bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrodeposition of Group III Doped PbTe Nanowires
Authors: Hillman Peter , Stacy Angelica M 
Published: August 2010

AbstractNanowire arrays of PbTe were electrodeposited into porous alumina templates with 40nm pores. Citric acid was used as a complexing agent for HTeO2+ shifting the reduction potential of HTeO2+/Te closer to that of Pb2+/Pb. Compositional analysis of the wires grown with the complexing agent show a 1:1 ratio of Pb:Te without any excess tellurium. Group III elements (In3+ and Tl+) can be added to the deposition solution and incorporated into the nanowires. It is proposed that indium incorporates into the PbTe lattice in a high energy interstitial site causing the lattice parameter to increase linearly with increasing indium incorporation. The addition of thallium to the deposition solution leads to a mixture of PbTe and TlTe nanowires. Upon annealing, the TlTe melts incongruently to Tl5Te3, which then alloys with PbTe, thereby increasing the lattice parameter.
Influence of Structural Defects on the Electronic Properties of Carbon Nanotubes Examined by Scanning Tunnelling Microscopy
Authors: Giusca Cristina E. , Silva Ravi 
Published: August 2010

AbstractThe electronic properties of carbon nanotubes are quite often drastically affected by the presence of defects that can develop during nanotube growth, processing or characterization too. Some of these defects such as pentagon-heptagon rings, substitutional impurities, vacancies and dislocations are of topological nature, and can sometimes create on-tube intramolecular junctions, as found by previous scanning tunnelling microscopy studies.Our recent STM experiments reveal for the first time a much more complicated junction structure, a hybrid single-walled carbon nanotube consisting of a distinct coiled structure located between two straight segments, each of different helicity. We characterise the hybrid junction at the atomic level and describe its electronic behaviour that has important implications in the practical design of functional components for nanoelectronic applications.
Tunability of Carbon NanoTubes Resistance Deposited by Inkjet Printing at Low Temperature
Authors: Pacchini Sebastien , Conédéra Véronique , Mesnilgrente Fabien , Fabre Norbert , Flahaut Emmanuel , Coccetti Fabio , Dragoman Mircea , Plana Robert 
Published: August 2010

AbstractA deposition method based on inkjet printing technology and conductive double-wall carbon nanotubes (DWNT) suspension is, hereby, presented. The approach exploits the selective transfer capabilities offered by the inkjet printing process and the excellent conductive characteristics of the available DWNTs, in order to realize microelectronic interconnects of arbitrary patter and given electrical properties. The DWNTs are prepared by CCVD process, oxidized and dispersed in ethylene-glycol (EG) and in water solution. The DWNTs lines are fabricated on tests structures and then characterized through impedance and current-voltage measurements. 400 μm long and 90 μm wide transmission lines have been printed by varying the number of overwrites for given DWNT density. The results confirm that the DC resistance of DWNTs lines can be changed according to the number of overwrites and that the lines preserve ohmic characteristics up to 100 MHz.
Stable and Responsive Fluorescent Carbon Nanotube Silica Gels
Authors: Gupta Gautam , Duque Juan G. , Doorn Stephen , Dattelbaum Andrew M. 
Published: August 2010

AbstractHere we report a general route to prepare silica nanocomposite gels doped with fluorescent single walled carbon nanotubes (SWNT). We show that tetramethylorthosilicate (TMOS) vapors can be used to gel an aqueous suspension of surfactant-wrapped SWNT while maintaining fluorescence from the semiconducting nanotubes. The vapor phase silica process is performed at room temperature and is simple, reproducible, relatively quick, and requires no dilution of SWNT dispersions. However, exposure of aqueous SWNT suspensions to TMOS vapors resulted in an acidification of the suspension prior to gelation that caused a decrease in the emission signal from sodium dodecylsulfate (SDS) wrapped SWNT. We also show that although the SWNT are encapsulated in silica the emission signal from the encapsulated SWNT may be attenuated by exposing the nanocomposites to small aromatic molecules known to mitigate SWNT emission. These results demonstrate a new route for the preparation of highly luminescent SWNT/silica composite materials that are potentially useful for future sensing applications.
In situ TEM Straining of Nanograined Al Films Strengthened with Al2O3 Nanoparticles
Authors: Hattar Khalid , Clark Blythe G. , Knapp James A , Follstaedt David M , Robertson I. M. 
Published: August 2010

