Synthesis, structural and magnetic characterization of nanocrystalline CuFe2O4 as obtained by a combined method reactive milling, heat treatment and ball milling

Abstract Nanocrystalline copper ferrite has been synthesized using a combined method which involves reactive milling, heat treatment and mechanical milling. After 4 h of reactive milling a solid solution between the starting oxides (CuO and α-Fe2O3) and a spinel phase is obtained. Increasing the milling time leads to a decomposition of those phases. After a heat treatment of the 30 h milled sample a single spinel CuFe2O4 phase is obtained. By mechanical milling the crystallite size of the copper ferrite is reduced down to 9 nm after 1 h of milling. For the CuFe2O4 samples milled between 2 and 4 h a decomposition of this phase is remarked and α-Fe2O3 is formed during milling. The spontaneous magnetization of the spinel decreases with increasing the milling time as results of the partial redistribution of the cations in the spinel and of spin canted effect. The magnetization of the milled samples does not saturate due to the presence of very fine ferrite particles which are superparamagnetic.