Atomic-scale structure of amorphous TiO₂ by electron, X-ray diffraction and reverse Monte Carlo simulations

Amorphous TiO₂ materials, layers and powders, have been produced by different preparation techniques. The layers have been subjected to electron diffraction and the bulk powders to X-ray diffraction experiments. Three-dimensional structure models consistent with the experimental structure functions have been constructed by reverse Monte Carlo simulations. Partial distribution functions, interatomic distances and coordination numbers have been extracted from the model atomic configurations. The atomic arrangement in all amorphous TiO₂ materials investigated has been found to resemble that occurring in brookite, a crystalline modification of TiO₂, and to be well described as an assembly of short, staggered chains of Ti-O octahedra. The crystallization behaviour of amorphous TiO₂ materials has also been discussed.