Bulletin of the American Physical Society
76th Annual Meeting of the Southeastern Section of APS
Volume 54, Number 16
Wednesday–Saturday, November 11–14, 2009; Atlanta, Georgia
Session JC: Nanomaterials |
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Chair: Nikolaus Dietz, Georgia State University Room: Paris |
Friday, November 13, 2009 1:30PM - 1:42PM |
JC.00001: Condensation of fluids adsorbed in nanopores: substrate relaxation effect Hye-Young Kim, Silvina Gatica In recent years, both experimental and computational studies have observed that fluids adsorbed in nanopores exert a force on the substrate that produces a compression or expansion of the host. However, an overwhelming majority of the theoretical studies have assumed that the environment provides a fixed, static potential in which the adsorbate moves. In this presentation, we report recent results of a series of theoretical studies on the system of classical and quantum fluids adsorbed in slit pores and in bundles of carbon nanotubes, incorporating the substrate relaxation. We find that, in case of classical gases adsorbed in a bundle of carbon nanotubes, the bundle contracts and the critical temperature of the condensation transition increases. Slit pores contract or expand depending on the initial spacing, producing in any case an increase in the critical temperature for the condensation transition of the film adsorbed. Quantum $^{3}$He in a relaxing slit pore becomes a liquid, while other two-dimensional $^{3}$He (free standing or in a narrow rigid pore) are predicted to be a gas. All these observations are a consequence of a cooperative effect of the dynamic system composed of gas and non-rigid substrate. [Preview Abstract] |
Friday, November 13, 2009 1:42PM - 1:54PM |
JC.00002: Static polarizability of a planar nanocluster: finite-size effect Zachary Bond, Hye-Young Kim One of the persistent scientific interests in nanotechnology has been that at what size and how would the atomic properties progress into those of a bulk material. In this presentation, we report recent results on how the static polarizability of a two-dimensional cluster progresses as its size increases. For finite size clusters, we use a microscopic method that involves all many-body interactions self-consistently. These numerical results of finite-size clusters will be analyzed by comparing to those of infinite-size clusters obtained from analytic methods. It is found that the size that reaches to the limit value of the infinite-size is surprisingly not so large. Also found are interesting characteristics of alternating directions and fluctuating magnitudes of the local polarizabilities within the cluster as we increase the size systematically. [Preview Abstract] |
Friday, November 13, 2009 1:54PM - 2:06PM |
JC.00003: Hydrogen storage of intrinsic and vanadium-decorated Mg nanostructures Yuping He, Yiping Zhao MgH$_{2}$ is very attractive for future solid state H-storage
applications,
due to its lightweight, low cost, and high H-storage capacity of
7.6 wt{\%}.
However, its practical application is limited by its high
thermodynamic
stability and sluggish reaction kinetics, which could be improved
by making
nanostructures with large surface-to-volume ratios to enhance
surface
reaction activity and by adding an appropriate catalyst to
accelerate
H-sorption kinetics. In this work, an oblique angle deposition
(OAD) or
oblique angle co-deposition (OACD) technique has been used to
sculpture Mg
nanostructures and incorporate a nanocatalyst. For an intrinsic
Mg film and
Mg nanoblade array by OAD on Ti coated Si, the hydrogenation
results show
that the nanoblades start to absorb H$_{2}$ at 523 K$ |
Friday, November 13, 2009 2:06PM - 2:18PM |
JC.00004: Electro-mechanical contact formation between conductive AFM cantilevers and carbon nanotubes Tarek Ghanem, Ellen Williams, Michael Fuhrer We present a study of the electro-mechanical contact formation between conductive atomic force microscope (AFM) cantilevers and carbon nanotubes. We study the dependence of the current through the contact on loading force, geometric parameters, bias conditions, and time. We find that for an optimized placement of the cantilever, the current through the contact becomes independent of the loading force beyond a certain threshold. In that load-independent regime, the current is also independent of bias conditions, and is stable in time. Under certain conditions of tip placement, the current through the contact exhibits non-monotonic behavior with loading. This behavior is well explained by the parasitic planar motion of the cantilever during loading. [Preview Abstract] |
Friday, November 13, 2009 2:18PM - 2:30PM |
JC.00005: Enhancement of the magneto-optical activity in thin films via surface Plasmon resonance excitation Kaida Yang, Cesar Clavero, Jonathan Skuza, Rosa A. Lukaszew Light can be localized and manipulated in appropriately designed metallic and metallo-dielectric nanoparticle arrays and/or thin film structures. In particular, interesting phenomena occur near the plasmon frequency where optical extinction is resonantly enhanced and at the plasma frequency where the real part of the dielectric function changes sign. This phenomenon is very sensitive to slight changes in the dielectric constant at the surface and therefore Surface Plasmon resonance has been successfully applied to bio-sensing. One interesting possibility is the use of magnetic fields to influence the propagation of surface plasmon polaritons (SPP) and therefore mixing magnetic and plasmonic materials, seems a promising approach for obtaining externally controlled and/or modulated systems. We have found that remarkable enhancement of the magneto-optical activity can be achieved in Au-Co-Au trilayers when the surface Plasmon resonance is excited. Our studies also indicated that the effect is very sensitive to the thickness of the intervening layers. We have now investigated Au-Co nano-composite films that were deposited on glass substrates at different temperatures and with controlled varied composition. We have found that in this case the concentration ratio between Au and Co can be optimized for highest magneto-optical enhancement. [Preview Abstract] |
