# Electrical transport in onion-like carbon - PMMA nanocomposites

## TL;DR

This study investigates the electrical conductivity of PMMA composites filled with onion-like carbon particles, revealing high conductivity at low loadings and pressure-dependent transport mechanisms influenced by dielectric effects.

## Contribution

It provides new insights into how pressure affects electron transport in onion-like carbon-PMMA nanocomposites, highlighting the role of dielectric permittivity enhancement.

## Key findings

- High electrical conductivity at low filler loadings
- Coulomb gap behavior at atmospheric pressure
- Activated transport under high pressure (2 GPa)

## Abstract

We report electrical conductivity measurements of Polymethyl-methacrylate filled by onion-like carbon particles with primary particle size of $\approx 5$ nm. We shown that the conductivity $\sigma$ is exceptionally high even at very low loadings, and that its low-temperature dependence follows a Coulomb gap regime at atmospheric pressure and an activated behavior at a pressure of $2$ GPa. We interpret this finding in terms of the enhancement under the applied pressure of the effective dielectric permittivity within the aggregates of onion-like carbons, which improves the screening of the Coulomb interaction and reduces the optimal hopping distance of the electrons.