bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low loss Photonic Crystal Cladding Waveguide with Large Photonic Band Gap
Authors: Yi Yasha , Bermel Peter , Akiyama Shoji , Sandland Jessica G. , Duan Xiaoman , Kimerling Lionel. C. 
Published: April 2011

ABSTRACTLight propagation in a low index core (e.g. SiO2) is realized by a Photonic Band Gap (PBG) cladding waveguide structure with large dielectric index contrast layers (Si/Si3N4). The waveguide is fabricated with a CMOS compatible process. The measured loss for the asymmetric PBG cladding waveguide is about 0.5dB/cm for both polarizations at a wavelength of 1550nm. Potential applications include optical amplification when the SiO2 core is doped with optical active materials (e.g. Er).
Optical and Crystallographic Properties of Inverse Opal Photonic Crystals Grown by Atomic Layer Deposition
Authors: King Jeffrey S. , Neff Curtis W. , Heineman Dawn L. , Graugnard Elton D. , Summers Christopher J. 
Published: April 2011

ABSTRACTWe report a technique for the formation of infiltrated and inverse opal structures that produces high quality, low porosity conformal material structures. ZnS:Mn and TiO2 were deposited within the void space of an opal lattice by atomic layer deposition. The resulting structures were etched with HF to remove the silica opal template. Infiltrated and inverse opals were characterized by SEM, XRD, and transmission/reflection spectroscopy. The reflectance spectra exhibited features corresponding to strong low and high order photonic band gaps in the (111) direction (γ-L). In addition, deliberate partial infiltrations and multi-layered inverse opals have been formed. The effectiveness of a post-deposition heat treatment for converting TiO2 films to rutile was also studied.
ANGULAR ROLL-OFF DEPENDENCE OF SPECTRAL EMISSION FROM A METALLODIELECTRIC PHOTONIC CRYSTAL
Authors: Irina Puscasu , U Pralle Martin , P McNeal Mark , Nicholas Moelders , T Daly James , C Greenwald Anton , Alan Ludwiszewski , A Johnson Edward , L Schaich William 
Published: April 2011

ABSTRACTWe are reporting on the analysis of a new design for a thermal source exploiting Si-based suspended micro-bridge structures. A device consists of a metal film perforated by a periodic array of apertures extending into the Si substrate and each of size on order of the wavelength of the light. This perforated film permits resonant coupling of the incident radiation from the underlying silicon photonic crystal with surface plasmons at the metal surface. The coupling provides for unusually high optical emission efficiencies when the structure is thermally excited. The radiation emitted exhibits an enhancement over a narrow wavelength range in the infrared and its spectral response is highly dependent on the direction of observation. The positions of the main resonances, for both reflection and emission from our structures, scale linearly with the periodicity of the metallo-dielectric structure. As one moves off normal incidence, a single main resonance splits into several smaller resonances whose locations scale roughly linearly with observation angle. These structures have been used as emitter/detector sensor chips to selectively detect industrial pollutants like carbon dioxide. Control of the wavelength of resonance, bandwidth and direction of emission play an important role in improving the sensitivity and selectivity of these gas sensors.
Conductive transparent probes and their application to high-density phase-change data storage by using current injection
Authors: Murashita Tooru 
Published: April 2011

ABSTRACTWith the goal of producing high-density terabits/inch2 storage, we are studying a method in which nanometer-sized marks are recorded on Ge2Sb2Te5 (GST) phase-change media by current beams injected from sharpened probes. The current beams can inject powers with lower transmission losses into nanometer-sized local regions that are much smaller than the refraction limit of light. Moreover, the difference in the conductivity between amorphous and crystalline GST is orders larger than the difference in their refraction index. Therefore, the current beams are advantageous for such high-density data storage with nanometer-sized marks.We have experimentally and numerically studied phase changes in GST using probe current injections. The structures of the media are composed of GST and a metal electrode stacked on a polycarbonate substrate. We simulated temperatures, crystallization rates, and mark sizes of GST as a function of power injection conditions. The results clarify that a small crystalline mark can be stably made in an amorphous region by injecting probe current pulses with the same beam sizes. For supplying higher injection powers to produce phase change, metal oxide, such as indium-tin- oxide (ITO), is more robust at high powers than metals. We have developed conductive transparent (CT) probes consisting of ITO coated on a fiber tapered to a point with a nanometer-scale radius. The CT probe can inject current in a nanometer-sized region and simultaneously illuminate the same local region. We also propose a new method of optical rewritable phase-change storage using the CT probes.
Thermal analysis of nonvolatile and non rotation phase change memory cell
Authors: Shi L. P. , Chong T. C. , Li J. M. , Yang H. X. , Mou J. Q. 
Published: April 2011

