bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Control of Epitaxial Growth of LiNbO3 Thin Films on R-Cut Sapphire
Authors: Fujimura Norifumi , Kakinoki Masami , Ito Taichiro 
Published: March 2011

AbstractIt is argued that epitaxial films of ionically-bonded materials are more easily achieved than of covalently bonded materials. Good epitaxy can be achieved despite relatively large lattice mismatch with respect to the substrate. However, the strong influence of interfacial energy can result in difficulty in controlling the orientation of epitaxial films.The crystallographic orientation of ionically-bonded LiNbO3 films was therefore studied. Growth orientation could be controlled by paying attention to the bonding between octahedra in the structure, and to the formation of the octahedra containing lithium and niobium ions. Lithium concentration could be increased by increasing the rf power, 02 partial pressure and total gas pressure, and decreasing the substrate temperature during deposition.The orientation of the film changed from (012) to (100) via (110) by increasing the Li concentration in the film. The (012) and (100) films were epitaxial with respect to the substrate. In particular, the (100) films were of exce lent quality, being single crystalline with smooth surfaces.
Preparation of Ferroelectric Films of LiNbO3 and SbSI by Artificial Epitaxy.
Authors: Pankrashov A.I , Givargizov E.I. 
Published: March 2011

AbstractHighly–ordered, up to nearly–single–crystalline films of SbSI and LiNbO3 on amorphous substrates (oxidized silicon, fused quartz) were prepared by laser zone–melting recrystallization basing on principles of artificial epitaxy, or graphoepitaxy. Some conclusions are made about tentative orientation mechanism(s) in these processes.
Gallogermanate Glasses As Near IR Optical Waveguides
Authors: Higby Paige L. , Merzbacher Celia I. , Aggarwal Ishwar D. , Friebele E. Joseph 
Published: March 2011

ABSTRACTAlkaline earth gallogermanate glasses are a possible low-loss oxide optical material which would be able to operate in the 1.6–2 μm wavelength range. Processing techniques investigated to date and pertinent optical property data are presented.
Materials Aspects of Optical Amplifiers
Authors: DiGiovanni D. J. 
Published: March 2011

ABSTRACTOptical amplifiers promise to revolutionize optical communication. Erbium-doped silica fiber amplifiers operating at 1.5 μm are now commercially available while the performance of devices using neodymium or praseodymium doped fiber in the 1.3 gtm telecommunications window are improving rapidly. This review discusses the importance of host material on amplifier characteristics.
Concentration Effect of Erbium-Doped Silica Based Multi-Component Glass Fibers
Authors: Morishita Y. , Muta K. , Sugiyama N. 
Published: March 2011

ABSTRACTSilica based multi-component glass fibers were fabricated using core glass doped with erbium concentration in the range of 650 to 34000wtppm. The highest gain of 18dB was achieved at the Er3+ concentraion of 7000wtppm under pump wavelength and power of 1.48μm and 40mW, respectively. The gain decreased at concentration over 7000wtppm due to clustering of Er3+ ions. The increases in the threshold value of the pump power caused by clustering of Er3+ ions was also recognized.
Erbium Doped Tellurite Glasses
Authors: Wang Jau-Sheng , Snitzer Elias , Sigel George H. 
Published: March 2011

ABSTRACTThe results to be presented focus on the optimization of tellurite glass compositions which are suitable both for doping with erbium oxide as well as subsequent for fiber drawing. The laser related properties, such as fluorescence spectrum, lifetime, and optical transition cross sections will be presented. Judd-Ofelt parameters for erbium in the glasses have been exploited to predict fluorescence lifetime, excited state absorption(ESA), ground state absorption(GSA) and ground state fluorescence(GSF). For comparison, the absorption cross section, emission cross section, excited state absorption(ESA)/ground state absorption(GSA)(0.8μm pumping) and fluorescence terminating in the ground state(GSF)/excited state absorption(ESA) ratios are calculated for both Al2O3-SiO2 and tellurite glasses.
Nonlinear Optical Properties of Cds-SiO2 Glass Composite Thin Films Prepared by RF-Sputtering
Authors: Tanahashi I. , Yoshida M. , Manabe Y. , Mitsuyu T. , Tokizaki T. , Nakamura A. 
Published: March 2011

