Epitaxial Growth of Spinel by Reaction in the Solid State

The condensed‐state reaction between single crystals of Al 2 O 3 and MgO was conducted in air at 1560°C. Spinel formed as two product layers which were shown to agree with the proposed mechanism. The crystallographic orientation of the parent crystals had no effect on the rate of spinel growth. The orientation of the spinel grown from sapphire was the same as that found by other investigators for isomorphic crystals. The orientation of spinel grown from periclase was largely dependent on the transport mechanism across the periclase‐spinel interface.