bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Dual Multi-Phase Intermetallic Alloys Composed of Geometrically Close Packed Ni3X(X:Al and V) Structures
Authors: Takasugi Takayuki , Kaneno Yasuyuki
Published: June 2019

Dual multi-phase intermetallic alloys composed of Ni3Al (L12)+Ni3V (D022) phases were developed, based on the Ni3Al-Ni3Ti-Ni3V pseudo-ternary alloy system. High-temperature tensile deformation, fracture behavior, and compression and tension creep were investigated using polycrystalline and single crystalline materials. The alloys with such a novel microstructure show extremely high yield and tensile strength with good temperature retention, and also reasonable tensile ductility. Also, creep test conducted at high temperature showed extremely low creep rate and long creep rupture time. The obtained results are promising for the development of a new-type of high-temperature structural material exceeding conventional superalloys.
Microstructures and Mechanical Properties of in-situ V-V3B2 Composites
Authors: Xie Sujing , George Easo P.
Published: June 2019

A series of binary V-B alloys, with compositions spanning the eutectic, were produced by arc melting and drop casting. Microstructural examination revealed that the fully eutectic structure occurs at V-11B rather than V-15B as reported in the V-B phase diagram (all compositions in at.%). The V-11B eutectic was directionally solidified in an optical floating zone furnace, resulting in a composite microstructure consisting of a V matrix and flake or trigonal shaped V3B2 phase. The boride flake spacing (ë) decreases with increasing growth rate (R), following the relation ë2.56R=C, where C is a constant. TEM observations showed that the orientation relationship between the V and V3B2 phases is given by: [001]V // [001]V3B2 and (100)V // (100)V3B2. The growth direction and the V/V3B2 interface are parallel to the [001] direction and (100) planes in the two phases, respectively. Tensile tests were used to investigate the temperature dependence of the strength and ductility of the composite. At temperatures to 600°C, the yield strength of the eutectic is about 140 MPa higher than that of a commonly used vanadium solid-solution alloy, V-4Cr-4Ti. Surprisingly, the eutectic shows 5% tensile ductility at room temperature which increases to 10% as the test temperature is raised to 800°C.
Deformation Behavior of ReCr Sigma Phase Diffusion Barrier on Ni-based Superalloy
Authors: Miura Seiji , Ohkubo Kenji , Mohri Tetsuo , Yoshioka Takayuki , Narita Toshio
Published: June 2019

In order to attain a better oxidation resistance of Ni-based superalloys for high performance engines, a ReCr-based sigma-phase diffusion barrier coating between the MCrAlY bond coat (Al reservoir) layer and a Ni-based superalloy substrate has been proposed to suppress the diffusion of Al and other elements. The deformation behavior of TMS82+ superalloy specimens with coating layers composed of an Al-rich surface layer (corresponding to a bond coat) and a ReCr sigma-phase inner layer is investigated. In-situ observation of the bending tests using a Laser scanning confocal microscopy revealed that the crack formation in the Al-rich surface layer(s) on the tension side of the bend specimen occurs at an early stage of bending. On the other hand, small cracks in the sigma-phase layer under the Al-rich surface layer(s) are formed at the slip traces in the Ni-based superalloy single crystal substrate. This suggests a good adhesion between the sigma-phase and the Ni-based superalloy. At the compression side, in both the Al-rich surface layer(s) and the sigma-phase layer no cracking was observed until the Al-rich surface layer(s) shows buckling.
Thermo-Mechanical Modelling of Pebble Beds in Fusion Blankets and its Implementation by a Return-Mapping Algorithm
Authors: Gan Yixiang , Kamlah Marc
Published: June 2019

In this investigation, a thermo-mechanical model of pebble beds is adopted and developed based on experiments by Dr. Reimann at Forschungszentrum Karlsruhe (FZK). The framework of the present material model is composed of a non-linear elastic law, the Drucker-Prager-Cap theory, and a modified creep law. Furthermore, the volumetric inelastic strain dependent thermal conductivity of beryllium pebble beds is taken into account and full thermo-mechanical coupling is considered.

