Structural and optical studies of Ni-doped ZnO

An investigation of structural and optical properties of Ni doped ZnO nanoparticles, prepared by modified sol-gel process at different annealing temperature. X-ray diffraction study reveals that there is no secondary phase formation and confirmed about its space group P63mc. Rietveld refinement of X-ray data shows decrease in c/a ratio of ZnO with Ni doping. Optical bandgap decreases with Ni doping for both the temperature and decrease most with higher temperature from∼3.21eV to∼3.18 eV. Ni doping cause formation of Urbach tails which increases with Ni doping and thereby reduces the bandgap.