Optical and structural properties of Se80Te15Bi5/PVA nanocomposite films

New nanocomposite films of polyvinyl alcohol (PVA) doped with different wt% (0.6, 1.6, 2.4) of Se80Te15Bi5 glass have been prepared by solution casting method for flexible optical device applications. X-ray diffractogram (XRD) of films exhibit polycrystalline nature. Scanning electron microscope (SEM) images confirmed the formation of nanoclusters having a mean diameter of 60 nm. Elemental composition of the samples was confirmed by energy dispersive X-ray analysis (EDAX) spectra. The optical constants of films were calculated based on the spectral data obtained using UV-Visible spectrophotometer in the wavelength range 200-800 nm. The possible optical transition in these films was found to be allowed indirect transition with energy gap values which decreases from 4.0 eV for pure PVA to 1.6 eV for the nanocomposite with 2.4 wt% of the glass. The calculated refractive index exhibits a normal dispersion and increases from 1.42 for pure PVA to 3.17 for the nanocomposite with 2.4 wt% of the glass. The optical dispersion parameters were determined according to Wemple and DiDomenico (WDD) model. Decrease in optical band gap while the increase in other optical parameters may be attributed to the formation of clusters during the dissolution of glass. (C) 2018 Elsevier B.V. All rights reserved.