Near-room temperature synthesis of Zn<sup>2+</sup>-doped γ-Ga<sub>2</sub>O<sub>3</sub> nanoparticles via direct oxidation of Zn–Ga alloy by ultrasound

Abstract

This study used ultrasound irradiation to fabricate Zn2+-doped γ-Ga2O3 nanoparticles (NPs) from Zn–Ga alloy at near-room temperature (60 °C). The Zn2+-doped γ-Ga2O3 NPs were obtained at 60 °C after two steps of ultrasound irradiation (miniaturization and oxidation of Zn–Ga alloy). The specific surface area of Zn2+-doped γ-Ga2O3 NPs with a zinc content of 4 at.% was 90.4 m2/g. The oxidation behavior of Zn–Ga liquid alloy significantly differed from that of liquid Ga. X-ray photoelectron spectroscopy spectrum and lattice constant of Zn2+-doped γ-Ga2O3 confirmed Zn2+-doping into the γ-Ga2O3 crystal structure. By annealing at 900 °C, the obtained Zn2+-doped γ-Ga2O3 did not transform to Zn2+-doped β-Ga2O3 but to the mixed phase of β-Ga2O3 and ZnGa2O4. The results indicate that Zn2+ cations, with larger ionic radii than Ga3+ cations, are more difficult to be introduced into the β-Ga2O3 crystal lattice. Thus, this ultrasound process can potentially synthesize various metal cations-doped γ-Ga2O3 NPs without using high temperatures and pressures.