bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiscale Modeling of Irradiation Induced Hardening in a-Fe, Fe-Cr and Fe-Ni Systems
Authors: Mastorakos Ioannis , Le Ngoc , Zeine Melody , Zbib Hussein M , Khaleel Moe 
Published: August 2010

AbstractStructural materials in the new Generation IV reactors will operate in harsh radiation conditions coupled with high levels of hydrogen and helium production, thus experiencing severe degradation of mechanical properties. The development of structural materials for use in such a hostile environment is predicated on understanding the underlying physical mechanisms responsible for microstructural evolution along with corresponding dimensional instabilities and mechanical property changes. As the phenomena involved are very complex and span in several length scales, a multiscale approach is necessary in order to fully understand the degradation of materials in irradiated environments. The purpose of this work is to study the behavior of Fe systems (namely a-Fe, Fe-Cr and Fe-Ni) under irradiation using both Molecular Dynamics (MD) and Dislocation Dynamics (DD) simulations. Critical information is passed from the atomistic (MD) to the microscopic scale (DD) in order to study the degradation of the material under examination. In particular, information pertaining to the dislocation-defects (such as voids, helium bubbles and prismatic loops) interactions is obtained from MD simulations. Then this information is used by DD to simulate large systems with high dislocation and defect densities.
Actinide Science with a Soft X-ray Scanning Transmission X-ray Microscope (STXM)
Authors: Glans Per-Anders , Szigethy Geza , Demoin Dustin , Tyliszczak Tolek , Xu Jide , Guo Jinghua , Raymond Kenneth N. , Shuh David K. 
Published: August 2010

AbstractSoft x-ray scanning transmission x-ray microscope (STXM) spectromicroscopy has been developed and employed to investigate several aspects of actinide chemistry and materials science at the Advanced Light Source Molecular Environmental Science (ALS-MES) Beamline 11.0.2 STXM end station. The basic approach and fundamentals of STXM experiments for radioactive materials systems is discussed. Representative results from STXM spectromicroscopy investigations of a mixed phase uranium nitride, single crystals of Eu(III)[TREN(Me-3,2-HOPO)]32H2O and hydrated Pu2(III)(C2O4)3(6H2O) 3H2O complexes are presented. The STXM images and soft x-ray absorption spectra illustrate the capabilities and utility of soft x-ray STXM for providing information about actinide materials, especially the light element constituents. Lastly, new and future opportunities for actinide science utilizing soft x-ray STXM are discussed in light of the planned upgrades for the STXM end stations at the ALS.
Nuclear Fuels – Present and Future
Authors: Olander Donald 
Published: August 2010

AbstractThe important developments in new nuclear fuels are reviewed and compared with the status of present light-water reactor fuels. The limitations of LWR fuels are reviewed with respect to important recent concerns, namely provision of outlet coolant temperatures high enough for use in H2 production, destruction of plutonium to eliminate proliferation concerns, and burning of the minor actinides to reduce the waste repository heat load and long-term radiation hazard. In addition to current oxide-based fuel-rod designs, the hydride fuel with liquid metal thermal bonding of the fuel-cladding gap is covered. Finally, two of the most promising Generation IV reactor concepts, the Very High Temperature Reactor(VHTR) and the Sodium Fast Reactor (SFR) , and the accompanying reprocessing technologies, aqueous-based UREX+1a for the VHTR and pyrometallurgical for the SFR, are summarized.
Electronic Properties of ζ-U-Pu Alloys
Authors: Havela Ladislav , Adamska Anna , Eloirdi Rachel , Colineau Eric , Griveau Jean-Christophe , Gouder Thomas , Huber Frank , Bouexière Daniel , Shick Alexander 
Published: August 2010

AbstractThe ζ-phase, existing between 35 and 70% U in Pu, belongs to the high density phases seen from the point of view of systematics of allotropic modifications of Pu metal. Despite the volume per actinide atom only slightly higher than for α-Pu, it magnetic susceptibility is much higher than for α-Pu and exceeds even the δ-Pu value. Similarly, the Sommerfeld coefficient γ > 40 mJ/mol Pu K2 exceeds the experimental δ-Pu value. The data confirm that the volume is not the primary control parameter affecting the situation around the Fermi level of common Pu phases and they point against the traditional belief that they are essentially narrow 5f band systems.
Capture and Sequestration of Radioactive Iodine
Authors: Westphal Brian , Cummings Daniel G. , Giglio Jeff J. , Wahlquist Dennis L. , Bateman Ken J. , McCartin William M. , Park Jang J. , Shin Jin M. , Begg Bruce D. 
Published: August 2010

