A5083261659- Carbon Nanotubes in Composites
- Physics of Superconductivity and Magnetism
- Graphene research and applications
- Quantum and electron transport phenomena
- Advancements in Battery Materials
- Force Microscopy Techniques and Applications
- Fiber-reinforced polymer composites
- Advanced Battery Materials and Technologies
- Superconductivity in MgB2 and Alloys
- Graphene and Nanomaterials Applications
- Superconducting Materials and Applications
- Conducting polymers and applications
- Magnetic and transport properties of perovskites and related materials
- Advanced Sensor and Energy Harvesting Materials
- Electron and X-Ray Spectroscopy Techniques
- Polymer Nanocomposites and Properties
- Nanotechnology research and applications
- Magnetic properties of thin films
- Surface and Thin Film Phenomena
- Supercapacitor Materials and Fabrication
- Advanced Condensed Matter Physics
- Electronic and Structural Properties of Oxides
- Iron-based superconductors research
- Mechanical and Optical Resonators
- Cold Atom Physics and Bose-Einstein Condensates
Temple University
2015-2024
Temple College
2017-2022
University of California, Berkeley
2021
East Carolina University
2021
Philadelphia University
2018
Northwestern University
2005-2014
Defense Advanced Research Projects Agency
2008-2010
University of Colorado Boulder
2008-2010
Texas State University
2009
The University of Texas at Austin
2008
Step-by-step controllable thermal reduction of individual graphene oxide sheets, incorporated into multiterminal field effect devices, was carried out at low temperatures (125-240 degrees C) with simultaneous electrical measurements. Symmetric hysteresis-free ambipolar (electron- and hole-type) gate dependences were observed as soon the first measurable resistance reached. The conductivity each fabricated devices depended on level (was increased more than 10(6) times progressed), strength...
Transparent and electrically conductive composite silica films were fabricated on glass hydrophilic SiOx/silicon substrates by incorporation of individual graphene oxide sheets into sols followed spin-coating, chemical reduction, thermal curing. The resulting characterized SEM, AFM, TEM, low-angle X-ray reflectivity, XPS, UV-vis spectroscopy, electrical conductivity measurements. the compared favorably to those thin carbon nanotubes in silica.
Conductive "alkylated" graphene paper is prepared by post-fabrication modification of oxide with hexylamine followed hydrazine reduction in a one-pot process. The "alkylation" stabilizes the stacked structure during reduction, maintaining its well-ordered morphology and resulting uniform conductivity good mechanical properties. Detailed facts importance to specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made...
We report that a homogeneous aqueous colloidal suspension of chemically cross-linked graphene oxide sheets was generated by addition polyallylamine to an followed sonication the mixture. This is first example for producing sheets. As demonstration utility such suspension, "paper" material samples made simple filtration from showed excellent mechanical stiffness and strength.
Ferromagnetism is usually considered to be incompatible with conventional superconductivity, as it destroys the singlet correlations responsible for pairing interaction. Superconductivity and ferromagnetism are known coexist in only a few bulk rare-earth materials. Here we report evidence their coexistence two-dimensional system: interface between two insulators, LaAlO(3) (LAO) SrTiO(3) (STO), system that has been studied intensively recently. Magnetoresistance, Hall, electric-field...
Organic dispersions of graphene oxide can be thermally reduced in polar organic solvents under reflux conditions to afford electrically conductive, chemically active (CARGO) with tunable C/O ratios, dependent on the boiling point solvent. The reductions are achieved after only 1 h reflux, and corresponding ratios do not change upon further thermal treatment. Hydroxyl carboxyl groups removed when is carried out above 155 °C, while epoxides removable temperature higher than 200 °C. increasing...
The electrical conductivity and gas-sensing characteristics of individual sheets partially reduced graphene oxide are studied, the results display a strong dependence on chosen reduction method. Three procedures considered here: thermal, chemical, combined chemical/thermal approach. Samples treated by highest whereas thermally samples fastest response times. chemo-resistive to water vapor adsorption is well fit linear driving force model. upon exposure measured as function gated electric...
