Synthesis, phase formation study and magnetic properties of CoFe2O4 nanopowder prepared by mechanical milling

In this work we report the phase formation and magnetic properties of CoFe2O4 nanopowder prepared by mechanical alloying technique using metallic cobalt and hematite powder (1:1 molar ratio) as the initial raw material in ambient air atmosphere. The formation of single phase cobalt ferrite of (Co 0.18 2+ Fe 0.82 3+ )[Co 0.82 2+ Fe 1.18 3+ ]O4 stoichiometry was confirmed for the samples milled above 15 h without any heat-treatment by XRD and Mossbauer techniques. The average crystallite size of the sample milled for 30 h was ∼13 nm. The highest room temperature value of the magnetization measured at 1.5 T was 51 e.m.u/g for the sample milled for 25 h which was much lower than the corresponding value of the bulk cobalt ferrite (80.8 e.m.u/g at 300 K) due to the size effect.