Substrate-Induced Anisotropic Growth of CuAlO(2) Platelets in a Liquid–Solid Reaction

[Image: see text] This study reports a simplified method to grow CuAlO(2) crystals of submillimeter sizes with a highly anisotropic shape of a platelet. The solid-state reaction of forming CuAlO(2) at ca. 1373 K in the first stage of the conventional flux method is no longer required. The CuAlO(2) platelets nucleated directly onto the (0001)(sapphire) surface in a melt of Cu(2)O saturated with Al(2)O(3) at 1473 K. The excess flux was mostly removed by the capped alumina plate on cooling with a limited amount of residue which can be leached afterward. The CuAlO(2) platelets all have a 3R crystal structure with no line and planar defects observed by TEM. The CuAlO(2) crystals emit a luminescence at 3.49 eV associated with resonant Raman effect resulted from a band-to-band transition in room-temperature PL measurement. The facile fabrication method for growing highly anisotropic CuAlO(2) crystals paves the way for their practical application in photoelectrochemical devices.