bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neutron Irradiation Resistance of RAFM Steels
Authors: Gaganidze Ermile , Dafferner Bernhard , Aktaa Jarir 
Published: June 2019

AbstractThe neutron irradiation resistance of the reduced-activation ferritic/martensitic (RAFM) steel EUROFER97 and international reference steels (F82H-mod, OPTIFER-Ia, GA3X and MANET-I) have been investigated after irradiation in the Petten High Flux Reactor up to 16.3 dpa at different irradiation temperatures (250-450 ¡ãC). The embrittlement behavior and hardening are investigated by instrumented Charpy-V tests with subsize specimens.Neutron irradiation-induced embrittlement and hardening of EUROFER97 was studied under different heat treatment conditions. Embrittlement and hardening of as-delivered EUROFER97 steel are comparable to those of reference steels. Heat treatment of EUROFER97 at a higher austenitizing temperature substantially improves the embrittlement behaviour at low irradiation temperatures. Analysis of embrittlement vs. hardening behavior of RAFM steels within a proper model in terms of the parameter C=DDBTT/Ds indicates hardening-dominated embrittlement at irradiation temperatures below 350 ¡ãC with 0.17 ¡Ü C ¡Ü 0.53 ¡ãC/MPa. Scattering of C at irradiation temperatures above 400 ¡ãC indicates non hardening embrittlement. A role of He in a process of embrittlement is investigated in EUROFER97 based steels, that are doped with different contents of natural B and the separated 10B-isotope (0.008-0.112 wt.%).Testing on small scale fracture mechanical specimens for determination of quasi-static fracture toughness will be also presented in a view of future irradiation campaigns.
Including the Effects of Electronic Excitations and Electron-Phonon Coupling in Cascade Simulations
Authors: Duffy Dorothy , Rutherford Alexis 
Published: June 2019

AbstractRadiation damage has traditionally been modeled using cascade simulations however such simulations generally neglect the effects of electron-ion interactions, which may be significant in high energy cascades. A model has been developed which includes the effects of electronic stopping and electron-phonon coupling in Molecular Dynamics simulations by means of an inhomogeneous Langevin thermostat. The energy lost by the atoms to electronic excitations is gained by the electronic system and the energy evolution of the electronic system is modeled by the heat diffusion equation. Energy is exchanged between the electronic system and the atoms in the Molecular Dynamics simulation by means of a Langevin thermostat, the temperature of which is the local electronic temperature. The model is applied to a 10 keV cascade simulation for Fe.
Ion Beam Lithography And Resist Processing for Nanofabrication
Authors: Arshak Khalil , Gilmartin Stephen F. , Collins Damien , Korostynska Olga , Arshak Arousian , Mihov Miroslav 
Published: June 2019

AbstractThe International Technology Roadmap for Semiconductors (ITRS) identifies the shrinking of lithography critical dimensions (CDs) as one of biggest challenges facing the semiconductor industry as it progresses to smaller geometry nodes. Nanolithography, the patterning of masking CDs below 100nm, enables both nanoscale wafer processing and the exploration of novel nanotechnology applications and devices.Focused Ion Beam (FIB) lithography has significant advantages over alternative nanolithography techniques, particularly when comparing resist sensitivity, topography effects, proximity effects and backscattering. FIB lithography uses the implantation of ions, such as Ga+, in its masking process. Ions implanted into resist in this manner typically have shallow penetration depths (<100nm for Ga+), and this would typically require the use of very thin resist layers during processing. This is often incompatible with subsequent fabrication steps such as plasma etching, where thicker resist layers are usually required to facilitate etch selectivity. Top surface imaging (TSI) is a solution to this problem.When compared with conventional microelectronic lithography, nanolithography techniques such as EUV, electron beam and nanoimprint lithography require expensive process equipment and the use of non-standard process materials.The 2-step negative resist image by dry etching (2-step NERIME) process is a FIB TSI scheme developed for DNQ/novolak based resists, and involves FIB exposure of resist with Ga+, followed by O2 plasma dry development using reactive ion etching. The 2-step NERIME process uses equipment sets and materials commonly found in microelectronic device fabrication (FIB tool, O2 plasma etcher, DNQ/novolak resists), and provides a low-cost and convenient nanolithography option for proof-of-concept nanoscale processing.To be of practical use, a nanolithography scheme must be capable of patterning nanoscale resist features over substrate topography while retaining resist profile control. The nanolithography scheme must also integrate with subsequent plasma etch processing steps that etch various material films such as metals, Si, SiO2, SiN. The 2-step NERIME FIB TSI process has been used to successfully pattern nanoscale (40nm-90nm) resist features on planar and topography substrates. We have also demonstrated sub-100nm etched features on topography substrates using the 2-step NERIME process, reporting 80nm Polycide and TiN etched features, and 90nm Ti etched features, that exhibit excellent profiles and minimal line edge roughness (LER).It is expected that the 2-step NERIME FIB TSI process will be further extended to etch sub-40nm features over topography substrates. The nanoscale etched features will be used to explore proof-of-concept geometry shrink & novel structures, with many possible applications, including NEMs and nanosensors research and development.
Effective Use of Focused Ion Beam (FIB) in Investigating Fundamental Mechanical Properties of Metals at the Sub-Micron Scale
Authors: Greer Julia R 
Published: June 2019

