Sakai Chemical Industry Co., Ltd.

Tatsuya Hida

Mizuho Wada

Shinji Nakahara

Hideji Yamamoto

Youichi Yamada

Yoshiki Fukatsu

Disclosed herein is fine acicular .alpha.-ferric oxide which has the crystallite diameter (D.sub.1014) in the direction perpendicular to the (1014) plane and the crystallite diameter (D.sub.1120) in the direction perpendicular to the (1120) plane such that their ratio D.sub.1014 /D.sub.1120 is in the range of 1-2, and also has a specific surface area of 40-50 m.sup.2 g. Disclosed also herein is fine acicular .alpha.-ferric oxide which has the crystallite diameter (D.sub.1014) in the direction perpendicular to the (1014) plane and the crystallite diameter (D.sub.1120) in the direction perpendicular to the (1120) plane such that their ratio D.sub.1014 /D.sub.1120 is the range of 1-2, and also has an average aspect ratio of 10-15 and a specific surface area of 20-40 m.sup.2 /g. They are produced by wet process including the step of hydrothermal reaction.

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Hiroshima, Japan

Tatsuya Hida