The effect of molecular impurities CO and CH4 on the structural characteristics of the C60 fullerene around the orientational phase transition

Abstract

X-ray studies of structural characteristics of С60(С)0.9 and С60(CH4)0.5 solid solutions were carried out in around the orientation phase transition in the C60 fullerene. It was established that the filling of octahedral cavities of the fullerene lattice by molecules of CO and CH4 results in a significant increase of the lattice parameter and the thermal expansion coefficients of the ordered phase and in a decrease in the volume change and phase transition temperature TC. In this case there also occurs a noticeable “smearing” of the phase transformation. Based on these results and on the data in the literature contradictions in the conclusions about the structural peculiarities of the formation of a glass state in the CO–C60 solutions were analyzed and discussed. Linear dependences of orientational transition temperature TC and glass transition temperature Tg on CO concentration in the octahedral cavities were obtained. Concentrations of CO in the previous study of specific heat of solid mixtures were calculated.