AbstractTrapping experiments have been performed at the Idaho National Laboratory to assess the performance of AgX sorbent media in capturing volatile iodine during the oxidation of irradiated oxide fuel. The demonstration of iodine release and capture from the used fuel has been accomplished with laboratory-scale equipment in a hot cell environment. Iodine loadings as high as 6 ug/g media have been achieved via chemical adsorption with filter efficiencies in excess of 90%. In addition to iodine, significant quantities of tritium have also been collected on the AgX filter media. Filter media loaded with radioactive iodine has been sequestered in a tin matrix by hot isostatic pressing at 200°C. The placement and encapsulation of the sorbent media was examined by neutron radiography, thus confirming the sequestration of radioactive iodine.
Characterization of the Penetration Mechanisms of Water into Polycrystalline UO2
Authors: Marchetti Ilaria , Belloni Fabio , Himbert Jerome , Carbol Paul , Fanghänel Thomas 
Published: August 2010

AbstractFollowing containment failure in the scenario of geological disposal of spent nuclear fuel, the penetration rate of groundwater into the UO2 matrix could cause a rapid increase of the fraction of inventory becoming available for prompt dissolution. In this respect, oxygen and water diffusion mechanisms are key issues to investigate. In this work, secondary-ion-mass-spectrometry (SIMS) depth profiling has been applied to characterize a polycrystalline UO2 pellet exposed to 18O-labelled water at room temperature. 18O depth profiling up to 25 μm beneath the pellet surface clearly indicates a combination of oxygen diffusion into the UO2 lattice and water diffusion along grain boundaries, behaving as high diffusivity paths. The lattice diffusion coefficient of oxygen, DL, and the quantity δDB – product of the grain boundary width, δ, and the grain boundary diffusion coefficient of water, DB – have been measured, resulting in DL = (2.5 ± 0.1) × 10-24 m2 s-1 and δDB = (7.5 ± 0.3) × 10-24 m3 s-1.
Structure and alteration kinetics of rare-earth rich borosilicate glasses with (64 – 2x) SiO2 / 18 B2O3 / 18 Na2O / x RE2O3 composition (RE = Y or Eu+ La)
Authors: Majerus Odile , Caurant Daniel , Li Ning , Baudouin Jean-Baptiste , Manolescu Gabriela , Barboux Philippe , Charpentier Thibault , de Ligny Dominique 
Published: August 2010

AbstractThe high level nuclear waste load is likely to increase in the future containment glasses, rising new questions about their long-term chemical durability. In this study sodium borosilicate compositions with Si substituted for RE (RE = rare earth) are altered under static conditions at fixed pH (8.5). The Na and B leached fractions reached just after the rate drop increase with the RE2O3 content. Part of the RE ions remain in the altered layer which is significantly de-polymerised (IR-ATR and NMR results). Their environment is reorganized and adopts a more centrosymetrical character. The higher leached fractions are attributed to rapid hydrolysis of Si/B-O-RE bonds with respect to Si-O-Si bonds.
Nanocrystalline silicon compacted by spark-plasma sintering: Microstructure and thermoelectric properties
Authors: Schierning Gabi , Claudio Tania , Theissmann Ralf , Stein Niklas , Petermann Nils , Becker Andre , Denker Joachim , Wiggers Hartmut , Hermann Raphael T. , Schmechel Roland 
Published: August 2010

AbstractNanocrystalline bulk silicon samples were fabricated using silicon nanoparticles from the gas phase, applying a spark-plasma sintering process. The mean diameter of the crystalline grains after sintering was 30 nm and smaller, the density above 97 % of that of crystalline silicon. Transmission electron microscopy showed a homogenous nanostructure. The thermal conductivity of such an n-type sample with a nominal doping level of 5×1020 cm-3 was around 11 Wm-1K-1 at room temperature. With Seebeck-coefficient α = -150 μV/K and specific conductivity σ = 290 S cm-1, the resulting efficiency ZT is approximately 0.02.
Performance Optimization of a TE Generator Element With Linear Material Profiles in a 1D Scheme
Authors: Zabrocki Knud , Seifert Wolfgang , Mueller Eckhard 
Published: August 2010

