Investigation of Phase Evolution of CoFe2O4 Nanoparticles Prepared by limited Mechanical Activation and Heat Treatment in Comparison to Conventional Powder Metallurgy Route

In this work، phase evolution of CoFe2O4 nanoparticles prepared by limited mechanical activation and heat treatment in comparison to conventional powder metallurgy route is reported (mixed oxides method). The starting raw materials for both methods were hematite and cobalt which were mixed together with the molar ratio of 1:1، (Co: Fe2O3=1:1). The mechanical activation was performed in a Spex 8000 high–energy vibratory mill for 1h. Various characterization techniques such as XRD and VSM were utilized to study the prepared samples. The study of phase evolution in samples produced by the mixed oxides method in comparison with those prepared by the mechanical alloying method، with heat treatment at the same temperature، suggests that formation of CoFe2O4 in samples produced by the latter method was started at a lower temperature and revealed stronger characteristic peaks of CoFe2O4. Furthermore، increased formation of CoFe2O4 phase was observed by increasing the heat treatment temperature. The study of magnetic properties of samples produced by the mentioned methods which were heat treated at 850 °C، suggests that samples produced by the mechanical activation method show considerably higher magnetic properties with respect to the samples made by the conventional method.