Title: Electric properties of carbon nano-onion/polyaniline composites: a combined electric modulus and ac conductivity study,
Abstract: The complex electric modulus and the ac conductivity of carbon
nanoonion/polyaniline composites were studied from 1 mHz to 1 MHz at isothermal
conditions ranging from 15 K to room temperature. The temperature dependence of
the electric modulus and the dc conductivity analyses indicate a couple of
hopping mechanisms. The distinction between thermally activated processes and
the determination of cross-over temperature were achieved by exploring the
temperature dependence of the fractional exponent of the dispersive ac
conductivity and the bifurcation of the scaled ac conductivity isotherms. The
results are analyzed by combining the granular metal model(inter-grain charge
tunneling of extended electron states located within mesoscopic highly
conducting polyaniline grains) and a 3D Mott variable range hopping model
(phonon assisted tunneling within the carbon nano-onions and clusters).