MOSSBAUER STUDIES OF SRTIO3 - FE57 SYSTEM

Mössbauer studies of the SrTiO3: Fe57 system used as an absorber have shown that iron enters the SrTiO3 lattice substitutionally at the Ti4+ site in its high-spin ferric state and is usually associated with a charge-compensating oxygen vacancy in agreement with the EPR evidence. On firing these samples in hydrogen, the quadrupole-split spectrum of Fe3+ associated with an oxygen vacancy transforms into a Zeeman-split spectrum with hf field and isomer shift characteristic of iron metal, indicating the formation of colloidal iron. Vacuum firing of the original air-fired samples tends to convert part of the Fe3+ ions into Fe2+ through the creation of more oxygen vacancies. The stages through which atomically dispersed Fe3+ ions are converted into colloidal iron on hydrogen firing and vice versa have been indicated. © 1968 The American Physical Society.