Accueil >
Production scientifique
(89) Production(s) de ALVAREZ L.
|
|
EXAFS investigations of iodine-doped carbon nanotubes 
Auteur(s): Michel T., Alvarez L., Sauvajol J.-L., Almairac Robert, Aznar R., Bantignies J.-L., Mathon O.
(Article) Publié:
Physical Review B, vol. 73 p.195419 (2006)
Ref HAL: hal-00498071_v1
Exporter : BibTex | endNote
Résumé: We report an x-ray absorption fine structure study at the iodine-K edge of the local structure in iodine-doped carbon nanotubes. The iodine-carbon host interaction is shown to be weaker in multiwalled carbon nanotubes (MWNTs) than in single-walled carbon nanotubes (SWNTs). Iodine species are only localized at the surface of the external tube for MWNTs, whereas iodine species enter inside SWNTs. For doped SWNTs, both the experimental and the theoretical EXAFS spectra allow us to establish the structure of the iodine chain as disordered pentaiodide at the saturation level.
|
|
|
|
Structural properties of carbon peapods under extreme conditions studied using in situ x-ray diffraction
Auteur(s): Chorro M., Rols Stéphane, Cambedouzou Jean, Alvarez L., Almairac Robert, Sauvajol J.-L., Hodeau J.L., Marques L., Mezouar M., Kataura H.
(Article) Publié:
Physical Review B, vol. 74 p.205425-1-5 (2006)
Ref HAL: hal-00498754_v1
Exporter : BibTex | endNote
Résumé: Structural properties of carbon peapods, C-60, trapped into single-walled carbon nanotubes (SWNT), have been studied under high-pressure/high-temperature conditions (HPHT) by in situ x-ray diffraction. The C-60 chain structure together with the influence of the filling on the SWNT change under HPHT treatment is investigated. Synthesis of a one-dimensional polymer chain of C-60 inside the single-walled carbon nanotubes is evidenced. At 4 GPa, increasing the temperature up to 1023 degrees C leads to a progressive C-60 polymerization that is associated to a shortening of C-60-C-60 distance down to 8.7 A. Back to ambient conditions, the C-60 chain remains polymerized, emphasizing the high stability of this material. In addition, our data strongly suggest a symmetry change of the two-dimensional bunde lattice under pressure.
|
 |
Science and application of nanotubes
Auteur(s): Bantignies J.-L., Baaba R., Alvarez L., Leonormand F., Parent P.
Conference: Annual meeting GDR-E 2006 (Obernai, France, FR, 2006-10-16)
|
|
Etude par spectroscopie d'absorption des rayons X du dopage des fagos de nanotubes monoparois
Auteur(s): Bantignies J.-L., Aznar R., Alvarez L.
(Affiches/Poster)
GFECI 2006 (Autrans, France, FR), 2006-03-28 |
|
Etude structurale des nanotubes popes au alcalins par spectroscopie d'absorption des rayons X
Auteur(s): Alvarez L.
(Affiches/Poster)
Soleil User's Meeting (Orsay, France, FR), 2006-01-18 |
|
|
|
EXAFS study of rubidium-doped single-wall carbon nanotube bundles
Auteur(s): Bantignies J.-L., Alvarez L., Aznar R., Almairac Robert, Sauvajol J.-L., Duclaux L., Villain F.
(Article) Publié:
Physical Review B, vol. 71 p.195419 (2005)
Ref HAL: hal-00498755_v1
Exporter : BibTex | endNote
Résumé: The local structure around the rubidium ions inserted in single-wall carbon nanotube bundles (Rb-doped SWCNT) is studied by Rb K-edge extended x-ray-absorption fine structure (EXAFS). The dependence of the local order around the rubidium ions is investigated as a function of the time of doping (i.e., as a function of the stoichiometry of the sample). The first coordination shell of the rubidium ions, related to the distance between rubidium and the first nearest-neighboring carbon atoms, has a clear time doping dependence. Comparison between ab initio simulations of the EXAFS spectra and experimental data questions the interstitial site (between three tubes) as the preferential insertion site in SWCNT bundles. The results indicate that the rubidium ions are mainly located inside the tubes and around the bundles. The results are in good agreement with combined x-ray and neutron diffraction experiments performed on the same samples.
|
