From a one-dimensional crystal to a one-dimensional liquid: A comprehensive dynamical study of C60peapods

Abstract

We report an inelastic neutron-scattering investigation of the longitudinal acoustic modes of C 60 chains confined inside single walled carbon nanotubes. We take advantage of the orientations of the chains within the plane of the pellet sample to isolate their scattering signatures in the (Q,ω) space, which we follow as a function of temperature from 260 K up to 1100 K. The results show the progressive evolution of the confined chain from a one-dimensional (1D) crystal to a linear liquid, the transition occurring within a temperature range of ∼150 K centered around 600 K. The comparison of the data obtained on monomer and polymer peapods allows extracting the speed of sound in the monomer crystalline chains (v mono = 3.5 km s −1 , v poly /v mono = 1.7). We find that the sound velocity is further reduced by half in the liquid state which reveals that the melting is not only due to harmonic additive thermal fluctuations, but that anharmonic terms in the intermolecular potential play an important role at high temperatures.

Superior carbon nanotube stability by molecular filling:a single-chirality study at extreme pressures

“…For that purpose, part of the nanotubes were heated up to the temperature of 550 • C in air with a ramp of 10 • C/min and then collected as soon as the target temperature was achieved. Aiming for a 10 % mass loss, this annealing allows to selectively open the nanotubes around the reactive sites located at the tips and the defects [42,43]. Further details on this sample preparation are reported in the SI, as well as a photo-luminescence excitation map of the Stock and final solutions (Fig.…”

In situ X-ray diffraction observation of two-step fullerene coalescence in carbon peapods

“…The asterisks indicate the first-and second-order peaks of the periodic C 60 chains. Below 800 • C, evolutions of the positions of the sawtooth peaks are reversible and correspond to the evolution in temperature of the mean interfullerene distance [19,27]. The (10) peak intensity, which is closely related to the amount of fullerenes inside the nanotubes [25], does not change in a noticeable way.…”

“…-We have prepared C 60 and C 70 peapods samples in the form of buckypapers, as described in refs. [18,19]. The peapods synthesis procedure consists essentially in heating opened nanotubes (in the form of buckypapers) together with a fullerene powder at 500 • C in vacuum, so that the powder sublimates and the fullerenes adsorb inside the nanotubes.…”