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Humberto Terrones

Publications and source records attributed to Humberto Terrones.

8 recordsLinked to original sources
PubMed2005

Femtosecond laser nanosurgery of defects in carbon nanotubes.

All self-assembled nanostructures, like carbon nanotubes, exhibit structural imperfections that affect their electronic and mechanical properties and constitute a serious problem for the development of novel electronic nanodevices. Very common defects in nanotubes are pentagon-heptagon pairs, in which the replacement of four hexagons by two pentagons and two heptagons disrupts the perfect hexagonal lattice. In this work, we demonstrate that these defects can be eliminated efficiently with the help of femtosecond laser pulses. By performing nonadiabatic molecular dynamics simulations, we show that in the laser-induced electronic nonequilibrium the pentagon-heptagon pair is transformed back into four hexagons without producing any irreversible damage to the rest of the nanotube.

Computer Simulation↗
PubMed2005

Atomic nanotube welders: boron interstitials triggering connections in double-walled carbon nanotubes.

Here we demonstrate that the incorporation of boron (B) atoms between double-walled carbon nanotubes (DWNTs) during thermal annealing (1400-1600 degrees C) results in covalent nanotube "Y" junctions, DWNT coalescence, and the formation of flattened multiwalled carbon nanotubes (MWNTs). These processes occur via the merging of adjacent tubes, which is triggered by B interstitial atoms. We observe that B atom interstitials between DWNTs are responsible for the rapid establishment of covalent connections between neighboring tubes (polymerization), thereby resulting in the fast annealing of the carbon cylinders with B atoms embedded in the newly created carbon nanotube network. Once B is in the lattice, tube faceting (polygonization) starts to occur, and the electronic properties are expected to change dramatically. Therefore, B atoms indeed act as atomic nanotube fusers (or welders), and this process could now be used in assembling novel electronic nanotube devices, nanotube networks, carbon nanofoams and heterojunctions exhibiting p-type electronic properties.

Boron↗
PubMed2004

Shape and complexity at the atomic scale: the case of layered nanomaterials.

In nature there are numerous layered compounds, some of which could be curved so as to form fascinating nanoshapes with novel properties. Graphite is at present the main example of a very flexible layered structure, which is able to form cylinders (nanotubes) and cages (fullerenes), but there are others. While fullerenes possess positive curvature due to pentagonal rings of carbon, there are other structures which could include heptagonal or higher membered rings. In fact, fullerenes and nanotubes could display negative curvature, thus forming nanomaterials possessing unexpected electronic and mechanical properties. The effect of curvature in other nano-architectures, such as in boron nitride and metal dichalcogenides, is also discussed in this account. Electron irradiation is a tool able to increase the structural complexity of layered materials. In this context, we describe the coalescence of carbon nanotubes and C(60) molecules. The latter results now open up an alternative approach to producing and manipulating novel nanomaterials in the twenty-first century.

Biocompatible Materials↗
PubMed2004

Zipper mechanism of nanotube fusion: theory and experiment.

We propose a new microscopic mechanism to explain the unusually fast fusion process of carbon nanotubes. We identify the detailed pathway for two adjacent (5,5) nanotubes to gradually merge into a (10,10) tube, and characterize the transition states. The propagation of the fused region is energetically favorable and proceeds in a morphology reminiscent of a Y junction via a zipper mechanism, involving only Stone-Wales bond rearrangements with low activation barriers. The zipper mechanism of fusion is supported by a time series of high-resolution transmission electron microscopy observations.

Journal Article↗
PubMed2003

The carbon nanocosmos: novel materials for the twenty-first century.

Carbon is one of the elements most abundant in nature. It is essential for living organisms and, as an element, occurs in several morphologies. Nowadays, carbon is encountered widely in our daily lives in its various forms and compounds, such as graphite, diamond, hydrocarbons, fibres, soot, oil, complex molecules, etc. However, in the last decade, carbon science and technology have enlarged its scope following the discovery of fullerenes (carbon nanocages) and the identification of carbon nanotubes (rolled graphene sheets). These novel nanostructures possess physico-chemical properties different from those of bulk graphite and diamond. It is expected that numerous technological applications will arise using such fascinating structures. This account summarizes the most relevant achievements regarding the production, properties and applications of nanoscale carbon structures and, in particular, of carbon nanotubes. It is believed that nanocarbons will be crucial for the development of emerging technologies in the following years.

Biocompatible Materials↗
PubMed2002

The formation of ReS(2) inorganic fullerene-like structures containing Re(4) parallelogram units and metal-metal bonds.

The encapsulation of ReO(x) within ReS(2) inorganic fullerene-like cages is described for the first time. The encapsulate was prepared by the sulfidization of both hand-milled and ball-milled samples of ReO(2); partial conversion of the oxide to the sulfide was achieved with the degree of sulfidization depending on the exposure to the sulfidizing agent, H(2)S.

Journal Article↗