| 摘要 |
PURPOSE:To manufacture ammonium yttrium fluoride hydrate having a novel composition by adding hydrofluoric acid to gelled amorphous yttrium hydroxide in the presence of a water soluble ammonium salt. CONSTITUTION:Hydrofluoric acid is added to gelled amorphous yttrium hydroxide or a gelled amorphous basic yttrium salt in the presence of a water soluble ammonium salt such as ammonium chloride. They are brought into a reaction at ordinary temp., and the reaction is sustained for >=about 30min. Said gel takes part in the reaction in the form of a slurry, and the concn. is 20- 600mmol/l (expressed in terms of yttrium). The amount of the ammonium salt used is >=1/3mol (expressed in terms of ammonium ion) per 1mol yttrium. Ammonium yttrium fluoride hydrate having a composition represented by a formula (NH4)Y4F13.H2O is manufactured, and anhydrous yttrium fluoride is obtd. by calcining the hydrate at about 300-1,000 deg.C in an inert atmosphere for about 30min-5hr.
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