Initial stages of the transformation of single-crystal anatase particles during high-energy ball milling

Abstract

The initial steps of the phase transformation of anatase by high-energy ball milling have been followed as a function of milling time by X-ray diffraction and transmission electron microscopy (TEM). The metastable TiO₂ II phase appears after several minutes of grinding. The anatase-TiO₂ II transformation occurs without particle fracture. TEM shows the simultaneous strain hardening of anatase particle cores and the formation of TiO₂ II crystallites at the surface of anatase particles. The TiO₂ II crystallites have an average diameter of about 10 nm. The possible mechanisms of the transformation are commented upon.