Size-controlled synthesis of monodisperse zinc gallium oxide particles via coprecipitation under hydrothermal conditions using trisodium citrate

Abstract

Monodisperse particles of zinc gallium oxide have been synthesized via coprecipitation under hydrothermal conditions in the presence of trisodium citrate, which acts as a ligand for the reactant metal ions to establish controlled homogeneous nucleation at an elevated temperature. This procedure enables the particle size to be tuned up to about 200 nm by changing the citrate concentration. Also, the spinel crystal structure can be maintained when the compositional ratio of Ga to Zn in the particle, f_Ga/Zn, varies, at least in the range of f_Ga/Zn = 1.3–2.7, depending on the citrate concentration and/or Ga³⁺/Zn²⁺ ratio in the reacting solution. The absorption edge of the diffuse reflectance spectra suggests that the present particles possess a band gap of 4.7–4.9 eV, which is almost independent of the synthesis conditions.