ABSTRACTIn this paper, a three-dimensional finite-element modeling is performed for the analyses of Chalcogenide Random Access Memory (C-RAM), a non-rotation nonvolatile phase change memory cell. The thermal effect generated by an incident electric pulse was mainly discussed. Thermal performances of the cell as a result of electrical and geometrical variations were quantified. Current density distribution, temperature profiles, temperature history, heating rate, cooling rate, and heat flow characteristics were obtained and analyzed. The study is useful for the failure analysis of the C-RAM.
Characteristics of OUM Phase Change Materials and Devices for High Density Nonvolatile Commodity and Embedded Memory Applications
Authors: Lowrey Tyler A. , Hudgens Stephen J. , Czubatyj Wally , Dennison Charles H. , Kostylev Sergey A. , Wicker Guy C. 
Published: April 2011

ABSTRACTPhase change memory devices were originally reported by S. R.Ovshinsky [1] in 1968. A 256-bit phase-change memory array based on chalcogenide materials was reported in 1970 [2] Recent advances in phase change materials, memory device designs, and process technology have resulted in significant advances in phase change device performance, and a new memory device, called Ovonic Unified Memory (OUM), has been developed. This paper will discuss various device and materials characteristics of OUM phase change memory materials of interest in applications for nonvolatile high-density memories. These materials are generally Te chalcogenide based, exploiting the congruent crystallization of the FCC phase and the associated reduction in resistivity that results from crystallization from the quenched amorphous state. Data storage is a thermally initiated, rapid, reversible structural phase change in the film. While rewriteable DVD disks employ laser heat to induce the phase change and modulate reflectivity, OUM technology uses a short electrical current pulse to modulate resistivity. The device geometry and thermal environment dictate the power and energy required for memory state programming.
Simulation of Crystallization Processes in Phase Change Optical Discs
Authors: Hyot Bérangère , Poupinet Ludovic , Desré Pierre 
Published: April 2011

ABSTRACTFuture development of erasable phase change recording requires a thorough understanding of the fundamental mechanisms involved in crystallization processes to be able to forecast the behavior of a new material or to guide its optimization when submitted to specific conditions. In this paper, we emphasize that a predictive simulation is valuable only if a good modeling and accurate values of the involved parameters are used. We will present the main characteristics of our phase change model (effect of the short-pulse laser excitation, chemical influence of the materials in contact with the PC layer, stabilization of the amorphous state for very thin film layers) and we will discuss experimental and simulated crystallization behaviors.
TEM study of InSbTe crystal morphology as a function of crystallization conditions
Authors: Verheijen Marcel A. , Mijiritskii Andrei , Kooi Bart J. 
Published: April 2011

ABSTRACTIn this work crystallization of an InSbTe alloy in Blu-ray Disc rewritable (BD-RE) media is studied using Transmission Electron Microscopy (TEM). Two different crystalline states can be formed in a thin InSbTe layer depending on crystallization conditions. These two states give rise to different reflectivity levels of the recording stack as well as a different level of normalized media noise. It is shown that the two states correspond to the same phase (R 3 m), but that they show clear differences in morphology as well as in texture.
Microgravimetric Corrosion Studies on UO2
Authors: Wegen Detlef H. , Gouder T. , Eckle M. , Wiss T. , Glatz J.-P. 
Published: April 2011

ABSTRACTFor the first time at ITU electrochemical quartz crystal micro-balance has been used for the investigation of UO2 thin film oxidation. The combination of cyclic voltammetry with nano-gram weight change measurements in-situ has shown at least two steps in the initial stages of UO2 dissolution under oxidising conditions relevant to spent fuel storage.
Development of Siting Factors and Commencement of Open Solicitation for Preliminary Investigation Areas of HLW disposal in Japan
Authors: Tsuchi Hiroyuki , Kobayashi Masanori , Kondo Hirofumi , Koike Akihisa , Hatamoto Hiroki , Seo Toshihiro 
Published: April 2011

