γ-Al2O3 formation from pulsed-laser irradiated sapphire
- 5 December 1994
- journal article
- conference paper
- Published by AIP Publishing in Applied Physics Letters
- Vol. 65 (23) , 2940-2942
- https://doi.org/10.1063/1.112960
Abstract
High‐resolution transmission electron microscopy was used to examine the effect of laser irradiation of sapphire (single crystalline α‐Al2O3). It was observed that laser‐melted material resolidified as γ‐Al2O3 epitactically grown on the (0001) plane of α‐Al2O3 having an orientation relationship (0001)α//(111)γ and [011̄0]α//[11̄0]γ. The interface between unmelted α‐Al2O3 and resolidified γ‐Al2O3 is atomically flat with steps of one to a few close‐packed oxygen layers. The high thermal gradient in the α‐Al2O3 did not produce any interfacial dislocations. However, pronounced lattice distortions existed in the resolidified γ‐Al2O3. It is argued that the very rapid cooling rate present during solidification prevents the ordering of Al atoms that is required for the formation of the stable α‐Al2O3 phase.Keywords
This publication has 8 references indexed in Scilit:
- Absence of solute drag in solidificationApplied Physics Letters, 1994
- Smooth polycrystalline ceramic substrates with enhanced metal adhesion by pulsed excimer laser processingApplied Physics Letters, 1994
- Studies of the optical and structural properties of ion-assisted deposited Al2O3 thin filmsVacuum, 1994
- Ablation, Melting, and Smoothing of Polycrystalline Alumina by Pulsed Excimer Laser RadiationMRS Proceedings, 1992
- Ion implantation and annealing of crystalline oxidesMaterials Science Reports, 1989
- Optical dielectric functions for amorphous Al2O3 and γ-Al2O3Journal of Applied Physics, 1988
- X-ray diffraction in γ-alumina whiskersJournal of Crystal Growth, 1987
- Characterization of transitional alumina by solid-state magic angle spinning aluminium NMRApplied Catalysis, 1983