AbstractGrowing interest in nanomaterials has raised many questions regarding the operating mechanisms active during the deformation and failure of nanoscale materials. To address this, a simple, effective in situ TEM straining technique was developed that provides direct detailed observations of the active deformation mechanisms at a length scale relevant to most nanomaterials. The capabilities of this new straining structure are highlighted with initial results in pulsed laser deposited (PLD) Al-Al2O3 thin films of uniform thickness. The Al-Al2O3 system was chosen for investigation, as the grain size can be tailored via deposition and annealing conditions and the active mechanisms in the binary system can be compared to previous studies in PLD Ni and evaporated Al films. PLD Al-Al2O3 free-standing films of various oxide concentrations and different thermal histories were produced and characterized in terms of average grain and particle sizes. Preliminary in situ TEM straining experiments show intergranular failure for films with 5 vol% Al2O3. Further work is in progress to explore and understand the active deformation and failure mechanisms, as well as the dependence of mechanisms on processing routes.
Three-dimensional Structure of Twinned and Zigzagged One-dimensional Nanostructures Using Electron Tomography
Authors: Kim Han Sung , Myung Yoon , Cho Yong Jae , Jang Dong Myung , Jung Chan Soo , Ahn Jae-Pyoung , Park Jeunghee 
Published: August 2010

AbstractElectron tomography and high-resolution transmission electron microscopy were used to characterize the unique 3-dimensional (3D) structures of twinned Zn3P2 (tetragonal) and InAs (zinc blende) nanowires synthesized by the vapor transport method. The Zn3P2 nanowires adopt a unique superlattice structure that consists of twinned octahedral slice segments having alternating orientations along the axial [111] direction of a pseudocubic unit cell. The apices of the octahedral slice segment are indexed as six equivalent <112> directions at the [111] zone axis. At each 30 degrees turn, the straight and zigzagged morphologies appear repeatedly at the <112> and <011> zone axes, respectively. The 3D structure of the twinned Zn3P2 nanowires is virtually the same as that of the twinned InAs nanowires. In addition, we analyzed the 3D structure of zigzagged CdO (rock salt) nanowires and found that they include hexahedral segments, whose six apices are matched to the <011> directions, linked along the [111] axial direction. We also analyzed the unique 3D structure of rutile TiO2 (tetragonal) nanobelts; at each 90 degree turn, the straight morphology appears repeatedly, while the in-between twisted form appears at the [011] zone axis. We suggest that the TiO2 nanobelts consist of twinned octahedral slices whose six apices are indexed by the <011>/<001> directions with the axial [010] direction.
Neutron Diffraction Study of NiO/LiCoO2Electrodes for Innovative Fuel Cell Development
Authors: Coppola Roberto , Henry Paul , Moreno Angelo , Rodríguez-Carvajal Juan , Simonetti Elisabetta 
Published: August 2010

AbstractNi-NiO 30% electrodes coated with LiMg0.05Co0.95O2cobaltite deposited on the substrate by complex sol-gel process were investigated by neutron diffraction. The measurements were carried out at the D20 diffractometer at the High Flux Reactor of the Institut Max von Laue – Paul Langevin. As the catalytic layer is only a few microns thick, the diffracting volume of the cobaltite phase was optimised by stacking small rectangular pieces cut from the original electrode and assuming that the catalytic layer on the electrodes was homogenous. A pure cobaltite sample was used as a reference for identifying in the complete electrode the diffraction peaks of the catalytic layer. Both an as-received sample and an electrode tested for 100 h at 650 °C in a cell were measured. Despite the small diffracting volume, due to the high flux available at D20, it was possible to detect the hexagonal phase of the catalytic layer and estimate its volume fraction in the as-received sample; in the tested electrode the original crystallographic structure is completely modified but information on the phases present can be obtained.
X-ray Detection on Fe-H Vibrations
Authors: Wang Hongxin , Guo Yisong , Kamali Saeed , Cramer Stephen P 
Published: August 2010

AbstractX-ray detection on hydrogen related events is difficult due to its extremely small scattering factor. In this report, we have used nuclear resonance vibrational spectroscopy (NRVS) to examine the nature of the Fe–H vibrational modes in several FeH model complexes, which shines light on the possible measurements on the Fe-H vibrations inside real biological systems in the future.
Mesoscale Simulations of Microstructure Evolution in a Temperature Gradient
Authors: Radhakrishnan Bala , Sarma Gorti 
Published: August 2010

