Enhanced optical properties of pure and Sr doped NiO nanostructures: A comprehensive study

We have discussed the detailed optical properties of Ni1-xSrxO (x = 0.0, 0.02, 0.04) nanoparticles calcined at 700 degrees C which have been synthesized using liquid-solid phase route such as sol-gel method. To discuss the optical behavior, we focus on the reflectance/transmittance spectra of pure and Sr doped NiO samples. Here, we found low reflectance about 15% and high transmittance 41.48% in the visible region which more confirm the high transparency in the visible region. The refractive index n (lambda) and extinction coefficient k (lambda) spectra of our samples show normal and anomalous dispersion in the range 200-800 nm. In addition, optical dielectric constants, optical conductivity (sigma), high frequency dielectric constant using dispersion through both of free carriers and bound carriers, static refractive index (n(o)), Wemple Di-Domenico (WDD) static refractive index (n(o)(WDD)), ratio of free carrier concentration, effective mass (N/m*) and plasma frequency (omega(p)) have been determined. The refractive index dispersive behavior is also examined through WDD single oscillator model and optical dispersion parameters E-o and E-d were calculated using WDD model. Simultaneoulsy, through deconvoluted PL spectra using Gaussian function for all the samples, we found extra green and yellow bands are originate in PL emission spectrum for pure NiO sample and further these bands supressed in Sr doped NiO samples which confirm the reduced defects in the NiO on the Sr doping.