AbstractThermoelectric (TE) effects as a coupling between heat and charge transfer can be described on a classical level in the framework of the Onsager theory. Under isotropic and steady state conditions the conservation equations can be combined to obtain a thermal energy balance containing the temperature distribution as target function. Besides the temperature the balance equation contains material properties represented by the Seebeck coefficient S, the electrical and thermal conductivities σ and κ, respectively. For the sake of simplicity, a 1D scheme has been chosen for the analytical and numerical treatment. Performance investigations are often done within the framework of the Constant Properties Model (CPM) or based on temperature dependent material properties. In the 1D steady state, there is an alternative approach available based on spatial material profiles. Following the approach by Müller and co-workers, the temperature profile T(x) is calculated numerically within a model-free setup directly from the 1D thermal energy balance, e.g., based on continuous monotonous gradient functions for all material profiles, and independent and free variability of the material parameters S(x), σ(x), and κ(x) is assumed initially. Doing so, the optimum electrical current density can be determined from the maximum of the global performance parameter (power output P or efficiency η). We present analytical results for the performance optimization calculating P and η with linear material profiles for S(x), a constant electrical and thermal conductivity, fixed TE element length L and fixed boundary temperatures.
Thermoelectric Properties of Non-equilibrium Synthesized Ce0.9Fe3CoSb12 Filled Skutterudites
Authors: Jie Qing , Zhou Juan , Dimitrov Ivo K. , Li Chang-Peng , Uher Ctirad , Wang Hsin , Porter Wallace D. , Li Qiang 
Published: August 2010

AbstractWe report on the thermoelectric properties of the filled skutterudite Ce0.9Fe3CoSb12 prepared via non-equilibrium synthesis method. Melt-spun ribbons were directly converting into single phase polycrystalline pellets under pressure. For comparison, pellets with the same composition were also prepared using the conventional solid-state reaction followed by long term annealing. It was found that the non-equilibrium synthesized samples have higher power factors and lower thermal conductivity, leading to substantially higher figure of merit.
Synthesis and Thermoelectric Properties of Doped Yb14MnSb11-xBix Zintls
Authors: Star Kurt , Zevalkink Alex , Huang Chen-Kuo , Dunn Bruce , Fleurial Jean-Pierre 
Published: August 2010

AbstractYb14MnSb11 is a very promising thermoelectric material for high temperature applications. This compound is a member of a large family of Zintl phases with a “14-1-11” A14MPn11 stoichiometry (Pn = P, As, Sb, Bi; A = Ca, Ba, La, Sr, Yb, Eu; M = Mn, Al, Cd, Ga, In, Nb, Zn). Yb14MnSb11 exhibits low lattice thermal conductivity values and a p-type semimetallic behavior with values of the non-dimensional figure of merit zT peaking at 1.4 above 1200 K. There is significant interest in investigating how substitutions on any of the atomic sites impact the charge carrier concentration and mobility, band gap and lattice thermal conductivity. Recent reports have studied substitutions on the Yb and Mn sites with the goal of reducing hole carrier concentration and improving carrier mobility values.High energy ball milling has been shown to be a convenient method of synthesis to prepare Yb14MnSb11 and it has been used here to explore the solid solution systems derived from this compound by substituting Sb with Bi. High energy ball milling is a non-equilibrium process and not all of the 14-1-11 compounds are easily formed with this method. Characterization of the synthesized compositions was done by X-ray diffraction, electron microprobe, and high temperature measurements of the electrical and thermal transport properties up to 1275 K. The experimental results on undoped and doped solid solution samples are compared to that of pure Yb14MnSb11 samples prepared by the same high energy ball milling technique.
Effects of MeV Si Ions Modification on the Thermoelectric Properties of SiO2/SiO2+Cu Multilayer Thin Films
Authors: Chacha John , Budak S. , Smith Cydale , Pugh Marcus , Ogbara Kudus , Heidary Kaveh , Johnson R. B. , Muntele Claudiu , ILA D. 
Published: August 2010

AbstractThe performance of the thermoelectric materials and devices is shown by a dimensionless figure of merit, ZT = S2σT/K, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature and K is the thermal conductivity. ZT can be increased by increasing S, increasing σ, or decreasing K. We have prepared 100 alternating multi-nano layer of SiO2/SiO2+Cu superlattice films using the ion beam assisted deposition (IBAD). The 5 MeV Si ions bombardments have been performed at the different fluences using the AAMU Pelletron ion beam accelerator to make quantum clusters in the multi-layer superlattice thin films to decrease the cross plane thermal conductivity increase the cross plane Seebeck coefficient and cross plane electrical conductivity. To characterize the thermoelectric thin films before and after Si ion bombardments we have measured the cross-plane Seebeck coefficient, the cross-plane electrical conductivity, and the cross-plane thermal conductivity for different fluences.
The Role of Nanoparticle Inclusions on High-performance half-Heusler Thermoelectric Materials
Authors: Yaqub Rumana , Sahoo Paranti Sahoo , Makongo Julien Pierre , Notling Westly M , Poudeu Pierre F. P. , Stokes Kevin L. 
Published: August 2010

