Structural and magnetic properties of ball milled copper ferrite Available to Purchase

The structural and magnetic evolution in copper ferrite $(CuFe2O4)$ caused by high-energy ball milling are investigated by x-ray diffraction, Mössbauer spectroscopy, and magnetization measurements. Initially, the milling process reduces the average grain size of $CuFe2O4$ to about 6 nm and induces cation redistribution between A and B sites. These nanometer-sized particles show superparamagnetic relaxation effects at room temperature. It is found that the magnetization is not saturated even with an applied field of 9 T, possibly as the result of spin canting in the partially inverted $CuFe2O4.$ The canted spin configuration is also suggested by the observed reduction in magnetization of particles in the blocked state. Upon increasing the milling time, nanometer-sized $CuFe2O4$ particles decompose, forming $α-Fe2O3$ and other phases, causing a further decrease of magnetization. After a milling time of 98 h, $α-Fe2O3$ is reduced to $Fe3O4,$ and magnetization increases accordingly to the higher saturation magnetization value of magnetite. Three sequential processes during high-energy ball milling are established: (a) the synthesis of partially inverted $CuFe2O4$ particles with a noncollinear spin structure, (b) the decomposition of the starting $CuFe2O4$ onto several related Fe–Cu–O phases, and (c) the reduction of $α-Fe2O3$ to $Fe3O4.$