Birch, Stewart, Kolasch & Birch, LLP
Magnetic powder, method for producing the same and use of the same
A magnetic powder containing MnBi, in which an average particle size of the magnetic powder is from 0.1 .mu.m to 20 .mu.m; a coercive force is from 3000 to 15,000 Oe at 300 K. and 50 to 1000 Oe at 80 K. when measured with applying a magnetic field of 16 KOe; an amount of magnetization is from 20 emu/g to 60 emu/g when measured at 300 K. with applying a magnetic field of 16 KOe; a degree of decrease of an amount of magnetization is 40% or less after being maintained in an atmosphere of 60.degree. C. and 90% RH for 7 days; and a content of metal bismuth (Bi) satisfies the following equation: Metal Bi/(MnBi+metal Bi)<0.5 in which "metal Bi" means a peak area assigned to the (012) plane in a X-ray diffraction pattern of Bi, and "MnBi" means a peak area assigned to the (101) plane in a X-ray diffraction pattern of MnBi, which magnetic powder is excellent in corrosion resistance, and suffers from very slight deterioration of saturation magnetization, and provides a magnetic recording medium that can prevent altering of recorded data.
Hitachi Maxell, Ltd.
Y H Y H G G Y G G Y Y Y H
Y10S H01F Y10T H01F G11B G11B Y10T G11B G06K Y10S Y10T Y10T H01F
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Noriaki Hisao Toshinobu Mikio Shinichi
Ohtani Kanzaki Sueyoshi Kishimoto Kitahata