AbstractWe report the effect of adding NiO nanoparticles on the transport properties of the half-Heusler alloys Zr0.5Hf0.5Ni1-xPdxSn0.99Sb0.01 (x=0, and 0.2). The half-Heusler matrix materials are prepared by traditional powder metallurgy methods. The resulting bulk matrix is mixed with different volume fractions of nanometer-sized NiO particles, previously synthesized by solution-phase chemical methods. The resulting mixture is densified under uniaxial pressure to form a composite. The resulting material is found to contain both half-Heusler and full-Heusler phases. The corresponding compounds have higher thermal conductivity and electron mobility.
Improvements of Thermoelectric Performances in AgSbTe2 System With in-situ Ag2Te Nano-Precipitations
Authors: Zhang Shengnan , Yang Shenghui , Jiang Guangyu , Shen Junjie , Zhu Tiejun , Zhao Xinbing 
Published: August 2010

AbstractAgSbTe2 is the critical component in both LAST-m and TAGS-x system, which are two state-of-the-art mid-temperature thermoelectric bulk nanocomposites. By adjusting the Ag2Te/Sb2Te3 ratio, Sb2Te3 and Ag2Te precipitated samples were obtained with x = 0.68 to 0.74 and x = 0.84 to 0.90 (x as in (Ag2Te)x/2(Sb2Te3)1-x/2), respectively. The single phased AgSbTe2 was obtained with the x value of 0.78 and 0.81, which is consistent of the previous results on the phase diagram of (Ag2Te)x(Sb2Te3)1-x system. Comparing the effect of the two different precipitates, Ag2Te are much effective for the improvements of thermoelectric properties in AgSbTe2 nanocomposites. Utilizing the high-resolution transmission electron microscopy, Ag2Te was observed as nanodots and nano-lamellae embedded in the AgSbTe2 matrix, which can be related to the energy filtering effect for the increase of Seebeck coefficient. The relationship among the composition, microstructure and thermoelectric properties was systematically studied. It can be noticed that the thermoelectric properties of AgSbTe2 system are very sensitive to the composition, especially at low temperature. The maximum figure of merit ZT value of 1.53 was obtained at 500 K for Ag0.84Sb1.16Te2.16 with 40% increase comparing with the single phased sample.
Spinodal Decomposition in Off-stoichiometric Zr0.5Hf0.5Co1-yIrySb1-zSnz half-Heusler Phases
Authors: Takas Nathan J. , Misra Dinesh , Gabrisch Heike , Poudeu Pierre F. P. 
Published: August 2010

AbstractThe formation of nanostructures within the matrix of half-Heusler thermoelectric materials can be produced by spinodal decomposition of off-stoichiometric compositions. CoSb is insoluble at high temperatures in Zr0.5Hf0.5Co1-yIrySb1-zSnz half-Heusler phases. This phase can be solubilized into the half-Heusler matrix by the use of high energy ball milling at room temperature as the synthetic method of choice. The metastable half-Heusler material decomposes in-situ while hot-pressing the powder sample into a compact pellet. Despite the fact that the thermal conductivity of the inclusion material, CoSb, is very large, (>35W/m•K), we observed reduction in the lattice thermal conductivity of the composite material. Furthermore, the electrical resistivity of the specimen was also reduced due to the metallic nature of the CoSb inclusion phase. Addition of a large fraction of the metallic inclusion leads to a percolation network of the metallic phase, thus reducing the Seebeck coefficient of the composites. Electron microscopy is carried out in order to examine boundaries between the two. Changes in the thermoelectric properties of Zr0.5Hf0.5Co1-yIrySb1-zSnz half-Heusler matrix with increasing mass percent of CoSb inclusion will be discussed.
Thermoelectric Properties of Zr0.5Hf0.5Ni0.8Pd0.2Sn0.99Sb0.01 half-Heusler Alloy with WO3 Inclusions
Authors: Makongo Mangan Julien Pierre Amelie , Paudel Pravin , Misra Dinesh , Poudeu Pierre F. P. 
Published: August 2010

