Electric properties of carbon nano-onion/polyaniline composites: a combined electric modulus and ac conductivity study

TL;DR

This study investigates the electric properties of carbon nano-onion/polyaniline composites through combined electric modulus and ac conductivity measurements across a wide temperature and frequency range, revealing hopping conduction mechanisms.

Contribution

It introduces a comprehensive analysis combining granular metal and Mott variable range hopping models to explain charge transport in the composite material.

Findings

Identification of hopping conduction mechanisms

Determination of cross-over temperature for conduction processes

Analysis of charge tunneling within the composite

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).