The filter picking the particular recrystallization which by the fact that it controls cools the saturation fluoridation tantalic acid kalium solution which designates the oxygen analysis mannered null fluoric acid of hypoxia fluoridation niobium Acid kalium crystal, and fluoridation tantalic acid kalium crystal and the fluoridation niobium Acid kalium crystal which are obtained with production

摘要

PROBLEM TO BE SOLVED: To provide a method of manufacturing a low-oxygen potassium tantalate fluoride crystal and a low-oxygen potassium niobate fluoride crystal, the crystals obtained by these methods, and a method of analyzing oxygen contained in them. SOLUTION: Thus, in a method of obtaining a crystal by cooling a saturated potassium tantalate fluoride solution under a controlled condition to form a recrystallized crystal, filtering and drying the recrystallized crystal in a dryer, the concentration of fluoric acid of the saturated potassium tantalate fluoride solution, which essentially contains fluoric acid, is regulated to be 0.5-10 mol/l.