Dr.
Mauricio Terrones Maldonado
INSTITUTO POTOSINO DE INVESTIGACIÓN CIENTÍFICA Y TECNOLÓGICA, A.C.
Coordinador
de Departamento
Miembro
del SNI. Nivel 2
-
Departamento de Materiales
Avanzados para la Tecnología Moderna
Camino a la Presa San José 2055
Col. Lomas 4a. sección C.P. 78216
San Luis Potosí, San Luis Potosí, México
e-mail: mterrones@ipicyt.edu.mx
Teléfono +52 (444) 8342000 Ext. 2039
-
Fax +52 (444) 8342010
Resumen Curricular
Licenciado en Ingeniería Física (1992) de la Universidad
Iberoamericana con el promedio más alto y mención honorífica, recibió la
medalla al mejor estudiante de México en Ingeniería Física que otorga el
CONACYT, ANUIES y el Diario De México en el año de 1992. En 1997, finalizó sus
estudios doctorales en Química-Física en la Universidad de Sussex, Inglaterra,
bajo la supervisión de Sir Harold W. Kroto (Premio Nobel del Química 1996 y
miembro de la "Royal Society" de Gran Bretaña). Posteriormente
realizó estudios posdoctorales en la Universidad de Sussex y en la Universidad
de California en Santa Bárbara (USA).
En Marzo de 1999, Mauricio Terrones ingresó al Instituto de Física de
la UNAM, Campus Juriquilla, como Investigador titular "A". En este
mismo año fue nombrado Investigador Nacional Nivel II (Sistema Nacional de
Investigadores -SNI-). En Octubre de 1999, la Fundación Alexander von Humboldt
lo galardonó con una membresía para realizar estudios sobre nanoestructuras de
carbono, por un periodo de 14 meses, en el Max-Planck-Institut für
Metallforschung en la ciudad de Stuttgart, Alemania.
A partir de Abril del 2001, Mauricio Terrones se incorporó al
Instituto Potosino de Investigación Científica y Tecnológica (IPICYT) como
investigador titular "C".
Latest Advances and Future Challenges of Nanotube
Science and Technology
Mauricio Terrones
Advanced Materials Department, IPICyT, Camino a la Presa San José 2055
78216 San Luis Potosí, SLP, México
Experimental
and theoretical research on nanomaterials continues to accelerate and, as a
consequence, novel structures with remarkable
chemical reactivity, as well
as mechanical and transport properties are being predicted
and developed. In particular, the synthesis of novel nanostructures (e.g.
nanotubes, inorganic fullerenes) using layered materials such as graphite, BN,
BC2N, WS2, MoS2, VS2, NiCl2,
CNx, etc. may
revolutionize technology in less than 10 years.
However, at
this point and from the experimental viewpoint, it is important to carefully control
stoichiometries of elements, homogeneity of the nanomaterials and to develop
novel self-assembly processes to grow or interconnect such fascinating
structures. In this context, it will be shown that that “substitution reactions” involving carbon nanotubes or metal oxide nanorods
in the presence of B2O3 or H2S yield stable BxCyNz
nanotubes (Fig. 1) and MS2 (M = W,
Mo, Re, Ta, Nb) nanotubes and nanoparticles respectively. These results provide
vital information for achieving growth control in the production of inorganic
nanotubes and homogenous
heteroatomic structures.
The importance of doping in carbon nanotubes will be emphasized, since
it is possible to alter significantly the electronic, mechanical and chemical properties
of the tubes. This opens up new avenues in the production of nanomaterials with
desired properties and stoichiometries. Therefore, the
controlled production of nanotubes made of layered BC2N (Fig. 1) and CNx will be
presented. In this context, the electronic and field emission properties, as
well as the density of states (DOS) of CNx and CBx nanotubes using scanning
tunneling spectroscopy (STS) will be discussed. It is also demonstrated that the presence of low concentrations of N and B inside carbon nanotubes are
responsible for introducing donor and acceptor states near the Fermi Level.
Novel applications of these doped materials will also be discussed in areas of chemistry (as
chemical sensors), biology (as protein immobilizers) and electronics (metallic
and semiconducting nanowires).
