Abstract
Single Crystals of two kinds of spinel-type oxide have been grown by the Verneuil method. (Mg, Mn)O-Al2O3 showed a distinct growth hillock on the top of the crystal and a characteristic distribution of dislocations. A more or less regular network of subboundaries is observed in the cross section, suggesting the presence of an easy atomic movement along the ⟨110⟩ direction which is not vertical to the growth direction and is located near the solid liquid interface in the growing process. This assumption explains the observed character of the growth hillock and of the internal structure, as being due to a polygonization of remaining edge dislocations. The characteristic of side planes observed in grown crystals of MgO-2.5Al2O3 as reported by Nakano et al. may also be explained by the same assumption. A single crystal of Fe3O4 was grown successfully. However, it contains a small amount of precipitates of α-Fe2O3.
