On a Possible Melting Curve of C60 Fullerite

TL;DR

This paper estimates the melting curve of C60 fullerite at high temperatures and pressures using thermodynamic models, providing a theoretical prediction of its melting behavior up to 15 kbar.

Contribution

It presents the first theoretical estimation of the melting curve of C60 fullerite using the Lindemann criterion and accounts for lattice anharmonicity.

Findings

Melting curve approximated by the Simon equation.

Estimated melting temperature at normal pressure is 1500 K.

Predicted melting temperature at 15 kbar is around 4000 K.

Abstract

We study thermodynamic properties of the high-temperature modification of fullerites on the basis of the Girifalco intermolecular potential. In the present work, using the Lindemann's melting criterion we estimate a possible melting curve Tm(P) of C60 fullerite. To take into account the lattice anharmonicity that has strong effect at T >700 K, we use the correlative method of unsymmetrized self-consistent field. The melting curve for C60 fullerite has been calculated from the melting point at normal pressure estimated at 1500 K up to 15 kbar which corresponds to 4000 K. The temperature dependence of the melting pressure is approximated very well by the Simon equation. We have calculated its parameters for C60. The temperature dependence of the molar volume along the melting curve is discribed by logarithmic function.