bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solid Micro-Beads Hetero-Structure Fuel for Ultra-high Temperature Applications
Authors: Popa-Simil Liviu , Vasilescu Gabriel 
Published: June 2019

AbstractHigher conversion efficiencies require high operation temperatures that are difficult to obtain due to the actual thermo-physical properties of the nuclear fuels. The initial intrinsic thermal conductivity of the actual fuel pellets, mainly ceramics like structures (oxides, nitrides, carbides, MOX, beads) is low. The center of the pellet is near melting temperature while the cladding operation temperature has to be low. The fission products deposition and burnup effects are further dimming the thermal conductivity. More the cooling agent's chemical reactivity increases with temperature is another main reasons of keeping the operation temperature low. The usage of a hetero-structure of solid fuel soaked into a drain fluid is increasing the thermal conductivity. Properly shaped beads structure drives to the possibility of preventing most of the fission products of being stored inside the fuel lattice deteriorating its properties, being drained outside the nuclear reactor. This changes inspired from the nature, makes the nuclear reactor resembling with a plant having self cleaning and curing properties while operating at higher temperatures. Immersing the fuel into liquid metal higher operation temperatures are allowed due to increase in thermal conductivity by 3 to 20 times. Making the fuel beads shorter than the range of fission products, their trajectories end in the drain liquid that is tolerant to nuclear recoils damage. Due to better thermal conductivity the temperature field differences inside the nuclear reactor becomes smaller, allowing the operating temperature to rise significantly without safety concerns. There is possible to continuously remove the fission products by smoothly circulating the drain liquid. The low flow is needed to give time to short lives fission products to decay inside the reactor highly shielded volume. There are several fissionable materials and drain liquids matching which assure high operation temperatures, and allow He cooling, and high temperatures gas turbines cycles. The conversion efficiency might be higher than 70% depending on the chosen actinide / drain-liquid / cooling-liquid combination. The new concept on fission products continuous release and separation minimizes the waste and the total radioactivity stored inside the reactor to few weeks integrated operation amount remaining constant over the time. That makes the fuel's remnant radioactivity lower by a factor >100 than the actual reactors level. The fuel reactivity might be controlled by poisoning and transmutation or by assuring specific reactive geometries which to allow a ultrahigh burnup without the need of over-criticality loads. The fuel's deformability opens the way for interesting applications. The advantages of micro structured nuclear fuel are higher thermal conductivity, fission products removal, appropriate reactivity, higher efficiencies and longer fuel life.
Chemically Enhanced Focused Ion Beam Selective Patterning of Titanium, Titanium Oxide and Nitride Thin Films
Authors: Stanishevsky Andrei , Melngailis John 
Published: June 2019

AbstractFocused ion beams (FIBs) provide maskless prototyping of 2-D and 3-D micro- and nano-structures for many applications in optics, electronics, and medicine. In many situations, the chemical enhancement of the FIB sputtering process is used to increase the selectivity and removal rate of different materials.In this study, Ti, TiO2, and TiN thin films of different origin were patterned using Ga+ FIB without or with chemical enhancement (or gas assisted etching, GAE). The effects of ion beam parameters and gas ambient on the sputtering yields, etching selectivity, roughening at the film/substrate interface, sub-micron and nano-scale patterning of these materials were investigated.Several gases, including XeF2, CO2, chlorine, bromine, and oxygen, were employed. The largest increase of the sputtering yield was achieved with XeF2 gas, whereas CO2 and oxygen depleted the sputtering rate. Among all gases tested, the Br2 FIB GAE produced the best uniformity of the material removal. It was found that the use of bromine gas provides the best selectivity between the titanium oxide and pure titanium or its nitride.
Focused Ion Beam Techniques for Butterfly Wing Scales Analysis and 3-D Reconstruction
Authors: Dovidenko Katharine , Le Tarte Laurie A. , Potyrailo Radislav A. 
Published: June 2019

AbstractWe have developed and successfully demonstrated a protocol for mounting and electrical grounding of a butterfly wing scale using a series of localized electron- and ion-beam assisted Pt depositions in the dual-beam Focused Ion Beam (FIB)-SEM system. This method eliminates introduction of silver paint or other typical mounting materials, along with their chemistries, and produces a stable structure for FIB cross-sectioning, electron imaging, chemical analysis by Energy Dispersive Spectrometry (EDS) and/or Auger Electron Spectroscopy (AES), and FIB milling for 3-D reconstruction.
Investigation of Cell-Sensor Hybrid Structures by Focused Ion Beam (FIB) Technology
Authors: Heilmann Andreas , Altmann Frank , Cismak Andreas , Baumann Werner , Lehmann Mirko 
Published: June 2019

