Morphology, UV-visible and ellipsometric studies of sodium lithium orthovanadate

Sodium lithium orthovanadates were prepared by the classic ceramic method technique. Structure, phase purity, composition, and morphology were characterized by X-ray powder diffraction, infrared spectroscopy, energy dispersive spectroscopy, scanning-electron microscopy and atomic force microscopy. The optical properties of NaxLi1-xCdVO4 (x = 0.5, 1) compounds prepared were recorded at room temperature using ultra-visible and ellipsometric spectroscopies in the spectral range (200-800) nm. The average reflectance of the pellets showed high reflectivity (over 80%) in the visible spectrum. The UV-Vis absorption bands are assigned to the charge transfer from the oxygen ligands to the central vanadium atom inside the [VO4](3-) groups in the orthovanadate compounds. The optical band gaps E-g of both samples are evaluated using Kubelka-Munk function. The analysis of the data revealed the existence of optical allowed direct transition for NaxLi1-xCdVO4 (x = 0.5, 1). Spectroscopic ellipsometry measurements have been performed on NaxLi1-xCdVO4 (x = 0.5, 1) specimens and their optical properties were analyzed using the Cauchy model.