Surface energy of spinel

The contributions of the Coulomb electrostatic interaction and the Born-Mayer repulsive interaction to the surface energy MgAl2O4 are calculated. These results are compared with the surface-energy values calculated from elastic constants. The results show that surfaces parallel to {111} planes are of lowest energy for MgAl2O4 spinel as well as some spinel ferrites. Except for qualitative evidence, most of these predictions await experimental verification, including the predictions of the composition of freshly cleaved spinel surfaces.