Dilute Magnetism and Mossbauer Study of Nanoscaled SnO2 Co-Doped with Fe, Co, and Sb, Prepared by Sol-Gel Method

SnO2-based oxides doped with Fe-57, prepared by a sol-gel method, are reviewed, and Sb doping effect on (Fe, Co)-doped SnO2 and Fe doping effect on (Sb, Co)-doped SnO2 were investigated. The crystalline grains of SnO2 were grown and the magnetic properties were improved in the doping range of 3-5 at.% of Sb. It was found that the intensity of magnetic broad sextet in Mossbauer spectra correlates with the saturation magnetization for 3 at.% Sb-, 1 at.% Co- and several at.% Fe-doped SnO2. When the doping exceeds 3 at.% of Fe, hematite (alpha-Fe2O3) clusters were produced in addition to maghemite (gamma-Fe2O3)-like clusters or defects inducing ferromagnetism. The origins of the dilute ferromagnetism are discussed.