"From Graphite to carbon nanotubes. A guide for its applications on"
From Graphite to carbon nanotubes. A guide for its applications on nanoscience and nanotechnology Juan Salvador Arellano Peraza Área de Física Atómica Molecular Aplicada, Universidad Autónoma Metropolitana Azcapotzalco, C.P. 02200, México D.F., México 2mev/atom: energy difference between graphite and graphene Motivation * Graphene, has been obtained (year 2004). This is a 2D and only one atom thick material. It can be converted to 0D buckyballas, 1D nanotubes or stacked in the best known 3D graphite. See Figure 1. * Graphite is formed by weakly interacting parallel planar carbon layers. Atoms and molecules can be intercalated between those layers giving rise to a variety of intercalated AB stacking, is the most abundant form compounds. of graphite (circles) rDensity Functional AA stacking (two adjacent graphene Formalism: FHI96MD code layers), present in the intercalated rExchange-Correlation compounds (triangles) functional: Local Density Approximation  rNonlocal norm-conserving LiC6  pseudopotential of Hamman et al. for Carbon (4 valence It is the richest Li compound existing at normal pressure electrons) Stage-1 compound rAll electron description of Lithium for all the lithium AA stacking of the graphene layers Figure 1  Figure 2  intercalated compounds. The Li atoms are placed midway between two parallel hexagons, above the center of the hexagon  Only one third of those positions are occupied by Li Hydrogen molecule adsorption on nanotube LiC2  This compound forms only by high pressure synthesis Experimental phase: AA stacking of the graphene layers The Li atoms are placed midway between two parallel hexagons, above the center of the hexagon circles: AA stacking stars: AB stacking circles: AA stacking stars: AB stacking Pb difussion along the /6,6) carbon nanotube LiC3 -49.22 Superdense compound formed by ball-milling; it is stable under ambient pressure ENERGÍA POTENCIAL TOTAL (u.a.) -140.70 ENERGÍA POTENCIAL TOTAL (u.a.) The X-ray diffraction pattern indicates Li atoms at ± 0.83 au from the medium plane between -49.24 -140.72 -49.26 -49.28 the graphene layers -140.74 -49.30 Li midway between graphene layers -140.76 -49.32 Li up and down the middle -49.34 relaxed Li positions 2 4 6 8 10 12 14 16 -140.78 DISTANCIA (u.a.) DE LA HOJA DE GRAFENO (CELDA 2X2) AL ÁTOMO DE PLOMO 0 5 10 15 20 DISTANCIA (u.a.) DEL EJE DEL NANOTUBO (6,6) AL ÁTOMO DE PLOMO Pb atom adsorption on a graphene layer. The The binding energy for the figure shows there are 8 carbon atoms per one Pb atom on the (6,6) Pb atom. The atom is adsorbed at a distance of 4.8 a.u., a little less than the equilibrium carbon nanotube axis is distance for the hydrogen molecule above the 0.27 eV. graphene layer, 5.07 a.u. These result was reported on reference . Conclusions The initial calculations for  A. K. Geim and K.S. Novoselov. Nature materials, Vol. 6, rAdequate description of graphite (AB packing, cohesion, compressibility) by DFT-LDA calculations the difussion of the Pb March 2007, p. 183. rLi intercalation changes the stacking of C layers from AB in graphite to AA in Li compounds atom along the carbon  J. S. Arellano, L.M. Molina, A. Rubio, M.J. López and J. A. rThe distance between graphene layers increases and the uniaxial compressibility decreases in Alonso. J. Chem. Phys. Vol. 117, No. 5, 1 August 2002, p. 2281- nanotube axis shows that 2288. LiC6 with respect to pure graphite  Juan Salvador Arellano Peraza, L. M. Molina, M. J. López, A. this could be and easy Rubio y J. A.. Alonso. “Resultados para litio intercalado en grafito, rDFT underestmates the expansion of the lattice and the uniaxial compressibility of LiC2 as LiC2 y LiC6 usando teoría de funcionaled de la densidad”. compared to the experimental values. Assuming AB stacking, we recover the experimental expansion of the process, that is, without Memoria de la XIV Semana de la Docencia e Investigación en lattice but the value of the uniaxial compressibility is similar (small) to that obtained with AA stacking Química. Universidad Autónoma Metropolitana-Azcapotzalco, rDFT calculations do not predict separation of the Li atoms from the medium plane between barrier energies. año 2001,p.113-123. graphene layers in the LiC3 compounds  J. S. Arellano, L.M. Molina, A. Rubio, and J. A. Alonso. J. Chem. Phys. Vol. 112, Number 18, 8 May 2000, p. 8114-8119. rIt has been given a brief scope of the possible applications of the graphene, graphite and carbonaceous materials as can be the design of new lithium batteries or the hydrogen storage. ¡There are many more applications under development!