Structural and magnetic properties of chemically synthesized Sn1-xMnxO2 nanocrystalline powders

Sn1-xMnxO2 nanocrystalline powders were synthesized by a wet chemical method (x <= 0.08). X-ray diffraction reveals that single-phase rutile Sn1-xMnxO2 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 Mn4+ for x=0.01 and as Mn3+ for x=0.02 and 0.04 at room temperature, but as Mn3+ 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 Sn1-xMnxO2 are discussed based on the competition between the free carrier mediated Ruderman-Kittel-Kasuya-Yosida interaction and antiferromagnetic superexchange interaction in the system. (c) 2007 American Institute of Physics.