Abstract:The changes in molecular chemical structure of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP), caused by doping PVA-PVP blend with cadmium chloride (CdCl 2 ), have been studied using UV-Visible (UV-Vis) spectroscopy, Fourier Transform Raman spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy. The formation of cadmium nano-structures and microstructures in CdCl 2 doped PVA-PVP blend has been visualized using Scanning Electron Microscopy (SEM), in the range of doping levels varying from 0.5 wt% up to 10.2 wt% (doping level in weight percentage). The incorporation of dopant in PVA-PVP blend is confirmed using Energy Dispersive x-ray Spectroscopy (EDS). The optical absorbance (UV-Vis) spectra of PVA-PVP blend films doped with CdCl 2 from 0.5 wt% up to 2.2 wt%, showed a prominent absorption hump with peak at the wavelength 370 nm, in addition to other intermediate energy bands caused by the interactions of CdCl 2 with molecules of PVA and PVP. The photo-luminescence (emission/ fluorescence) spectra show significant quenching of fluorescence in CdCl 2 doped PVA-PVP blend films. Analysis of FTIR and Raman spectra suggest the possible modes of interaction of cadmium ions (Cd 2+ ) and chlorine ions (Cl -) with reactive functional groups (C-N, hydroxyl and carbonyl groups) of polymeric molecules in the blend. A reaction scheme for interaction of CdCl 2 with PVA-PVP blend is proposed, on the basis of spectroscopic studies on these films.
Films of Poly(vinyl alcohol) (PVA) - Poly(vinyl pyrrolidone) (PVP) blend, doped withcadmium chloride (CdCl2) from 0.5 wt% up to 40 wt% andprepared by solution casting method,were studied using temperature dependent direct current (DC)electrical measurements. The DC electrical data were analyzed using Variable Range Hopping (VRH) modelin the temperature range varying from 303K up to 318K. The Mott parameters are determined. The study of time evolution of current passing through the sample, when a constant voltage is applied across it reveals that ions are the majority charge carriers, but the role of electrons in charge transport cannot be neglected. The activation energy (Ea) for mobility of charge carriers has been calculated from VRHand Arrhenius models.
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