Production manner of high purity rare earth fluoride

摘要

PURPOSE:To enable easy production of rare earth fluorides of high purity, extremely reduced in transition metal impurities and rare earth impurities. Further, the use of the product as a starting substance for optical fibers made of fluoride glass gives fluoride glass optical fiber of super-low loss. CONSTITUTION:An aqueous solution of La or Y is passed through a cationexchange resin column 2 filled with a strongly acidic cationexchange resin to allow the resin 1 to adsorb La or Y. Then, 0.2 to 1.0 M alpha- hydroxyisobutyric acid solution of pH 3.5 to 4.5 is passed through the column as an eluent and the eluate of La or Y is combined with a fluorinating agent such as hydrofluoric acid, acidic ammonium fluoride, or hydrogen fluoride gas to form fluoride precipitate of La or Y. The precipitate is dehydrated, dried, then combined with acidic ammonium fluoride, and fired at 600 to 800 deg.C to give LaF3 or YF.