AC Conductivity and Correlation Effects in Nano Granular Pt/C

Authors: S.K. Mishra

Country: India

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Abstract: Nano-granular metals are materials that fall into the general class of granular electronic systems in which the interplay of electronic correlations, disorder and finite size effects can be studied. The charge transport in nano-granular metals is dominated by thermally-assisted, sequential and correlated tunnelling over a temperature-dependent number of metallic grains. Here we study the frequency-dependent conductivity (AC conductivity) of nano-granular Platinum with Pt nano-grains embedded into amorphous carbon (C). We focus on the transport regime on the insulating side of the insulator metal transition reflected by a set of samples covering a range of tunnel-coupling strengths. In this transport regime polarization contributions to the AC conductivity are small and correlation effects in the transport of free charges are expected to be particularly pronounced. We find a universal behavior in the frequency dependence that can be traced back to the temperature-dependent zero frequency conductivity (DC conductivity) of Pt/C within a simple lumped-circuit analysis. Our results are in contradistinction to the work on nano-granular Pd/ZrO2 in the very weak coupling regime where polarization contributions to the AC conductivity dominated. We describe possible future applications of nano-granular metals in proximity impedance spectroscopy of dielectric materials.

Keywords: Alternating Current, Disordered Materials, Scaling Behaviour, Non-percolating Resistance, Relative Humidity

Paper Id: 1664

Published On: 2022-03-10

Published In: Volume 10, Issue 2, March-April 2022

Cite This: AC Conductivity and Correlation Effects in Nano Granular Pt/C - S.K. Mishra - IJIRMPS Volume 10, Issue 2, March-April 2022.

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