The instability of a solid-liquid interface (ISLI) on MgO single crystals with a CaMgSiO4 liquid containing either CoO or NiO was investigated. As a result of a reaction with CoO-CaMgSiO4, a (Mg,Co)O solid solution layer with a uniform thickness developed at the surface of the MgO crystal. In contrast, when a MgO single crystal was reacted with NiO-CaMgSiO4, severe liquid penetration into the single crystal occurred, which resulted in a sponge-like structure. The results were examined in terms of the ISLI induced by the coherency strain energy, which were confirmed by conventional Transmission Electron Microscopy (TEM) observations, Convergent Beam Electron Diffraction (CBED) and Electron Probe Micron Analysis (EPMA).

Keywords: MgO single crystal, Diffusion, Solution-reprecipitation, Coherency strain energy, Instability of solid-liquid interface (ISLI)