염화 홀뮴

Holmium chloride is obtained from rare-earth minerals. Recovery steps are discussed above (see Holmium). The rare-earth mineral is cracked by acid attack by heating with hydrochloric acid. The water-soluble chloride salt is filtered and separated from insoluble residues. The hydrated chloride salt is heated at 350°C in a current of hydrogen chloride to yield anhydrous HoCl3 . Heating in air in the absence of hydrogen chloride yields holmium oxychloride, HoOCl. Holmium chloride may be purified by distillation or vacuum sublimation. Holmium chloride also can be prepared by heating holmium oxide with ammonium chloride: Ho2O3 + 6NH4Cl-->2HoCl3 + 6NH3 + 3H2O