Surface characteristics and microstructure of dispersed TiO 2 nanoparticles prepared by diffusion flame combustion

Abstract

Via properly changing concentration of titanium precursor, tuning the residence time and controlling of the temperature field in the reaction region, nanocrystalline TiO 2 powders were synthesized by the diffusion flame method with well-dispersed behavior and controlled crystal structures and particles size. The XPS and IR results showed that there existed high hydration and oxygen vacancies on the surface of the as-prepared nanocrystalline TiO 2 powders, which played a dominant role in controlling polymorph fraction by altering the critical particles size of phase transition. The thermodynamics analysis demonstrated that the high hydration on TiO 2 surface can produce the lattice contraction, which effectively stabilizes anatase phase. However, the oxygen vacancies on TiO 2 surface can decrease activation energy of phase transition of anatase to rutile, which facilitates the phase transformation.