New and Unforeseen Crystal Growth Processes for a Metal Oxide.

The synthesis of corundum (α-AlO) via a layered AlO-MoO system was directly observed for the first time. This revealed a new crystal growth process with three key features: (1) the formation of an Al(MoO) intermediate layer through a solid-solid interaction in the temperature range of ∼705-860 °C; (2) the melting of the Al(MoO) layer between approximately 870 and 890 °C; and (3) the decomposition of Al(MoO) to corundum between 950 and 1100 °C. This molten intermediate decomposition (MIND) mechanism produced corundum, which was light bluish-gray in color and was defined in CIE () color space as = 76.