| 摘要 |
PURPOSE:To obtain cobalt-substituted barium ferrite magnetic powder in which the temperature characteristic of coercive force adapted for vertical magnetic recording medium is improved by containing specific amount of one or more elements of Ni, Cu, Zn, Mg and Mn in specific cobalt-substituted barium ferrite crystal particles. CONSTITUTION:0.2-3 moles of metal element M2 (where M2 is one or more elements of Ni, Cu. Zn, Mg and Mn) with respect to 1 mole of Co is contained in cobalt-substituted barium ferrite crystal particles of a range of molar ratio of metal elements of 1/4>=Ba/(Fe+Co+M1)>=1/12 (where M1 is one or more elements of Ti, Sn, Zr, Ge, Nb and V, the mean ion valency of Co+M1 is 3 and molar ratio (x) to Fe is 0.2>=x>0). Thus, the cobalt-substituted barium ferrite magnetic powder in which the control of desired preferable coercive force and the temperature characteristic of its coercive force are remarkably improved as vertical magnetic recording magnetic powder can be effectively obtained with a relatively simple constitution. |
