Abstract
Cobalt oxide (Co3O4) nanoparticles (NPs), with average crystallite size <61 nm, were prepared by a sol-gel method. Two allowed direct optical band gaps of 1.445 and 1.915 eV are found for Co3O4 NPs. Sodium carboxymethyl cellulose (Na-CMC)/polyvinyl alcohol (PVA) blend was doped with Co3O4 at different concentrations < 1.0 wt.% to study the electrical and dielectric properties of these nanocomposite films. Scanning electron microscopy images revealed a good dispersion of Co3O4 NPs on the surface of the CMC/PVA films. The current-voltage characteristics are of non-ohmic behavior. The dielectric permittivity (epsilon') was studied in the frequency and temperature range of 5.0 kHz-5.0 MHz and 308-408 K and was found to depend on the Co3O4 content. The dielectric loss (epsilon") also increases and shows wave-like behavior with increasing Co3O4 ratio. Increasing Co3O4 NPs content leads to the formation of more number of three-dimensional semiconducting connected networks inside CMC/PVA matrix, leading to increasing both DC and AC conductivities. The correlated barrier hopping (CBH) is the most suitable mechanism to explain the AC conduction behavior in the Co3O4/Na-CMC/PVA nanocomposite films.