Mossbauer spectroscopic properties of tin-doped iron oxides

The Fe-57 Mossbauer spectra recorded in situ from tin-doped Fe3O4 at elevated temperature in vacuo shows the Curie temperature to decrease with increasing concentrations of the dopant. Thermal treatment under oxidising conditions results in the initial formation of tin-doped gamma-Fe2O3 which subsequently undergoes a phase transformation to tin-doped alpha-Fe2O3. Fe-57 Mossbauer spectroscopy at elevated temperatures shows the Neel temperature for tin-doped gamma-Fe2O3 to be lower than that of pure gamma-Fe2O3. The Sn-119 Mossbauer spectra recorded from all the tin-doped iron oxides show the presence of a hyperfine magnetic field at the Sn4+ site which is more complex in the spectra recorded from tin-doped gamma-Fe2O3 and alpha-Fe2O3.