X-ray diffraction study into the effects of interaction of fullerite C60 crystals with Ne atoms

The powder x-ray diffraction method was used to study the process of saturation by Ne atoms of C60 at room temperature and a Ne gas pressure of 1 bar. We also studied the temperature dependence of the lattice parameters of the saturated sample. We have found that the filing of octahedral voids of the fcc lattice of C60 by neon results in an observable increase of the lattice parameter. This increase as a function of the saturation time is consistently described by an exponential law with the characteristic time constant τ = (179 ± 24) h, which is almost two orders of magnitude longer than at elevated pressures. The ultimate occupancy of the voids by neon reaches the value (48 ± 3)%. The neon impurity virtually does not affect the reflection intensities but during the initial stage of intercalation considerably increases the width of reflections. We show that the most likely migration pathway of neon atoms in crystalline fullerite C60 is from octahedral to octahedral via tetrahedral voids. A considerable hysteresis stretching from to 270 K has been observed in temperature dependence of the lattice parameter