Structural, electrical and dielectric studies of nano-composite polymer blend electrolyte films based on (70–x) PVA–x PVP–NaI–SiO2

Abstract

Nano-composite polymer electrolytes (NCPEs) films based on PVA-PVP-NaI-SiO2 have been prepared using solution casting technique. Investigation of prepared films have been made using various experimental techniques like x-ray diffraction (XRD), attenuated total reflection–fourier transform infrared (ATR-FTIR), differential scanning calorimetric (DSC) and ac impedance spectroscopy. XRD determines the structural properties and shows the significant variation in the characteristic peaks related to semi-crystalline/amorphous phase of different PVA-PVP polymer blend ratio for fixed loading of NaI and SiO2. Complexation of PVA-PVP polymer blend with NaI and SiO2 has been confirmed by ATR–FTIR analysis. Variation in glass transition temperature (Tg) and melting temperature (Tm) of PVA-PVP-NaI-SiO2 NCPE system having various concentration of PVP were observed by DSC analysis. It has been observed that ac conductivity spectra strongly obeys the Jonscher's universal power law [σ=σdc+Afn] with power exponent, n < 1. The dielectric permittivity (ε′&ε″) and electric modulus (M′&M″) measurements were performed in a wide frequency range (10 mHz-10 MHz). Variation of conductivity with temperature shows that the ion conduction and polymer segmental motions are closely related and are governed by Arrhenius mechanism. A couple of peaks observed in loss tangent (tan δ) shows two types of relaxation processes interpreted in terms of dipole segmental motion (α-relaxation) and side chain dipole group motion (β-relaxation).