Synthesis And Electrocatalysis Of Pdcu Alloy Nanocrystals,
2013
State Key Laboratory of Eleetroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
Synthesis And Electrocatalysis Of Pdcu Alloy Nanocrystals, Hai-Bin Wu, Rui-Zhong Zhang, Wei Chen
Journal of Electrochemistry
Monodispersed PdCu alloy nanoparticles were synthesized by co-reduction of Cu(acac)2 and Pd(acac)2 with 1, 2-hexadecanediol. The spherical and popcorn-like shapes of PdCu alloy nanoparticles were obtained by changing the ratios of mixed surface protecting ligands of 1-octadecene, and oleylamine or oleic acid. TEM and XRD measurements showed that both PdCu nanoparticles are alloy nanocrystals dominated with (111) planes and the average sizes are 12.7 ± 0.18 and 20.4 ± 0.31 nm for he spherical and popcorn-like PdCu nanoparticles, respectively. The electrocatalytic activities of the PdCu nanocrystals for formic acid oxidation were evaluated by electrochemical cyclic voltammetry (CV). The result showed …
Evidence For Effective Mass Reduction In Gaas/Algaas Quantum Wells,
2013
University of Minnesota - Twin Cities
Evidence For Effective Mass Reduction In Gaas/Algaas Quantum Wells, A. T. Hatke, M. A. Zudov, J. D. Watson, Michael J. Manfra, L. N. Pfeiffer, K. W. West
Birck and NCN Publications
We have performed microwave photoresistance measurements in high mobility GaAs/AlGaAs quantum wells and investigated the value of the effective mass. Surprisingly, the effective mass, obtained from the period of microwave-induced resistance oscillations, is found to be about 12% lower than the band mass in GaAs, m(b)*. This finding provides strong evidence for electron-electron interactions which can be probed by microwave photoresistance in very high Landau levels. In contrast, the measured magnetoplasmon dispersion revealed an effective mass which is close to m(b)*, in accord with previous studies. DOI: 10.1103/PhysRevB.87.161307
Modification Of Nanostructures Via Laser Processing,
2013
Virginia Commonwealth University
Modification Of Nanostructures Via Laser Processing, Louis Franzel
Theses and Dissertations
Modification of nanostructures via laser processing is of great interest for a wide range of applications such as aerospace and the storage of nuclear waste. The primary goal of this dissertation is to improve the understanding of nanostructures through two primary routes: the modification of aerogels and pulsed laser ablation in ethanol. A new class of materials, patterned aerogels, was fabricated by photopolymerizing selected regions of homogeneous aerogel monoliths using visible light. The characterization and fabrication of functionally graded, cellular and compositionally anisotropic aerogels and ceramics is discussed. Visible light was utilized due to it’s minimal absorption and scattering by …
Investigation Of Surface Properties For Ga- And N-Polar Gan Using Scanning Probe Microscopy Techniques,
2013
Virginia Commonwealth University
Investigation Of Surface Properties For Ga- And N-Polar Gan Using Scanning Probe Microscopy Techniques, Josephus Daniel Ferguson Iii
Theses and Dissertations
Because the surface plays an important role in the electrical and optical properties of GaN devices, an improved understanding of surface effects should help optimize device performance. In this work, atomic force microscopy (AFM) and related techniques have been used to characterize three unique sets of n-type GaN samples. The sample sets comprised freestanding bulk GaN with Ga polar and N polar surfaces, epitaxial GaN films with laterally patterned Ga- and N-polar regions on a common surface, and truncated, hexagonal GaN microstructures containing Ga-polar mesas and semipolar facets. Morphology studies revealed that bulk Ga-polar surfaces treated with a chemical-mechanical polish …
Thermoelectric Properties Of Epitaxial Scn Films Deposited By Reactive Magnetron Sputtering Onto Mgo(001) Substrates,
2013
Birck Nanotechnology Center, Purdue University