ABSTRACTCdS-microcrystallites-embedded films of SiO2 were successfully prepared by rf-sputtering. The optical absorption edge of the film with 18.5 at% CdS clearly exhibited a blue shift by 0.13 eV compared to bulk CdS, indicating the quantum size effect due to confinement of electrons and holes in CdS microcrystallites. The blue-shift decreased with increasing the CdS concentration. The photoluminescence spectra of the films also exhibited the blue shift in band-edge emission. From decay curves of the band-edge emission, the dominant decay time was estimated to be 100 ps, and longer components were weak. Optical nonlinear susceptibility of the films was measured by degenerated four-wave mixing experiments near band-edge. The third-order nonlinear susceptibility was estimated to be 5.0 × 10−7 esu at 77K for the film with 46.3 at% of CdS.
Anisotropic Metallic Island Films for Polarizers
Authors: Baba Kazutaka , Katsu Jun-Ichiro , Miyagi Mitsunobu 
Published: March 2011

ABSTRACTUltra-thin gold island films with optical anisotropy have been fabricated by stretching ordinary isotropic island films in the high temperature. The origin of optical anisotropy seems to come from an elongated prolate island shape.
Waveguides Fabricated in LiNbO3 by Proton Implantation
Authors: Moretti P. , Thevenard P. , Wirl K. , Hertel P. 
Published: March 2011

ABSTRACTOptical planar waveguides, with a controllable thickness in a very wide range, typically from 3 to 20 μm, can be fabricated by thermally controlled proton implantation in LiNbO3. In the nuclear stopping region at the end of the ion's tracks a sufficient decrease in refractive index is obtained, thus forming an adequate optical barrier. The mode confinement was investigated by dark line mode spectroscopy, and the refractive index profiles were reconstructed. The effects of different ion fluences and ion energies in the Mev range on the refractive index profile at 300 K have been investigated.
Surface Chemistry of Fe Oxide Impregnated Porous Vycor Glass
Authors: Sunil D. , Rafailovich H. , Sokolov C. , Gafney H. D. , Schwarz S. A. , Wilkens B. J. 
Published: March 2011

ABSTRACTX-ray absorption and Mossbauer spectroscopy were used to study chemical and magnetic properties of photodeposited Fe in Porous Vycor Glass(PVG). Extended X-ray Absorption Fine Structure(EXAFS) measurements of Fe samples show that after photolyzation, the Fe atoms are surrounded by two shells of six oxygen atoms and eight Fe atoms. The Fe-O and Fe-Fe distances are 1.84 °A and 1.99 °A respectively. After heating to 650 °C and 1200 °C shortening of bond lengths are observed. The second shell of Fe in unheated and heated to 650 °C samples have Fe-Fe distances of 3.0 °A and 2.98 °A respectively. Samples consolidated at 1200 °C show the Fe atoms to be surrounded by two shells of Fe atoms at 2.86 and 3.03 °A. This data together with Mossbauer and XANES spectra suggest that Fe exists in two different configrations, one is an Fe-Fe compound and the other is an octahedral Fe oxide similar to Fe2O3.
Materials Effects on the Radiation Sensitivity of Single Mode Optical Fibers, II
Authors: Friebele E. J. , Askins C. G. , Putnam M. A. , Harrington C. C. , Gingerich M. E. , Schmidt W. H. 
Published: March 2011

ABSTRACTThe effect of varying single mode fiber fabrication factors such as core and clad dopant concentrations, deposition conditions, and draw parameters on the recovery of the nuclear radiation-induced attenuation at 1.3 μm has been studied. Statistically significant correlations of core factors have been established with a 24 experimental design, and separate one-dimensional experiments revealed the effect of clad [Ge] and [F].
Pulse Energy Dependence of Defect Generation in Bragg Grating Optical Fiber Materials
Authors: Tsai T. E. , Askins C. G. , Friebele E. J. 
Published: March 2011

ABSTRACTGe-associated defect centers induced by 5 eV (∼ 245 nm) photons of various intensities in Ge-doped silica were studied using electron spin resonance (ESR). We found that Ge E' centers observed in Bragg grating Ge-doped silica core fibers are induced and bleached by one- and two-photon absorption processes, respectively. The observation that Ge E's are the only paramagnetic centers induced by low intensity 5 eV photons supports the proposal that the Ge E' center is responsible for the photoinduced structures observed in both Bragg grating and second-harmonic-generation (SHG) fibers.
Characterization of Critical Properties of Optical Fiber Coatings
Authors: Shea John W. , Turnipseed John M. , Taylor Carl R. , Petisce James R. , Overton Bob J. 
Published: March 2011

