Dilute Magnetism and Mossbauer Study of Nanoscaled SnO_2 Co-Doped with Fe, Co, and Sb, Prepared by Sol-Gel Method

摘要

SnO_2-based oxides doped with ~(57)Fe, prepared by a sol-gel method, are reviewed, and Sb doping effect on (Fe,Co)-doped SnO_2 and Fe doping effect on (Sb,Co)-doped SnO_2 were investigated. The crystalline grains of SnO_2 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 SnO_2. When the doping exceeds 3 at.% of Fe, hematite (a-Fe_2O_3) clusters were produced in addition to maghemite (γ-Fe_2O_3)-like clusters or defects inducing ferromagnetism. The origins of the dilute ferromagnetism are discussed.