Raman studies on laser induced crystallization of Co(II) doped titania;: effect of the dopant concentration

Crystallization induced by continuous laser irradiation at 514.5 nm on Co(II)-doped titania matrices prepared by sol-gel process, is reported for different Co(II) concentrations. The cobalt ions improve the energy. absorption at this wavelength, reducing the laser power required to induce the amorphous to anatase or rutile phase transition in the titania as the Co concentration increases. The crystallization threshold (the minimum laser power to induce the phase transition) was determined for the different cobalt concentrations. Crystallization kinetics was monitored in real time by Raman spectroscopy and analyzed using a simple model. (C) 2002 Elsevier Science B.V. All rights reserved.