AbstractThe evolution of pore and grain structure in a nuclear fuel environment is strongly influenced by the local temperature, and the temperature gradient. The evolution of pore and grain structure in an externally imposed temperature gradient is simulated for a hypothetical material using a Potts model approach that allows for porosity migration by mechanisms similar to surface, grain boundary and volume diffusion, as well as the interaction of migrating pores with stationary grain boundaries. First, the migration of a single pore in a single crystal in the presence of the temperature gradient is simulated. Next, the interaction of a pore moving in a temperature gradient with a grain boundary that is perpendicular to the pore migration direction is simulated in order to capture the force exerted by the pore on the grain boundary. The simulations reproduce the expected variation of pore velocity with pore size as well as the variation of the grain boundary force with pore size.
Direct Energy Conversion From Gamma Ray to Electricity Using Silicon Semiconductor Cells
Authors: Hashizume Kenichi , Kimura Hiroki , Otsuka Teppei , Tanabe Tetsuo , Okai Tomio 
Published: August 2010

AbstractSpent fuels and high level radioactive wastes which emit high doze of gamma rays could be a promising and long-lasting power source, if the gamma ray energy was effectively converted other forms of energy. In the present study, we have tried to convert gamma ray to electricity directly, with using silicon semiconductor cells made of p-type Si single crystal wafers with various specific resistivities ranging from 0.01 to 1000 Ohm∙cm. On both surfaces of the cell (20×20×0.5mm3), Al and Sb were deposited in vacuum to make electrodes at room temperature. The voltage-current measurement of the cells showed a rectification effect, and Al side was found to work a cathode. This suggests a Schottky junction was formed at the interface between the deposited Al and Si wafer. The cell irradiated by gamma ray in Co-60 irradiation facility in Kyushu Univ. with an absorbed dose of about 200Gy/h, and output voltage and current generated by the irradiation with external resistances varying from 200 to 100,000 Ohm were measured. The maximum electric power obtained for each cell ranged from 0.002 to 200 micro-W/m2, and clearly increased with increasing the specific resistivity of Si wafers. For comparison, a single crystal Si solar cell (2400mm2×0.5m, 0.5V×450mA in AM1.5 condition) was also exposed to the gamma ray, and its maximum electric power was 2 micro-W/m2. The output power of the present cell with high resistivity was two orders of magnitude higher than that of the Si solar cell.Energy deposition in the Si cell during gamma irradiation was evaluated with the Monte Carlo Simulation for N Particles (MCNP) code. For Si with 0.5 mm thickness, the deposited energy was calculated to be 17000 micro-W/m2 for 200Gy/h. Comparing the output energy by the gamma irradiation, the energy conversion efficiency of the present Si cells reached about 1%. Unfortunately, the present cells were unstable even in ambient atmosphere, the conversion ratio of which decreased to less than one tenth in six months. Further development of the cells with higher conversion ratio and improvement of its stability will be discussed.
MARS, A New Facility for X-ray Diffraction and X-ray Absorption for Radioactive Matter Studies
Authors: Schlutig Sandrine , Solari Pier Lorenzo , Hermange Hervé , Sitaud Bruno 
Published: August 2010

AbstractThe MARS (Multi-Analyses on Radioactive Samples) beamline, at Synchrotron Soleil (France) is fully dedicated to advanced structural and chemical characterizations of radioactive matter (solid or liquid), coupling analytical tools such as X-ray absorption spectroscopy, X-ray diffraction, X-ray fluorescence and associated micro-beam techniques. This beamline is now partially operational and has completed its first year of working with samples below exemption limits. This paper describes the beamline design and its technical specifications as well as the standard equipment of the experimental stations and the first obtained results.
Thermochemistry of Elementary Actinide Sulfide Molecules: A Gas-Phase Study of Curium Sulfide
Authors: Pereira Cláudia C. L. , Marçalo Joaquim , Gibson John K. 
Published: August 2010

