Relation between Structure and Magnetic Property of Ti1-xNixO2 Nano-Particles

Ti_1-xNi_xO₂ (x =0.00-0.12) nano-particle samples were prepared by sol-gel method. We investigated the effect of Ni doping on the structural and Raman scattering properties of the Ti_1-xNi_xO₂ system. SEM and XRD measurements show that the particle size of the powder is in nano-scale, and that the magnetic Ni impurities substitute for the Ti sites in the anatase TiO₂ phase. Raman spectra also clearly support that the Ni atoms go into the Ti-site in TiO₂. Some of the samples, which are found to be weakly ferromagnetic, show additional Raman peaks at around 420 and 620 cm^-1. Other samples that do not show the additional Raman peaks are superparamagnetic. The ferromagnetic behavior seems to be due to the existence of Ni or Ni oxide clusters in the Ti_1-xNi_xO₂ system.