The effect of the glass transition in fullerite C60 on Ar impurity diffusion

TL;DR

This study investigates how the glass transition in fullerite C60 affects argon impurity diffusion, revealing a significant decrease in activation energy and altered diffusion behavior across a broad temperature range.

Contribution

It provides new insights into the impact of the glass transition on impurity diffusion mechanisms in fullerite C60.

Findings

Diffusion coefficients decrease monotonically with temperature.

Glass transition causes an order-of-magnitude reduction in activation energy.

New diffusion pathways likely emerge due to the glass transition.

Abstract

The kinetics of sorption and subsequent desorption of argon gas by a C60 powder has been investigated in the temperature interval 58-290 K. The temperature dependence of the coefficients of Ar diffusion in fullerite has been obtained using the measured characteristic times of sorption. The diffusion coefficients of Ar decrease monotonically with lowering temperature in the whole range of the investigated temperatures, which corresponds to the thermally activated diffusion of Ar atoms in fullerite. The glass transition in fullerite induces an order-of-magnitude decrease in the activation energy of Ar diffusion in fullerite. Most likely this is because new directions may appear due to the glass transition in which the barriers separating the interstitial voids in the C60 lattice are significantly lower