Magnetic particle powder of acicular ferric oxide used for magnetic recording material and a process for producing the same

摘要

The present invention relates to a process for producing magnetic particle powder of acicular ferric oxide used for a magnetic recording material comprising (A) reducing acicular goethite particle powder to obtain acicular magnetite particle powder, (B) heating said acicular magnetite particle powder and thereby making the partial pressure of oxygen in said acicular magnetite particle powder reach the equilibrium value and (C) oxidizing said acicular magnetite particle powder to obtain gamma-hematite (maghemite) particle powder, and magnetic particle powder produced thereby.