Journal article

Formation of rutile nuclei at anatase {112} twin interfaces and the phase transformation mechanism in nanocrystalline titania

RL Penn, JF Banfield

AMERICAN MINERALOGIST | MINERALOGICAL SOC AMER | Published : 1999

Abstract

In nanocrystalline anatase coarsened under hydrothermal conditions (250 °C, P(sat)), the anatase-to-rutile phase transformation is nucleated at anatase {112} twin boundaries formed by oriented attachment. The anatase twin boundary is constructed from structural elements common to rutile. Specifically, rutile nucleation involves displacement of only one half the titanium cations within the twin slab. Subsequent transformation of bulk anatase involves rupture of 7 of the 24 Ti-O bonds per unit cell and cooperative displacement of Ti and O. As the transformation advances into the bulk material, adjacent slabs of anatase octahedra are destabilized, resulting in rapid progression of the transform..

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