Investigation showed that the Drucker-Prager-Cap model implemented in ABAQUS can not fulfill the requirements of both the prediction of large creep strains and the hardening behaviour caused by creep, which are of importance with respect to the application of pebble beds in fusion blankets [1]. Therefore, UMAT (user defined material's mechanical behaviour) and UMATHT (user defined material's thermal behaviour) routines are used to re-implement the present thermo-mechanical model in ABAQUS. An elastic predictor radial return mapping algorithm is used to solve the non-associated plasticity iteratively, and a proper tangent stiffness matrix is obtained for cost-efficiency in the calculation. An explicit creep mechanism is adopted for the prediction of time-dependent behaviour in order to represent large creep strains in high temperature. Finally, the thermo-mechanical interactions are implemented in a UMATHT routine for the coupled analysis.

The oedometric compression tests and creep tests of pebble beds at different temperatures are simulated with the help of the present UMAT and UMATHT routines, and the comparison between the simulation and the experiments is made.
Structural Study of SiC Nanoparticles Grown by Inductively Coupled Plasma and Laser Pyrolysis for Nanostructured Ceramics Elaboration
Authors: Leconte Yann , Leparoux Marc , Portier Xavier , Herlin-Boime Nathalie , Siegmann Stephan , Rohr Lukas , Reynaud Cecile
Published: June 2019

Refractory carbide nanostructured ceramics as SiC constitute interesting materials for high temperature applications and particularly for fourth generation nuclear plants. To elaborate such nanomaterials, weighable amounts of SiC nanopowders have to be synthesized first with an accurate control of the grain size and stoichiometry. The inductively coupled plasma and the laser pyrolysis techniques, respectively developed at EMPA Thun and CEA Saclay, allow meeting these requirements. Both techniques are able to produce dozens of grams per hour of silicon carbide nanopowders. The particle size can be adjusted down to around 20 nm for the plasma synthesis and even down to 5-10 nm for the laser pyrolysis. The stoichiometry Si/C can be tuned by the addition of methane into the plasma and acetylene for the laser process.
Microstructure and Mechanical Properties of n-Irradiated Fe-Cr Model Alloys
Authors: Matijasevic Milena , Al Mazouzi Abderrahim
Published: June 2019

High chromium ( 9-12 wt %) ferritic/martensitic steels are candidate structural materials for future fusion reactors and other advanced systems such as accelerator driven systems ADS). Their use for these applications requires a careful assessment of their mechanical stability under high energy neutron irradiation and in aggressive environments. In particular, the Cr concentration has been shown to be a key parameter to be optimized in order to guarantee the best corrosion and swelling resistance, together with the least embrittlement.

In this work, the characterization of the neutron irradiated Fe-Cr model alloys with different Cr % with respect to microstructure and mechanical tests will be presented. The behavior of Fe-Cr alloys have been studied using tensile tests at different temperature range ( from -160°C to 300°C). Irradiation-induced microstructure changes have been studied by TEM for two different irradiation doses at 300°. The density and the size distribution of the defects induced have been determined. The tensile test results indicate that Cr content affects the hardening behavior of Fe-Cr binary alloys. Hardening mechanisms are discussed in terms of Orowan type of approach by correlating TEM data to the measured irradiation hardening.
Solid Micro-Beads Hetero-Structure Fuel for Ultra-high Temperature Applications
Authors: Popa-Simil Liviu , Vasilescu Gabriel
Published: June 2019

Higher 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

Focused 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

We 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

For 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

Thermally 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

The 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

We 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

Specific 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

The 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

In 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

A 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

Titanate 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

The 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

Nanocrystalline 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

In 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

The 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

Clathrates 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

The 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.
Materials Discovery by Crystal Growth
Authors: Mugavero III Samuel J. , Gemmill William R , zur Loye Hans-Conrad
Published: June 2019

The growth of new phases out of high temperature hydroxide solutions as a means of discovering new materials is discussed. We have succeeded in solubilizing rare earth cations and platinum group metal cations in molten hydroxides and have grown single crystals with a large number of new compositions and new structure types. The use of sealed silver tubes has enabled us to control the water content and, hence, the acidity of the hydroxide melts, and thereby to grow crystals via slow cooling. The synthetic conditions and structures of several new oxides including Ln1-xNa1+xIrO4 (Ln = Gd-Er, Y; x = 0.04-0.26), Ln3RuO7 (Ln = La, Sm, Eu), LnNaPd6O8 (Ln = Tb-Lu, Y) and La9RbIr4O24 are presented.
Amplified Photochemistry with Slow Photons
Authors: Chen Jennifer I. L. , von Freymann Georg , Choi Sung Yeun , Kitaev Vladimir , Ozin Geoffrey A.
Published: June 2019

