JPS6051699A - Manufacture of tin oxide single crystal - Google Patents

Abstract

PURPOSE:To obtain easily a large single crystal of tin oxide by using copper as a solvent for tin oxide to be dissolved. CONSTITUTION:Tin oxide as a solute and copper or an alloy of copper and metals such as tin and zinc for depressing the m.p. of copper as a solvent are mixed in the range of (5:95)-(1:99). The mixture is charged into a crucible, etc., and heated and melted in the atmosphere of an inert gas, etc. The melt is heated to a temp. higher than the m.p. of the solvent, and then cooled. The solidified material is taken out, and the solvent is dissolved with an acid or an alkali to obtain a tin oxide single crystal. A large single crystal of tin oxide having >=about 3X2X2mm. crystal size can be obtained by said method. The tin oxide single crystal can be used as a material for electronic parts and an infrared ray absorbent.

Description

[Detailed description of the invention] The present invention relates to a method for producing a tin oxide single crystal.

Since tin oxide is transparent and conductive, its single crystals are expected to be used as materials for electronic components and infrared absorbing materials.

Conventionally, tin oxide single crystals are produced by a gas phase method. According to this method, the crystal growth rate is slow and the crystals obtained are plate-shaped or needle-shaped, making it difficult to obtain a single crystal that can be put to practical use for many years.

An object of the present invention is to solve the above-mentioned problems and to provide a method for easily producing large tin oxide single crystals.

As a result of research to achieve the above object, the present inventor has discovered that a metal that lowers the melting point of @ or copper as a solvent is a metal that lowers the melting point of copper or copper and copper using tin oxide as a solute. This method uses an alloy of 1 as a solvent and allows tin oxide to be precipitated and grown as a single crystal from the solvent.

The ratio of the solute to the solvent may be either lower than or higher than the amount of tin oxide dissolved in copper. However, after single crystal precipitation and growth, single crystals are grown from the solidified melt. A preferred range is a ratio of tin oxide:copper of 5=95 to 1:99.

A mixture of tin oxide and copper is placed in a crucible and heated and melted in an inert gas atmosphere or an R& element atmosphere to the extent that the solvent is not oxidized. This is heated to a temperature higher than the melting point of the solvent, preferably 1300 to 1500°C, and immediately,
Alternatively, start cooling after holding for several hours. Since crystallinity deteriorates if the cooling rate is too fast, the cooling rate is set to 100°C or less per hour, preferably 20 to 1°C per hour. After the melt is solidified, it is slowly cooled down to room temperature. Take out the solidified material,
When this is dissolved in a solvent with an acid or alkali such as aqua regia, nitric acid, or aqueous ammonium, a tin oxide single crystal is obtained.

Precipitation of tin oxide single crystals at lower temperatures can be accomplished by using an alloy of copper and a metal that lowers the melting point of the copper. Examples of metals that lower the melting point of copper include tin and zinc. However, these metals have 1iIl! It is not limited, but any gold F1 that lowers the melting point may be used. It is not necessary to add these metals in advance as an alloy with copper, but it is sufficient to add these metals to the solvent. Depending on the type and amount of metal added, it is possible to adjust the red color. When tin is used, the melting point can be lowered to 400°C or lower.

When such a copper alloy is used as a solvent, a tin oxide single crystal can be precipitated and grown in the same manner as described above, with the only difference being the melting temperature.

Example 1 99.99% tin oxide 22 and 99.99% @io
.

This mixture was placed in an SSA-S aluminum crucible. This crucible is placed in an electric furnace where the atmospheric gas can be controlled, and the temperature is reduced to 10 times per minute using violet gas as the atmosphere.
It flowed. The temperature of the electric furnace is increased to 1300℃ at a rate of 50℃ per hour.
The mixture was melted by increasing the temperature to . After being held at this temperature for 8 hours, it was allowed to cool at a rate of 2.7°C per hour. During the growth period, tin oxide single crystals were precipitated and grown. After the melt solidified, it was slowly cooled to around room temperature and the crucible was taken out. The solidified melt was boiled in a nitric acid solution to dissolve the copper and washed to obtain a tin oxide single crystal. This crystal had a size of 3×2×2111111 or more.

Example 2 99.99% tin oxide 22 and 99.99% as solvent
A mixture was prepared by adding 20 f of 99.9% tin to 80 g of copper (melting point was below 800° C.). The kernel mixture was melted as in Example 1. 1300℃
After being maintained at a temperature of 8 hours, it was cooled at a rate of 287°C per hour. The solidified molten material was slowly cooled to around room temperature and then taken out. The solidified melt was boiled in aqua regia to dissolve the solvent and washed to obtain a tin oxide single crystal. The crystal size was more than 3X3X2.

As described above, according to the present invention, large crystals for tin oxide can be easily produced and have excellent effects.

Patent applicant: Yu Fuji, director of the Institute for Inorganic Materials, Science and Technology Agency

Claims (1)

[Claims] 1. Using tin oxide as a solute, copper or an alloy of steel and a metal that lowers the melting point of copper is used as a melt wire, and the solute tin oxide is precipitated and grown as a single crystal from the solvent. A method for producing a tin oxide single crystal, characterized by: