Phase stability frustration on ultra-nanosized anatase TiO 2

Abstract

This work sheds light on the exceptional robustness of anatase TiO 2 when it is downsized to an extreme value of 4â €‰nm. Since at this size the surface contribution to the volume becomes predominant, it turns out that the material becomes significantly resistant against particles coarsening with temperature, entailing a significant delay in the anatase to rutile phase transition, prolonging up to 1000â €‰°C in air. A noticeable alteration of the phase stability diagram with lithium insertion is also experienced. Lithium insertion in such nanocrystalline anatase TiO 2 converts into a complete solid solution until almost Li 1 TiO 2, a composition at which the tetragonal to orthorhombic transition takes place without the formation of the emblematic and unwished rock salt Li 1 TiO 2 phase. Consequently, excellent reversibility in the electrochemical process is experienced in the whole portion of lithium content.