METHOD OF PRODUCING TRIFLUORIDES OF RARE-EARTH ELEMENTS Russian patent published in 2012 - IPC C01F17/00 

FIELD: chemistry.

SUBSTANCE: invention relates to inorganic chemistry and specifically to a method of producing trifluorides of rare-earth elements used in laser and infrared technology. The method of producing trifluorides of rare-earth elements involves exposing powder of sesquialteral sulphides α - Ln₂S₃ (Ln=La-Dy) with particle size 30-60 mcm to hydrofluoric acid with concentration of not less than 50%, taken in excess of 30-50%, at room temperature until the end of hydrogen sulphide gas release. Aqueous acid solution is decanted from the residue. The remaining liquid phase is removed during vacuum drying, residual pressure of up to 1 Pa and heating at temperature ranging from room temperature to 60-80°C. The obtained powder is thermally treated in a vacuum at 0.1 Pa at temperature of up to 200°C.

EFFECT: efficient production of trifluorides of rare-earth elements with minimum content of impurities of oxygen-containing phases.

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