A comprehensive study on structural, optical, electrical, and dielectric properties of PVA-PVP/Ag-TiO2 nanocomposites for dielectric capacitor applications

Abstract

Nanocomposites made from polymers and nanoparticles (NPs) have a wide range of uses. Herein, the polymer nanocomposite electrolyte films were prepared by blending polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) with hybrid NPs of silver (Ag) and titanium dioxide (TiO2). The structural, optical, electrical, and dielectric properties of the resulting PVA-PVP/Ag-TiO2 nanocomposite electrolytes were analyzed. XRD analysis revealed that the PVA-PVP blend had a semicrystalline structure, and the addition of hybrid NPs reduced the crystallinity ratio. FTIR analysis showed that the intensity decreased as the content ratio of hybrid NPs increased. Optical measurements showed that the nanocomposite electrolyte samples' direct and indirect optical energy gap decreased with the increasing content of hybrid NPs. The electrical conductivity also increased with the hybrid NPs' content, likely due to the higher conductivity of the hybrid NPs compared to the polymer blend matrix's electrical conductivity. The dielectric constant (εr) and dielectric loss (εi) increased with the concentration of hybrid NPs at lower frequencies, indicating the polarization effects of space charges. The capacitance–frequency (C–f) and conductance–frequency (G/ω–f) curves of the prepared polymer nanocomposites exhibited a discernible enhancement correlating with the increased content of Ag-TiO2 nanofillers. The impedance spectroscopy data were analyzed using Nyquist plots, which showed a single semicircular arc whose radius of curvature decreased with increasing the hybrid NPs loading, indicating a decrease in the overall impedance of the nanocomposite electrolytes with the mixed NPs loading. The impedance reduction and dielectric feature increase were attributed to the interfacial polarization between the hybrid NPs and the polymeric matrix. These findings suggest that the PVA-PVP/Ag-TiO2 nanocomposite electrolytes could be used for thin-film dielectric capacitor applications.