ABSTRACTThis paper describes four key measurements of critical coating performance attributes which can affect coated optical fiber performance. The four measurement methods to be described are: 1) primary coating adhesion, 2) coating toughness, 3) primary coating equilibrium modulus, and 4) primary coating glass transition temperature.
The Hydrothermal Stability of Cement Sealing Materials in the Potential Yucca Mountain High Level Nuclear Waste Repository
Authors: Krumhansl J. L. , Hinkebein T. E. , Myers J. 
Published: March 2011

ABSTRACTCementitious materials, together with other materials, are being considered to seal a potential repository at Yucca Mountain. A concern with cementitious materials is the chemical and mineralogic changes that may occur as these materials age while in contact with local ground waters. A combined theoretical and experimental approach was taken to determine the ability to theoretically predict mineralogic changes. The cementitious material selected for study has a relatively low Ca:Si ratio approaching that of the mineral tobermorite. Samples were treated hydrothermally at 200°C with water similar to that obtained from the J-13 well on the Nevada Test Site. Post-test solutions were analyzed for pH as well as dissolved K, Na, Ca, Al, and Si. Solid phases formed during these experiments were characterized by scanning electron microscopy and X-ray diffraction. These findings were compared with predictions made by the geochemical modeling code EQ3NR/EQ6. It was generally found that there was good agreement between predicted and experimental results.
Interactions between Concrete and Brine at the Waste Isolation Pilot Plant (WIPP) Site, New Mexico
Authors: Lambert Steven J. , Nowak E. James , Wakeley Lillian D. , Poole Toy S. 
Published: March 2011

ABSTRACTA concrete liner emplaced in 1984 in a shaft at the Waste Isolation Pilot Plant has served as a natural laboratory for observing interactions among concrete, evaporite rocks, and brine. During a routine inspection of the liner in the spring of 1990, discoloration, deposition of secondary salts, wet areas with exposed aggregate grains, softening of paste, surficial spalling, and cracking were observed locally on the concrete surface of the liner. Some construction joints showed apparent leakage of brine from behind the liner, which was nominally 50 cm thick. Seepage brines were nearly saturated relative to CaCl2 and contained lesser amounts of MgCl2 and KCl, and minor NaCl. The liner surface was locally altered to a 1–2 cm friable hygroscopic layer containing little cement paste; concrete cores (7 or 10 cm diameter) through the liner at depths of 248, 254, 255, and 271 m showed similar degrees of alteration at the liner/rock interface. The most profound alteration of concrete was developed in a ˜7 cm zone sub-parallel to and straddling the construction joint cored at a depth of ˜254.5 m. This zone was extensively microfractured, transected aggregate grains, and contained brucite, gypsum, magnesium hydroxychloride hydrate, and locally calcium chloroaluminate instead of the usual phases of hydrated portland cement. Several mechanisms of chemical degradation have been proposed, the most likely being attack by magnesium ions.
Synthesis, Crystal Chemistry and Stability of Ettringite, A Material with Potential Applications in Hazardous Waste Immobilization
Authors: McCarthy Gregory J. , Hassett David J. , Bender Jason A. 
Published: March 2011

ABSTRACTRecent results on synthesis, crystal chemistry, structure and stability of ettringite*, with specific reference to use of this material in hazardous waste immobilization, are presented. Ettringites with selenate, chromate, borate, sulfite and carbonate replacing sulfate have been synthesized and characterized by XRD for phase purity and structure. In X-ray powder diffractograms, selenate and chromate etringites have the normal trigonal P31cettringite structure, whereas the borate, sulfite and carbonate ettringites can be indexed on a hexagonal unit cell with a halved c parameter. In excess of 95% of the Se and B in solutions spiked with various concentrations of these elements has been removed by precipitation of ettringite. Ettringites appear to be unstable in solutions outside of the approximate pH range 11.0-12.5, and there is a potential for some oxyanion exchange between ettringites and oxyanion-containing solutions. Buffering of pH, and dissolved Ca, Al and sulfate activities by other components of ettringite-based hazardous waste forms, combined with low-reactivity C-S-H matrices, could largely mitigate these concerns.
Cross-Linking Reactions in Macro-Defect Free Cement Composites
Authors: Desai P. G. , Young J. F. , Wool R. P. 
Published: March 2011

