bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasmall Lasers Based on Photonic Crystal Line Defects
Authors: Baba Toshihiko 
Published: April 2011

ABSTRACTIn this paper, we discuss unique light localization in a single line defect, which is effective for constructing photonic crystal light lasers. The localization is based on additional defect doping that breaks the symmetry of the line defect. Even though such a defect is opened to the line defect, the optical field is well confined around the defect at cutoff frequencies of the line defect. This concept expands the design flexibility of microcavities; for example, the composite of point and line defects and waveguide components such as bends and branches can be microcavities. It also allows effective mode controls such as the singlemode operation in relatively large cavities. The lasing operation of these cavities in a GaInAsP photonic crystal slab was experimentally observed by photopumping at room temperature. This paper reports lasing characteristics and the dependence on various structural details.
Interfacial Energy and Materials Selection Criteria in Composite Microstructured Optical Fiber Fabrication
Authors: Hart Shandon D. , Fink Yoel 
Published: April 2011

ABSTRACTThe recently expanding field of microstructured optical fibers relies on the controlled fabrication of sub-micron features in a fiber drawn in the viscous fluid state. Microstructured fibers have generated great interest owing to their potential in areas such as photonic bandgap guidance of light in low-index media; high-energy laser transmission; and unique control over waveguide non-linearities, dispersion and modal properties [1–6]. These fibers have been made from a single material with air holes [7, 8] and as multi-material ‘composite’ fibers where air is not a part of the microstructured region [6, 9]. While single-material microstructured fibers generally rely on the established technology base of fused silica, the use of less conventional materials may enable applications not possible using silica [6]. Multi-material fibers may also present certain fabrication advantages due to their incompressible domains and simple cylindrical geometries. However, the use of more than one material raises questions about which types of materials can be combined in the drawing of a microstructured fiber. This problem can be approached by analyzing the relative importance of different materials properties such as viscosity, interfacial energy, and thermal expansion. In this study we focus on the effects of interfacial energy in composite microstructured fibers. We measure the interfacial energies at high temperature of a chalcogenide glass and an organic polymer recently employed in the fabrication of composite photonic bandgap optical fibers. We discuss the effect of interfacial energy during fiber draw, as well as the interplay between surface and viscous forces. Finally, we comment on the implications of this analysis for understanding what classes of materials can be used in composite microstructured fiber fabrication.
Visualization of electrons and holes localized in the gate thin film of metal-oxide nitride-oxide semiconductor type flash memory by using scanning nonlinear dielectric microscopy
Authors: Honda Koichiro , Cho Yasuo 
Published: April 2011

ABSTRACTWe used scanning nonlinear dielectric microscopy to observe the position of electrons and holes in the gate SiO2-Si3N4-SiO2 (ONO) film of metal-oxide-nitride-oxide semiconductor type Flash memory. The electrons were detected in the Si3N4 part of the ONO film. The holes, on the other hand, were found in the Si3N4 film as well as in the bottom SiO2 film.
Local Surface Modification of ECR Sputtered Carbon Film and Its Application to Ultra High Density Data Storage
Authors: Tsuchitani S. , Isozaki M. , Kaneko R. , Tanaka I. , Hirono S. 
Published: April 2011

ABSTRACTWe propose a probe storage using a carbon film deposited by electron cyclotron resonance plasma (ECR) sputtering as a recording material. Such storage has a potential to achieve an electrical data storage with small writing voltage and ultra high recording density due to super hardness and large electric conductivity of the ECR sputtered carbon (ECR-C). The ECR-C film is deposited on a silicon substrate covered by a thermal oxide. Recording experiments are performed by a conductive atomic force microscope with a gold coated tip. The electrical resistance of the film surface is decreased locally by applying voltages smaller than 2V between the film and the tip. The resistance decrease of the film by the voltage application are caused by a thermal reaction due to Joule's heat at contact portion of the film with the tip. Data bits with size of about 70nm can be formed by applying a pulse row as a writing voltage.
Media Technologies for 20 GB Single Layer and 36 GB Dual Layer Phase Change Rewritable Disc “HD DVD-ARW”
Authors: Ashida Sumio , Yusu Keiichiro , Nakai Tsukasa , Tsukamoto Takayuki , Ichihara Katsutaro , Ohmachi Noritake , Morishita Naoki , Ogawa Akihito , Nakamura Naomasa 
Published: April 2011

