Preparation of Co2+-doped ZnAl2O4 nanoparticles by citrate sol-gel method

Nano-sized ZnAl2O4 particles doped with Co2+ ions were prepared by a citrate sol-gel method. The precursor was prepared from metal nitrates and citric acid and heat-treated at 600-900 °C. The nanocrystalline Co2+:ZnAl2O4 is characterized by X-ray diffraction, transmission electron microscopy and luminescence spectroscopy. The precursor gel began to crystallize to the ZnAl2O4 nanopowders at 600 °C. The average particles size was estimated as 16-30 nm in the temperature range of 600-900 °C. The emission spectra of Co2+:ZnAl2O4 in the visible region were characterized by the tetrahedrally coordinated Co2+.