Tuning of energy gap and photoluminescence behaviour of Zn_(0.96)Ni_(0.04)O nanostructure by Cr substitution

摘要

The Cr-doped Zn_(0.96)Ni_(0.04)O (Zn_(0.96-x)Ni_(0.04)Cr_x_ O) nanoparticles with different Cr concentrations from 0 to 6 % have been synthesized successfully by sol-gel method. The obtained nanoparticles were systematically characterized by X-ray diffraction, energy dispersive X-ray spectra, scanning electron microscope, Fourier transformation infrared spectroscopy, UV-Vis spectroscopy and photoluminescence spectra. X-ray diffraction patterns revealed that Cr was incorporated into the ZnO crystal lattice without disturbing the original wurtzite crystal structure. The increase of lattice parameters by Cr-doping concluded that both Cr~(3+) and Cr~(2+) ions co-exist, and occupy Zn~(2+) in the ZnO host lattice. The observed higher transmittance, energy gap and emission intensity at Cr = 2 % indicate that this is selected as optimized Cr concentration in the host lattice. The blue shift of energy gap and the variation in intensity and position of emission bands in photoluminescence spectra were discussed based on size and defects density.