ABSTRACTIn an effort to achieve as high a storage capacity as possible on a disc format that is similar to conventional DVD using blue-violet laser, a number of new technologies have been implemented for the phase change rewritable media. The technologies include the ways to meet challenges in obtaining larger signal amplitude for shorter bit lengths and lowering the cross erase for narrower track pitches. Technologies developed for both the single layer and the dual layer discs are discussed.
Optical Properties of Multi-layer Chalcogenide Thin Film for Optical Recording Media
Authors: Kang Myung-Jin , Park Chan-Gyung , Choi Se-Young 
Published: April 2011

ABSTRACTWe present the results of optical properties of multi layer thin films as in the media of phase change optical disk data storage. Reflectance and optical contrast of multi layer thin films increased rapidly between 100 °C and 150 °C. Moreover, optical contrasts at different wavelength were also studied. The refractive index and the optical band gap decreased, while the extinction coefficient increases as the crystallization occurs. The Egopt of crystalline thin film was ∼0.6 eV lower than that of amorphous thin film. Egopt decreased as the number of stacked layer increased.
Secondary Phases on the Surface of Real Vitrified Radioactive Waste Disposed in a Loamy Soil
Authors: Ojovan Natalie V. , Sartceva Irene V. , Barinov Alexander S. , Mokhov Andrew V. , Ojovan Michael I. , Möbus Günter 
Published: April 2011

ABSTRACTThis work examines secondary phases formed on the surface of radioactive borosilicate glass K-26 during 12 years of testing in the loamy soil. This glass has been produced to immobilise intermediate level operational nuclear power plant (NPP) radioactive waste. An altered layer has been formed at the glass surface that had been contacting with the repository environment. The layer is morphologically following the bulk waste glass. The layer is chemically inhomogeneous and non-uniform in thickness and structure. It contains in addition to the major vitreous phase, alpha quartz, calcite, aluminium hydrochlorides, and molybdenum compounds.
Ceramic Wasteforms for the Conditioning of Spent MOxFuel Wastes
Authors: Maddrell E. R. , Abraitis P. K. 
Published: April 2011

ABSTRACTCrystalline ceramic wasteforms have been fabricated to immobilise a combined fission product and actinide waste stream arising from spent MOx fuel. The fuel is conditioned by a UREX process, as contrasted to PUREX, to produce a waste stream containing fission products and transuranics. Zirconia rich Synroc derivatives have been formulated to minimise formation of perovskite. This ensures that the transuranics are predominantly immobilised in zirconolite. For comparison, a wasteform has also been produced in which transuranics and rare earth element fission products are immobilised in a radiation resistant cubic zirconia solid solution, whilst caesium, strontium and barium are partitioned to an alumina rich magnetoplumbite phase.
Examination of Synthetic Murataite Structure Using Data of Mossbauer Spectroscopy
Authors: Urusov Vadim S. , Rusakov Vyacheslav S. , Yudintsev Sergey V. , Stefanovsky Sergey V. 
Published: April 2011

ABSTRACTMurataite-based ceramics were recently suggested as promising matrices for immobilization of rare earths and actinides from high-level waste (HLW). Nevertheless, the crystal-chemical formula of the phase has not been accurately determined yet. We have examined structural features of murataite with Mössbauer spectroscopy. Initial batches were prepared from CaO, Al2O3, Fe2O3, MnO2, ZrO2, TiO2, ZrO2, and UO2. Mixtures were melted in platinum crucibles in a resistive furnace in air at 1450°C for 1 h followed by cooling to 1000°C at the rate of 10°C/min. and final cooling down with the furnace switched-off. Study with XRD, SEM, and TEM showed the samples are composed of two co-existing murataite-type phases with five- and eight-fold elementary fluorite cells. To investigate the valence and structural position of iron ions, Mössbauer spectroscopy on 7Fe nuclei in geometry “on absorption” was used. The data obtained let us conclude that in both murataite varieties trivalent iron is distributed almost statistically (3:1) between B octahedra and C five-vertex polyhedra, while tetrahedral sites T are probably not populated. Taking into account these suggestions, the idealized crystal chemical formula of synthetic murataites can be simplified to A3[8]B6[6]C2[5]O22-x/2. Recalculation of chemical analyses to atomic numbers results in the conclusion that average cation valence for murataites is 3.33. Then, calculation for the generalized formula M11O22-x/2 (M=A,B,C) gives a value x/2 = 3.7, i.e., the number of O atoms in the formula is 22–3.7 = 18.3. Final conclusions on the murataite formulae have to be verified by direct structural research on a single crystal.
Effects of pH and Uranium Valence State on the Aqueous Dissolution of Brannerite
Authors: Zhang Y. , Loi E. , Blackford M. , McLeod T. , Li H. , Begg B. 
Published: April 2011

