Dr. Maria J. Lopez Profile

Dr. Maria J. Lopez

at Univ de Valladolid

SPIE Involvement:

Author

Publications (2)

Proceedings Article | 29 April 2003 Paper

Interaction of molecular and atomic hydrogen with single-wall carbon nanotubes

Julio Alonso, Juan Arellano, Luis Molina, Angel Rubio, Maria Lopez

Proceedings Volume 5118, (2003) https://doi.org/10.1117/12.500133

KEYWORDS: Molecules, Hydrogen, Chemical species, Absorption, Molecular interactions, Carbon, Graphene, Carbon nanotubes, Chemisorption, Single walled carbon nanotubes

Read Abstract +

Proceedings Article | 29 April 2003 Paper

Deformations and thermal stability of carbon nanotube ropes

Maria Lopez, Angel Rubio, Julio Alonso

Proceedings Volume 5118, (2003) https://doi.org/10.1117/12.502002

KEYWORDS: Picosecond phenomena, Carbon nanotubes, Crystals, Chemical species, Polymerization, Laser crystals, Carbon, Graphene, Annealing, Computer simulations

Read Abstract +

As it is well known, carbon nanotubes may be one fold (Single Wall Carbon Nanotubes, SWCNT) or contain several cylinders nested one inside another (Multi Wall Carbon Nanotubes, MWCNT). SWCNT's, in many cases, self-organize into crystalline bundles (set of a few to a few hundred aligned tubes arranged in a two-dimensional triangular lattice in the plane perpendicular to their common axes). A thorough understanding of carbon nanotubes (CNT's) includes the detailed and comprehensive characterization of their possible deformations due to interactions with a substrate or with other tubes, and their stability under thermal treatment or chemical agents. In this communication we concentrate on i) the structural characteristics and ii) the structural transformations under thermal treatment of bundles of SWCNT's. i) Deformations of the tubes away from their ideal circular cross sections may have non trivial effects in their properties such as conductivity or phonon spectrum. We have being able to synthesize novel crystalline bundles of 'polygonized' SWCNT's. Our finding opens up the question of what is the equilibrium configuration of a lattice of aligned tubes and the possibility of the existence of several metastable structures which could be obtained depending on the growth conditions. To shed some light on this problem we have performed extensive molecular dynamics simulations of lattices of monodisperse armchair and zigzag SWCNT's as a function of tube diameter. We find several metastable structures of the lattice characterized by different tube cross sections, hexagonal, rounded-hexagonal and circular, and increasing cell volume. The competition between different tube shapes is analyzed and compared to experiments. ii) On the other hand, CNT's are metastable; (the most stable form of carbon is graphite). Due to their metastable character CNT's may transform into more stable structures under the appropriate annealing conditions. We have found that bundles of SWCNT's coalesce forming MWCNT's, containing from two to six nested tubes, under thermal treatment at high temperatures. This structural transformation is confirmed by extensive Molecular Dynamics (MD) simulations. The simulations suggest a 'patching--and--tearing' mechanism for the SW-- to MWCNT's transformation underlying the 'concerted' coalescence of the tubes that begins with their polymerization. Tubes of different sizes and chiralities are considered.

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years