We demonstrate monochromatic and white light optical amplification of the photo-oxidation of adsorbed methylene blue using an inverse colloidal photonic crystal fashioned from anatase nanocrystals, denoted i-nc-TiO2-o. Enhanced photo-activity that drives the oxidation of the dye is attributed to slow photons in i-nc-TiO2-o. When the slow photon wavelength is optimized with respect to the electronic excitation energy of i-nc-TiO2-o, the photo-oxidation rate of the dye is doubled compared to conventional nc-TiO2. By increasing the probability of absorbing photons in i-nc-TiO2-o relative to nc-TiO2, a larger population of electron-hole pairs is generated enabling more efficient photo-oxidation. Slow photons in photonic crystals portend a myriad of opportunities for amplified photo-processes in chemistry and biology.
Computer Modeling of Nanoporous Materials: An ab initio Novel Approach for Silicon and Carbon
Authors: Valladares Ariel A. , Valladares Alexander , Valladares R. M.
Published: June 2019

Carbon and silicon have been consistently proposed as elements useful in the generation of porous materials. Carbon has been insistently postulated as a promising material to store hydrogen, and crystalline silicogermanate zeolites have recently been synthesized and are being considered in catalytic processes. In the present work we report an approach to generating porous materials, in particular porous carbon and silicon, which leads to the existence of nanopores within the bulk. The method consists in constructing a crystalline diamond-like supercell with 216 atoms with a density (volume) close to the real value, then halving the density by doubling the volume (50% porosity), and subjecting the resulting supercell to an ab initio molecular dynamics process at 300 K for Si, and 1000 K for carbon, followed by geometry relaxation. The resulting samples are essentially amorphous and display pores along some of the “crystallographic” directions. We report their radial distribution functions and the pore structure where prominent.
Feedback Loops Along The Pre-Requisite Tree
Authors: Bieler T.R. , Huebner M. , Soutas-Little R.W. , Crimp M.J.
Published: June 2019

The ABET Engineering Criteria 2000 is stimulating development of quantitative feedback systems in the context of Engineering education. Efforts in developing feedback loops that carry quantitative information to facilitate the improvement of student learning in several engineering majors is summarized. Feedback loops are designed around the course learning objectives that were developed in the context of professional criteria specified by professional societies as well as ABET EC 2000 criteria 2 and 3, which define capabilities that all engineers must gain. Two feedback structures are described – one brings information from external sources such as alumni, employers, and the external advisory board, while the other moves information up and down the pedagogical prerequisite tree. Both loops go through the ABET/curriculum committee for assessment of progress and identification of needed changes. The tool developed to facilitate communication up and down the prerequisite tree is the course evaluation form, on which student and faculty assess students' mastery of the learning objectives. This form is passed through feedback loops that operate on many scales. Progress toward implementation is described, with emphasis on service courses that see student flow between different departments.
A New Masters Course Program in Materials Science and Engineering at the University of Kiel
Authors: Paul Frank , Foell Helmut , Dolgner Kai , Jaeger Wolfgang
Published: June 2019

An international study course program in Materials Science and Engineering based on innovative concepts in engineering education has been introduced by the Faculty of Engineering at the University of Kiel for students from Germany and especially from abroad. The study program offers advanced materials science education culminating in the internationally recognized degree “Master of Materials Science and Engineering”. It aims at providing students with the necessary skills to meet the challenges of a global job market and the demands of industry and research institutions in modern industrial societies. Some of the main characteristics of the program for which tuition fees are not required comprise theoretical teaching and lab training modules held in English language, internet teaching modules, a broad choice of courses including courses in nontechnical skills, a Master thesis in areas of functional or structural materials, collaboration with research institutes, as well as participation in the European credit point transfer system for international acceptance of the course work. The program has started successfully in 1999 with students coming mainly from the Eastern European countries.
Resources Center for Materials Science Education
Authors: Stoebe Thomas G. , Clark Darcy , Roy Rustum
Published: June 2019