ABSTRACTThe dissolution of the thorium analogue of brannerite (ThTi2O6-I) and U(IV)/U(V) doped Th-brannerite (Th0.97U0.03Ti2O6-II and Th0.955U0.03Ca0.015Ti2O6-III) in aqueous media under atmospheric conditions has been studied to elucidate the effects of pH and uranium valence state on the dissolution rate.The dissolution of I is nearly stoichiometric but slightly preferential release of U occurs for II and preferential release of Ca and U occur for III. The V-shape pH dependence previously observed for U-brannerite only occurs for U (not other matrix elements) for II, indicating that the pH dependence is related to the U oxidation state upon dissolution. The normalised U dissolution rates of III are nearly an order of magnitude higher than those of II for pH values over 3, suggesting brannerite is less durable with U(V) doping. TEM examination of specimens after leaching revealed few surface alteration products, which is consistent with the nearly stoichiometric dissolution of thorium brannerite.
Effects of the Environmental Pressure in the Corrosion Potential of the Copper that Will Be Used as Container of High Level Radioactive Waste
Authors: Escobar I. , Silva E , Lamas C. , Silva C. , Werme L. 
Published: April 2011

ABSTRACTThe SKB project of Sweden has considered copper as the most appropriate metal to be used as container for high activity radioactive waste. However, it is still necessary to carry out some studies that can assure that their chemical, physical, mechanical properties, etc. do not loose stability in a period so long as 100.000 years.In this work we show using anodic polarization, the corrosion potential (Ecorr) behaviour in different pressurized environment. The copper surface was characterized using optical microscopy. The electrochemical cell was mounted in a high pressure chamber that allowed to work up to 40 atm. The electrolyte solution simulates the deep groundwater, being the composition reported in literature [1].The experimental results in solutions without bentonite show only slightly changes of the corrosion potential to cathodic values. At pressures of 40 atm, products of corrosion are observed, covering micropitting, that can be induced because of a bigger interaction metal/ ion at these pressures.In the other case, bentonite presence produces beneficial effects in the resistance of the copper corrosion, since it is observed that the corrosion potential is displaced to more anodics values. This effects could be explained due to that this clay is able to retain ions that are aggressives for copper, such as chloride, sulphide, etc., and it liberates others that don't produce deterioration, such as sodium, that is in concordance with others authors[15].
The Effect of EDZ on the Migration of Radionuclides in a KBS-3 Type Repository
Authors: Autio Jorma , Hjerpe Thomas , Siitari-Kauppi Marja 
Published: April 2011

ABSTRACTThe role of excavation damaged zone (EDZ) in a KBS-3 type repository for spent nuclear fuel depends significantly on the design of the engineered barrier systems such as tunnel backfill since one obvious function of the backfill is to prevent the growth of EDZ. Main results of EDZ studies based on using 14C-PMMA method carried out at Äspö Hard Rock Laboratory in Sweden, and at Research Tunnel at Olkiluoto in Finland by Posiva and SKB in co-operation are presented. The significance of the results is evaluated quantitatively and qualitatively. The EDZ around the deposition hole on migration of radionuclides diffusing out of a waste canister was found unlikely to be a significant migration route in the absence of large hydraulic gradients. According to the study the EDZ caused by state-of-the-art drill and blast excavation adjacent to walls and roof of deposition tunnels was found negligible, however the EDZ adjacent to deposition tunnel floor is evidently more extensive and more significant.
Effects of Cement Additives on Radionuclide Mobility
Authors: Dario Mårten , Molera Mireia , Allard Bert 
Published: April 2011

ABSTRACTThe effects of organic cement additives (totally 7) on the sorption of Eu on cement and TiO2 were measured with variation of the concentration of the additive (0.001–10% of the water phase) and reaction time (up to 420 d). There was a significant reduction of the sorption of Eu on cement as well as on TiO2 after 24 h of exposure time in the presence of additives at levels that would be obtained in a cement/water system if the total load of the additive in the cement (up to 3%) would be released into the water phase. Sorption increased with time and would be expected to reach constant levels after 100–200 d. Storage of the additives at 60 and 120 °C, pH 12.5, for up to 110 d (in order to degrade them) did not lead to significantly altered sorption behaviour.
Sorption of Actinides onto Granite and Altered Material from Äspö HRL
Authors: Kienzler Bernhard , Römer Jürgen , Schild Dieter , Bernotat Walter 
Published: April 2011

