Nanostructure, optical and photoluminescence properties of Zn_1−xNi_xO nanoclusters by co-precipitation method

Zn_1−xNi_xO (x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) nanoclusters have been successfully synthesized by co-precipitation method. The synthesized samples have been characterized by powder X-ray diffraction, energy dispersive X-ray spectra, UV–visible spectrophotometer and Fourier transform infrared spectroscopy. The XRD and SEM measurements reveal that the prepared undoped and Ni-doped nanoclusters have different microstructure without changing a hexagonal wurtzite structure. The calculated average crystalline size from XRD measurement decreases from 37.5 to 26.6 nm for x = 0 to 0.05 which was confirmed by SEM micrographs. The change in lattice parameters, micro-strain, shift of XRD peaks and the blue shift of energy gap from 3.18 to 3.33 eV (ΔE_g = 0.15 eV) for Ni = 0–0.02 and red shift of E_g from 3.33 to 3.14 eV (ΔE_g = 0.19 eV) for Ni = 0.02 to 0.05 reveal the substitution of Ni²⁺ ions into Zn–O lattice. The presence of functional groups and the chemical bonding are confirmed by FTIR spectra. The shift of NBE UV emission between 374 and 395 nm, the shift of green band emission between 517 and 531 nm, the change in intensity and the broadening effect in the photoluminescence spectra confirms the substitution of Ni²⁺ ions into the Zn–O lattice. Ni-doped ZnO system shows a great pledge for the fabrication of nano-optoelectronic devices like tunable light emitting diode in the near future.