AbstractRecent advances in the 2-beam focused ion beams technology has enabled researchers to not only perform high-precision nanolithography and micro-machining, but also to apply these novel fabrication techniques to investigating a broad range of materials' properties at the sub-micron and nano-scales. In our work, the FIB is utilized in manufacturing of sub-micron cylinders, or nano-pillars, as well as of TEM cross-sections to directly investigate plasticity of metals at these small length scales. Gold nano-pillars, ranging in diameter between 200 nm and several micrometers were fabricated from bulk gold and epitaxial gold films on MgO substrates and subsequently compressed using a Nanoindenter fitted with a custom-fabricated diamond flat punch. We show convincingly that fundamental mechanical properties like flow stress, yield strength, and stiffness strongly depend on the sample size, as some of our smaller specimens were found to plastically deform in uniaxial compression at stresses as high as 800 MPa, a value ~50 times higher than for bulk gold.We believe that these high strengths are hardened by dislocation starvation. In this mechanism, once the sample is small enough, the mobile dislocations have a higher probability of annihilating at a nearby free surface than of multiplying and being pinned by other dislocations. Therefore, plasticity is accommodated by the nucleation and motion of new dislocations rather than by interactions of existing dislocations, as is the case for bulk crystals. To validate this mechanism, direct observation of dislocations was accomplished by utilizing the Omniprobe micromanipulator, coupled with FIB-milling and Pt deposition, for fabrication of site-specific TEM specimens. Preliminary TEM images show the lack of mobile dislocations in deformed pillars, which agrees with the proposed dislocation starvation mechanism, as discussed.
On the electronic configuration in Pu
Authors: Tobin J G , Soderlind P , Landa A , Moore K T , Schwartz A J , Chung B W , Wall M A , Wills J M , Haire R G , Kutepov A L 
Published: June 2019

AbstractX-Ray Absorption Spectroscopy (XAS) and Photoelectron Spectroscopy (PES) have been performed upon highly radioactive samples, particularly Plutonium, at the Advanced Light Source in Berkeley, CA, USA. First results from alpha and delta Plutonium are reported as well as a detailed analysis of sample quality.
Facilities for the Performance of Fano Effect Measurements as a Probe of Electron Correlation
Authors: Tobin J. G. , Tobin S. W. , Komesu T , Chung B W , Morton S. A. , Waddill G. D. 
Published: June 2019

AbstractFano Effect measurements are the key to direct observation of the Kondo or spin shielding intrinsic to models of electron correlation. The Fano Effect is the observation of spin polarized photoelectron emission from NONMAGNETIC materials, under chirally selective excitation, such as circularly polarized photons. Below are described three spectrometers, with which Fano Effects measurements have been made.
Electronic Structure of AC-Clusters and High-Resolution Xray Spectra of Actinides in Solids
Authors: Kulagin Nicolay Alex 
Published: June 2019

AbstractAb initio calculations using SCF approach for and analysis of results of investigation of the electronic structure of the clusters RA+n:[L]k with rare earths or actinides were carried out for the clusters in solids and liquids. Theoretical results for the electronic structure, radial integrals and energy of X- ray lines are presented for AC ions with unoccupied 5f-shell in the clusters in oxides, chlorides and fluorides environment. Possibility of collaps of nf-shell for the separate clusters and identification of electronic state of ions with unstable nuclei, are discussed, too.
Systematic Investigation of the Superconducting Behavior in Aged PuCoGa5
Authors: Jutier Frédéric , Colineau Eric , Griveau Jean-Christophe , Rebizant Jean , Wastin Franck 
Published: June 2019