ABSTRACTWithin the scope of a bilateral cooperation between Svensk Kärnbränslehantering AB (SKB) and Forschungszentrum Karlsruhe, Institut für Nukleare Entsorgung (FZK-INE), actinide migration experiments with Pu, Am, and Np are conducted at the Äspö Hard Rock Laboratory. Migration experiments are complemented by batch experiments providing detailed information on the relevant retention processes for actinides onto granite and altered fracture material. The same kinds of experiments are performed with well defined minerals. α-autoradiography and XPS were used to quantify local sorption properties of the rock samples. It is shown that Np is retained by reduction to Np(IV) in the presence of Fe(II) minerals. The sorption coefficient for Pu is significantly higher compared to Np or U. Pu retention takes place on a multitude of minerals. Sorption of U is also strongly correlated with the occurrence of Fe oxide phases.
Surface Site Densities of Uranium Oxides: UO2, U3O8
Authors: Clarens F. , Pablo J. de , Casas I. , Giménez J. , Rovira M. 
Published: April 2011

ABSTRACTThe estimation of the surface site density for UO2 (main component of the SF matrix) is an important aspect to take into account in the development of radiolytical models for the dissolution of the spent nuclear fuel (SF). Also, other oxides can be formed on the SF surface due to the effect of radiolytically-formed oxidizing species. Due to the lack or reliable data in literature we have studied the surface site densities of two uranium oxides: UO2 and U3O8.For this determination, the knowledge of both the reactive surface area and the surface charge of the solid are necessary. In this work the reactive surface area of the two solids was determined by the BET method while the surface charge was determined by potentiometric acid-base titrations of suspensions of the solids at different ionic strengths (0.001, 0.01, and 0.1 mol·dm−3) under N2 atmosphere.The amount of adsorbed protons was calculated by subtracting blank titration from thesolid suspension titration. The single-site nonelectrostatic model (NEM) was used to describe titration data. Uranium speciation in solution was included in the model as well.The surface area values obtained were 0.15 ± 0.01 m2·g−1 for UO2 and 0.77 ± 0.02 m2·g−1 for U3O8, while the surface acidic site densities were determined to be 165 ± 10 sites·nm−2 and 48 ± 3 sites·nm−2 for UO2 and U3O8, respectively.
The Oxidative Dissolution Mechanism of Uranium Dioxide. The Effect of pH and Oxygen Partial Pressure
Authors: Pablo Joan de , Casas Ignasi , Giménez Javier , Clarens Frederic , Duro Lara , Bruno Jordi 
Published: April 2011

ABSTRACTThe dissolution of the unirradiated uranium dioxide, UO2, is largely affected by chemical variables like pe, pH and carbonate concentration in solution. In a previous paper [1], we studied the kinetics of the dissolution of UO2as a function of pH and oxygen partial pressure and the experimental dissolution rates obtained showed a fractional dependence on both parameters. These fractional orders indicate a dissolution occurring via a surface mediated mechanism.In this work we have developed a mechanism accounting for the oxidative dissolution of UO2, which depends on the oxygen concentration in solution and on the pH and a general rate equation has been deduced. This mechanism has been used to explain the results obtained by different authors and to explain and predict the dissolution of the spent nuclear fuel matrix.
Spent Fuel Leaching under Anoxic Conditions and the Effect of Canister Materials
Authors: Cui Daqing , Low Jeanett , Lundström Max , Spahiu Kastriot 
Published: April 2011

