Studies on structural, electrical and dielectric properties of nickel ion conducting polyvinyl alcohol based polymer electrolyte films

Abstract

Polyvinyl alcohol (PVA) complexed with different weight percent ratios of Nickel Bromide (NiBr₂) salt were prepared by using solution cast technique. X-ray diffraction analysis confirmed the complexation of the salt with the polymer. Differential scanning calorimetry was used to determine the glass transition and melting temperatures of pure PVA and PVA:NiBr₂ complexed films. Electrical conductivity was measured using ac impedance analyzer in the frequency and temperature range 1 Hz–1 MHz and 303–373 K respectively. It was observed that the magnitude of electrical conductivity increases with NiBr₂ salt concentration as well as temperature. Frequency dependence electrical conductivity of the complexed polymer electrolyte films follows the Jonscher’s equation. The dielectric behavior was analyzed using dielectric permittivity$\left( {{\varepsilon ^\prime}} \right)$ and loss tangent $\left( {\tan \delta } \right)$ of the samples. Relaxation time was determined from the variation of loss tangent with frequency at different temperatures. The modulus spectra indicated the non-Debye nature of the material.