Relationship between the structural and magnetic properties of Co-doped Sn O2 nanoparticles

In this paper, we present the results of a detailed investigation of the structural, optical, and magnetic properties of chemically synthesized pure and Co-doped Sn O2 powders using x-ray diffraction (XRD), diffuse reflectance spectroscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, and magnetometry. In Sn1-x Cox O2 samples prepared at 600°C with low doping concentrations of Co (≤1%), the Sn O2 lattice contracts, band gap energy decreases, and a ferromagnetic behavior is developed. Increasing the Co doping concentration to >1% leads to a rapid expansion of the lattice and significant structural disorder evidenced by changes in the XRD and Raman spectra presumably due to additional interstitial incorporation of Co. This higher Co doping completely destroys the ferromagnetism. The striking similarity between the changes in the lattice parameters and the magnetic properties of Sn1-x Cox O2 indicates a structure-magnetic property relationship.