β-phase gallium oxide (β-Ga 2 O 3 ) is an important wide-bandgap semiconductor material, and in its powder form, it serves as a critical raw material for semiconductor and optoelectronic applications. In this study, a novel preparation method for β-Ga 2 O 3 powder with a shortened process design was developed to address the limitations of conventional synthesis methods for this material. First, during precursor preparation, only gallium (Ga, purity 99.99%) was used as the reactant, with ultrapure water as the reaction solvent. No other impurity ions or organic solvents were introduced. Using 2 g of Ga, 10 mL of H 2 O, a reaction temperature of 200 ℃, and a reaction time of 4 h, the rod-shaped Ga 2 O 3 precursor, GaOOH, was synthesized via a subcritical heterogeneous reaction. This preparation stage offers the advantages of a low raw material cost, environmental friendliness, and short process flow. During the subsequent calcination and transformation, the GaOOH precursor decomposed into α-Ga 2 O 3 at approximately 400 ℃. With an increase in the temperature to 700–800 °C, the α-Ga 2 O 3 phase transformed into β-Ga 2 O 3 , ultimately yielding a product with a purity exceeding 99.9%. Thus, this study achieves the short-process, green, and low-cost synthesis of 99.9% purity β-Ga 2 O 3 powder using only metallic Ga and ultrapure water, providing a new raw material preparation route for β-Ga 2 O 3 . • A novel method for synthesizing high-purity β-Ga 2 O 3 via subcritical heterogeneous reaction coupled with calcination transformation. • Using gallium (99.99% purity) and ultrapure water as raw materials, the GaOOH precursor was successfully synthesized under reaction conditions of 200 ℃ for 4 hours. • The decomposition temperature of the precursor is approximately 400 ℃, at which temperature the precursor decomposes into α-Ga 2 O 3 . • At a calcination temperature of 700 ℃, the GaOOH precursor decomposed and transformed into β-Ga 2 O 3 with a purity of 99.9%.
Wang et al. (Fri,) studied this question.