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTPolymer−Graphite Nanocomposites: Effective Dispersion and Major Property Enhancement via Solid-State Shear PulverizationKatsuyuki Wakabayashi, Cynthia Pierre, Dmitriy A. Dikin, Rodney S. Ruoff, Thillaiyan Ramanathan, L. Catherine Brinson, John M. TorkelsonView Author Information Department of Chemical Biological Engineering, Materials Science Mechanical Northwestern University, Evanston, Illinois 60208 Cite...
An individual carbon nanocoil was clamped between two AFM cantilevers and loaded in tension to a maximum relative elongation of ∼42%. The deformation the agrees well with an analytical model spring constant that accounts for geometric nonlinearity. behaves like elastic K 0.12 N/m low strain region. No plastic detected. High-resolution microscopy images electron energy loss spectrum (EELS) indicate nanocoils are amorphous sp2/sp3 bonded-carbon ratio ∼4:1.
A simple optical method is presented for identifying and measuring the effective properties of nanometer-thick, graphene-based materials, based on use substrates consisting a thin dielectric layer silicon. High contrast between materials substrate obtained by choosing appropriate thickness layer. The refractive index absorption coefficient graphene oxide, thermally reduced are comparing predicted measured contrasts.
A series of observations polymer sheathing in multiwalled carbon nanotube (MWCNT)−polycarbonate composites are presented. This was observed images the composite fracture surface and is consistent with diameter distributions as-received embedded MWCNTs. novel nanomanipulation experiment, where balls up when contacted by an AFM tip, confirms this phenomenon. layer direct evidence substantial MWCNT−polymer interaction will influence mechanical properties MWCNT-polymer composites.
Abstract Mechanical, thermal, and electrical properties of graphite/PMMA composites have been evaluated as functions particle size dispersion the graphitic nanofiller components via use three different nanofillers: “as received graphite” (ARG), “expanded graphite,” (EG) “graphite nanoplatelets” (GNPs) EG, a materials with much lower density than ARG, was prepared from ARG flakes an acid intercalation thermal expansion. Subsequent sonication EG in liquid yielded GNPs thin stacks platelets...
The thermal stability and reduction kinetics of graphene oxide were studied by measuring the electrical resistivity single-layer films at various stages in high vacuum performing temperature programmed desorption (TPD) measurements multilayer ultrahigh vacuum. was exfoliated from graphite source material slow-stirring aqueous solution, which produces platelets with an average lateral size ∼10 μm. From TPD measurements, it determined that primary products for temperatures up to 300 °C are...
Catalyst-free growth of boron nanoribbons was observed by pyrolysis diborane at 630−750 °C and ∼200 mTorr in a quartz tube furnace. Nanodiffraction analysis indicates the are single crystal α-tetragonal boron. TEM images show nanoribbon is covered 1−2 nm thick amorphous layer. Elemental EELS, EDX, XPS shows consist with small amounts oxygen carbon. Infrared Raman spectra also reported.
The dispersion functions for the refractive index and extinction coefficient of single- multiple-layer graphene oxide samples were measured by imaging spectroscopic ellipsometry in wavelength range 350−1000 nm compared to previously reported results confocal microscopy. thin platelets also those obtained standard on a deposit consisting many overlapping layers. Changes observed both thickness deposits values parameters following heating. A model is proposed explain these observations, based...
Graphene oxide paper can be systematically modified with alkylamines in both solution- and vapor-phase, the latter process being significantly slower. After removal of physisorbed amine, increases gallery spacing, physical thickness, mass amine-modified papers directly correlated to length intercalated alkyl chain. While tensile strength slightly decreases increasing amine lengths, their "effective graphene moduli" were essentially unchanged, suggesting that is sole contributor stiffness papers.