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

Abstract

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 Eg 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.