RU1075758C - Method of obtaining yttrium monoaluminate for monocrystal growing - Google Patents

Description

The invention relates to chemistry, in particular, to a technology for producing a raw material for growing single crystals of yttrium monoaluminate, activated with neodymium, which are used in laser technology.

A known method for producing yttrium aluminate for growing single crystals by the Czochralski method involves melting the nopoiJuKOB oxide of yttrium and aluminum in a crucible. With this method of preparation of the charge, the melt is sprayed during the melting of oxides, which leads to a violation of its stoichiometry, which is a disadvantage of this method,

The closest to the proposed method is a method of producing yttrium orthoaluminate for growing laser single crystals, including the precipitation of yttrium and aluminum compounds with oxalic acid and ammonia from the aqueous solution of their salts, sludge mixing, its separation, substance and heat treatment.

The disadvantages of this method are its complexity, multistage and duration (the production time of 1 kg of the product is 141 hours). The method is associated with the release of harmful substances into the air. Industrial stocks require special treatment facilities (in the production of 1 kg of the product in the industrial effluent, 1.7 kg of ammonium sulfate, 1 kg of ammonium chloride, 0.44 kg of oxalic acid, 0.24 kg of ammonium hydroxide are contained). Insufficient purity and significant deviations in the stoichiometry of the final product are due to the large number of stages of the process, including acid treatment of the initial components, significant adsorption capacity of the precipitate precipitated by ammonium hydroxide and oxalic acid, which is much worse than the initial components.

The aim of the invention is to improve the stoichiometry of the composition, reduce the content of impurities and simplify the process.

This goal is achieved by taking pre-calcined yttrium and aluminum oxides as starting compounds, mixing is carried out with simultaneous grinding, and heat treatment is carried out at 1200-1250 ° C.

The preliminary calcination of each of the starting oxides allows the removal of volatile impurities from them, as a result of which the stoichiometry of the target product is improved.

Separation of the solid phase from the liquid is carried out by filtration on a suction filter or by evaporation. As a result of single-stage heat treatment (at a temperature of 1200–1250 ° C for 2–2.5 h), solid phase interaction of yttrium and aluminum oxides occurs.

A portion of the calcined yttrium oxides and

aluminum, taken in a stoichiometric ratio, is loaded into the drum of the mill, liquid (water, alcohol, etc.) is added in an amount of 1-1.2 liters per 1 kg of a mixture of oxides

0 and stirred on the rolls until the mixture is completely homogenized. The resulting suspension is evaporated or filtered on a suction filter. The precipitate is dried and calcined at a temperature of 1200-1250 ° C for 2-2.5 hours

5 The resulting product can be used in the form of a powder and in the form of tablets.

For the examples, a plexiglass mill was loaded with 716.39 g of yttrium oxide calcined at 1200 ° C for 3 hours and 323.61 g of alumina calcined at 1000 ° C for 3 hours, 1 liter of distilled water was added and stirred for 1.5 hours The resulting suspension is evaporated, dried and calcined for 2 hours at a temperature of 1200 ° C. The yield of the product is 96%.

Stoichiometric composition,%; yttria oxide 68.8, alumina 31.0. Content of impurities,%: iron 5-10, silicon 1-10, magnesium, lead, copper less.

0 Duration 22 hours

Example 2. 2.579 kg of yttrium oxide and 1.165 kg of alumina, calcined as in Example 1, are added to a plexiglas mill; 4.0 liters of alcohol are added, mixed

5 on the rolls for 5 hours. The suspension is filtered on a suction filter, dried in a drying cabinet and calcined at a temperature of 1250 ° C for 2 hours. The product yield is 95%. Yttria oxide content is 68.7%, aluminum oxide is 31.0%.

0 Content of impurities%: iron 5-10, silicon 2, lead, chromium, magnesium less, nickel, cobalt, molybdenum, copper less than 1 10, manganese less than 5-10. The process time is 66 hours.

5 Get 3.55 kg of the mixture. The evaporated alcohol is condensed and used in the next synthesis.

The mixture obtained by the proposed method, the stoichiometric composition, the content of trace impurities, the efficiency of the process exceeds the mixture obtained in a known manner.

The proposed method does not require the use of acids and ammonia, the duration of the synthesis is reduced by 5-7 times.

(56) U.S. Patent No. 3,314,666. Cl., 331-945. 1969.

USSR author's certificate N 686237. class. From 01 F 17/00, 1979.

Claims (1)

Invention Formula A METHOD OF OBTAINING YTTRI MONOALYMUNATE FOR CULTIVATION OF SINGLE CRYSTALS, including mixing compounds containing the starting components in a liquid medium, separating the solid phase and then drying and heat treatment, characterized in that. In order to improve the stoichiometry of the composition, reduce the content of impurities and simplify the process, precursor calcined yttrium and aluminum oxides are used as starting compounds, the mixing is carried out at their simultaneous milling, and the heat treatment is carried out at 1200-1250 ° C. 0