Substrate-Induced Anisotropic Growth of CuAlO2 Platelets in a Liquid-Solid Reaction

Cheng-Hung Shih; Cheng-Chia Chang; Kuang-Kuo Wang; Hui-Chun Huang; Liuwen Chang; Mitch M C Chou

doi:10.1021/acsomega.2c06672

Substrate-Induced Anisotropic Growth of CuAlO₂ Platelets in a Liquid-Solid Reaction

ACS Omega. 2023 Jan 30;8(5):4703-4710. doi: 10.1021/acsomega.2c06672. eCollection 2023 Feb 7.

Authors

Cheng-Hung Shih^{1

2}, Cheng-Chia Chang¹, Kuang-Kuo Wang¹, Hui-Chun Huang¹, Liuwen Chang^{1

2}, Mitch M C Chou^{1

2}

Affiliations

¹ Department of Materials and Optoelectronic Science, National Sun Yat-sen University, Kaohsiung80424, Taiwan, ROC.
² Center for Crystal Researches, National Sun Yat-sen University, Kaohsiung80424, Taiwan, ROC.

Abstract

This study reports a simplified method to grow CuAlO₂ crystals of submillimeter sizes with a highly anisotropic shape of a platelet. The solid-state reaction of forming CuAlO₂ at ca. 1373 K in the first stage of the conventional flux method is no longer required. The CuAlO₂ platelets nucleated directly onto the (0001)_sapphire surface in a melt of Cu₂O saturated with Al₂O₃ 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 CuAlO₂ platelets all have a 3R crystal structure with no line and planar defects observed by TEM. The CuAlO₂ 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 CuAlO₂ crystals paves the way for their practical application in photoelectrochemical devices.