LUMINESCENCE INVESTIGATION OF POWDER ZNO NANOPARTICLES DOPED WITH SM AND LI IONS PREPARED BY COPRECIPITATION METHOD

The present study focuses on the structural and optical properties of ZnO doped with Sm and Li at very dilute concentrations, with compounds Zn1-x-ySmxLiyO (x = 0, 0.03 and y =0, 0.01, 0.03, 0.05). These compounds have been synthesized by a chemical coprecipitation method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman microscopy. The XRD pattern of all the samples showed ZnO hexagonal wurtzite structure, sharp and intense peaks with small change in lattice parameters due to doping in ZnO, indicating the substitution of Sm and Li ions for Zn sites. For Raman spectra, the strongest peak centered at about 435-437 cm-1 can be observed in all the samples, and the intensity of this peak decreases with Sm doping and increases with Li doping. The optical properties of the samples were systematically studied by ultraviolet-visible spectroscopy (UV-V) and photoluminescence (PL) spectroscopy. The maximum absorption of ZnO and Zn0.97Sm0.03O samples appears around 370 and 374 nm respectively near the absorption edge. Doping with Li affects the absorption edge and make it shift toward ultra violet and that the absorption increase with increasing Li content. The PL spectra show a broad and strong visible emission at 564 nm emission covering a large part of the visible region indicating the presence of intrinsic defects like vacancies.