Theoretical calculations, using density-functional-based
tight-binding (DFTB), of other layered nanotube materials will be
presented. In particular, the different electronic
properties of MoS2, WS2
and NbS2 nanotubes will be compared. For MoS2 and WS2 nanotubes we
predict small band gap semiconducting behavior (much lower than the bulk
material) depending on diameter and chirality. This band gap tends to vanish
for diameters < 10 Å. Electronic calculations on NbS2 nanotubes
indicate that these tubes are always metallic and could behave as
superconductors at higher temperatures, when compared to the Tc
observed for bulk NbS2. Following our predictions, researchers have been able to synthesis NbS2 nanotubes, and have also confirmed experimentally the electronic properties of WS2 nanotubes. It is therefore clear
that any layered material would be able to curve in order to form tubes and
cages, thus the development of novel composite materials with
outstanding electronic and mechanical properties are being reinforced.
Regarding single-walled carbon nanotubes (SWNTs), we will demonstrate, that irradiation
exposure
at elevated temperatures, can be used as an effective tool to covalently
coalesce and weld SWNTs in order to create larger tubules and molecular
junctions of various geometries. We have fabricated “Y”, “X” and “T-like”
junctions (Fig. 2),
that are stable. Tight binding molecular dynamics calculations demonstrate that
vacancies, formed under the electron beam, trigger the formation of molecular
junctions involving seven or eight membered carbon rings (Fig. 2). We envisage that our
results will pave the way towards controlled fabrication of novel 3-dimensional
nanotube
based molecular circuits, nanotube fabrics and network architectures.
Fig. 1 (a) Low resolution bright field TEM image of two
bundles of aligned BCxN (1 ≤
x ≤ 5) nanotubes; (b) EELS carbon mapping (green) of the image shown in (a); (c) EELS boron mapping
(red) of (a) and (d) nitrogen mapping (blue) of the image shown in (a). It is
clear that the material uniformly composed of B, C and N. Any segregation of BN
and C domains is notably absent.
Fig.
2 (a-c) HRTEM images of a “T-like”
junction formed after irradiating a “Y”
junction. It is possible to thin one of the tubes of the “Y” junction, which
eventually breaks and forms a “hook” (not shown here). It is also possible to
observe the evolution of this junction during irradiation and the rotation by 180°
under the
electron beam; note the circular cross-section in one of the
tubes (b).
References
1.
M.
Terrones. Ann. Rev. Mater. Res. 33 (2003) 419.
2.
M. Terrones, F. Banhart, N. Grobert, J.-C.
Charlier, P.M.
Ajayan. Phys. Rev. Lett. 89 (2002) 075505 (2002).
3.
M. Terrones, H. Terrones, J.-C. Charlier, F. Banhart, P.M. Ajayan. Science
288 (2000) 1226.
4.
M. Terrones, D. Golberg, N. Grobert, T. Seeger, M. Reyes-Reyes, M. Mayne,
R. Kamalakaran, P. Dorozhkin, Z.C. Dong, H. Terrones, M. Rühle, Y.
Bando. Advanced Materials 15 (2003) 1899.
5.
F. Banhart, E. Hernández
& M. Terrones. Phys. Rev. Lett. 90 (2003) 185502.
6.
H. Terrones & M. Terrones New Journal of
Physics 5 (2003) 126_1.
Dr.
Mauricio Terrones
Narrative Curriculum Vitae
Dr.
Mauricio Terrones, Professor at the Instituto Potosino de Investigación
Científica y Tecnológica (IPICYT) in Mexico, is a leading researcher with a
long experience in nanostructured carbon materials. A native of Mexico City, born
in 1968, he obtained his B.Sc. degree in Engineering Physics at the Universidad
Iberoamericana (1992, Mexico City). He received the highest grade point average
(GPA) award and the highest recognition for his B.Sc. thesis ("Mención
Honorífica"). In that year, he was also awarded a Medal for being one of
the best students of México (a recognition given by the Mexican President).
After lecturing at Universidad Iberamericana for two years, in 1993 he was awarded
a Fulbright fellowship to carry out doctoral studies in the USA. However, he
did not take this fellowship and preferred to travel to the UK and work for a
Ph.D. with Prof. Harold W. Kroto (Nobel Prize Winner in Chemistry 1996). He
pursued his graduate studies sponsored by CONACYT-Mexico. In 1997, he obtained
his doctorate degree and started to work as a postdoctoral research fellow at
the University of Sussex. After a postdoctoral year, funded by the Materials
Research Laboratory (UC-Santa Barbara) and the Royal Society, he was appointed
Royal Society Research Fellow at the Fullerene Science Centre.