AbstractFor the investigation of the adhesion of mammalian cells on a semiconductor biosensor structure, nerve cells on silicon neurochips were prepared for scanning electron microscopy investigations (SEM) and cross-sectional preparation by focused ion beam technology (FIB). The cross-sectional pattern demonstrates the focal adhesion points of the nerve cells on the chip. Finally, SEM micrographs were taken parallel to the FIB ablation to investigate the cross section of the cells slice by slice in order to demonstrate the spatial distribution of focal contact positions for a possible three-dimensional reconstruction of the cell-silicon interface.
Focused Ion Beam Study of Ni5Al Single Splat Microstructure
Authors: Wu Yuhong , Qu Meng , Giannuzzi Lucille A , Sampath Sanjay , Gouldstone Andrew 
Published: June 2019

AbstractThermally sprayed (TS) coatings are widely used for surface engineering across a range of industries, including aerospace, infrastructure and biomedical. TS materials are formed via the successive impingement, rapid quenching and build-up of molten powder particles on a substrate. The impacted ‘splats’ are thus the fundamental microstructural constituents of the coatings, and their intrinsic properties, as well as intersplat bonding and morphology, dictate coating behavior. Beyond the obvious practical considerations, from a scientific standpoint, splats represent a fascinating template for study, due to the highly non-equilibrium processing conditions (rapid deceleration from sub-sonic velocities, million-degree/sec cooling rates). In the literature, many studies of isolated splats on substrates have been carried out, but these have focused on overall morphology (disc-shape vs fragmented). Direct observations of microstructure, in particular cross-section, are limited in the specimen preparation stage due to splat size (tens of microns in diameter, 1-2 microns in thickness). However, Focused Ion Beam (FIB) techniques have allowed this problem to be addressed in a robust manner; in this paper we will discuss such approaches to observe Ni5Al splats on stainless steel substrates. Cross-sections through the splat and the substrate were created by recourse to ion milling and the ion beam itself provided good channeling contrast for grain imaging. The typical splat microstructure with sub-micron Ni(Al) columnar grains, a chill zone at the bottom and a lift off area is observed in high detail. In addition, an amorphous aluminum oxide top layer of 100-200 nm is partially present on top of the Ni(Al) columnar grains. At the splat/substrate interface, defects such as micro- and nano-scale pores were characterized for the first time and will be discussed. These observations provide insights into splat and interface formation during the deposition process and may drastically improve our current understanding of Ni5Al splat properties.
Electronic Structure Theory of the Ground State and Photoemission Spectra of Non-Magnetic δ-Pu, fcc-Am, and Pu-Am Alloys
Authors: Shick Alexander , Havela Ladislav , Kolorenc Jindrich , Drchal Vaclav 
Published: June 2019

AbstractThe around-the-mean-field version of the LDA+U correlated band theory is applied to investigate the electronic and magnetic structure of δ-Pu, Am, their alloys and compounds. It gives correct non-magnetic ground state for Pu and Am, and provides a good agreement with experimental equilibrium volumes and bulk moduli. For Pu-Am alloys, despite a lattice expansion caused by the Am atoms, neither tendency to 5f localization nor formation of local
Fermi surface properties of PuIn3
Authors: Haga Yoshinori , Aoki Dai , Matsuda Tatsuma D , Yamagami Hiroshi , Homma Yoshiya , Shiokawa Yoshinobu , Nakajima Kunihisa , Arai Yasuo , Yamamoto Etsuji , Nakamura Akio , Onuki Yoshichika 
Published: June 2019

AbstractWe report Fermi surface and magnetic properties of a cubic PuIn3 grown by the indium flux method. Fermi surfaces detected by the de Haas-van Alphen effect can be well explained by the band calculations assuming itinerant 5f electrons.
Specific Heat in the Pu-Am system
Authors: Havela Ladislav , Javorský Pavel , Shick Alexander , Wastin Franck , Colineau Eric 
Published: June 2019