AbstractIn this work, we have undertaken to follow the evolution of the PuCoGa5superconducting behavior as a function of the damages created by self-radiation effects induced from the Pu-decay. It is shown that the critical temperature is particularly sensitive with ageing. Ageing effects on fundamental parameters such as the lattice parameters of the PuCoGa5and the electrical resistivity provide some new hints of the unconventional character of the superconductivity in this class of materials
Using Correlations to Understand Changes in Actinide Bonding
Authors: Haire Richard G. , Heathman Stephen 
Published: June 2019

AbstractAn important issue in actinide science is the changing role of the 5f electrons, both when progressing across the series, as well as how experimental variables affect these roles in a particular element's chemistries and physics. The function of these 5f electrons can be changed by experimental conditions: temperature and pressure being two of many such variables. The 5f electrons of several actinide metals, their alloys and compounds are affected greatly by pressure, due to the very large decreases in interatomic distances encountered under pressure. The latter bring about significant changes in the total energy of the system and in the electronic energy levels, which in turn affect the potential for overlap/hybridization) of their orbitals, promotion of electrons to other orbitals, etc. The physical state, temperature, pressure, specific structures, magnetic interactions and spin polarization effects are all critical parameters for bonding. Often correlations of behavior with these parameters can provide unique insights and understanding into the bonding and the changes that occur in it. With the advancement of modern computation approaches using FPMTO, or other approaches, theory has enlightened greatly the understanding of not only the bonding behavior of these elements but also the understanding of changes observed experimentally. But these computational efforts have some complications and limitations, and at times experimental findings and theory are not always in full agreement. In contrast to the behaviors of the elements, changes observed with compounds often are not be linked directly to the involvement of 5f electrons, due in part to the presence and bonding role of non-actinide atoms. The latter affect both the actinide interatomic distances and the type of electronic orbtals that interact. Presented here is an overview of the pressure behavior several actinide elements, some insights into the bonding behavior of compounds under pressure and selected correlations that help explain changes occurring in electronic configurations and bonding.
Observation of Radiolytic Field Alteration of the Uranyl Cation in Bicarbonate Solution
Authors: Snow Lanee , McNamara Bruce , Sinkov Sergei , Cho Herman , Friese Judah 
Published: June 2019

AbstractAuto radiolysis of uranium (VI) carbonate solutions between pH 5.9 and 7.2 is shown to alter the uranium speciation over relatively short periods of time and was followed by 13C NMR and visible spectrophotometry, using dissolved [233(UO2)3(CO3)6]6- both as the radiolysis source (DÑ= 14.9 Gy/hr) and as a trap for the newly formed hydrogen peroxide. The speciation is different than the uranyl mixed peroxy carbonate species that have been reported for higher pH carbonate solutions.
Phase Formation and Dielectric Properties of Ln3NbO7 (Ln = Rare Earth Elements)
Authors: Cai Lu , Guzmán Julián , Pérez Louis A. , Nino Juan C. 
Published: June 2019

AbstractThe structure and dielectric properties of rare earth niobate compounds within the Ln3NbO7 (Ln = Nd, Gd, Dy, Er, Yb and Y) and Ln2(Ln',Nb)O7 (Ln = Nd, Sm and Ln' = Yb) series are investigated. The crystal structure of the all the studied materials is found to be fluorite-related including webertite-type, pyrochlore, and defect fluorite structures. It is observed that the relative permittivity of the defect fluorite Ln3NbO7 (Ln = Dy, Er, Yb and Y) increases with the increase in temperature and exhibits low dielectric loss up to approximately 350 K. Above 350 K, the dielectric loss increases rapidly with increasing temperature as the onset of electrical conductivity takes place. Of particular interests are Gd3NbO7 and Nd3NbO7, which exhibit a frequency and temperature dependent dielectric relaxation behavior. At 1 MHz Gd3NbO7 reaches its maximum relative permittivity of ∼34 at about 330K, while at the same frequency, the maximum relative permittivity of Nd3NbO7 is attained at about 500 K. By contrast, Nd2(Yb,Nb)O7 and Sm2(Yb,Nb)O7, which crystallize in a pyrochlore-type structure, do not show dielectric relaxation and, comparatively, exhibit a more temperature-stable dielectric permittivity response.
Interlayer Charge Conversion Through Intercalation of Polycations into a Synthetic Swelling Mica
Authors: Hata Hideo , Kobayashi Yoji , Mallouk Thomas E 
Published: June 2019

