57Fe Mössbauer study of sol–gel synthesized Sn1−x−yFexSbyO2−δ powders

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Abstract

Samples of SnO2 doped with different amount of Fe (10–20%) and Sb (5–25%) were prepared by sol–gel method. Room temperature ferromagnetism was found to increase as a result of co-doping with Sb, as compared to SnO2 doped only with Fe. 57Fe Mössbauer spectra of almost all samples exhibited two paramagnetic doublets and a small subspectrum referring to magnetic relaxation at room temperature. Only the samples Sn0.65Fe0.2Sb0.15O2−δ and Sn0.85Fe0.1Sb0.05O2−δ with 4 h long annealing time showed well developed sextets and larger magnetic coercivity compared to that of the other samples. The sextet observed was considered to be due to precipitates like Sn doped α-Fe2O3. The results suggest that the origin of the magnetic interactions is enhanced by the presence of magnetic defects, which can interact with the iron ions by free carrier electrons. For the sample with precipitates, the grain boundary defects may play an important role of enhanced ferromagnetism.

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