Dielectric and Electrical Features of PVA/CMC/MnW 0.9 Mo 0.1 O 4 /THAI Nanocomposites Reinforced with Graphene Oxide

This study investigates the structural, dielectric, and electrical properties of novel quaternary polymer nanocomposite films based on a polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) blend, incorporating molybdenum-doped manganese tungstate (MnW 0.9 M 0.1 O 4 ), tetrahexylammonium iodide (THAI), and varying concentrations of graphene oxide (GO) from 0.0 to 0.2 wt%. Films were prepared via solution casting. X-ray diffraction (XRD) confirmed the semi-crystalline nature of the blend and successful filler integration. Scanning electron microscopy (SEM) revealed uniform filler dispersion. Dielectric and electrical characterizations were performed over 100 Hz–1 MHz at 303–363 K. The real ( ϵ ′) and imaginary ( ϵ ″) permittivities showed strong frequency and temperature dependence governed by Maxwell–Wagner–Sillars interfacial polarization. At 1 kHz and 363 K, ϵ ′ varies non-monotonically: 33.40 (0 wt%), 22.52 (0.10 wt%), 19.55 (0.15 wt%), and 28.18 (0.20 wt%). The corresponding ϵ ″ values are 4.83, 1.68, 1.68, and 7.63, respectively. AC electrical conductivity at 1 kHz and 363 K first decreases by 65% (from 2.68 × 10 −7 to 9.34 × 10 −8 S m −1 at 0.10 wt% GO) then increases by 86% to 4.99 × 10 −7 S m −1 at 0.20 wt% GO. Nyquist analysis shows that bulk resistance decreases by 93% (from 6.7 × 10 7 Ω to 4.7 × 10 6 Ω) at 0.10 wt% GO. The correlated barrier hopping (CBH) conduction mechanism is confirmed, with activation energies of 0.32 eV (0.15 wt% GO) and 0.21 eV (0.20 wt% GO). The low-field energy density peaks at 0.01765 J m −3 for 0.15 wt% GO – a relative figure of merit for permittivity, not an absolute energy storage value. Key novelties: (i) optimal GO loading for this relative energy density (0.15 wt%) differs from that for minimum bulk resistance (0.10 wt%), revealing a decoupled optimization landscape; (ii) the frequency exponent s exceeds 1 at low temperatures for 0.10 wt% GO (e.g. s = 1.046 at 313 K), indicating a transient deviation from ideal CBH behavior due to early percolation; (iii) THAI increases crystallinity but elevates bulk resistance to the highest level among all compositions – an antagonistic effect overcome only by GO ≥0.10 wt%. Electric modulus and impedance spectroscopy confirm thermally activated relaxation, with distinct peaks only in GO-containing samples at higher temperatures. Importantly, true energy-storage capability would require separate high-field breakdown strength, leakage current, and charge–discharge measurements, which are beyond the present scope. Therefore, these nanocomposites are presented as a material platform for fundamental study of decoupled dielectric/percolation optimization, not as ready-to-use energy storage devices.