Use of Thin‐Film Substrates to Study Enhanced Solid‐State Phase Transformations

A thin‐film substrate geometry is described for the study of enhanced solid‐state phase transformations. A thin film of the seed material is grown on a suitable bulk substrate forming the thin‐film substrate. A sol of the material for which seeding is to be studied is then deposited and the sample heated. Cross sections are prepared to study both the extent of the transformation and its crystallography, using electron microscopy. The special feature of this approach is that the position of the original seed/coating interface is known precisely and the thickness of the transformed layer can be measured directly at different stages of the transformation. As an example of this approach, thin films of hematite have been used as substrates for the study of the seeded phase transformation of a boehmite‐derived transition‐alumina to α‐Al2O3 Copyright © 1994, Wiley Blackwell. All rights reserved