The influence of nitrogen sorption on fullerite C60 properties in a wide temperature range

The influence of nitrogen sorption on structural and thermodynamic properties of fullerite C60 was studied using the powder x-ray diffraction methods under the gas pressure of 30 atm in the saturation temperature range 200-550 C°. The kinetics of nitrogen sorption was studied at different temperatures by monitoring the time dependence of fullerite lattice parameter. It is found that the sorption mechanism is changed with in-creasing temperature. The diffusion mechanism of lat-tice void filling with nitrogen molecules at temperatures below 450 ? goes way to a chemical interaction be-tween nitrogen with fullerene molecules at higher tem-peratures, resulting in the formation of a new molecular material, namely, nitride fullerene C 60Hx. It is estab-lished that the transition from physical to chemical ab-sorption of nitrogen by fullerite (adsorption crossover) occurs in the temperature range 450 C° > T > 400 C°. It is shown that nitrogenation of C60 dramatically increas-es the volume of the C 60 cubic cell, decreases intensities of x-ray lines and increases their half-width. The maxi-mum deformation levels of the fcc lattice, and the char-acteristic times of diffusion voids filling as well as the time of nitrogenation are determined. It is established that at nitrogenation decreases thermal expansion of sol-id C60, suppresses both orientation phase transition and glass state formation. © I.V. Legchenkova, K.A. Yagotintsev, N.N. Galtsov, V.V. Meleshko, Yu.E. Stetsenko, and A.I. Prokhvatilov 2014.