Laboratory for Nanoscience and Nanotechnology Research LINAN

Col. Bosques de las Lomas, Mexico

Laboratory for Nanoscience and Nanotechnology Research LINAN

Col. Bosques de las Lomas, Mexico
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Gullapalli H.,Rice University | Vemuru V.S.M.,Rice University | Kumar A.,Rice University | Botello-Mendez A.,Laboratory for Nanoscience and Nanotechnology Research LINAN | And 4 more authors.
Small | Year: 2010

The fabrication of a mechanically flexible, piezoelectric nanocomposite material for strain sensing applications is reported. Nanocomposite material consisting of zinc oxide (ZnO) nanostructures embedded in a stable matrix of paper (cellulose fibers) is prepared by a solvothermal method. The applicability of this material as a strain sensor is demonstrated by studying its real-time current response under both static and dynamic mechanical loading. The material presented highlights a novel approach to introduce flexibility into strain sensors by embedding crystalline piezoelectric material in a flexible cellulose-based secondary matrix. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Elias A.L.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Botello-Mendez A.R.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Meneses-Rodriguez D.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Gonzalez V.J.,Laboratory for Nanoscience and Nanotechnology Research LINAN | And 6 more authors.
Nano Letters | Year: 2010

We report the use of transition metal nanoparticles (Ni or Co) to longitudinally cut open multiwalled carbon nanotubes in order to create graphitic nanoribbons. The process consists of catalytic hydrogenation of carbon, in which the metal particles cut sp2 hybridized carbon atoms along nanotubes that results in the liberation of hydrocarbon species. Observations reveal the presence of unzipped nanotubes that were cut by the nanoparticles. We also report the presence of partially open carbon nanotubes, which have been predicted to have novel magnetoresistance properties. 1 The nanoribbons produced are typically 15-40 nm wide and 100-500 nm long. This method offers an alternative approach for making graphene nanoribbons, compared to the chemical methods reported recently in the literature. © 2010 American Chemical Society.


Kumar A.,Oceanit Laboratories, Inc. | Gullapalli H.,Rice University | Balakrishnan K.,Rice University | Botello-Mendez A.,Laboratory for Nanoscience and Nanotechnology Research LINAN | And 3 more authors.
Small | Year: 2011

Materials with the ability to harness multiple sources of energy from the ambient environment could lead to new types of energy-harvesting systems. It is demonstrated that nanocomposite films consisting of zinc oxide nanostructures embedded in a common paper matrix can be directly used as energy-conversion devices to transform mechanical and thermal energies to electric power. These mechanically robust and flexible devices can be fabricated over large areas and are capable of producing an output voltage and power up to 80 mV and 50 nW cm -2, respectively. Furthermore, it is shown that by integrating a certain number of devices (in series and parallel) the output voltage and the concomitant output power can be significantly increased. Also, the output voltage and power can be enhanced by scaling the size of the device. This multisource energy-harvesting system based on ZnO nanostructures embedded in a flexible paper matrix provides a simplified and cost-effective platform for capturing trace amounts of energy for practical applications. Nanocomposite films consisting of ZnO nanostructures embedded in common paper are used as energy-conversion devices. The paper matrix makes these devices flexible while retaining their mechanical strength. This composite material can transform multiple sources, such as mechanical and thermal energy, into electric power, to provide a simplified and cost-effective platform for scavenging energy for practical applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Elias A.L.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Ayala P.,University of Vienna | Zamudio A.,University of Guadalajara | Grobosch M.,Leibniz Institute for Solid State and Materials Research | And 7 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2010

We have studied in detail the carbon and nitrogen bonding environments in nitrogen-doped single-walled carbon nanotubes (SWCNTs). The samples consisting of long strands of N-doped SWCNTs were synthesized using an aerosol assisted chemical vapor deposition method involving benzylamine-ethanol-ferrocene solutions. The studied samples were produced using different benzylamine concentrations in the solutions, and exhibited a maximum concentration of ca. 0.3%at of N, determined by X-ray photoelectron spectroscopy (XPS). In general, we observed that the ratio between substitutional nitrogen and the pyridine-like bonded nitrogen varied upon the precursor composition. Moreover, we have observed that the sp 2-like substitutional configuration of the C-N bond does not exceed the 50% of the total N atomic incorporation. In addition, we have characterized all these samples using Raman spectroscopy and electron microscopy. Copyright © 2010 American Scientific Publishers All rights reserved.


Shimamoto D.,Shinshu University | Muramatsu H.,Shinshu University | Kim Y.J.,Shinshu University | Kim Y.A.,Shinshu University | And 4 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2010

Changes in the optical properties of thermally coalesced single-walled carbon nanotubes (SWCNTs) caused by heat treatment between 1300 and 2800 °C in argon, have been monitored using optical absorption and photoluminescence spectroscopy. For SWNTs heat treated at 1900 °C, we found a complete disapperance of small-diameter tubes (<1.0 nm) as well as the appearance of enlarged, defective tubes. The decreased sp 2/sp 3 ratio for tubes heat treated below 2100 °C suggests that adjacent small-diameter SWNTs transform into energetically stable larger-diameter SWNTs by the presence of structural non sp 2 defects. Copyright © 2010 American Scientific Publishers All rights reserved.