ABSTRACTThe Nuclear Waste Management Organization of Japan (NUMO) has developed a set of “Siting Factors (SFs)” to guide choice of preliminary investigation areas (PIAs) of HLW disposal. A call for municipalities to volunteer PIAs was initiated, which included published SFs, in December 2002 as the first stage of a stepwise site selection procedure. This paper describes the way that SFs were developed and the outlines how they will be applied.
The Role of Water Diffusion in the Corrosion of the French Nuclear Waste Glass SON 68 under Solution Saturation Conditions
Authors: Ferrand Karine , Abdelouas Abdesselam , Grambow Bernd , Crovisier Jean-Louis 
Published: April 2011

ABSTRACTThe alteration kinetics of the French borosilicate glass SON 68 have been investigated in a dynamic system at 50°C and 90°C under solution saturation conditions. The pH was adjusted to 4.8, 7.2 and 9.8 with addition of chemical buffers or/and by bubbling CO2 in solution. In all experiments, Li and Cs leaching seems to be controlled by a diffusion process. The Li- and Cs-concentrations were used to calculate the sum of ionic exchange and matrix dissolution rates of the glass while Mo-concentrations indicate matrix dissolution. The final leaching rates in saturation condition of Mo were in the order of 10–4–10- g.m-2.d-1 in good agreement with those given in literature for static tests. The glass surface was studied by scanning and transmission electron microscopy (SEM, STEM) for analysis of the corrosion products and by infrared spectroscopy (FTIR) for water speciation and concentration. A good inverse correlation between the water content and the alkali concentrations released from the glass has been obtained. About three hydrogen ions replaced one alkali ion. Modeling of the experimental data using GM 2001 model gives water diffusion coefficients between 10–20 and 10–22 m2.s-1.
Ceramics for the Immobilization of Plutonium and Americium: Current Progress of R&D of the V.G. Khlopin Radium Institute
Authors: Anderson Evgeniy B. , Burakov Boris E. 
Published: April 2011

ABSTRACTSince 1990, the Laboratory of Applied Mineralogy and Radiogeochemistry of the V.G. Khlopin Radium Institute (KRI) has been developing several different types of crystalline host-phases acceptable for the economically feasible and environmentally safe immobilization of actinide wastes. We proposed that ceramics that are based on host phases similar to naturally occurring accessory minerals including zircon, (Zr,Hf,…)SiO4; hafnon, (Hf,Zr,…)SiO4; baddeleyite (monoclinic zirconia), (Zr,Hf,…)O2; tazheranite (cubic zirconia), (Zr,Hf,Ca,Ti,…)O2; garnet, (Ca,Fe,Gd,…)3(Al,Fe,Si,…)5O12; perovskite, (Ca,Gd,…)(Al,Fe,Ti,…)O3, and monazite, (La,Ce,…)PO4, are the most efficient materials for actinide immobilization in deep geological formations. Solid solution of Pu in zirconia, (Zr,Pu)O2, could be used as a ceramic nuclear fuel that is competitive with mixed oxide fuel (MOX). To date, the following crystalline materials doped with 239Pu, 238Pu and 243Am have been successfully synthesized and studied at KRI: zircon; hafnon; cubic and tetragonal zirconia; monazite; aluminate garnet and perovskite. The maximum actinide loading was (in wt.% el.): 239Pu -37; 238Pu-10; 243Am-23. All Pu-Am-doped samples were made in air atmosphere under glove boxes conditions. Polycrystalline (ceramic) materials were made by sintering or melting of sol-gel, co-precipitated hydroxides, oxalates and phosphates or ground oxide precursors; single crystals were grown by a flux method. It was demonstrated that all ceramic samples obtained are characterized by high chemical durability and typical normalized actinide losses in deionized water at 90°C do not exceed 10−2–10−3 g/m2 (without correction for ceramic porosity). However, investigation of long-term behavior of ceramic waste forms requires taking into account the results of accelerated radiation damage study and modeling of ceramic alteration by underground solutions. The principal features of Pu-Am-doped samples obtained so far at KRI and their synthesis conditions are discussed.
Behavior of 238Pu-Doped Cubic Zirconia under Self-Irradiation
Authors: Burakov Boris E. , Yagovkina Maria A. , Zamoryanskaya Maria V. , Kitsay Alexander A. , Garbuzov Vladimir M. , Anderson Evgeniy B. , Pankov Alexey S. 
Published: April 2011

