Characterization of high concentration Ga-doped ZnO nano-powders prepared by sol–gel combustion

Abstract High concentration (up to 20 mol%) Ga-doped ZnO (GZO) nano-powders were prepared by a sol–gel combustion method. The crystal structure, morphology, and crystallite size of GZO were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that Ga 3+ ions had been successfully doped into ZnO, and all GZO samples were of a single phase and had the same wurtzite structure as pure ZnO. Moreover, the crystal growth rate of ZnO was suppressed by the presence of Ga, and the crystallite size of ZnO can be reduced to around 5.7 nm at the presence of 20 mol% Ga. The absorption spectra showed that the optical band gap energy ( E g ) of GZO nano-powder was in the range of 3.013–3.219 eV. The reflectance spectra showed that all the samples had very high reflectivity in the wavelength region between 450 and 2500 nm, which indicated the potential use in cooling materials. The photocatalytic activities of ZnO and GZO nano-powders were evaluated using methyl orange degradation in aqueous solution under sunlight and UV light irradiation. The results showed that the photocatalytic activities and the adsorption capacities increase with Ga content.