Thermoelectric Properties Of Epitaxial Scn Films Deposited By Reactive Magnetron Sputtering Onto Mgo(001) Substrates, Polina V. Burmistrova, Jesse Maassen, Tela Favaloro, Bivas Saha, Shuaib Salamat, Yee Rui Koh, Mark S. Lundstrom, Ali Shakouri, Timothy D. Sands
Birck and NCN Publications
Epitaxial ScN(001) thin films were grown on MgO(001) substrates by dc reactive magnetron sputtering. The deposition was performed in an Ar/N-2 atmosphere at 2 x 10(-3) Torr at a substrate temperature of 850 degrees C in a high vacuum chamber with a base pressure of 10(-8) Torr. In spite of oxygen contamination of 1.6 +/- 1 at. %, the electrical resistivity, electron mobility, and carrier concentration obtained from a typical film grown under these conditions by room temperature Hall measurements are 0.22 m Omega cm, 106 cm(2) V-1 s(-1), and 2.5 x 10(20) cm(-3), respectively. These films exhibit remarkable thermoelectric …
Length And Temperature Dependent 1/F Noise In Vertical Single-Walled Carbon Nanotube Arrays,
2013
Birck Nanotechnology Center, Purdue University
Length And Temperature Dependent 1/F Noise In Vertical Single-Walled Carbon Nanotube Arrays, Robert A. Sayer, Jeffrey D. Engerer, N. S. Vidhyadhiraja, Timothy S. Fisher
Birck and NCN Publications
We report measurements of temperature-and length-dependent 1/f noise in vertical single-walled carbon nanotube (SWCNT) arrays. Carbon nanotubes are synthesized in a porous anodic alumina template with sub-micrometer channel lengths ranging from 100 to 700 nm. A significant difference is observed in the 1/f noise magnitude of quasi-ballistic and diffusive SWCNT devices, with quasi-ballistic devices exhibiting 1/f noise levels that are one to two orders of magnitude less than diffusively conducting devices. Furthermore, 1/f noise was measured from 90 to 400 K, and the noise prefactor decreased significantly at temperatures below 250 K. (C) 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4800856]
Atomic Force Microscopy-Coupled Microcoils For Cellular-Scale Nuclear Magnetic Resonance Spectroscopy,
2013
Birck Nanotechnology Center, Purdue University
Atomic Force Microscopy-Coupled Microcoils For Cellular-Scale Nuclear Magnetic Resonance Spectroscopy, Charilaos Mousoulis, Teimour Maleki, Babak Ziaie, Corey Neu
Birck and NCN Publications
We present the coupling of atomic force microscopy (AFM) and nuclear magnetic resonance (NMR) technologies to enable topographical, mechanical, and chemical profiling of biological samples. Here, we fabricate and perform proof-of-concept testing of radiofrequency planar microcoils on commercial AFM cantilevers. The sensitive region of the coil was estimated to cover an approximate volume of 19.4 x 10(3) mu m(3) (19.4 pl). Functionality of the spectroscopic module of the prototype device is illustrated through the detection of H-1 resonance in deionized water. The acquired spectra depict combined NMR capability with AFM that may ultimately enable biophysical and biochemical studies at the …
Mechanism Of Fatigue Performance Enhancement In A Laser Sintered Superhard Nanoparticles Reinforced Nanocomposite Followed By Laser Shock Peening,
2013
Purdue University
Mechanism Of Fatigue Performance Enhancement In A Laser Sintered Superhard Nanoparticles Reinforced Nanocomposite Followed By Laser Shock Peening, Dong Lin, Chang Ye, Yiliang Liao, Sergey Suslov, Richard Liu, Gary J. Cheng
Birck and NCN Publications
This study investigates the fundamental mechanism of fatigue performance enhancement during a novel hybrid manufacturing process, which combines laser sintering of superhard nanoparticles integrated nanocomposites and laser shock peening (LSP). Through laser sintering, TiN nanoparticles are integrated uniformly into iron matrix to form a nanocomposite layer near the surface of AISI4140 steel. LSP is then performed on the nanocomposite layer to generate interaction between nanoparticles and shock waves. The fundamental mechanism of fatigue performance enhancement is discussed in this paper. During laser shock interaction with the nanocomposites, the existence of nanoparticles increases the dislocation density and also helps to pin …
