Sol-gel Synthesized Co-Doped Anatase TiO2 Nanoparticles: Structural, Optical, and Magnetic Characterization

A simple sol-gel method was used to synthesize cobalt doped TiO2 nanoparticles. TiO2 (titania) nanoparticles with Co doping concentration within the range 0, 2, 4, 6 and 8mol% were prepared. For the purpose of samples characterization under the effect of changing the Co concentration on structural, optical, surface morphology and magnetic properties of the samples X-ray diffraction (XRD), Fourier transform infrared, UV/Vis/NIR diffuse reflectance spectroscopy (DRS), UV-visible absorption, transmission electron microscopy, and vibrating sample magnetometer (VSM) system techniques were employed. The XRD results confirmed the formation of TiO2 (titania) nanoparticles in anatase phase for all the undoped and Co-doped samples. The microstructure studies of the samples confirmed the incorporation of Co ions into the host titania matrix is occurring via substitution for the Ti sites. All the investigated samples exhibited a room temperature ferromagnetic behavior as observed by VSM measurements with non-monotonic dependence of FM characteristic parameters on Co concentration. The samples showed optical energy gap (E-g) values similar to 3.59eV with an extension of the band gap into the visible light region with Co doping as confirmed by DRS study. The absorption band shows shift from 510nm to 720nm as Co concentration in the samples increased.