ABSTRACTTo investigate the resistance of cubic zirconia to accelerated radiation damage, which simulates effects of long term storage, 238Pu-doped polycrystalline samples of cubic zirconia, (Zr,Gd,Pu)O2, were obtained and studied using X-ray diffraction analysis (XRD), electron probe microanalysis (EPMA), optical and scanning electron microscopy (SEM), and modified MCC-1 static leach test. The ceramic material was characterized by the following chemical composition (from EPMA in wt.% element): Zr = 50.2, Gd = 15.4, Pu = 12.2. This corresponds to the estimated formula, Zr0.79Gd0.14Pu0.07O1.99. The content of 238Pu estimated was approximately 9.9 wt.%. The XRD measurements were carried out after the following cumulative doses (in alpha decay/m3 × 1023): 3, 27, 62, 110, 134, 188, 234, and 277. Even after extremely high self-irradiation, cubic zirconia retained its crystalline structure. All XRD analyses showed no phases other than a cubic fluorite-type structure. The following results of normalized Pu mass loss (NL, in g/m2, without correction for ceramic porosity) were obtained from static leach tests (in deionized water at 90°C for 28 days) for 4 cumulative doses (in alpha decay/m3 × 1023):The results obtained confirm the high resistance of cubic zirconia to self-irradiation. This allows us to consider zirconia-based ceramic as the universal material that is suitable for actinide transmutation and geological disposal.
Study of the Effects of Potential Impurities from Actinide Flux on the Zirconolite Microstructure
Authors: Leturcq G. , Auzemerie B. 
Published: April 2011

ABSTRACTZirconolite ceramics are candidate hosts for the containment of minor actinides from the reprocessing of spent fuel in France. Although actinide-doped or rare earth-doped zirconolite ceramics have been successfully produced from pure chemical precursors, there has been little focus on the effect of impurities on the zirconolite microstructure. However, this aspect is crucial for technical feasibility to guarantee a microstructure acceptable for nuclear waste management needs.First, chemical elements from the reprocessing process that could enter into the actinide flux as impurities were listed. We considered rare earths, zirconium, platinoids (Ru, Rh, Pd), molybdenum, barium, cadmium, silver, caesium, iron, and strontium. As we know rare earths and zirconium entering into the zirconolite microstructure they were not included in the study. For each other impurity listed, a zirconolite batch containing 1 wt% oxide impurity, and enriched in Nd simulating minor actinides, was synthesised then examined by SEM. Impurities were then categorised into those digested into the zirconolite microstructure, those partially digested into the zirconolite microstructure but also forming their own phases, and those that did not enter into zirconolite and formed their own separate phases.A sample was then produced containing all the impurities, to assess any interference effects. Three minor phases were observed: barium molybdenum oxide, noble metal alloy and zirconium titanium dioxide. These minor phases should not decrease the chemical durability of the ceramic, and therefore, we can conclude that zirconolite is not seriously affected by the impurities introduced.
Measurement of Dissolution Rates of UO2 Matrix with the Isotope Dilution Method
Authors: Ollila K. , Oversby V. 
Published: April 2011

ABSTRACTThe objective of this work was to measure the actual rates of matrix dissolution of UO2 in synthetic groundwater by using an isotope dilution method to provide a quantitative estimate of precipitation effects. A preliminary series of tests was performed under oxidising conditions, in contact with air. The second series of tests was under reducing conditions produced by actively corroding iron. The solid phases were fragments of unirradiated fuel pellets and intact pellets. The aqueous phase was a dilute, synthetic groundwater - so-called modified Allard water that is buffered by sodium bicarbonate/carbonate. This paper gives results for the experiments under oxidising conditions and preliminary tests under reducing conditions. In contact with air, the U concentrations reached higher levels than measured in previous experiments with spent fuel or with UO2 pellets. The comparison of the U concentrations calculated from isotopicratios with the experimental results suggests precipitation has begun at later stages of restarted tests. The measurements in the presence of actively corroding iron gave very low concentrations in the aqueous phase. At contact times longer than one week, all U seemed to disappear from solution and sorb or precipitate on UO2 or Fe surfaces in the test vessel.
Representation of Fracture Zone Interpretation Uncertainty in 3D Geological Models of the Mizunami Underground Research Laboratory, Japan
Authors: White Matthew J. , Saegus Hiromitsu 
Published: April 2011

