous solution from the supply pipe 14, which is connected to a water level holding device (not shown) provided on the lower side of the ultrasonic nebulizer 1.

(Effects of the Invention) In summary, according to the present invention, a multi-component inorganic fine powder with a precisely controlled composition can be produced under extremely easy manufacturing conditions by using a non-aqueous solution or an aqueous solution with a precisely adjusted composition ratio. Therefore, it is possible to produce raw material fine powders for various types of glasses and ceramics whose compositions are more precisely controlled, and has an extremely wide range of applications.

[Brief explanation of drawings]

The drawings are schematic diagrams showing one embodiment of the invention. In the figure, 1 is an ultrasonic nebulizer, 2 is an ultrasonic vibrator, 3 is a reaction tube, and 5 is a bubbler.

Claims (1)

[Claims] 1. A non-aqueous solution is prepared by dissolving one or more other inorganic cation salts in a predetermined ratio into a liquid inorganic cation salt, and the non-aqueous solution is further aerosolized to form a reaction system. A method for producing a multi-component inorganic fine powder, characterized in that the cations in the non-aqueous solution are reacted to produce an inorganic fine powder comprising various cationic compounds. 2 SiCl ₄ TiCl ₄ as a liquid inorganic cation salt,
The method according to claim 1, wherein BBr ₃ and GeCl ₄ are used. 3. The method according to claim 1, wherein a rare earth perchlorate, POCl ₃ , is used as the other inorganic cation salt. 4 Prepare an aqueous solution by dissolving a predetermined amount of one or more inorganic cation salts, and introduce the aerosolized aqueous solution and other gasified inorganic cation salts into the reaction system to carry out a hydrolysis reaction. 1. A method for producing a multi-component inorganic fine powder, characterized in that the inorganic fine powder is made of oxides of various cations. 5. The method according to claim 4, wherein the gasified other inorganic cation salt is supplied to the reaction system in excess of the aqueous solution.