Growth of spinel particles on alumina thin films-I. Orientation relationships and shape of the particles

Spinel particles have been grown on thin films of alumina and then examined by transmission electron microscopy. In the first of two papers, the shape of the particles has been examined and related to their crystallography. The particles have been grown on thin-foil alumina substrates of different orientations. Five different orientation relationships between the spinel particles and the alumina have been identified; two of these have been reported for other systems but the other three appear to be new. The existence of all five variants can be understood by considering the alignment of densely packed planes in the two materials and the desire to minimize lattice misfit. The shape of spinel particles is principally determined by the strong tendency for the spinel surface to facet parallel to {111} planes. © 1994.