The effect of molecular impurities CO and CH4 on structural characteristics of C60 fullerite in region of orientation phase transition

The x-ray studies of structural characteristics of C60(CO)0.9 and C60(CH4)0.5 solid solutions were carried out in the region of orientation phase transition in fullerite C60. It is established that the filling of the octahedral cavities of the fullerite lattice by molecules of CO and CH4 results in a significant increase of the lattice parameter and thermal expansion coefficients of the ordered phase and 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 literature data, the contradictions in the conclusions about the structural peculiarities of the formation of a glass state the CO-C60 solutions are analyzed and discussed. Linear dependences of orientational transition temperature TC and glass transition one Tg on CO concentration C in the octahedral cavities are obtained. The CO concentration in the previous study of specific heat of solid mixtures are calculated.