REFRACTIVE INDEX OF TUNGSTEN OXIDE NANOSTRUCTURED THIN FILMS GROWN AT ROOM TEMPERATURE BY CHEMICAL BATH DEPOSITION METHOD FOR OPTICAL GAS SENSING

Abstract

Refractive index is a dimensionless number that gives the indication of the light bending ability of the medium. It determines how much the path of light is bent or refracted when entering a material. It also determines the amount of light that is reflected when reaching the interface, as well as the critical angle for total internal reflection and their intensity. It can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values. Tungsten Oxide (WO₃) Nanostructured thin films were successfully developed on glass substrates using chemical bath deposition method at a temperature of 300K. The sources of W⁺ is Na₂WO₄.2H₂O. EDTA was used as a complexing agent. WO₃ nanostructured thin film was prepared at the deposition periods of 24 and 29 hours. The optical characterization was done using Prolab-U756S UV-Vis Spectrophotometer measurements in the wavelength range from 200 ̶ 1100nm, i.e. within the ultraviolet, visible and NIR regions of electromagnetic spectrum. My interest in this paper is on the effects of the concentrations of the precursor on the refractive indices of the thin films. Since the refractive indices of the film samples with tungsten oxide nanostructured concentrations of 0.1 ̶  0.4M are 2.12, 2.30, 2.04 and 2.64 ( which are above unity) respectively. The steadiness and stability of the refractive indices across the visible and infrared regions qualify these films good candidates for optical gas sensors.