AbstractZr0.5Hf0.5Ni0.8Pd0.2Sn0.99Sb0.01 composites with various concentrations of WO3 inclusions were synthesized by mechanical alloying using high energy shaker mill. High density hot pressed pellets of the synthesized materials were characterized using powder X-ray diffraction and transmission electron microscopy and their thermoelectric properties were investigated in the temperature range from 300 to 750 K. The electrical conductivity of the composites at 300 K decreases from 2500 S/cm for 0 wt.% WO3 alloy to 2200 S/cm for the composite with 2 wt.% WO3 inclusion. The electrical conductivity of composites containing 5 wt.% and 10 wt.% WO3 inclusions showed sharp increases with increasing WO3 content. The electrical conductivity of the composites monotonically decreases with rising temperature. All samples showed n-type semiconducting behavior and the thermopower values decrease with increasing WO3 content. The lattice thermal conductivity of the composites increases with increasing WO3 content. However, these values are about 30% lower than that of Zr0.5Hf0.5Ni0.8Pd0.2Sn0.99Sb0.01 alloy prepared by high temperature solid-state techniques. The synthesized composites showed lower figure of merit than the half-Heusler matrix due to large reduction in the thermopower values with increasing WO3 content.
Study of Nanostructure Inclusion Effects on the Thermoelectric Behavior of Ca3Co4O9 Thin Films Grown by Pulsed Laser Deposition
Authors: Thomas Evan Lyle , Song Xueyan , Yan Yonggao , Martin Joshua , Wong-Ng Winnie , Ratcliff Margaret , Barnes Paul N. 
Published: August 2010

AbstractThe influence of incorporating nanoparticulate additions into Ca3Co4O9 (CCO) thin films prepared by pulsed laser deposition using composite targets of CCO and CCO + 3wt% BaZrO3 (BZO) on Si and LaAlO3 substrates is investigated. X-ray data and high-resolution scanning electron microscopy reveal preferred c-axis orientation of the films deposited on Si substrates with the formation of nanoparticles between ∼ 10 – 50 nm. Preliminary thermoelectric behavior shows an enhancement of the power factor α2/ρ at room temperature. The microstructure and thermoelectric behavior of the CCO films are compared to the BZO-doped films.
Synthesis of Optimized CZTS Thin Films for Photovoltaic Absorber Layers by Sputtering from Sulfide Targets and Sulfurization
Authors: Nukala Haritha , Johnson Jeffrey L. , Bhatia Ashish , Lund Elizabeth A , Oo W.M Hlaing , Rieth Loren W , Nowell Matt , Scarpulla Michael A 
Published: August 2010

AbstractCu2ZnSnS4 (CZTS) is a promising alternative for Cu(In,Ga)Se2 (CIGS) absorber layers in thin film solar cells and is comprised of commodity elements which will enable scale-up of chalcopyrite panel production unhindered by elemental supplies and costs. Various CZTS synthesis methods, especially sulfurization of stacked metal or metal sulfide layers, are being studied and have led to cell efficiencies up to 6.7% [1]. Here we report our studies of CZTS thin film synthesis via room temperature sputtering from a single CZTS target and co-sputtering from Cu2S, ZnS and SnS2 binary targets, both followed by sulfurization between 500 C - 600 C using either elemental sulfur vapor or in-situ generated H2S. Sputtering from sulfur-containing targets is designed to increase the sulfur content in the precursor films to promote stoichiometry. We report on the effects of processing including deposition on soda-lime and borosilicate glasses and deposition of Na-containing layers on film morphology (AFM/SEM), composition (EDS), phase (XRD), grain size (XRD/EBSD), grain boundary structure (EBSD), optical (spectroscopic ellipsometry) and electrical properties. Processing conditions producing desirable Zn-rich/Cu-poor films are identified [1]. The formation of MoSe2 at Mo/CIGS interface is believed to promote Ohmic contacts, but in CZTS we associate excessive formation of frangible MoS2 with film delamination from Mo/borosilicate glass substrates. Strategies for preventing delamination including adhesion layers are investigated and discussed. P-N junctions are formed with CdS/ZnO using chemical bath deposition and sputtering, and I-V characteristics are reported. Schottky junctions are formed and C-V measurements are used to determine the doping in the CZTS absorber layers.[1] H. Katagiri, et al., MRS Symp. Proc. 1165 1165-M04-01 (2009).
Hot Embossing of Microfluidic Channel Structures in Cyclic Olefin Copolymers
Authors: Leech Patrick William , Zhang Xiaoqing , Zhu Yonggang 
Published: August 2010

AbstractThe dynamic mechanical behaviour of a series of cyclic olefin copolymers (COCs) with varying norbornene content has been examined in the vicinity of the glass transition temperature, Tg. The temperature of the transition has been shown to increase linearly with increase in norbornene content. Measurements of both the elastic storage modulus, E′, and loss modulus, E″, have decreased exponentially with rise in temperature above Tg . A levelling-off in E″ occurred at >20 °C above Tg for all copolymers. The results of Dynamic Mechanical Thermal Analysis (DMTA) have been used in the identification of optimum conditions for hot embossing. At >20 °C above Tg in a region of viscous liquid flow, the hot embossing of COC has resulted in a full replication of channel depth without cracking or distortion.