Laser induced phase transformation influenced by Co doping in TiO2 nanoparticles

The structural transformation and light absorption in the TiO2 play an important role for its reliable applications in dye based solar cells, optoelectronic devices, photochemical and photocatalytic activities. The aim of this report is to investigate the influence of low concentration cobalt doping in TiO2 nano-particles on their structural transition and optical properties. The undoped and Co doped TiO2 nano-particles were synthesized by sol-gel method and studied by XRD, UV-Vis, FTIR, EDX, TEM and Raman spectroscopy. The Co doped TiO2 nanomaterials have lower band gap than the undoped TiO2. To get deep insight into the structural properties, Raman measurements were performed with laser light at different powers under ambient conditions. The lattice expansion plays an important role in Co doped TiO2 system for optically controlled laser power dependent structural transformation. The Raman active vibrational modes shows reversible behavior for undoped TiO2 lattice, whereas the Co doped TiO2 lattice shows irreversible response for the anatase to rutile phase transformation as the function of incident laser power. (C) 2018 Elsevier B.V. All rights reserved.