Effects of strain energy on precipitate morphology in MgO

Differences between the morphology of MgFe₂O₄ precipitates, which form octahedra with {111} habit planes and grow into dendritic forms propagating along 〈100〉; MgCr₂O₄ and MgAl₂O₄, which assume plate-like morphology with a {100} habit plane; and Sc₂O₃, which precipitates as randomly oriented platelets, are discussed in terms of the differences in strain energy associated with exsolution of the phases in MgO. The strain energy effects, which occur both during nucleation and subsequent growth, provide a rational explanation of the observed behavior.