Hydrothermal synthesis and characterization of ZnGa2O4 spinel fine particles

Abstract

The influences of solution pH, cation concentration, treatment temperature, time, and ZnO/Ga2O3 molar ratio of the starting solution on the crystallite size, morphology, lattice parameters and chemical composition of hydrothermally synthesized ZnGa2O4 spinel particles were investigated. Nanocrystalline ZnGa2O4 spinel particles were prepared from gallium sulfate and zinc sulfate in the presence of aqueous ammonia under hydrothermal conditions in the pH range of 2.5 to 10. Their crystallite size increased and their chemical composition approached ZnO/Ga2O3 = 1 with increasing treatment temperature, time, and starting ZnO/Ga2O3 molar ratio. ZnGa2O4 spinel particles with a stoichiometric composition were synthesized by controlling the starting ZnO/Ga2O3 molar ratio under hydrothermal conditions at 240 °C for 50 h. The formation mechanism of the ZnGa2O4 spinel particles was discussed, and the diffusion of Zn2+ ions seemed to be the key for the synthesis and growth of the spinel, especially for obtaining a stoichiometric composition.