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Modelling of the Cluster-Nature Solvent Features of Single-Wall Carbon Nanohorns

Francisco Torrens 

Universitat de Valencia-ICMol (UVEG), Ed. Insts. Paterna, P.O. Box 22085, Valencia 46071, Spain

Abstract

The existence of single-wall carbon nanotubes (SWNTs) in organic solvents, in the form of clusters, is discussed. A theory is developed based on a bundlet model for clusters, describing the distribution function of clusters by size. The phenomena have a unified explanation in the bundlet model of clusters, in accordance with which the free energy of an SWNT, involved in a cluster, is combined from two components: a volume one, proportional to the number of molecules n in a cluster, and a surface one proportional to n^(1/2). The bundlet model for clusters enables describing the distribution function of SWNT clusters by size. The droplet model is formally analogous to the one for fullerene clusters. From purely geometrical differences the models predict different behaviours. Single-wall carbon nanocones (SWNCs) of various disclinations are investigated via energetic and structural analyses. Several SWNC's terminations are studied, which are different among each other because of the type of closing structure and the arrangement of them. The SWNC packing efficiencies, and interaction-energy parameters, are intermediate between the ones of fullerene and SWNT clusters; an in-between behaviour is expected. However, SWNC properties are calculated closer to those of fullerene and more distant from those of SWNT. Provisional conclusions follow. (1) Close packings are the tightest way to pack spheres. Atoms and fullerenes being nothing but tiny spheres often arrange in this way. Furthermore it is also possible to deduce atomic structures of metal alloys, salts and oxides by fitting the voids of close-packed spheres. (2) The single-wall carbon nanocone-nanohorn packing efficiencies, and interaction-energy parameters, are intermediate between those of fullerene and single-wall carbon nanotube clusters. Therefore an in-between behaviour is expected.

 

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Presentation: Poster at E-MRS Fall Meeting 2009, Symposium H, by Francisco Torrens
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-11 16:15
Revised:   2009-06-07 00:48