Effect of Crystallization on the Formation of Mesostructured TiO₂ Thin Films

Abstract

Strict control of the crystallization of TiO₂ is one of the most important factors in forming mesoporous structured TiO₂ thin films. Effects of the crystallization of TiO₂ on the formation of mesoporous structures have been studied by transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) observation and X-ray diffractometry (XRD) analysis. The obtained well-ordered mesoporous TiO₂ thin films, calcined at 450°C to remove the template, are composed of a continuous non-crystalline TiO₂ matrix containing TiO₂ nanocrystals, whose mean size is sufficiently small to support the mesostructure. In the mean time, the mesoporous TiO₂ materials that almost lose their ordered structure after calcination consist of large TiO₂ crystallites (over 6 nm), and the overgrowth of TiO₂ crystallites cause a collapse of the mesoporous structure.