Synthesis and study of magnetic properties of Co-doped anatase TiO 2 nanoparticles

Abstract

Anatase phase Ti0.97Co0.03O2 nanoparticles were synthesized using two different preparation methods. The prepared samples were investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF) analysis, and magnetization measurements. The particle diameters were controlled by adjusting the annealing temperature, and they ranged from 4.2-7.0 nm for Ti 0.97Co0.03O2 encapsulated in amorphous SiO 2, and from 14-61 nm for Ti0.97Co0.03O 2 that was not encapsulated in amorphous SiO2. Magnetization measurements were performed on the 7.0-nm sample from the former sample set, and on the 14-nm sample from the latter sample set, and both these samples exhibited an identical crystal structure and an equal number of magnetic ions, as confirmed by XRF and XRD measurements. The magnetization curves for the two samples indicated their ferromagnetic behavior at room temperature. However, the magnetic parameters of saturation magnetization MS and coercive force HC were clearly different for these two samples. We attribute this difference in magnetic properties between these samples to magnetic impurities present due to the different degrees of solubility of Co ions in the TiO2 lattice.