Thermal expansion and polyamorphism of N2–C60 solutions

Abstract

The linear coefficients α(T) of N2–C60 solutions with 9.9% and 100% of the C60 lattice thermal expansion interstitials filled with N2 are investigated in the interval 2.2–24K. The dependence α(T) has a hysteresis suggesting co-existence of two types of orientational glasses in these solutions. The features of the glasses are compared. The characteristic times of phase transformations in the solutions and reorientation of C60 molecules are estimated.

Intercalation of fullerite C60 with N2 molecules. An investigation by x-ray powder diffraction

“…This also applies to heating and cooling the sample in the temperature region where an orientational glass exists, below T = 60 K. It is important to realize that these differences observed between the lattice parameters measured on cooling subsequent heating exceed the possible error in the measurement. These effects, when converted into thermal expansion coefficients, agree with the directly measured dilatometric data for this solution [33]. As well as these observed phenomena, it is also found that both T c and T g are displaced considerably towards lower temperatures for the C 60 -N 2 solutions in comparison to the corresponding values for pure C 60 (Fig.…”

“…aration and measurement of the thermal expansion coefficients [33]. The obtained linear dependence is slightly higher but still close to the a(x) values for C 60 -Ar [2][3][4] solutions.…”

Evidence for high saturation of porous amorphous carbon films by noble gases

“…Last years many experimental groups carry out investigations of fullerenes and nanotubes saturation by different gaseous admixtures and study various aspects of relevant processes [7][8][9][10][11][12]. One of the most important tasks connected with potential applications is to attain as high saturation as possible, which, additionally, would be stable at elevated temperatures.…”

Specific features of thermal expansion and polyamorphism in CH4–C60 solutions at low temperatures

“…Investigations of the thermal expansion of such orientational glasses based on C 60 and at the same time being saturated with atomic and diatomic gases [2][3][4][5], has revealed interesting features in their low-temperature behavior, amongst these being the first-order phase transition at around liquid helium temperatures -the so-called phenomenon of polyamorphism [3]. These investigations of the coexisting orientational glasses concentrated primarily on the distinctions between the two glasses, such as the characteristic times of system thermalization and reorientation of the C 60 molecules but as well as these, the temperature of the phase transition as well as the characteristic time for phase interconversion between the glasses, was also studied.…”

“…The choice of CH 4 as an impurity was also motivated for the following reasons. Firstly, the effect of admixed tetrahedral symmetric molecules upon the thermal expansion of fullerite had so far until these studies, not been investigated.…”