Optical properties and microstructure of Ni doped ZnAl2O4 nanopowders synthesized by sol–gel method

Zn1−xNixAl2O4 (x = 0, 0.025, 0.05, 0.075, 0.10) nanopowders were successfully synthesized by sol–gel method, and the microstructure, morphology and optical properties were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM), fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL). The experiment results show that all samples synthesized by this method possess spinel structure with good crystallization, no other impurity phase are observed, the morphology are dandruff-like. The band gap values of the Zn1−xNixAl2O4 samples are 4.02, 3.80, 3.70, 3.63 and 3.55 eV, respectively. The band gap of samples decreases with the increasing Ni doping concentration, and the PL spectra of the samples show the photoluminescence quenching.