Synthesis of cubic-GaN nanoparticles using the Na flux method: A novel use for the ultra-high pressure apparatus

Nano-scale cubic-GaN particles were successfully synthesized using the Na flux method under about 500 atm with a belt-type ultra-high pressure apparatus. High pressure nitrogen gas of about 500 atm was sealed in the ultra-high pressure apparatus, which enabled the dissolution of pressurized nitrogen gas into a Ga-Na melt at 500°C without a compressor. In contrast, the conventional Na flux method is carried out under a pressure of 150 atm, the maximum pressure of a nitrogen gas cylinder. A characteristic feature of the process used herein is that the high-pressure reaction gas is dissolved into a flux within the ultra-high pressure apparatus. The c-GaN nanoparticles obtained by this method show excellent crystallinity and a low mixing ratio of hexagonal-GaN, and thus the method solves two common problems in the synthesis of c-GaN.