ABSTRACTThe results of a spent fuel leaching experiment in which a fuel pin (17.7 g) was contacted with 380 mL of a 10 mM NaCl, 2 mM NaHCO3 solution by taking special care to minimize atmospheric oxygen contamination are presented. During the first 287 days, the fractions of inventory in the aqueous phase per day (f/d) increased nearly constantly for all nuclides (except for 100Mo), but were higher for fission products f/d(137Cs)=1.210−6, f/d(99Tc)=1.1·10−6 and f/d(90Sr)= 6.7 · 10−7 than for actinides: f/d (238U) =1.0 · 10−7, f/d(237Np)= 2.6 · 10−7 and f/d(239Pu) = 5.1 ·10−9. After adding iron, cast iron and copper foils (of ∼30 mm2 size), the concentrations of 238U, 237Np and 99Tc decreased by 80%, 97% and 88% to relatively stable levels (500ppb, 0.2 ppb and 0.6 ppb respectively). 239Pu concentrations increased from a level around 0.05 ppb to PuO2 solubility level, 0.5 ppb, and stabilized. The leaching process for 137Cs, 100Mo and 90Sr seems not to be influenced by the addition of metal foils. The observations in the present work contribute to an improved understanding of the behavior of spent fuel under near field repository conditions.
Evolution of the Cavern-Extended Storage (CES) Concept for Flexible Management of HLW
Authors: McKinley Ian G. , Neall Fiona B. , Smith Paul A. , West Julia M. , Kawamura Hideki 
Published: April 2011

ABSTRACTThe search for greater public acceptance for radioactive waste disposal has meant that repository planning increasingly includes monitoring, institutional control and flexibility with respect to retrieval and reversability. However, the fundamental repository designs are generally unchanged. This paper describes an alternative – the Cavern Extended Storage concept – which aims to incorporate requirements for flexibility and choice for future generations into a deep geological disposal concept that provides a much safer option than extended surface storage.
Absence of enhanced stability in deuterated amorphous silicon thin film transistors
Authors: Lin Shufan , Flewitt Andrew J. , Milne William I. , Wehrspohn Ralf B. , Powell Martin J. 
Published: April 2011

ABSTRACTA comparison of the threshold voltage shift after gate-bias stress in hydrogenated and fully deuterated amorphous silicon thin film transistors (TFTs) is presented. A series of fully deuterated bottom gate TFTs consisting of a deuterated n+ contact layer, deuterated intrinsic amorphous silicon (deposited at a range of pressures) and deuterated silicon nitride gate insulator have been produced. A similar series of fully hydrogenated bottom gate TFTs have also been produced, and the stability of the two sets of devices compared. Deuterated and hydrogenated amorphous silicon deposited under the same process conditions do not have the same material properties due to the difference in the ion energy of H and D in the plasma. However, deuterated and hydrogenated material deposited at the same growth rate have almost identical structural properties. Hydrogenated and deuterated TFTs are found to exhibit the same variation in stability as a function of growth rate. In particular, there is no evidence for increased stability in deuterated TFTs. Previous reports of more stable deuterated TFTs, by other groups, can be explained by a change in the Si network properties due to the higher ion energy of deuterium in comparison with hydrogen, when using similar deposition conditions. The implication of our experimental results is that, for the same amorphous network and hydrogen/deuterium concentration, the stability is identical for hydrogenated and deuterated TFTs. Therefore, there is no giant isotopic effect in amorphous silicon TFTs. The study also further supports the idea that Si-Si bond breaking is the rate-limiting step for Si dangling bond defect creation, rather than Si-H bond breaking.
Correlation between Surface Charge Accumulation and Excitation Intensity Dependent Red-Shifted Micro-Photoluminescence of Si-Implanted Quartz with Embedded Si Nanocrystals
Authors: Lin Chun-Jung , Yu Kuo-Cheng , Kuo Hao-Chung , Ou-yang Miao-Jia , Lin Gong-Ru 
Published: April 2011

ABSTRACTThe excitation intensity dependency of nanocrystallite Si (nc-Si) related micro-photoluminescence (μ-PL) from the multi-recipe Si-implanted quartz is characterized. The μ-PL at 724 nm contributed by nc-Si with 3-4 nm diameter is maximized after annealing at 1100°C for 3 hours. By increasing the excitation intensity from 10 kW/cm2 to 300 kW/cm2, the μ-PLs of 1-hr and 3-hr annealed quartz significantly red-shift from 723 nm to 725 nm and from 724 nm to 735 nm, respectively. This can be explained by the anomalous quantum stark effect due to a surface electric field oriented from photo-ionized nc-Si dots to quartz surface. After 1-hr illumination at power of 300 kW/cm2, the μ-PL peak wavelength of 3-hr annealed sample is further red-shifted by 2.5 nm. By measuring the accumulated surface charges built up during optical excitation process, the correlation between excitation-intensity dependent PL wavelength red-shift and the photo-ionized nc-Si surface electric-field related quantum stark effect is primarily elucidated.