ABSTRACTThe Japan Nuclear Cycle Development Institute (JNC) is undertaking research into the deep geological environment in Japan in the Tono area of Japan. In the Mizunami Underground Research Laboratory (MIU) Project, located in the Tono area, JNC is carrying out surface-based investigations and will excavate an Underground Research Laboratory (URL) in order to establish comprehensive techniques for investigating and characterising the geological environment. The MIU Project focuses on the investigation of the granitic rocks of the Toki Granite. The geological structure and hydrogeological properties of the Toki Granite are closely affected by the regional fracture zones and faults. The interpretation of these features is undertaken in 3D and directly linked into 3D hydrogeological models. Significant uncertainty exists in the 3D interpretation of the fracture zones, and geologists must make several assumptions regarding the 3D structure in order to develop the 3D interpretation. In order that these assumptions are communicated to the hydrogeologists, a methodology has been developed for representing uncertainty in the 3D geological models. An important part of the uncertainty representation, is the development of a fracture zone classification in which the uncertainty in both the presence and the geometry of the fracture zone is assigned. Other elements include the development of alternative models, visualisation of raw data, development of conceptual models, development of bounding models, and suitable quality assurance and archiving of modelling projects.
Mineralogical Characterisation of Sediments at the Drigg Low Level Radioactive Waste Disposal Site and the Influence on Groundwater Chemistry
Authors: Randall M. G. , Trivedi D. P. , Graham J. , Small J. S. , Hughes C. 
Published: April 2011

ABSTRACTPetrographic microscopy, scanning and transmission electron microscopy, X-ray diffractometry, surface area and cation exchange analyses have been undertaken on a suite of ‘bulk’ and size separated sediment fractions from the Drigg site. The data indicate a complex phyllosilicate assemblage consisting of illitic and vermiculite material derived from the complex weathering history of the siliceous, micaceous, feldspathic and chloritic parent clasts. Coarse grains range from clean fresh looking ‘polished’ clasts to heavily coated with iron oxides and oxyhydroxides. The surfaces of most igneous clasts (granites and volcanics) are usually highly altered to micaceous (‘illitic’), chloritic and vermiculitic clays. Carbonates, such as calcite, dolomite and siderite, are present, particularly in the more shallow formations. The properties of the sediments have a clear impact on the evolution of groundwater chemistry. Redox conditions are consistent with equilibrium between iron oxyhdroxides and siderite, both present in Drigg sediments. Drigg groundwater samples are close to equilibrium with calcite, which not only controls the concentration of dissolved calcium and bicarbonate ions, but also the groundwater pH. Concentrations of potassium and magnesium are controlled by ion exchange reactions, while both mineralogical and groundwater evidence show that some weathering of aluminosilicate minerals is occurring, although equilibrium is not reached.
Solubility of Plutonium in Water Containing Carbonate under Reducing Conditions
Authors: Ödegaard-Jensen Arvid , Albinsson Yngve , Nilsson Hans 
Published: April 2011

ABSTRACTIn order to investigate the dissolution of plutonium(III) under reducing condition and in a carbonate rich water solid phases of plutonium hydroxide and carbonate were made. The still wet solid phases were placed in vessels which contained 1 M NaClO4. The atmosphere in the vessels was either H2 or a mixture of H2 and 0.03% CO2.The preliminary results shows that after some time the plutonium concentration in the solutions reached a value between 10−9 M and 10−7 M. The pH in the solutions is dependent of the atmosphere. In a pure H2 atmosphere the pH is changing over time whereas in the H2+CO2 atmosphere the pH stays between 7 and 7.5. At pH 8 the total carbonate concentration in the water was between 10−4 M and 10−3 M. This is the same order of magnitude as the ground water surrounding the proposed repository.