High-Resolution Correlation Spectroscopy Of 13c Spins Near A Nitrogen-Vacancy Centre In Diamond,
2013
City College of New York—CUNY
High-Resolution Correlation Spectroscopy Of 13c Spins Near A Nitrogen-Vacancy Centre In Diamond, Abdelghani Laraoui, Florian Dolde, Christian Burk, Friedemann Reinhard, Jorg Wrachtrup, Carlos A. Meriles
Department of Mechanical and Materials Engineering: Faculty Publications
Spin complexes comprising the nitrogen-vacancy centre and neighbouring spins are being considered as a building block for a new generation of spintronic and quantum information processing devices. As assembling identical spin clusters is difficult, new strategies are being developed to determine individual node structures with the highest precision. Here we use a pulse protocol to monitor the time evolution of the 13C ensemble in the vicinity of a nitrogenvacancy centre. We observe long-lived time correlations in the nuclear spin dynamics, limited by nitrogen-vacancy spin–lattice relaxation. We use the host 14N spin as a quantum register and demonstrate that hyperfine-shifted resonances …
The Effect Of Network Transitions On Spontaneous Activity And Sycnhrony In Devloping Neural Networks,
2013
Louisiana Tech University
The Effect Of Network Transitions On Spontaneous Activity And Sycnhrony In Devloping Neural Networks, Jude P. J. Savarraj
Doctoral Dissertations
Connectivity patterns of developing neural circuits and the effects of its dynamics on network behavior, particularly the emergence of spontaneous activity and synchrony, are not clear. We attempt to quantify anatomical connectivity patterns of rat cortical cultures during different stages of development. By culturing the networks on dishes embedded with micro electrode arrays, we simultaneously record electrical activity from multiple regions of the developing network and monitor its electrical behavior, particularly its tendency to fire spontaneously and to synchronize under certain conditions. We investigate possible correlations between changes in the network connectivity patterns and spontaneous electrical activity and synchrony. Cocultures …
Intrinsic Mode Function Synchronization Measures For The Anticipation Of Seizures In Epilpsy,
2013
Louisiana Tech University
Intrinsic Mode Function Synchronization Measures For The Anticipation Of Seizures In Epilpsy, Daniel William Moller
Doctoral Dissertations
Epileptic seizures affect as many as 50 million people and often occur without warning or apparent provocation. We explore the applicability of noise-assisted Ensemble Empirical Mode Decomposition (EEMD) for patient-specific seizure anticipation synchronization measures as applied to the EEMD intrinsic mode function (IMF) output. Intracranial EEG data were obtained from pre-surgical monitoring at the Epilepsy Center of the University Hospital of Freiburg. Data from twenty patients were analyzed. For each recorded channel, non-overlapping time windows were submitted to the EEMD algorithm, producing twelve levels of IMFs. IMF synchronization measures (mean and maximum coherence, mean and maximum cross-correlation, correlation coefficient and …
Thickness-Shear Vibration Of A Rectangular Quartz Plate With Partial Electrodes,
2013
University of Nebraska-Lincoln
Thickness-Shear Vibration Of A Rectangular Quartz Plate With Partial Electrodes, Huijing He, Jiashi Yang, John A. Kosinski, Ji Wang
Department of Mechanical and Materials Engineering: Faculty Publications
We study free vibration of a thickness-shear mode crystal resonator of AT-cut quartz. The resonator is a rectangular plate partially and symmetrically electroded at the center with rectangular electrodes. A single-mode, three-dimensional equation governing the thickness-shear displacement is used. A Fourier series solution is obtained. Numerical results calculated from the series show that there exist trapped thickness-shear modes whose vibration is mainly under the electrodes and decays rapidly outside the electrodes. The effects of the electrode size and thickness on the trapped modes are examined.
