Dowa Mining Co., Ltd.

Hidekazu Kato

Kenichi Harigae

Kouki Toishi

Shigetoshi Uchino

Kishio Tayama

Takashi Ohgami

Takeharu Yamamura

Kanichi Okuda

In a process for separating impurities from a raw gallium material containing impurities, a process for refining gallium comprising progressively solidifying a raw gallium material provided in a liquid state inside a vessel while applying stirring, such that the diameter of the tubular solidification boundary gradually advances from the inner wall plane of the vessel towards the center of the vessel to reduce the diameter of the tubular solidification boundary, and separating the liquid phase remaining in the central portion of the vessel from the solidified phase before the entire raw material inside the vessel is solidified. The process above is repeated as required by using, as the raw gallium material, the solidified phase from which the liquid phase is separated. A metallic gallium favorably used for the preparation of a compound semiconductor can be obtained by analyzing the impurity concentration of the impurity-concentrated Ga separated from the solidified layer.

High purity gallium for preparation of compound semiconductor, and method and apparatus for purifying the same

An aqueous sodium carbonate solution is added in an equivalent amount to an aqueous silver nitrate solution (Ag=100 g/L) under stirring and, with nitric acid and sodium hydroxide being added to adjust the pH to 5.5-6.5, a silver carbonate precipitate is formed and subsequently washed thoroughly and dried at 250.degree. C. or below to produce a silver oxide powder, which satisfactory characteristics for use in cells, as exemplified by high water absorption, good shape of granules, high strength, non-stickiness to the molding punch, high fluidity and low residual carbon content. The pellet of the powder has high cell capacity.

Silver oxide for use in cells and a process for producing the same

Growing community of inventors

Funabashi, Japan

Hidekazu Kato