AbstractSpecific heat of Pu doped with Am was studied for several Am concentrations (8-20%) ensuring the δ-Pu fcc structure. The results reveal that the γ value of the low temperature specific heat is lower than originally assumed (γ of 35 - 55 mJ/mol K2 can be deduced for Pu-8%Am) and does not increase with the Am-induced lattice expansion. The findings can be taken as an indication of the absence of the Pu-5f states at the Fermi level.
Changes in Delta-Plutonium Due to Aging as Observed by Continuous in-situ X-Ray Scattering
Authors: Saw Cheng K , Wall Mark A. , Chung Brandon W. 
Published: June 2019

AbstractThe aging in plutonium is predominantly caused by its internal self irradiation. The self-irradiation in Pu-239 is by the decay process of transmuting the Pu atom into uranium atom and emitting an α-particle. Most of the lattice damage comes from the uranium recoil resulting in Frenkel type defects consisting of vacancies and self-interstitial atoms, helium in growth and defect clusters and possibly even though it is not yet observed, the generation of voids. As part of the stockpile stewardship, it is important to understand the changes in the structure and microstructures and their correlations to the physical properties. Changes in the physical properties has direct relationship to the quality of the structure, in terms of formation of defects and defect clustering, accumulation of voids, grain boundaries, phase changes and etc. which can adversely affects the stability of the material. These changes are very difficult to monitor because of the high activity of the sample, high atomic number making x-ray and synchrotron probe into the bulk very difficult (neutron probe is not feasible) and the long life time which normally requires decades to measure. In this paper we describe the development of an in-situ in-house transmission x-ray diffraction (XRD) experimental technique used to monitor the structural changes in these materials. This technique calls for a very thin sample of less that 2 μm and to accelerate the aging process due to self-irradiation, spiked alloy of 7.5 weight percent of Pu-238 is used. This is equivalent to roughly 17 times the normal rate of aging. Current results suggest that over a period of 2.8 equivalent years, an increase of 0.5% in unit cell parameter is observed. The increase appears to be an abrupt jump at about 1.1 equivalent years, brought about by the collapsing of the atoms from the interstitials to the lattice sites. Further data analysis is on the way.
Identifying and Quantifying Actinide Radiation Damage in Ceramics with Radiological Magic-Angle Spinning Nuclear Magnetic Resonance
Authors: Farnan Ian , Cho Herman , Weber William J. 
Published: June 2019

AbstractIn the characterisation of amorphisation or local disordering due to actinide radiation damage, nuclear magnetic resonance (NMR) spectroscopy is attractive because it is element specific and equally sensitive to local structure in crystalline and amorphous materials. Here, we have applied high-resolution solid-state NMR spectroscopy (magic-angle spinning) to radiation damaged natural minerals containing 238U/232Th to determine the ‘number fraction’ of amorphous material (fa) through spin-counting techniques. In samples with a known alpha dose, the number of atoms displaced per alpha decay may be determined from an integration of the spectrum. A protocol for performing similar radiological magic-angle spinning experiments on plutonium containing ceramic samples with an activity of > 5 GBq isp described. Results obtained have allowed data from ancient, radiation damaged mineral samples of ZrSiO4 (238U/232Th) to be compared with modern 238/239Pu doped ceramic ZrSiO4 samples. The number of atomic displacements per alpha particle from 239Pu is similar to that for 238U/232Th (4980 ± 300/α). At lower ?-doses there are significant differences in the amorphous volume fraction (observed by density and x-ray diffraction) and the number fraction of displaced atoms (as measured by NMR) as a function of cumulative dose. These differences arise from local density considerations that manifest themselves in the local structure of the amorphous and crystalline phases. Using ab initio simulations of the damaged crystalline and amorphous regions, the magnetic response of these structures and hence the NMR shifts can be compared with experiment to reveal the nature of radiation induced changes occurring at the local scale.
Solution-Processed Oxide Films, Devices, and Integrated Circuits
Authors: Anderson Jeremy T , Keszler Douglas A. , Meyers Stephen T , Chiang Hai Q , Hong David , Presley Rick E , Wager John F 
Published: June 2019

AbstractA distinct class of precursor chemistries has been developed for solution-phase deposition of oxide thin films. Rapid liquid-to-solid conversions are facilitated by using high nuclearity species and labile inorganic ligands to promote fast condensation reactions. Consequently, applied deposition strategies differ from conventional sol-gel and surface mediated growth reactions. Select oxide materials have been incorporated in transistor devices and circuits as evidence of thin-film quality and proof of function.
Photoluminescence Spectral Change in Self-Assembled Layered Titanate Oxide Intercalated with Eu3+
Authors: Ida Shintaro , Unal Ugur , Izawa Kazuyoshi , Ogata Chikako , Matsumoto Yasumichi 
Published: June 2019