AbstractA layered host material with the ability to encapsulate anionic substances was synthesized by intercalating polycations into a synthetic fluoromica. A cationic polyelectrolyte coiled in the interlayer galleries to overcompensate the negative charge on the silicate sheets, and bulky anionic dye molecules could site-selectively be intercalated into interlayer in which the polyelectorlyte coiled.
Bio-Inspired Hydrogel-Calcium Carbonate Core-Shell Particles
Authors: Kim Yi-Yeoun , Catino John W , Tomaino Gary P , Cox Sherman D 
Published: June 2019

AbstractIn this report, we present a bio-inspired encapsulation process to create nanocluster-assembled core-shell particles under aqueous, room temperature and non-toxic conditions. The approach to synthesize calcium carbonate core-shell particles is accomplished by employing a Polymer-Induced Liquid-Precursor (PILP) process. We demonstrate the amorphous mineral precursor is coated around a core of hydrogel nanoparticles, and subsequently solidified and crystallized. The synthesized core-shell particles are 300∼500nm diameter and ∼100 nm shell-thickness. We investigate the role of the hydrogel core of the particle using time-resolved XRD, thermal-XRD and thermal analysis. The organic hydrogel appears to influence the transformation of mineral phases, stabilizing the amorphous phase of calcium carbonate.
Magnetic Properties of Vanadium Oxide Nanotubes, Nanourchins, and Nanorods.
Authors: Jacobs Chris , Roppolo Megan , Butterworth Kristin , Ban Chunmei , Chernova Natasha A. , Whittingham M. Stanley 
Published: June 2019

AbstractA better understanding of magnetic interactions, charge distribution, and redox properties of vanadium oxide nanotubes (VONTs) is necessary for accurate structure and mechanism of formation determination. Magnetic properties have been determined for pristine and lithiated VONTs and for the VONTs arranged in nanourchin morphology. Presence of paramagnetic V4+ ions and V4+ ions coupled in magnetic dimers is found, and their amounts are estimated. Both lithiation and change of morphology to nanourchin destroy the spin-gap behavior, which indicate changes in charge distribution. No ferromagnetic response is observed in lithiated VONTs. Magnetic properties of vanadium oxide nanorods with δ-V4O10 structure are also characterized.
A Scrolled Sheet Precursor Route to Niobium Oxide Nanotubes
Authors: Kobayashi Yoji , Hata Hideo , Mallouk Thomas E. 
Published: June 2019

AbstractPotassium hexaniobate (K4Nb6O17) is one of the few relatively well-studied oxides which, upon exfoliation, rolls up into scrolls almost quantitatively with monodisperse length (∼300 nm) and diameter (30 nm). The tubes have high surface area (250-300 m2/g) and a wall thickness of 2-3 nm. These H4Nb6O17 scrolls were converted to Nb2O5 via a thermal dehydration process, yielding high surface area (150-200 m2/g) Nb2O5 nanotubes. Despite extensive atomic rearrangement during dehydration at 400-450 °C, little sintering is occurs, and so the tubular morphology is retained. Attempts to conduct further reactions to obtain LiNbO3 and KNbO3 nanotubes from reaction with molten alkali salts failed to yield the intended nanotubular oxides.
Microstructured Optical Fibers as New Nanotemplates for High Pressure CVD
Authors: Baril Neil , Badding John , Savio Pier , Gopalan Venkatraman , Won Dong-Jin , Scheidemantel Thomas , Finlayson Chris , Amezcua-Correa Adrian , Jackson Bryan 
Published: June 2019

AbstractSolid state chemists have long been interested in templated growth of materials using many approaches. The resulting materials have been useful in areas as diverse as photonics and catalysis. Microstructured optical fibers (MOFs) form a new class of nanotemplates that can have sub 20 nm pores that are meters to kilometers long. We have developed a high-pressure microfluidic chemical process that allows for conformal deposition of materials within MOFs to form the most extreme aspect ratio semiconductor nanowires known. The wires can be spatially organized with respect to each other at dimensions down to the nanoscale because the MOF templates can be designed with almost any desired periodic or aperiodic pattern. Many if not most of the chemistries used for conventional chemical vapor deposition (CVD) can be adapted for this process. The resulting materials should enable a large range of scientific and technological applications.
Spontaneous Transformations in the Solid State: Towards Porous and Biphasic Materials
Authors: Toberer Eric S. , Seshadri Ram 
Published: June 2019

