On thermoelastic phenomena around orientational ordering transition in crystalline C60

TL;DR

This paper investigates thermoelastic effects during the orientational phase transition in solid C60, using Landau theory to analyze coupling between order parameters and elastic strains, and compares theoretical predictions with experimental data.

Contribution

It applies Landau theory to model the coupling of order parameters with elastic strains in C60, predicting coexistence of phases and thermodynamic properties.

Findings

Coexistence of FCC and SC phases from 260 K to 160 K

Calculated thermodynamic properties agree with experimental data

Landau theory is applicable to fullerene ordering transitions

Abstract

Thermoelastic phenomena associated with orientational phase transition in solid C60 are considered. Coupling of the order parameter with elastic strain is analyzed in the Landau theory of phase transitions. Wide range of possible coexistence of the FCC phase with SC one in C60 has been found from 260 K down to critical temperature 160 K of the instability of high-symmetry phase. The specific heat, thermal expansion coefficient and isothermal compressibility for low-symmetry phase are calculated as function of temperature and pressure in an agreement with reported data. Applicability of the Landau theory to ordering transition in fullerenes is discussed.