Review of the anatase to rutile phase transformation

TLDR

Titanium dioxide exists as anatase and rutile polymorphs, and the relative presence of these phases influences its photocatalytic performance. This review investigates the anatase‑to‑rutile phase transformation in TiO₂. The authors survey synthesis routes, material properties, thermodynamic aspects, and dopant effects on the transformation, presenting a cationic radius–valence plot that separates inhibitors from promoters. Based on this analysis, the review predicts dopant influences on the phase transformation, including for elements lacking experimental data.

Abstract

Titanium dioxide, TiO2, is an important photocatalytic material that exists as two main polymorphs, anatase and rutile. The presence of either or both of these phases impacts on the photocatalytic performance of the material. The present work reviews the anatase to rutile phase transformation. The synthesis and properties of anatase and rutile are examined, followed by a discussion of the thermodynamics of the phase transformation and the factors affecting its observation. A comprehensive analysis of the reported effects of dopants on the anatase to rutile phase transformation and the mechanisms by which these effects are brought about is presented in this review, yielding a plot of the cationic radius versus the valence characterised by a distinct boundary between inhibitors and promoters of the phase transformation. Further, the likely effects of dopant elements, including those for which experimental data are unavailable, on the phase transformation are deduced and presented on the basis of this analysis.