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Studies on the brookite-rutile transformation

Rao, CNR and Yoganarasimhan, SR and Faeth, PA (1961) Studies on the brookite-rutile transformation. In: Transactions of the Faraday Society, 57 (3). pp. 504-510.

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Abstract

Brookite, the orthorhombic modification of titanium dioxide, transforms to the tetragonal modification, rutile, on heating. The kinetics and energetics of the transformation have been studied. Below 715±10°C, the rate of transformation is extremely slow. There appears to be little or no induction time. The kinetic data can be fitted reasonably well by the first-order equation. The energy of activation is about 60 kcal/mole and the frequency factor is of the order of 1013 h-1. The entropy of activation from Eyring's theory is about -18 cal/mole deg. at 800°C. The heat of this transformation is -100±75 cal/mole. The kinetic results may be explained qualitatively in terms of various analogies but more clearly by the application of the order-disorder theory to diffusionless transformation in solids. It has been shown that the ratio of propagation rate constant to the nucleation rate constant is small and that there is little or negligible phase aggregation.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Royal Society of Chemistry..
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 15 Jun 2010 11:39
Last Modified: 28 Oct 2011 10:24
URI: http://eprints.iisc.ernet.in/id/eprint/28419

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