AbstractExperiments to explore the reactivity and thermochemistry of elementary transuranium sulfide molecules have been initiated to expand the basis for a fundamental understanding of actinide bonding, and to enable the development of advanced theoretical methodologies which will be of general applicability to more complex molecular systems. Bimolecular gas-phase reactions between transuranium actinide ions and neutral reagents are employed to obtain thermochemical information. The initial actinide sulfide studies have focused on obtaining the 298 K bond dissociation energy for the CmS+ ion, D[Cm+-S] = 475±37 kJ mol-1; from this result and an estimate of IE[CmS] ≈ IE[CmO] + 0.5 eV, we obtain D[Cm-S] = 563±64 kJ mol-1. The bond dissociation energies, D[Cm+-S] and D[Cm-S] are approximately 200 kJ mol-1 and 150 kJ mol-1 lower than for the corresponding oxides, CmO+ and CmO. The nature of the bonding in the CmS+ ion appears to be generally similar to that in other oxophilic metal sulfides. Comparisons with previous bond dissociation energies reported for ThS and US may suggest a difference in the An-S bonds for these early actinide sulfides as compared with CmS.
Electronic structure theory of Pu-Am and Pu-Ce alloys, and thin δ-Pu films
Authors: Kolorenc Jindrich , Shick Alexander , Havela Ladislav , Lichtenstein Alexander 
Published: August 2010

AbstractWe study effects of electron correlations on the electronic structure and spectra of Pu, Am and their alloys. We make use of the LDA + Hubbard-I approximation being implemented in the full-potential LAPW basis and including self-consistency over the charge density. We demonstrate that this approximation correctly captures trends observed in the experimental photoemission spectra of plutonium and its compounds: insensitivity of the f electron spectral features to alloying with another element and enhancement of f electron localization in thin films compared to the bulk material.
Photoelectron Spectroscopy of U Oxide at LLNL
Authors: Tobin James G , Yu Sung Woo , Chung Brandon W , Waddill G. Dan 
Published: August 2010

AbstractX-ray photoelectron spectroscopy has been used to characterize a sample of UO2 grown on an underlying substrate of Uranium. Both AlKα (1487 eV) and MgKα (1254 eV) emission were utilized as the excitation.
Anisotropy of antiferromagnetic spin fluctuations in the heavy fermion superconductors of CeMIn5 and PuMGa5 (M=Co, Rh)
Authors: Sakai Hironori , Kambe Shinsaku , Tokunaga Yo , Haga Yoshinori , Baek Seung -H. , Ronning Filip , Bauer Eric , Thompson Joe D 
Published: August 2010

AbstractThe anisotropy of antiferromagnetic spin fluctuations has been investigated microscopically in the heavy fermion systems of CeMIn5 and PuMGa5 (M=Co, Rh) by means of nuclear magnetic resonance (NMR). Both systems are known to be relatively high-Tc superconductors among the heavy fermion systems, especially PuCoGa5, which has a Tc=18.5 K almost one order of magnitude larger than for CeCoIn5 ( Tc=2.3 K). Analysis of the Knight shift and spin-lattice relaxation rates suggests XY-type anisotropy in the antiferromagnetic spin fluctuations in the normal states of these unconventional superconductors. Moreover, the 115 superconductors with larger XY-type fluctuations have a higher Tc, compared to the anisotropy of spin fluctuations in the related paramagnetic system UFeGa5 and antiferromagnets UPtGa5, NpCoGa5, NpFeGa5.
Establishment of Uncertainty Ranges and Probability Distributions of Actinide Solubilities for Performance Assessment in the Waste Isolation Pilot Plant
Authors: Xiong Yongliang , Nowak Jim , Brush Laurence H. , Ismail Ahmed E. , Long Jennifer 
Published: August 2010

AbstractThe Fracture-Matrix Transport (FMT) code developed at Sandia National Laboratories solves chemical equilibrium problems using the Pitzer activity coefficient model with a database containing actinide species. The code is capable of predicting actinide solubilities at 25 °C in various ionic-strength solutions from dilute groundwaters to high-ionic-strength brines. The code uses oxidation state analogies, i.e., Am(III) is used to predict solubilities of actinides in the +III oxidation state; Th(IV) is used to predict solubilities of actinides in the +IV state; Np(V) is utilized to predict solubilities of actinides in the +V state. This code has been qualified for predicting actinide solubilities for the Waste Isolation Pilot Plant (WIPP) Compliance Certification Application in 1996, and Compliance Re-Certification Applications in 2004 and 2009.We have established revised actinide-solubility uncertainty ranges and probability distributions for Performance Assessment (PA) by comparing actinide solubilities predicted by the FMT code with solubility data in various solutions from the open literature. The literature data used in this study include solubilities in simple solutions (NaCl, NaHCO3, Na2CO3, NaClO4, KCl, K2CO3, etc.), binary mixing solutions (NaCl+NaHCO3, NaCl+Na2CO3, KCl+K2CO3, etc.), ternary mixing solutions (NaCl+Na2CO3+KCl, NaHCO3+Na2CO3+NaClO4, etc.), and multi-component synthetic brines relevant to the WIPP.
Uranium (VI) Solubility in Carbonate-Free ERDA-6 Brine
Authors: Lucchini Jean-Francois , Khaing Hnin , Reed Donald T. 
Published: August 2010