ABSTRACTThe key to the processing and properties of Macro-Defect Free (MDF) cement composites is the interaction between the cement and the polymer. In calcium aluminate (CA) / polyvinyl alcohol (PVA) MDF composites, it has been hypothesized that aluminate (Al(OH)4−) ions released from the cement cross-link PVA in a manner similar to the well known interaction of the borate (B(OH)4−) ions with PVA. In this investigation, stable aluminate/PVA solutions at different concentrations have been studied. Results indicate that the nature of interaction of aluminate ions is not similar to that of borate ions in dilute and semidilute polymer solutions.
Self-Generating Zeolite-Cement Composites
Authors: Larosa Judith L. , Kwan Stephen , Grutzeck Michael W. 
Published: March 2011

ABSTRACTZeolites can be synthesized in mixtures containing 80 wt% Class F fly ash and 20 wt% ordinary Portland cement if they are mixed with a concentrated NaOH solution and cured at temperatures of 60–90° C. Zeolite Y and NaP-type zeolite were grown in situ in a coexisting calcium silicate hydrate matrix. Those samples made with NaOH, which contained the zeolites, had higher compressive and flexural strengths than equivalent samples made with water.
The Use of Natural Fiber in Cementitious Composites
Authors: Chen Y. , Park C.K. , Silsbee M.R. , Roy D.M. 
Published: March 2011

ABSTRACTVariations in the mechanical properties of wood fiber reinforced cementitious (WRFC) materials containing treated fiber and water soluble polymers were investigated. Flexural strength is greatly improved by the addition of polymer. The interface bonding is enhanced by the fiber pre-treatment. The mechanism responsible for the strength increase in WRFC was studied by mercury intrusion porosimetry. Experimental results indicate that the increased strength results from an enhancement in the strength of the interface and reduced porosity.
Effects of Interfacial Zone Percolation on Cement-Based Composite Transport Properties
Authors: Snyder K.A. , Winslow D.N. , Bentz D.P. , Garboczi E.J. 
Published: March 2011

ABSTRACTIn portland cement mortar and concrete, interfacial zones exist around the aggregate particles that have larger pore sizes and pore volumes than the bulk cement paste. If there are enough aggregate particles present, these zones may overlap so as to percolate. A computer simulation model has been developed that can predict this percolation point as a function of interfacial zone thickness, volume fraction of aggregates, and aggregate particle size distribution. The model was used to simulate 1cm3 of mortar, using approximately 10,000 aggregate particles. Results from this model are used to explain recent mercury porosimetry results on mortars having a variety of sand contents. The implications of interfacial zone percolation for the transport properties of mortar and concrete are discussed.
In Situ Transmission Electron Microscopy (TEM) Investigation of Fracture Mechanisms in a Calcium Aluminate MDF Cement.
Authors: Popoola O. O. , Kriven W. M. , Young J. F. 
Published: March 2011

ABSTRACTFracture mechanisms in calcium aluminate macro-defect-free-cement were studied by in situ deformation in the TEM. Fracture occurred predominantly at the cement / polymer interface. The toughening mechanism involved crack bridging at the interphase / polymer interface. XPS studies of the chemistry of the interphase revealed it to be made up of an AlOC complex in addition to the amorphous hydration product phase.
Microstructural Development in Pore Reduced Cement (PRC)
Authors: Macphee D.E. , Lachowski E.E. , Taylor A.H. , Brown T.J. 
Published: March 2011

ABSTRACTPore Reduced Cement (PRC) is a high density, high strength material which may have specialist use in the construction industry. It is produced by the high pressure processing of Ordinary Portland cement (OPC) pastes, or blends of OPC with certain supplementary cementing materials, such that effective water/cement ratios (w/c) are significantly reduced relative to those used for mixing. A previous paper [1] describes the mechanical properties of PRC (patent pending) during the early stages of product development and more recent data show that improved preparative techniques are leading to increasing densities and strengths. However, fundamental data on the microstructure, mineralogy and durability properties have not previously been reported. The present paper is directed towards the study of microstructural development in the closely compacted matrix using electron microscopy. Mineralogical and porosity data are also presented.
Setting and Strengthening Mechanisms of Cementitious Materials
Authors: Jiang W. , Roy D.M. 
Published: March 2011

ABSTRACTThis paper highlights the physico-chemical characteristics of cementitious materials responsible for or involved in setting, and how these are related to the strengthening and mechanical properties. Five main mechanisms which can be used to increase cementitious materials strength were discussed. The substantially improved cement matrix materials can be obtained by deliberately using one or more above mechanisms. Experiments have been performed on ordinary portland cements and phosphate cements used as construction materials, whose setting time is several hours, and dental cement, whose setting time is several minutes.
Conversion of Red Muds into Pozzolans
Authors: Pera Jean 
Published: March 2011

