Processing and cation redistribution of MnZn ferrites via high-energy ball milling

Abstract

We have produced MnZn ferrites via high-energy ball milling (HEBM) of elemental oxides MnO, ZnO, and Fe2O3. X-ray diffraction (XRD) indicates a pure phase spinel forms after 21 h of HEBM. Extended x-ray absorption fine structure (EXAFS) analysis shows a nonequilibrium cation distribution, with an unusually high population of Zn cations on the octahedral sublattice. We then used EXAFS modeling to study cation site occupancy in an equilibrium MnZn-ferrite standard subjected to HEBM. We found that HEBM produces an increased preference for octahedral-site occupation among all cations for milling durations up to 300 min. After an initial improvement in magnetic properties, the magnetization diminishes steadily throughout this interval. With further increases in milling duration these structural and magnetic trends reverse, possibly due to annealing effects evidenced by XRD.