Friday, November 13, 2009 2:30PM - 2:42PM |
JC.00006: Functional Carbon Nanotube Junctions Synthesized from Tailored Graphene Nanoribbons Jun-Qiang Lu, Lan He, Hanqing Jiang We report an approach for synthesizing carbon nanotube (CNT) junctions from two tailored graphene nanoribbons (GNRs). Using molecular dynamic simulations, CNT junctions with two-, three- and four terminals can be synthesized from GNRs either with perfect or irregular tailoring. The functionality of the CNT junctions is confirmed by charge transport simulations. [Preview Abstract] |
Friday, November 13, 2009 2:42PM - 2:54PM |
JC.00007: Site occupancy and magnetic properties of aluminum substituted barium hexaferrite Amitava Moitra, Sungho Kim, Seong-Gon Kim, YangKi Hong, Steven Erwin Aluminum substituted barium hexaferrite has been studied using density functional theory (DFT). The substitution has been carried out for BaFe$_{12-x}$Al$_{x}$O$_{19}$ from x = 1 to x = 3 in steps of 0.5. With the aid of accurate DFT study, our result show that the Al$^{3+}$ ions preferentially occupy the 2a and 12k site, unlike the previously reported 4f2, 2a, 4f1, and 12k sites. Our result confirms the experimental fact that with increasing of Al substitution the total magnetic moment monotonically decreases. We also present a possible reason of the site preference of 2a and 12k. [Preview Abstract] |
Friday, November 13, 2009 2:54PM - 3:06PM |
JC.00008: Design of Catalytic Nanomotors by Dynamic Shadowing Growth John Gibbs, Yiping Zhao Catalytic nanomotors are inorganic replicas of cellular motor proteins that convert chemical energy into work for mobility. These nanostructures achieve self-propelled mobility by carrying an on-board catalyst releasing stored chemical energy. Many researchers use template-directed electroplating (TDEP) which allows simple geometries such as cylindrical rod structures. We use a different method combining physical vapor deposition with dynamic shadowing growth (DSG) to fabricate artificial catalytic nanomotors. DSG allows for the construction of a wide range of structures and the asymmetric deposition of the catalyst layer necessary for nanomotor propulsion. We have constructed a multi-component rotary structure consisting of a silica microbead with a long arm attached, and the motion can be tuned by depositing the catalyst on different locations. We also have studied the propulsion mechanism associated nanomotor movement. The catalytic reaction most often studied is the break-down of hydrogen peroxide into water and oxygen gas. We have observed that the structures are propelled away from the catalyst, and we have developed a bubble propulsion model using a spherical microbead half-coated with Pt. Our model suggests propulsion arises by the release and ejection of oxygen. We predict a dependence upon the concentration of hydrogen peroxide as well as surface tension of the solution fitting empirical evidence. [Preview Abstract] |
Friday, November 13, 2009 3:06PM - 3:18PM |
JC.00009: High power electric double-layer capacitors based on carbon with ordered 2 nm pores Adam Kajdos, Gleb Yushin High surface area carbons find numerous applications in energy storage. In this project we were interested in investigating how we could improve the capacity retention, frequency response and power characteristics of electric double-layer capacitor (EDLC) electrodes if we employ high surface area porous carbon particles with aligned nanopores. We synthesized porous carbon replicas of zeolite Y particles using low-pressure chemical vapor deposition of carbon on a zeolite Y template, which was subsequently removed. X-Ray diffraction revealed aligned and ordered pores in the produced carbon, while scanning electron microscopy confirmed the conformation of shape during the templating process. Transmission electron microscopy showed the very uniform microstructure of the produced carbon. The zeolite-templated carbon was used as electrodes in EDLC's and showed exceptional energy storage characteristics. At low current densities the specific capacitance exceeded 200 F/g, among the highest values reported. The specific capacitance in excess of 100 F/g could be maintained at frequencies as high as 10 Hz and current densities as high as 20 A/g, which is unprecedented for carbon materials. [Preview Abstract] |
Friday, November 13, 2009 3:18PM - 3:30PM |
JC.00010: Highly ordered nanoelectronics switches fabricated by electrochemical processes in alumina templates Holli Null, Ryan Marson, Lam Yu Periodic arrays of layered structures fabricated by template synthesis in anodized alumina substrates are the basis of a new type of nanoelectronics switches. We performed electrical characterization on these nanoscale devices, and our results suggested that the mechanism for the switching behavior observed is based on nano-filament formation in the layered structures. We will present preliminary data demonstrating the functionality of these nanoscale devices and outline the fabrication process of these structures. [Preview Abstract] |
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