ABSTRACTRed muds are waste materials obtained from the aluminium extraction industry. They consist mainly of clays, aluminium and iron hydrated oxides. Three muds were studied; they differed in chemical and mineralogical compositions. They were converted into reactive pozzolans by calcination in the temperature range 600–800°C for five hours. Pozzolanicity was investigated on calcined red mud-OPC mixes studying strength development and lime consumption as evaluated by DTA. The nature of hydrates formed during hardening was also identified.The mineralogical composition of the mud is the most important factor affecting its pozzolanicity. Blended cements containing 30% calcined red mud develop significant strengths.
Ferroelasticity, Pseudoelasticity, and Shape Memory Effect in an Ionic Material Pb3(PO4)2
Authors: Yamada Y. 
Published: March 2011

AbstractA theory of pseudoelasticity is developed within the framework of the phenomenological Ginzburg-Landau Scheme. The system with ℈stripe℉-type ferroelastic domain structure has been discussed using Transfer-Integral method, which directly gives the equillibrium density of domain boundaries and the response of domain pattern against the external stress. The results are applied to the case of Pb3(PO4)2, an ionic ferroelastic material which shows pseudoelasticity and shape memory effect. It is suggested that in this particular case, random stress field is mainly responsible for pseudoelastic behavior. The observed stressstrain curve has been analyzed quantitatively from this standpoint. The origin of the two-way shape memory effect has also been inferred qualitatively from the same stand point.
The Effect of Cyclic Transformation on the Shape Memory Characteristic in an Fe-Mn-Si-Cr-Ni alloy
Authors: Ohtsuka Hideyuki , Kajiwara S. , Ishihara T. 
Published: March 2011

AbstractEvaluation of the shape memory characteristics under thermal and stress cycles is indispensable to ensure the reliability of shape memory alloys used in nuclear power reactors. Then the effect of γ↔E cyclic transformation on the shape memory characteristics was investigated in Fe-14Mn-6Si-9Cr-5Ni (wt%) alloy. ε martensites were stress-induced by pulling specimens at room temperature, and they were reverse transformed by heating under various stresses. The change of surface relief during reverse transformation was observed by a hightemperature optical microscope equipped with a tensile machine. The recovery stress was measured by this apparatus after the “yclic transformation” was repeated various times. The reverse-transformed microstructures were observed by transmission electron microscopy. As a result, the amount of residual ε martensite increased with increasing stress applied during reverse transformation. As the “cyclic transformation” was repeated, the recovery stress remarkably increased at first, and then gradually decreased. This rapid increase of recovery stress is attributed to not only the increase of elongation when specimen is deformed but also the increase of stacking faults which act as nucleation sites of martensite. The decrease of recovery stress is attributed to the decrease of elongation.
Characterization of NiTi Shape Memory Wires by Differential Scanning Calorimetry and Transmission X-ray Diffraction
Authors: Kao Ming-Yuan , Fariabi Sepehr , Thoma Paul E. , Ozkan Husnu , Cartz Louis 
Published: March 2011

AbstractThe reversible transformations between the Austenite (A) and Martensite (M) phases of NITI shape memory wires having a 78°C austenlte finish temperature (950°C annealed) were studied In the cold work and heat treatment ranges between 14 to 62% and 400 to 525°C respectively. The ranges of peak Transformation Temperatures (TI), determined by Differential Scanning Calorimetry (DSC) at a 10°C/min rate, were found to be 56 to 75°C, -28 to 33°C, and 38 to 52°C for the respective high temperature A, low temperature M, and the Intermediate Rhombohedral (R) phases. The degree of cold work and heat treatment had significant effects on the TT of NITI wires. The peak TT of A and M decreases with Increasing cold work. Except for the 14% cold worked wires, the peak TT Increases with Increasing heat treatment temperature for M, and Increases with Increasing heat treatment temperature for A for temperatures higher than 450°C. The peak IT of R Increases with Increasing cold work and decreasing heat treat temperature.Using MoKα radiation, transmission x-ray diffraction analysis was utilized to determine the phases at room temperature on wires thinned down to 0.05 to 0.01 mm in diameter. The diffraction patterns of body-centered cubic austenite (132) and monodlinic martenslte (B19) for NITi were both Identified. In addition, extra diffraction lines observed for various samples were tentatively assigned to M and the Intermediate R-phase. Depending on the thermal history and the processing conditions, the NITI wires consist of either a pure M, a mixture of A and R, or a mixture of A, R, and M at room temperature.