In March 1999, Dr. Terrones became a faculty
member as Professor "category A", at the Institute of Physics -UNAM.
In this year, he became National Researcher (Sistema Nacional de Investigadores
SNI) level II. In 1999, he was also awarded an Alexander von Humboldt
Fellowship to carry out research for 14 months at the Max-Planck-Institut für
Metallforschung in Stuttgart (Germany). In April 2001, he became full Professor
(category "C") at IPICYT. In September that year he received the
National Prize for Chemistry and the "Andres Manuel del Rio" Medal.
In November 2001, he was awarded the "Javed Husain" Prize for young
scientist by UNESCO, for his contributions in Nanotechnology of Carbon, and
received the "Albert Einstein" UNESCO medal. He is now one of the
persons responsible of the installation of a new field emission microscope (the
best analytical transmission microscope in Latin America) at IPICYT. Dr. Terrones
has co-authored more than 100 publications in prestigious refereed journals
such as Nature, Science, Physical Review Letters, Chemical Physics Letters,
Applied Physics Letters, Chemical Communications, Journal of the American
Chemical Society, Advanced Materials, Chemical Society Reviews, Chemistry of
Materials, etc.
The scientific impact and quality of his
publications has given him more than 800 independent citations in international
journals and books (he now receives ca. 15 citations per month). In addition,
he has written 5 book chapters, 20 articles in conference proceedings and 9
miscellaneous publications. He has presented his research in more than 60
international conferences. The average impact factor of his publications is ca.
3.72, according to the Institute for Scientific information 1998. As a result,
he has been invited to present his research in more than 30 international
conferences (i.e. England, Austria, USA, Hungary, Belgium, Germany and Japan)
devoted to nanotubes. Terrones is currently writing (in collaboration with H.
Terrones) a book entitled "Shape and Properties of Layered Nanostructures:
Theory and Experiment", which will be published by Academic Press in 2003.
He has refereed more than 150 scientific papers
for various journals such as Science, Chemical Communications, Chemical Physics
Letters, Applied Physics Letters, Physical Review Letters, Carbon, Chemistry of
Materials, etc. He has also reviewed two books in Nanostructures and
Nanocomposites published by Gordon Breach and Cambridge University Press.
Dr. Terrones has closely participated in the
creation of the first Fullerene and Nanotube Laboratory in Mexico (Departamento
de Física Aplicada y Tecnología Avanzada, UNAM). In 1999, he became visiting
research Fellow at Brikbeck College (University of London). In 2000, he was
also appointed Lecturer in Chemical Physics at Sussex University.
His research involves an interdisciplinary
approach, combining the production of nanomaterials with electron microscopy
techniques for analysis, and molecular simulations for predicting the stability
and properties of nanostructures. As a result, Terrones has developed, on his
own initiative, a novel self assembly route to matrices of aligned carbon
nanotubes. In addition, he has jointly developed a novel and low cost route to
nanotubes and metal nanowires using condensed-phase electrolysis, and produced
novel B/C/N fullerene-like nanomaterials, which may prove useful in
nanoelectronics. These techniques are now used by other research groups in
order to produce nanocomposite materials.
From the theoretical point of view, Dr. Terrones
was the first to: (1) explain the sphericity of giant nested fullerenes based
upon the introduction of defects (heptagons and additional pentagons), (2)
generate (together with H. Terrones) a closed fullerene with only heptagons and
hexagons, namely finite zeolites or holey balls, (3) explain and observe
in-situ coalescence of carbon nanotubes (together with P. M. Ajayan and J. C.
Charlier) and (6) predict novel metallic forms of carbon and the electronic
properties of MoS2, WS2 and NbS2 nanotubes (in collaboration with H. Terrones,
H. Hernández and G. Seifert).
Dr. Terrones has co-supervised various B.Sc. and
Ph.D. theses. One of them, co-supervised together with Harold W. Kroto and
David R. M. Walton (Dr. Nicole Gorbert's dissertation), was awarded the CARBON
PRIZE as the best doctoral thesis in CARBON Science 2000-2001. Dr. Terrones has
co-organised three international conferences in Nanotechnology of Carbon
(NANOTEC).