Microscopic study on the structure and phase transition behavior from anatase to rutile TiO2

TiO 2 was widely applied in fields such as catalysis, coatings, and cosmetics due to its excellent properties. Anatase and rutile were the two common phases of TiO 2 , and although their structures and phase transition were extensively studied, a consensus had not been reached. In this work, we investigated the structural evolution during the thermal-driven transformation of anatase to rutile from a microscopic perspective. It was demonstrated that the thermally induced anatase-to-rutile transition was not influenced by the environmental atmosphere. First, the Rietveld method was employed to determine the unit cell structures of the prepared anatase and the transformed rutile. Their stability was further confirmed through density functional theory (DFT) calculations and Ab initio molecular dynamics (AIMD) simulations. Based on the orientation relationship of (112) A || (010) R between the two phases, an atomic move pathway for the phase transformation was proposed. Finally, the phase transition of spherical particles was simulated by analyzing the variation of O-Ti-O bond angles in the TiO 2 structure. The sintering processes at different-size particles were also simulated with the calculations of centroid shrinkage ratio. This work clarified the structure and phase transition mechanism of TiO 2 at the atomic scale, which contributed to understanding and regulating the synthesis of TiO 2 -based materials.