Nano-particles of Co doped TiO2 anatase:: Raman spectroscopy and structural studies

Ti1-xCoxO2 (x = 0.00 - 0.13) nano-particle samples were prepared by sol-gel method and compared with the samples by forced hydrolysis method. SEM, XRD, Raman spectroscopy and magnetization measurements (VSM) were carried out. We investigated the effects of Co doping on the structural and Raman scattering properties of the Ti1-xCoxO2 system prepared by both methods. SEM and XRD measurements show that the particle size of the powder is in nano-scale and that the magnetic Co impurities substitute for the Ti sites in the anatase TiO2 phase. Raman spectra also clearly support that the Co atoms go into the Ti-site in TiO2. Some of the samples prepared by the sol-gel method show additional Raman peaks at around 490 and 690 cm(-1) and are found to be weakly ferromagnetic. Other samples that do not show the additional Raman peaks are superparamagnetic. The magnetic behavior seems to be determined by the existence of Co or Co oxide clusters in the Ti1-xCoxO2 system.