A variety of educational resources are available in the area of materials science and engineering. These resources are widely dispersed and are often hard to find. Several efforts to collect and categorize the wide variety of educational modules, demonstrations, laboratories and texts have been launched in recent years, but none have been able to incorporate the vast majority of resources. The current effort is funded by NSF and has been collecting information from a variety of sources over the past year. It is being integrated with the Materials Education Library project that has been under way at the University of Michigan since 1997. These projects will result in a fully searchable database, published both on the world wide web and in a print catalog, with the first edition being available by summer 2000. The draft web site may be found at http://msewww.engin.umich.edu/MEL/; a permanent web site will be available by the end of 2000.
A New Role for Engineering Educators: Managing for Team Success
Authors: Larson Debra S.
Published: June 2019

For a variety of reasons, collaborative learning teams, project teams or design teams are now a part of undergraduate engineering education. In response, the current education-related literature is flourishing with team-type topics that include when and why teams, team dynamics, and how to structure teams. Almost non-existent, however, are discussions about the role and impact of the faculty member in and on student teams.

Extrapolating from the professional project management literature, project and team success is heavily influenced by positive management. Businesses that fail to train and reinforce positive management run unacceptable risks. The risks to us as educators, who use teams in less than ideal situations, include a lack of learning, project failure, and dysfunctional teams that foster an aversion to teams. This is in direct contrast to what we hoped and what we have been asked to do, which is to provide an understanding about the power of teams, to develop teaming skills, to enable design successes, and to enhance the learning.

Proper management of student teams requires skills and strategies that are much different from those that most faculty members are experienced with. The strategies include planning for and implementing an understood work process, providing a suitable organization compatible to that process, structuring and communicating with the team, and holding the individual accountable. The skills start with two risk taking beliefs: (1) you do not have to have all the answers and (2) it is not you against them, but about you with them. With the right attitude, the skills of leading by example, guiding towards peak performance, and managing for optimal team experiences follow.
Further Study of the Effect of Group Size on Student Performance
Authors: Sutko A. A.
Published: June 2019

In a 1992 issue of the International Journal of Engineering Education, this author reported on the effects of laboratory group size on student performance. Most of the information was obtained from a material science laboratory. The data indicate that individuals in groups of two or four students tended to receive better final course grades than those from groups of three. Discussion was given concerning the possible reasons for this finding along with information from the then current literature. This paper includes the key components of the 1992 paper and updates it with data obtained since then. It also includes information from other literature published in the recent past. The conclusions reached in the 1992 paper appear to remain valid.
Feeding the Recruitment of Inner City Kids to MSE by Keeping 5TH Graders on Track for Engineering in College
Authors: Brower William E.
Published: June 2019

The fifth grade inner city volunteer teaching project (5GVP) at Marquette University's College of Engineering has attempted to inform and inspire Milwaukee's inner city fifth graders about engineering for the last ten years. Each year I have recruited our engineering students to volunteer to take self contained science lessons into the Milwaukee Public Schools'fifth grade classrooms. Although the lessons are on science and the career touted is engineering in general, the lessons are flavored by my being in MSE. Being excited about a career is certainly a precursor to choosing that career. I have found the fifth graders very excited about seeing and experiencing science in action as the engineering students present it to them. Hopefully, the program at Marquette will result in more inner city students choosing to enter college as engineers, with MSE garnering its usual share.
Why Does a Light Bulb Burn Out?
Authors: McKelvy Michael J. , Mitan P. , Hintze Kirsten , Patrick Eric , Allagadda K. , Ramakrishna B.L. , Denny Carrie , Pryor Brandt , Chizmeshya A.V.G. , Pizziconi V.
Published: June 2019

The online educational module “Why Does a Light Bulb Burn Out?” is an inquiry-based introduction to the concepts of materials and material properties through the interactive exploration of the life of the incandescent light bulb that students use every day. The module offers an exploration of the history of the light bulb, its components, and important filament properties. Students discover the relationship between temperature and incandescence, along with electrical power and resistance through interactive Java applets. Then students “invent” their own filaments through virtual temperature, performance and longevity tests of a variety of candidate materials. Next, students follow the filament aging process using scanning-electron/atomic-force microscopy images. The module culminates in students designing their own materials experiments using SPM Live! online at http://invsee.asu.edu. Student evaluations indicate students both enjoy and learn effectively using the module.
“Collective Undergraduate Research: A Teaching / Learning Tool For MSE Students”
Authors: Wahby Wafeek Samuel
Published: June 2019