AbstractTitanate layered oxide intercalated with hydrated Eu3+ was synthesized by the electrostatic self-assembly deposition (ESD) method. The emission intensity of Eu3+ decreased rapidly with time during irradiation by UV light having energy higher than the band gap energy of the host Ti1.81O4 (TiO) layer. This is presumably due to the decrease in energy transfer from the host TiO layer to Eu3+ as a result of the change in the hydration state of water molecules surrounding Eu3+, which is caused by the hole produced in the TiO valence band. When irradiation was discontinued, the emission intensity gradually recovered. The recovery time increased when the water in the interlayer is removed by heat treatment. This indicates that the state of interlayer water changes during irradiation and returns to its initial state after discontinuation of irradiation. The excitation spectra changed drastically at any given wavelength upon irradiation with UV light. A comparison of the excitation spectra before and after irradiation reveals that only the excitation peak at around the irradiation wavelength decreased upon irradiation, as in the case of spectral hole burning. The hydration state of water molecules surrounding Eu3+ presumably changes depending on the irradiation wavelength.
Crystal and Magnetic Structures of High Pressure Perovskite-Type Oxyfluorides,PbFeO2F and 0.5PbFeO2F-0.5PbTiO3 [Pb(Fe0.5Ti0.5)O2.5F0.5]
Authors: Katsumata Tetsuhiro , Takase Akihiro , Yoshida Masashi , Inaguma Yoshiyuki , Greedan John E. , Barbier Jacques , Cranswick Lachlan M. D. , Bieringer Mario 
Published: June 2019

AbstractThe perovskites PbFeO2F and 0.5PbFeO2F-0.5PbTiO3 were synthesized at high temperatures (1000°C) and high pressures (4 – 6 GPa). The crystal and magnetic structures were determined using powder neutron diffraction. Quenched PbFeO2F has the cubic perovskite-type, Pm3m, structure in which the Pb ion shifts from ideal A-site along the <110> directions, which is in good accordance with a previous report. The magnetic structure is antiferromagnetic G-type with propagation vector k = (1/2 1/2 1/2) and an Fe3+ ordered moment of 3.83 μB at 283K. The Néel temperature is 655(5) K. Annealed PbFeO2F has a tetragonal perovskite-type structure at room temperature and transforms reversibly from tetragonal to cubic at approximately 470 K. A superlattice with dimensions a × a × 5c is observed both in electron and x-ray diffraction. The solid solution 0.5PbFeO2F-0.5PbTiO3 belongs to the non-centrosymmetric space group P4mm. The magnetic structure is G-type antiferromagnetic and shows a weak ferromagnetic moment at 4 K. Consequently, 0.5PbFeO2F-0.5PbTiO3 is simultaneously ferroelectric and a weak ferromagnet at low temperature. The Néel temperature is 450 K but the temperature dependence of the ordered Fe moment is anomalous.
Nanocrystalline Doped Ceria-Zirconia Fluorite-Like Solid Solutions Promoted by Pt: Structure, Surface Properties and Catalytic Performance in Syngas Generation
Authors: Sadykov Vladislav A , Mezentseva Natalia , Alikina Galina , Lukashevich Anton , Muzykantov Vitalii , Kuznetsova Tatiana , Batuev Lubsan , Fedotov Martin , Moroz Ella , Zyuzin Dmitrii , Kolko Vera , Kriventsov Vladimir , Ivanov Vyacheslav , Boronin Andrei , Pazhetnov Egor , Zaikovskii Vladimir , Ishchenko Arcady , Rogov Vladimir , Ross Julian , Kemnitz Erhard 
Published: June 2019

AbstractNanocrystalline ceria-zirconia samples doped with rare-earth (Gd, Pr, Sm, La) cations were prepared via modified Pechini route. Effect of their real structure and surface composition characterized by a combination of sophisticated physical methods (XRD, TEM +EDX, EXAFS, WAXS, UV-Vis, XPS, SIMS) on the mobility and reactivity of the lattice oxygen estimated by oxygen isotope exchange, H2, CH4 and CO TPR was analyzed. For the reaction of acetone autothermal reforming into syngas, catalytic activity correlates rather well with the oxygen mobility controlled by the type and content of a dopant
Synthesis and Electrochemistry of Layered Double Hydroxide Thin Films by Layer-by-Layer Assembly Method
Authors: Unal Ugur , Altuntasoglu Ozge , Ida Shintaro , Matsumoto Yasumichi 
Published: June 2019

