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- HIGH PRESSURE BEHAVIOUR OF POLYIODIDES CONFINED INTO SINGLE WALLED CARBON NANOTUBES: A RAMAN STUDY

Auteur(s): Alvarez L., Bantignies J.-L., Le Parc R., Aznar R., Sauvajol J.-L., Merlen Alexandre, San miguel Alfonso, Machon Denis

Conference: Groupement de Recherche "Graphène et Nanotubes" Science et Applications (Dourdan, FR, 2011-02-07)


Résumé:

The high pressure behaviour of polyiodides confined into the hollow core of single walled carbon nanotubes organized into bundles has been studied by means of Raman spectroscopy. Several regimes of the structural properties are observed for the nanotubes and the polyiodides under pressure. Raman responses of both compounds exhibit correlations over the whole pressure range (0-17 GPa). Modifications in particular take place respectively between 1 and 2.3 GPa for polyiodides and between 7 and 9 GPa for nanotubes, depending on the experiment. Differences between one experiment to another are discussed in terms of nanotube filling homogeneity. These transitions can be presumably assigned to the tube ovalization pressure and at the tube collapse pressure. A non reversibility of several polyiodide mode modifications is evidenced and interpreted in terms of a progressive linearization of the iodine polyanions and a reduction of the charged species on pressure release. Furthermore, the significant change of the mode intensities could be associated to an enhancement of lattice modes, suggesting the formation of a new structure inside the nanotube. Changes of the nanotube mode positions after pressure release features point out a decrease of the charge transfer in the hybrid system consistent with the observed evolution of the charged species.