Influence of zinc doping on the structural and magnetic properties of α-Fe2O3

Zinc-doped alpha -Fe2O3 has been prepared by hydrothermal methods. The zinc K-edge EXAFS and interatomic potential calculations indicate that Zn2+ ions substitute for Fe3+ ions in the lattice and are accompanied by oxygen vacancies. The Fe-57 Mossbauer spectra recorded between 296 and 18 K demonstrate that the Morin transition in alpha -Fe2O3 is completely suppressed within this temperature range by the presence of zinc. The 57Fe Mossbauer spectra recorded in situ at temperatures between 300 and 915 K show the material to undergo conversion to the spinel-related ZnFe2O4 phase in this temperature regime. The results demonstrate that the structural and magnetic properties of zinc-doped alpha -Fe2O3 and its behavior at elevated temperatures are different from those of magnesium-doped alpha -Fe2O3. (C) 2001 Academic Press.