Nanopatterning Of Metal-Coated Silicon Surfaces Via Ion Beam Irradiation: Real Time X-Ray Studies Reveal The Effect Of Silicide Bonding,
2013
Birck Nanotechnology Center, Purdue University
Nanopatterning Of Metal-Coated Silicon Surfaces Via Ion Beam Irradiation: Real Time X-Ray Studies Reveal The Effect Of Silicide Bonding, Osman El-Atwani, Sean Gonderman, Alexander Demasi, Anastassiya Suslova, Justin Fowler, Mohamad El-Atwani, Karl Ludwig, Jean Paul Allain
Birck and NCN Publications
We investigated the effect of silicide formation on ion-induced nanopatterning of silicon with various ultrathin metal coatings. Silicon substrates coated with 10 nm Ni, Fe, and Cu were irradiated with 200 eV argon ions at normal incidence. Real time grazing incidence small angle x-ray scattering (GISAXS) and x-ray fluorescence (XRF) were performed during the irradiation process and real time measurements revealed threshold conditions for nanopatterning of silicon at normal incidence irradiation. Three main stages of the nanopatterning process were identified. The real time GISAXS intensity of the correlated peaks in conjunction with XRF revealed that the nanostructures remain for a …
Full Band Calculations Of The Intrinsic Lower Limit Of Contact Resistivity,
2013
Birck Nanotechnology Center, Purdue University
Full Band Calculations Of The Intrinsic Lower Limit Of Contact Resistivity, Jesse Maassen, C. Jeong, A. Baraskar, M. Rodwell, Mark S. Lundstrom
Birck and NCN Publications
The intrinsic lower limit of contact resistivity (rho(LL)(c)) for InAs, In0.53Ga0.47As, GaSb, and Si is calculated using a full band ballistic quantum transport approach. Surprisingly, our results show that rho(LL)(c) is almost independent of the semiconductor. An analytical model, derived for 1D, 2D, and 3D, correctly reproduces the numerical results and explains why rho(LL)(c) is very similar in all cases. Our analysis sets a minimal carrier density required to meet the International Technology Roadmap for Semiconductors call for rho(c) x 10(-9) Omega-cm(2) by 2023. Comparison with experiments shows there is room for improvement, which will come from optimizing interfacial properties. …
Coupled Vibrational Modes In Multiple-Filled Skutterudites And The Effects On Lattice Thermal Conductivity Reduction,
2013
Birck Nanotechnology Center, Purdue University
Coupled Vibrational Modes In Multiple-Filled Skutterudites And The Effects On Lattice Thermal Conductivity Reduction, Liang Guo, Xianfan Xu, J. R. Salvador, G. P. Meisner
Birck and NCN Publications
The influence of guest atoms on thermal conduction in filled skutterudites was studied using ultrafast reflectance spectroscopy. Different filling species cause coupled vibrational modes between the guest atoms and the host lattice at different frequencies, which scatter phonons in different spectral spans. Using a Debye model for the measured lattice thermal conductivity together with the measured vibration frequencies and scattering rates, it is shown that scattering due to the coupled vibrational modes has a considerable contribution to the suppression of lattice thermal conduction. This demonstrates that filling with multiple species can efficiently reduce the lattice thermal conductivity in skutterudites. (C) …
Thermoreflectance Imaging Of Sub 100 Ns Pulsed Cooling In High-Speed Thermoelectric Microcoolers,
2013
Birck Nanotechnology Center, Purdue University; University of California - Santa Cruz
Thermoreflectance Imaging Of Sub 100 Ns Pulsed Cooling In High-Speed Thermoelectric Microcoolers, Bjorn Vermeersch, Je-Hyeong Bahk, James Christofferson, Ali Shakouri
Birck and NCN Publications
Miniaturized thin film thermoelectric coolers have received considerable attention as potential means to locally address hot spots in microprocessors. Given the highly dynamic workload in complex integrated circuits, the need arises for a thorough understanding of the high-speed thermal behavior of microcoolers. Although some prior work on transient Peltier cooling in pulsed operation is available, these studies mostly focus on theoretical modeling and typically deal with relatively large modules with time constants well into the millisecond range. In this paper, we present an extensive experimental characterization of 30 x 30 mu m(2) high-speed coplanar SiGe superlattice microcoolers subjected to 300 …