AbstractWhen present, uranium is usually an element of importance in a nuclear waste repository. In the Waste Isolation Pilot Plant (WIPP), uranium is present in significant quantities, with about 647 metric tons to be placed in the repository [1]. Therefore, the chemistry of uranium, and especially its solubility, needs to be determined under WIPP-relevant conditions.Long-term experiments were performed to measure the solubility of uranium (VI) in carbonate-free ERDA-6 brine, a simulated WIPP brine, at pCH+ values between 8 and 12.5. These data, obtained from the over-saturation approach, were the first WIPP repository-relevant data for the VI actinide oxidation state. The solubility trends observed pointed towards low uranium solubility in WIPP brine and a lack of amphotericity. At the expected pCH+ in the WIPP (˜ 9.5), measured uranium solubility approached 10-7 M. The objective of these experiments was to establish a baseline solubility to further investigate the effects of carbonate complexation on uranium solubility in WIPP brines, during the ongoing research program in actinide solubility under WIPP-relevant conditions.
The Role of the Actinides in a Performance Assessment of a Nuclear Waste Repository. SKB's Supporting Actinide Research
Authors: Werme Lars , Butorin Sergei , Oppeneer Peter M 
Published: August 2010

AbstractAfter a few hundred years, the actinides will dominate the radiotoxicity of spent nuclear fuel. This does not necessarily mean that the actinides will dominate the dose to organisms at the surface above a geologic repository. Quite the contrary, in most performance assessments this dose is dominated by long-lived fission products, activation products and, in the very long perspective, actinide daughters.This makes the far-field migration properties of the actinides less interesting for further research. There are, however, other aspects of the presence of actinides in spent nuclear fuel and some of these and SKB's research in these fields is presented and discussed here.
Selective Radionuclide (Cs+, Sr2+, and Ni2+) Ion-exchange by K2xMgxSn3-xS6(x=0.5-0.95) (KMS-2)
Authors: Mertz Joshua Leighton , Manos Emmanouil J. , Kanatzidis Mercouri 
Published: August 2010

Abstract137Cs and90Sr, both byproducts of the fission process, make up the majority of high-level waste from nuclear power plants.63Ni is a byproduct of the erosion-corrosion process of the reactor components in nuclear energy plants. The concentrations of these ions in solution determine the Waste Class (A,B, or C) and thus selective removal of these ions over large excesses of other ions is necessary to reduce waste and cut costs. Herein we report the use of the Inorganic Ion Specific Media (ISM) K2xMgxSn3-xS6(x=0.5-0.9) (KMS-2) for the ion exchange of Cs+, Sr2+, and Ni2+in several different conditions. We will also report the stability of this new material in the general conditions found at nuclear power plants (pH ˜6-8) and DOE sites (pH>10). Measurements at low concentrations were conducted with inductively coupled plasma mass spectrometry and Kd values are reported for each of the ions in a variety of conditions.
Assessment of Concrete Cracking at Nuclear Waste Disposal Facilities via Fiber Optic Sensors
Authors: Lair Sanaan Cherie , Walton John C. , Woocay Arturo , Motta Antonio 
Published: August 2010

AbstractFiber optic sensors offer a novel approach to monitoring of fractures in concrete waste disposal vaults and offer the possibility of determining the quantity, width and location of the cracks as they form. Fiber optics can directly detect cracks if they form within the path of a fiber optic as well as monitor secondary indicators of cracking such as temperature changes and strain. When cracks form in concrete waste disposal vaults they can fill with water which has a high heat capacity, this enables cracks to be observed by monitoring temperature variations near the crack. An analytical solution for heat transfer is applied to estimate the propagation of temperature waves around cracks. It is demonstrated that discharge rates through the concrete which are less than 10-5 m3/m-s do not produce a meaningful temperature wave through the concrete. Fractures in the concrete must be larger than 0.07 cm to produce a measurable result and temperature sensors must be located within 0.5 meters of a crack to detect a change in temperature produced by seasonal groundwater flow through a crack. A distributed system of fiber optic sensors may be embedded in the concrete vault and used to monitor crack formation, temperature variations and strain.