COBALT-CONTAINING MAGNETIC IRON OXIDE POWDER AND MAGNETIC RECORDING MEDIUM USING THE SAME

摘要

PROBLEM TO BE SOLVED: To obtain both a cobalt-containing magnetic iron oxide powder especially suitable for a magnetic recording medium, especially an image recording medium and the magnetic recording medium using the same. SOLUTION: Iron oxide powder containing Fe2+ in the ratio of 0.10-0.36 calculated as Fe2+/total Fe is obtained from γ-FeOOH as a precursor. A cobalt compound or the cobalt compound and another metal compound are bonded to the surface of the iron oxide powder to give cobalt-containing magnetic iron oxide powder satisfying formula I 20<=SSA<=50, formula II -16.70<=log[V]<=-3.05log[SSA]-11.35 and formula 0.10<=Fe2+/total Fe<=0.30 [SSA is BET specific surface area (m2/g) and V is a flux reversal volume (cm3).