Intercalation of C60 fullerite with helium and argon at normal temperature and pressure

Powder x-ray diffractometry was used to study the effect of intercalating C60 fullerite with helium and argon atoms on the fullerite structure. The samples were saturated at room temperature and normal pressure. The dependences obtained for the lattice parameter and half-width of certain reflections on the intercalation time with helium atoms showed that the voids in the C60 lattice were filled in two stages. Helium filled the octahedral voids relatively rapidly first and then the tetrahedral subsystem, but much more slowly. Both intercalants affected the half-width and intensity of the reflections, the matrix lattice parameters, the phase transition temperature, the volume jump at the transition, and the thermal expansion coefficients of C60 fullerite.