PRODUCTION OF MAGNETIC POWDER OF BARIUM FERRITE OF COBALT-SUBSTITUTED HEXAGONAL SYSTEM, MAGNETIC POWDER AND MAGNETIC RECORDING MEDIUM

摘要

PURPOSE:To obtain magnetic powder of barium ferrite having controlled coercive force by coating magnetic powder of barium ferrite of cobalt-substituted hexagonal system with a sulfur-containing inorganic compound and heat-treating. CONSTITUTION:Magnetic powder of raw material shown by the formula is coated with a sulfur-containing inorganic compound and then heat-treated at 200-800 deg.Cm to give the objective magnetic powder of barium ferrite of cobalt- substituted hexagonal system having coercive force controlled to 200-2,000 (Oe). By this method, a magnetic recording medium having desired coercive force can also be obtained by using the magnetic powder. In the formula, (a), (b), (c) and (d) show number of atoms of Ba, Fe, Co, and O, respectively and (a) is 0.5-3.0, (b) is 8-12, (c) is 0.01-3.0 and (d) is number of atoms of oxygen satisfying valences of the other elements; X shows Mg, Sc, Y, V, Si, Ta, Mo, W, Re, Sr, Ru, Os, Ca, etc.