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A model of growth of titanium dioxide crystals with simultaneous transformation from anatase to rutile

Lookup NU author(s): Dr Ian Cooper, Dr Terry Egerton, Dr Fulian Qiu

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Abstract

This study simulates the combination of crystal growth by evaporation-condensation with the potential for a phase change once the crystals have reached a critical size. Crystal growth has been simulated as a two-dimensional Monte Carlo process in which the probability of accepting or rejecting an individual evaporation-condensation step is given by the Metropolis algorithm. Crystals, taken to be of the anatase form of TiO2, which have grown larger than a specified critical size may transform irreversibly to a second phase, taken to be rutile. The probability of conversion increases with increasing crystal size. For each critical size there exists a limited range over which the transformation kinetics follow the familiar relationship alpha = 1 - exp(-kt(n)) (where alpha is the fractional conversion at time, t). The dependence of the mean size of the two polymorphs and of the rutile size-spread (rms) on critical size have been investigated. The most significant aspect. of the plots of the normalized size-spread, rms/mean-size, is its gradual increase as the rutile fraction increases from 0.75 to 0.98. (C) 2008 Elsevier Ltd. All rights reserved.

Publication metadata

Author(s): Cooper IL, Egerton TA, Qiu FL

Publication type: Article

Publication status: Published

Journal: Journal of the European Ceramic Society

Year: 2009

Volume: 29

Issue: 4

Pages: 637-646

ISSN (print): 0955-2219

ISSN (electronic): 1873-619X

Publisher: Elsevier

URL: .http:dx.doi.org/10.1016/j.jeurceramsoc.2008.07.059

DOI: 10.1016/j.jeurceramsoc.2008.07.059

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