Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Shigeo Iiri

Hiroshi Endo

Masaru Hayashi

Isao Suzuki

Satoshi Yamaguchi

Toshihiko Oguchi

Motoo Seimiya

Tsutomu Yamashita

Masashi Awa

Naoyuki Hirate

High-purity molybdenum or tungsten powder can be produced by a process comprising (a) decomposing a powder or an oxide powder of molybdenum or tungsten with hydrogen peroxide water; (b) bringing the resulting aqueous solution of molybdenum or tungsten into contact with a cation exchange resin; (c) concentrating the aqueous solution; and (d) reducing a concentrated solid material. By omitting reducing step (d), one can obtain high-purity molybdenum or tungsten oxide powders. Because the Mo and W powders and MoO.sub.3 and WO.sub.3 powders prepared by this invention are of an extremely high purity, they are useful as materials for targets of VLSI elements.

Methods for preparing high-purity molybdenum or tungsten powder and

Barium-ferrite series powders are prepared from an alkaline aqueous solution containing a prescribed ratio of ions of the metals equal to those contained in the powder. In the first stage, the alkaline aqueous solution is heated at a constant volume at 150.degree. to 300.degree. C. to precipitate a precursor of the barium-ferrite series powder. Then, the precursor is baked at 700.degree. to 1,000.degree. C. to crystallize the precursor.

Method of producing barium-ferrite series powder

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Yokohama, Japan

Shigeo Iiri