Villalpando-Paez F.,Massachusetts Institute of Technology | Muramatsu H.,Shinshu University | Kim Y.A.,Shinshu University | Farhat H.,Massachusetts Institute of Technology | And 3 more authors.
Nanoscale | Year: 2010

We measure resonant Raman scattering from 11 individual C 60-derived double-wall carbon nanotubes all having inner semiconducting (6,5) tubes and various outer metallic tubes. The Raman spectra show the radial breathing modes (RBM) of the inner and the outer tubes to be simultaneously in resonance with the same laser energy. We observe that an increase in the RBM frequency of the inner tubes is related to an increase in the RBM frequency of the outer tubes. The Raman spectra also contain a sharp G- feature that increases in frequency as the nominal diameter of the outer metallic tubes decreases. Finally, the one-phonon second-order D-band mode shows a two-way frequency splitting that decreases with decreasing nominal wall-to-wall distance. We suggest that the stress which increases with decreasing nominal wall-to-wall distance is responsible for the hardening that is observed in the frequencies of the RBM, D and G- modes of the inner (6,5) semiconducting tubes. © 2010 The Royal Society of Chemistry.


Trejo-Valdez M.,National Polytechnic Institute of Mexico | Torres-Martinez R.,Research Center en Ciencia Aplicada | Perea-Lopez N.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Santiago-Jacinto P.,National Autonomous University of Mexico | Torres-Torres C.,Seccion de Estudios de Posgrado e Investigacion
Journal of Physical Chemistry C | Year: 2010

We measured the absorptive and refractive nonlinearities in Au nanoparticles when they are embedded in a TiO2 film and when they are suspended in ethanol. The morphology of the nanoparticles was estimated by using HRTEM microscopy. Different contributions related to electronic polarization and two-photon absorption were observed in the samples using a self-diffraction technique with pulses of 26 ps at 532 nm. Transmittance experiments were performed in order to confirm the mechanisms of optical absorption. The Au nanoparticles were grown by the photoreduction of TiO 2 sol-gel solutions which contain Au3+ ions. The thin films were prepared by using the dip coating technique with fresh UV exposed sol-gel solutions. We observed that when the sample does not present any important nonlinear absorption it is possible to enhance the participation of the nanoparticles in the optical Kerr response of the media. © 2010 American Chemical Society.


Meneses-Rodiguez D.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Munoz-Sandoval E.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Ramirez-Manzanares G.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Ramirez-Gonzalez D.,Laboratory for Nanoscience and Nanotechnology Research LINAN | And 5 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2010

We report the production, characterization, thermal transformations (400-1000 °C), and magnetic properties of nanoparticles encapsulated in nitrogen-doped multiwall carbon nanotubes (CN x-MWNT), which were embedded in silicon oxide (SiO x) matrices via sol-gel techniques. The vapor chemical deposition (CVD) method with ferrocene-benzelamine mixtures was used to synthesize Fe and Fe 3C nanoparticles inside CN x-MWNTs. Composites consisting of CN x-MWNTs (filler) and SiC\ (matrix) were fabricated and thermally treated to different temperatures and expo-sure times (t). All samples were characterized using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), thermogravimetic analysis (TGA), and magnetometry (vibrating sample). We found that upon thermal treatment, the ferromagnetic nanoparticles modify their morphology, composition and aspect ratio, thus resulting in drastic changes in the magnetic and structural properties. In particular, as produced encapsulated nanoparticles mainly consisting of Fe and Fe 3C phases were thermally modified into magnetite (Fe 30 4). We have also observed that the hysteresis loops are very sensitive to the thermal treatment of the sample. Thus we can control the magnetic properties of the samples using thermal treatments. © 2010 American.


Rebollo-Plata B.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Munoz-Sandoval E.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Lopez-Urias F.,Laboratory for Nanoscience and Nanotechnology Research LINAN | Hernandez-Cortina E.L.,Laboratory for Nanoscience and Nanotechnology Research LINAN | And 2 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2010

We fabricated vapor sensors using nitrogen-doped (CNx) and pure multi-walled carbon nanotubes (MWNTs), and compared their performance. The sensors were constructed by dispersing the nanotube materials in methanol so as to form millimeter-long foils (nanotube paper), consisting of compact arrays of crisscrossing nanotubes. The devices were characterized by electrical resistance measurements and SEM studies. For CNx-based sensors, we observed that low concentrations of vapors such an acetone, ethanol, and chloroform were efficiently detected within 0.1-0.3 seconds via a physisorption mechanism. This physisorption is explained in terms of a weak interaction of the vapor molecules with the pyridinic sites (N bonded to two carbon atoms) present in the doped tubes. We believe that the methanol used for preparing the foils has a strong effect in saturating substitutional N atoms (N atoms bonded to three carbon atoms) that are also located in the CNx tubes. However, when pure carbon MWNTs were tested as sensors, we witnessed chemisorption of these vapors. First-principles density functional calculations confirmed that the gaseous molecules are able to interact with N-doped carbon nanotubes, via a physisorption mechanism, in which pyridine sites play a crucial role. Copyright © 2010 American Scientific Publishers All rights reserved.

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