Selective synthesis and structural stability of anatase and rutile Ti1-xFexO2 nanoparticles

Anatase and rutile Ti1-xFexO2 nanocrystals with x = 0.0 - 0.05 were synthesized selectively in an aqueous solution. X-ray diffraction with refinements showed that TiO2 crystals calcined at 500 and 800 .deg. C were pure anatase and rutile phases, respectively. However, TiO2 calcined at 550 ≤T ≤ 600 .deg. C showed a mixture of anatase and rutile phases. Ti1-xFexO2 nanoparticles calcined at 500 .deg. C had a high-quality anatase structure with no extra phases while Ti1-xFexO2 calcined at 800 .deg. C showed mainly a rutile structure. More disorder was observed in anatase than rutile Ti1-xFexO2 nanoparticles. The results suggest that rutile Ti1-xFexO2 nanoparticles are more stable than anatase Ti1-xFexO2 nanoparticles. No change was observed from anatase or rutile TiO2 nanoparticles when annealed at 900 .deg. C, suggesting that both anatase and rutile TiO2 nanoparticles are quite stable, once TiO2 is crystallized.