Synthesis and characterisation of tin-doped iron oxides

Rietveld structure refinement of the X-ray powder diffraction data recorded from tin-doped Fe3O4 prepared by heating metallic iron, alpha-iron(III) ox ide and tin(IV) oxide in sealed evacuated quartz ampoules shows the tin to substitute on the octahedral sites of the inverse spinel-related structure. Tin-doped gamma-Fe2O3, prepared by boiling a precipitate derived from iron (III), iron(II) and tin(II) under reflux, also adopts an inverse spinel-rel ated structure containing tin on the octahedral sites and, compared to pure gamma-Fe2O3, is stabilised with respect to conversion to alpha-Fe2O3. Fe-5 7 Mossbauer spectroscopy shows the Neel temperature for gamma-Fe1.9Sn0.1O3 to be between 750 and 820 K. Tin-doped alpha-Fe2O3 prepared by hydrothermal methods is shown by Rietveld structure refinement of the X-ray powder diff raction data to contain tin in both the substitutional and interstitial oct ahedral sites of the corundum related structure.