Synthesis of Ba hexaferrite Fe magnetic composites

Magnetic composite materials (MCM) had been synthesized from commercially pure Ba hexaferrite and pure iron, by means of high energy ball milling under air or argon atmosphere. Thermal transformations of the bah-milled powder were studied in air and argon atmosphere from room temperature to 1300 K with the aid of DTA (Differential Thermal Analysis). Milling and heat treating in Ar produces Fe3O4 + Fe + BaO, with low remanence and coercivity. Milling in air or Ar and heat treating iu air produces the formation of phase M + Fe2O3 with coercivity Hc = 4800 Oe, close to the larger values obtained by other methods. When milling is produced in air and the heat treatment iu Ar, the final product is phase M + Fe3O4 with a nanostructure such that partial exchange coupling occurs among the particles of each phase.