Ferromagnetic Oxide Particles for Recording Materials

Abstract

The conditions had been studied for the formation of ferromagnetic precipitates of M_xFe₃-_xO₄ (M = divalent metal ion, such as Fe₂₊, Zn₂₊, Co₂₊or Mn₂₊), BaFe₁₂O₁₉ and SrFe₁₂O₁₉ in the presence of aqueos media. We succeeded in preparing the needlelike xCoFe₂O₄(1-x)Fe₃O₄ and platelike 6xFe₃O₄(1-x) BaFe₁₂O₁₉ particles for magnetic recording materials. This paper describes the conditions for their formation and their magnetic properties at room temperature.