AbstractEpitaxial thin films of Mn3O4 and ZnMn2O4 have been grown hydrothermally on (100) and (111) MgAl2O4 substrates. Film growth was characterized as a function of pH, concentration, and time and thin film X-ray diffraction revealed that the resulting films are an epitaxial continuation of the underlying spinel lattice. Reduction of these films to MnO occurred topotactically and in the case of ZnMn2O4, resulted in mesopores aligned along the <100> directions. As the films maintain an epitaxial relationship with the substrate, the mesopores are aligned macroscopically within a single crystal lattice.
Synthesis and Luminescent Property of Nanocrystalline Phosphors via Solvothermal Processes
Authors: Tung Chien-Yuen , Chang Shyue-Ming , Chen Teng-Ming 
Published: June 2019

AbstractWe have synthesized a series of nanocrysatlline (5±3 nm in diameter) and submicrom ZnS:Ag,Al phosphors with various dopant compositions via a newly developed emulsion method. The X-ray diffraction (XRD), EDS, SEM, and TEM were utilized in the characterization of phase purity and microstructure of phosphor particles. Photoluminescence (PL) and cathodoluminescence (CL) spectra were also utilized to characterize the optical properties of blue-emitting phosphor. The CL intensity of submicron ZnS:Ag,Al phosphor was found to be weaker than that of corresponding commercial product, which was attributed to the poor crystallinity and small grain size. In this article we described the synthesis of ZnS:Ag,Al nanophosphor with emphasis on the correlation between spectroscopic features and the microstructure.
Superconductivity in Clathrates Ba24IV100( IV = Si and Ge ) with Rattling Motions
Authors: Rachi Takeshi , Kumashiro Ryotaro , Fukuoka Hiroshi , Yamanaka Syoji , Tanigaki Katsumi 
Published: June 2019

AbstractBoth Ba24Si100and Ba24Ge100with crystallographically identical structure are the superconductors whose critical temperatures are 1.45 and 0.27 K, respectively. Intriguingly, physical properties of the both compounds are extremely different. The observed differences are considered to be associated with Ba rattling motions. We have exemplified such unique motions in terms of x-ray diffraction data using MEM/Rietveld analyses. We present these exotic systems especially focusing on the relation between superconductivity and the rattling phonons.
Probing Octahedral Tilting in Dion-Jacobson Layered Perovskites With Neutron Powder Diffraction and Raman Spectroscopy
Authors: Kurzman Joshu A. , Geselbracht Margret J. 
Published: June 2019

AbstractTwo new Dion-Jacobson type layered perovskite solid solutions, RbCa2-xSrxM3O10 (M = Nb, Ta; 0 ≤ x ≤ 2), were prepared and studied by X-ray powder diffraction, neutron powder diffraction, and Raman spectroscopy. X-ray powder diffraction confirmed single-phase solid solution formation with continuous expansion of the idealized primitive tetragonal unit cell with increasing strontium content. Neutron powder diffraction studies of selected samples revealed lower symmetries and larger unit cells, as necessitated by octahedral tilting within the perovskite slabs, compared to the idealized primitive cell. As the average size of the A-cation in the perovskite slab is varied from Sr2+ to Ca2+, more extensive octahedral tilting is introduced. Vibrational modes of the perovskite slab observed using Raman spectroscopy show subtle changes as a function of calcium/strontium content and more intriguing differences between the isostructural niobates and tantalates.
Electrochemical Insertion of Li into Sr2MO2Cu2S2 (M = Mn, Co, Ni)
Authors: Indris Sylvio , Zeng Dongli , Cabana Jordi , Smura Catherine F. , Rutt Oliver J. , Clarke Simon J. , Grey Clare P. 
Published: June 2019

AbstractThe layered oxysulfides Sr2MO2Cu2S2 (M = Mn, Co, Ni) consist of alternating perovskite-type Sr2MO2 layers and copper sulfide layers. We studied the electrochemical insertion of Li into these three samples. By this we were able to study the influence of the nature of the transition metal on the Li insertion process which appears to be at least partially reversible. While the Mn compound clearly shows a Cu-Li exchange reaction, the electrochemical process for the two other compounds is more complex. The lithiated materials were studied by 7Li MAS NMR.