Tutomu Nomura

Improvement in the temperature coefficient of coercivity for barium ferrite particles

An improvement in the temperature coefficient of coercivity, dHc/dT, for Co-Ti-substituted Ba ferrite particles for high-density magnetic recording media has been sought by substituting various third elements into the particles. The substitution of Sn ions for some of the Ti ions was found to be promising for this purpose, effectively reducing dHc/dT. The substitution was not detrimental to saturation magnetization or to the size distribution of the particles. The coercivity and particle size of the Co-Ti-Sn-substituted particles could be widely controlled. The value of dHc/dT was reduced to below half of that for Co-Ti-substituted particles. Ba ferrite media utilizing these particles provide an improved margin for operating temperature changes and high-performance recording. >