Structural and magnetic properties of chemically synthesized Sn_(1-x)Mn_xO_2 nanocrystalline powders

摘要

Sn_(1-x)Mn_xO_2 nanocrystalline powders were synthesized by a wet chemical method (x ≤ 0.08). X-ray diffraction reveals that single-phase rutile Sn_(1-x)Mn_xO_2 was obtained for x up to about 0.06. Evolution of cell parameters, x-ray photoelectron spectroscopy measurements, thermogravimetric analysis, and quantitative evaluation of the magnetization data all indicate that Mn element acts as Mn~(4+) for x=0.01 and as Mn~(3+) for x=0.02 and 0.04 at room temperature, but as Mn~(3+) for all the samples at 5 K. Magnetization data show that the average magnetic moment per Mn site decreases with increasing x at 5 K, while the effective fraction of the Mn ions contributing to the magnetization decreases. The magnetic properties of the Sn_(1-x)Mn_xO_2 are discussed based on the competition between the free carrier mediated Ruderman-Kittel-Kasuya-Yosida interaction and antiferromagnetic superexchange interaction in the system.