Na to tailor the band gap and morphology of ZnO nanograins

Sodium doped and undoped zinc oxide compounds are synthesized using sol–gel auto combustion method. The doping has five different concentrations of sodium in zinc oxide. They are characterized for phase and crystal structure using X-ray diffractrometer. It is confirmed that the doping of the impurity atoms show lattice changes. The average particle size of samples are found to be in the range between 32 and 62 nm. Williamson–Hall plots show strain induced in crystallites. Scanning electron microscope micrographs show the morphology of the Na doped samples as nano pebbles, nano platelets and nano rods having considerable width and length; while small thickness. Fourier transform infra-red spectrophotometer and FT Raman studies show the persistent peaks corresponding to characteristic Zn–O bonds. Ultraviolet–visible–near infra-red spectrophotometer studies reveal the decrease in absorbance and red shift in band gap with increasing Na content. The fluorescence spectral analysis of the samples demystifies the existence of oxygen deficient sites. The varying of oxygen vacancy helps band gap tailoring while enhancing Na doping in ZnO.