Shape Memory Metamaterials With Tunable Thermo-Mechanical Response Via Hetero-Epitaxial Integration: A Molecular Dynamics Study,
2013
Birck Nanotechnology Center, Purdue University
Shape Memory Metamaterials With Tunable Thermo-Mechanical Response Via Hetero-Epitaxial Integration: A Molecular Dynamics Study, Karthik Guda Vishnu, Alejandro Strachan
Birck and NCN Publications
We show that nanoscale epitaxial superlattices (SLs) can be used to engineer the energy landscape that governs the martensitic transformation in shape memory alloys and tune their thermo-mechanical response. We demonstrate the approach using large-scale molecular dynamics simulations of a SL material consisting of alternate layers of a shape memory Ni-rich NiAl alloy and NiAl B2 alloy. The non-martensitic NiAl alloy was chosen to reduce the energy barrier that separates the martensite and austenite phases of the SL and its incorporation leads to a reduction in the thermal hysteresis of the transition. This is a desirable feature in applications involving …
Effects Of Forming Gas Anneal On Ultrathin Ingaas Nanowire Metal-Oxide-Semiconductor Field-Effect Transistors,
2013
Birck Nanotechnology Center, Purdue University
Effects Of Forming Gas Anneal On Ultrathin Ingaas Nanowire Metal-Oxide-Semiconductor Field-Effect Transistors, Mengwei Si, Jiangjiang Gu, Xinwei Wang, Jiayi Shao, Xuefei Li, Michael J. Manfra, Roy G. Gordon, Peide D. Ye
Birck and NCN Publications
InGaAs gate-all-around metal-oxide-semiconductor field-effect transistors (MOSFETs) with 6 nm nanowire thickness have been experimentally demonstrated at sub-80 nm channel length. The effects of forming gas anneal (FGA) on the performance of these devices have been systematically studied. The 30min 400 degrees C FGA (4% H-2/96% N-2) is found to improve the quality of the Al2O3/InGaAs interface, resulting in a subthreshold slope reduction over 20mV/dec (from 117mV/dec in average to 93mV/dec). Moreover, the improvement of interface quality also has positive impact on the on-state device performance. A scaling metrics study has been carried out for FGA treated devices with channel lengths …
Laser Direct Writing Of Silicon Field Effect Transistor Sensors,
2013
Birck Nanotechnology Center, Purdue University
Laser Direct Writing Of Silicon Field Effect Transistor Sensors, Woongsik Nam, James I. Mitchell, Chookiat Tansarawiput, Minghao Qi, Xianfan Xu
Birck and NCN Publications
We demonstrate a single step technique to fabricate silicon wires for field effect transistor sensors. Boron-doped silicon wires are fabricated using laser direct writing in combination with chemical vapor deposition, which has the advantages of precise control of position, orientation, and length, and in situ doping. The silicon wires can be fabricated to have very rough surfaces by controlling laser operation parameters, and thus, have large surface areas, enabling high sensitivity for sensing. Highly sensitive pH sensing is demonstrated. We expect our method can be expanded to the fabrication of various sensing devices beyond chemical sensors. (C) 2013 American Institute …
Deuterium Uptake In Magnetic-Fusion Devices With Lithium-Conditioned Carbon Walls,
2013
University of Tennessee - Knoxville; Oak Ridge National Laboratory
Deuterium Uptake In Magnetic-Fusion Devices With Lithium-Conditioned Carbon Walls, P. S. Krstic, Jean Paul Allain, C. N. Taylor, J. Dadras, S. Maeda, K. Morokuma, J. Jakowski, A. Allouche, C. H. Skinner
Birck and NCN Publications
Lithium wall conditioning has lowered hydrogenic recycling and dramatically improved plasma performance in many magnetic-fusion devices. In this Letter, we report quantum-classical atomistic simulations and laboratory experiments that elucidate the roles of lithium and oxygen in the uptake of hydrogen in amorphous carbon. Surprisingly, we show that lithium creates a high oxygen concentration on a carbon surface when bombarded by deuterium. Furthermore, surface oxygen, rather than lithium, plays the key role in trapping hydrogen. DOI: 10.1103/PhysRevLett.110.105001