AbstractIn this study, we have investigated the synthesis of several Layered Double Hydroxides (LDHs), such as Ni-Ga, Mg-Ga and Ni-Al LDHs with hydrothermal method. Total metal content and ratio of the hydrolysis agent in the reaction solution have found to be determining factors for the crystallinity and morphology of LDH products. In addition, we were able to obtain highly crystalline LDHs in a relatively short reaction times, when the reaction was carried out under stirring at moderately higher temperatures.	Delamination of LDHs was carried out in formamide and delamination was confirmed by the images obtained from Atomic Force Microscope (AFM). The observed thickness of sheets was in agreement with the theoretical thickness of LDH layers. Delaminated single nanosize sheets were deposited on a substrate by Layer-by-Layer Assembly (LBL) method, which utilizes the electrostatic attraction principles between oppositely charged units. UV-vis spectroscopy of the films showed that deposition of intercalated LDH thin films with LBL was successfu. Electrochemical properties of the films were also investigated in this study. Cyclic voltammograms of the films revealed that LDH layers and intercalated species are electrochemically active. The redox peaks of Ni/Ni2+ couple were observed for Ni2+ containing LDHs in the region of -0.45 V vs Ag/AgCl.	In conclusion, we have demonstrated in this study that various LDH nanosize sheets can be intercalated with anionic species in a Layer-by-Layer deposition manner. In addition, LDH thin films prepared by LBL method showed electrochemical response.
Structure and Magnetism in the Kagome Antiferromagnet RBaCo4O7
Authors: Mitchell John F. , Zheng Hong , Huq Ashfia , Chapon Laurent C. , Radaelli Paolo G. , Stephens Peter W. 
Published: June 2019

AbstractThe mixed-valent compound RBaCo4O7 (R=Rare earth, Y), hereafter abbreviated as R-114, is built up of Kagomé sheets of CoO4 tetrahedra, linked in the third dimension by a triangular layer of CoO4 tetrahedra in an analogous fashion to that found in the known geometrically frustrated magnets such as pyrochlores and SrCr9xGa12-9xO19 (SCGO). We have undertaken a study of the structural and magnetic properties of the Y-114 and Yb-114 compound using combined high resolution powder neutron and synchrotron X-ray diffraction. Both compounds undergo a first order trigonal → orthorhombic phase transition that breaks the trigonal symmetry of the structure. We show from Bond Valence Sum arguments that this transition occurs as a response to a markedly underbonded Ba2+ site in the high-temperature phase. The symmetry-lowering transition relieves the geometric frustration of the structure, and a long-range ordered 3-D antiferromagnetic state develops at low temperature. The magnetic structure of the Y compound has been solved and shows a compromise between the well-known 120° structure of the Kagomé net and a collinear antiferromagnet in the third dimension
Structure and Electronic Properties of Silicon and Germanium Network Polyhedra
Authors: Tanigaki Katsumi , Rachi Takeshi , Kumashiro Ryotaro , Nishino Takuya , Narita Kiyotsugu , Komatsu Naoya 
Published: June 2019

AbstractClathrates of type I to type III are presented from the two points of views. The first one is intriguing electronic states appearing from the variation in phonons. The various phonons ranging from lattice phonons, intra-cluster phonons and atomic phonons are described in connection to the electronic states created via electron-phonon interactions. The other issue is the application to thermoelectric power materials on a basis of the concept of phonon-glass-electron-crystal (PGEC).
Thermoelectric Power in Ruthenates : Dominant Role of the Spin Degeneracy Term
Authors: Klein Yannick , Hébert Sylvie , Maignan Antoine , Hardy Vincent , Raveau Bernard , Dabrowski Bogdan , Tomes Petr , Hejtmanek Jiri 
Published: June 2019

AbstractThe Seebeck coefficients of several ruthenates which structures derive from the perovskite, have been measured up to 800K. All the values above 300K are found to be in the range +25μV.K-1 to +35 μV.K-1, with a very weak dependence on both T absolute value and electrical resistivity. This demonstrates that S at high T depends mainly on the spin degeneracy term of the modified Heikes formula. The insensitivity of thermopower to the chemical doping confirms the applicability of the model. The present study also shows the good properties of ruthenates as thermoelectric p-type oxides for high T energy conversion.