Structural and Mossbauer studies of Mn_(0.5)Co_(0.5)Fe_2O_4 ferrites prepared by high energy ball milling and glycolthermal methods

摘要

We have investigated the properties of three Mn_(0.5)Co_(0.5)Fe_2O_4 ferrites synthesized directly from high purity metal oxides (Sample A) and from MnFe_2O_4 and CoFe_20_4 ferrites (Sample B) by mechanical milling and by glycolthermal process (Sample C). XRD results show essentially single phase spinel structure. Sample C is the best sample followed by Sample B based on the presence of minor impurity peaks near 2θ ≈38° and 52°. More impurity peaks appear to grow after annealing above 400°C. Samples A and B have been found to have similar Fe-57 Mossbauer spectra before and after annealing at 1050°C. The spectrum for each sample changes significantly after annealing. This is attributed to changes of both grain sizes and impurity phases with thermal annealing. At least two sextets and two doublets are used to fit the Mossbauer spectra.