Synthesis and magnetic properties of ZnFe2O4 obtained by mechanochemically assisted low-temperature annealing of mixtures of Zn and Fe oxalates

The mechanism of formation of zinc ferrite (ZnFe2O4) from ZnC2O4·1.8H2O–2FeIIC2O4·2H2O and ZnC2O4·1.8H2O–Fe2III(C2O4)3·6H2O mixtures is investigated. By combination of TG and XRPD measurements it has been shown that microcrystalline ZnFe2O4 forms from physical mixtures after prolonged annealing at 1000 °C while nanocrystalline ZnFe2O4 powders are produced by mild annealing (1 h at 500 °C in air) of mechanically activated mixtures. The magnetic properties of ZnFe2O4 powders obtained from physical and from milled mixtures are compared.