Influence of CO molecular impurity on the structural and thermodynamic properties of fullerite C60, in a broad range of sorption temperatures

Abstract

An x-ray diffraction study of how sorption of CO gas at a pressure of 30 atm in the temperature range of 150–600 °C influences the structural characteristics of polycrystalline and single crystal fullerite C60. The sorption kinetics are studied by constructing a dependence of the lattice parameter on the time it takes for fullerite to be saturated by CO molecules. At temperatures Tsorb > 300 °C there is an observed dissociation of carbon monoxide, accompanied by the precipitation of carbon powder and the chemical interaction of atomic oxygen with C60 and CO molecules, and possibly with the carbon condensate. These processes have a strong influence on the structural characteristics of fullerite, thus creating, in part, a nonmonotonic dependence of the parameter and lattice matrix volume on the impurity saturation temperature. The concentrations of solid solutions C60(CO)x poly- and single crystal samples are determined in the physisorption range for two modes (150 and 250 °C). It is found that the CO impurity has a linear effect on the lattice parameter and the temperature of the orientational transition of fullerite C60.