A new experiment to implement and collectively publish undergraduate students' research was started at the School of Technology, Eastern Illinois University in the Fall of 1998. A summary of the procedures followed in this experiment, its assessment and its progress are presented. Collective research publications, authored by undergraduate engineering students and edited by their faculty can be used as an effective teaching / learning tool that benefits students/authors, their peers, faculty/editors, local and other institutions, and industry at large, particularly when this research is interactively posted on the Internet. Through a research study format, undergraduates learn the subject matter much better, become familiar with research methods and techniques early in their careers, and polish their technical writing abilities. As the experiment also fosters teamwork and peer collaboration and evaluation, undergraduates sharpen their oral communication skills through group discussions and in-class presentations. The experiment provided an opportunity for students to independently select and research a particular topic and helped them discover the research resources and reference materials available on the subject matter. As one of the few creative opportunities offered in a class, this experiment presented a variety of learning environments to undergraduates and helped promote their creativity and self-directed learning. It was confirmed that most undergraduate students hold unlimited potential for success as researchers, and that enthusiasm, hard work, self-motivation, and dedication of students are likely to constitute better indicators of success than the conventional grades they earned in the past.
Materials Science in General Chemistry for Freshman Engineering Majors
Authors: Nikles David E.
Published: June 2019

The College of Engineering at the University of Alabama is a member of the Foundation Coalition. We have created a new freshman engineering curriculum that integrates subject matter from calculus, chemistry, physics and general engineering studies courses. To motivate the study of chemistry, materials science themes were incorporated into the general chemistry course sequence.
Robert Bárány, a scientist with many interests
Authors: Maranhão-Filho Péricles , Bárány Anders
Published: June 2019

ABSTRACT Austrian-born Robert Bárány was a scientist with many interests. This article highlights some of these interests and also some personal traits. He enrolled as a surgeon in World War I, was captured by the Russians in 1915 and, while still in the prison camp, was awarded the 1914 Nobel Prize in Physiology or Medicine for his work in otology. In 1916, he accepted an offer from Uppsala University, Sweden, and worked there for almost 20 years. He died shortly before his 60th birthday, in 1936.
Bleeding risk of small intracranial aneurysms in a population treated in a reference center
Authors: Lepski Guilherme , Lobão Carlos A. F. , Taylor Stella , Mesquita Filho Paulo M. , Tatagiba Marcos
Published: June 2019

ABSTRACT Large multicenter studies have shown that small intracranial aneurysms are associated with a minimal risk of bleeding. Nevertheless, other large series have shown that most ruptured aneurysms are, in fact, the smaller ones. In the present study, we questioned whether small aneurysms are indeed not dangerous. Methods: We enrolled 290 patients with newly-diagnosed aneurysms at our institution over a six-year period (43.7% ruptured). We performed multivariate analyses addressing epidemiological issues, cardiovascular diseases, and three angiographic parameters (largest aneurysm diameter, neck diameter and diameter of the nutrition vessel). Risk estimates were calculated using a logistic regression model. Aneurysm size parameters were stratified according to receiver operating characteristic (ROC) curves. Finally, we calculated odds ratios for rupture based on the ROC analysis. Results: The mean largest diameter for the ruptured versus unruptured groups was 13.3 ± 1.7 mm versus 22.2 ± 2.2 mm (p < 0.001). Multivariate analysis revealed a positive correlation between rupture and arterial hypertension (p < 0.001) and an inverse correlation with all three angiographic measurements (all p < 0.01). Aneurysms from the anterior cerebral artery bled more often (p < 0.05). According to the ROC curves, at the largest diameter of 15 mm, the sensitivity and specificity to predict rupture were 83% and 36%, respectively. Based on this stratification, we calculated the chance of rupture for aneurysms smaller than 15 mm as 46%, which dropped to 25% for larger aneurysms. Conclusion: In the population studied at our institution, small aneurysms were more prone to bleeding. Therefore, the need for intervention for small aneurysms should not be overlooked.