Phase Evolution of Ga 2 O 3 Produced from Morphology‐Controllable α‐ GaOOH Nanocrystals

Fine powders of GaOOH nanocrystals are synthesized via a facile hydrolysis process through the solution–solution interface reactions of anhydrous GaCl 3 and distilled water followed by subsequent solvothermal treatment at mild conditions. Well‐faceted α‐ GaOOH hexagonal prism‐like nanorods are prepared through solvothermal treatment at 180°C with CTAB as the morphology controlling surfactant. Ga 2 O 3 nanocrystals are fabricated via the pyrolysis of α‐ GaOOH hexagonal prism‐like nanostructures at temperatures above 410°C. A peculiar back‐transformation from β‐ Ga 2 O 3 to α‐ Ga 2 O 3 has been observed to occur between about 557°C and 719°C, which is considered to be responsible for the coexistence of the two phases. The phase transformation mechanisms of Ga 2 O 3 at elevated temperatures, as well as the possible transformation route, have been postulated from a thermodynamic point of view.