Effect of type and concentration of cobalt precursor on structural, optical and defect properties of ZnCoO nanoparticles

ZnO and ZnCoO nanoparticles were synthesized by hydrothermal route via various Cobalt precursors (cobalt chloride hexahydrate, cobalt nitrate hexahydrate, and cobalt acetate tetrahydrate) and different Cobalt precursor concentrations (10 %–30 %) in synthesis solution. Incorporation of Cobalt into the ZnO structure and its effect were examined by means of elemental, structural, optical and photoluminescence studies. It was observed that the outcome of cobalt incorporation varied according to the dopant source used in the synthesis solution. Besides, the dopant source not only affected the doping ratio but also the morphological, crystal, optical properties of synthesized nanoparticles. Once cobalt acetate tetrahydrate was determined as the adequate precursor, effects of doping on photoluminescence and point defects were studied for different precursor concentrations and reaction times. It was observed that cobalt doping significantly reduces concentration of point defects in nanoparticles.