PRODUCTION OF COBALT-CONTAINING MAGNETIC IRON OXIDE

摘要

A process is provided for coating the particle surfaces of a phosphor-containing magnetic iron oxide powder with a cobalt compound after subjecting said powder to an activation treatment with an aqueous alkaline and/or acidic medium. The cobalt-containing magnetic iron oxide powder obtained according to this process has excellent coercivity and thermal stability, and the magnetic tape produced by using said powder has not only high coercivity but also excellent squareness, orientability and remanent induction.