| 摘要 |
PURPOSE:To obtain a rare earth metal powder having high uniformity and fine particle size, free from coagulation, and suitable as a sintering assistant, by adding ammonia to an aqueous solution of a rare earth metal salt in the presence of fine carbon particles, separating the precipitated rare earth metal hydroxide and calcining the hydroxide. CONSTITUTION:Fine carbon powder having an average particle diameter of 0.01-0.1mum (e.g. carbon black) is dispersed in an aqueous solution of a rare earth metal salt such as yttrium nitrate, yttrium chloride, etc. The amount of the carbon is 0.1-2pts.wt. per 1pt. of the rare earth metal (in terms of oxide) in the aqueous solution of the rare earth metal salt. Ammonia is added to the solution to precipitate rare earth metal hydroxide, and the precipitate is separated and calcined to obtain the powder of the objective rare earth metal oxide (e.g. yttrium oxide). Fine rare earth metal oxide powder can be produced without using a mechanical means. Since the ammonia is used as the alkali, it can be removed by calcination, and a rare earth metal oxide having low impurity content can be produced.
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