bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sims Depth Profiling Studies of Sphene-Based Ceramics and Glass Ceramics Leached in Synthetic Groundwater
Authors: Hayward P.J. , Hocking W.H. , Doern F.E. , Cecchetto E.V. 
Published: March 2011

ABSTRACTGlass ceramics and ceramics based on the mineral sphene (CaTiSiO5) are being developed to host the wastes arising from possible future CANDU* fuel reprocessing. Results from leaching tests in deionized water and in synthetic groundwater indicate that these materials are highly durable. Secondary Ion Mass Spectrometry (SIMS) depth profiling of leached specimens suggests that leaching in the glass ceramics is predominantly confined to the glass phase. The high ionic strength and composition of the groundwater have a significant passivating effect on leaching and surface alteration phenomena, and encourage the precipitation of new phases on the ceramic surface. Leaching results, scanning electron microscope (SEM) observations and SIMS depth profile measurements are compared and discussed.
Development of a Backfill for Containment of High-Level Nuclear Waste
Authors: Hodges Floyd N. , Westsik Joseph H. , Bray Lane A. 
Published: March 2011

ABSTRACTSodium and calcium bentonites, pressed to densities between 1.9 and 2.2 g/cm3, have hydraulic conductivities in the range of 10−11 to 10−13 cm/s. Batch sorption distribution ratios (Rd) indicate that Sr, Cs, and Am are strongly sorbed on bentonites and zeolites, that Np and U are moderately sorbed on bentonites and zeolites, and that Am, Np, U, I, and Tc are strongly sorbed on charcoal. Sorption results with basalt and tuff ground waters are similar; however, iodine in tuff ground water sorbs more strongly on bentonites Thermal diffusivity measurements for dry, compacted (p ∼ 2.1 g/cm3) sodium bentonite indicate that the thermal conductivity of a high density bentonite backfill should be roughly similar to that of silicate host rocks (basalt, granite, tuff). These results indicate that a bentonite backfill can significantly delay the first release of many radionuclides into the host rock and that by forming a diffusion barrier a bentonite backfill can significantly decrease the longterm release rate of radionuclides from the waste package.
Analysis of the Corrosion Products Formed on Ti and a Ti-Pd Alloy During Exposure in Hot Water
Authors: Olefjord Ingemar , Mattsson HÅkan 
Published: March 2011

ABSTRACTThis is a preliminary report dealing with the surface analysis of reaction products formed on Ti and a Ti-Pd alloy during their exposure in hot water. The compositions of the aqueous media were varied with respect to the dissolved oxygen and the content of chloride ions. The temperature was 60°C and the exposure times were 10 min. and 6 months. Work is in progress in which samples are exposed at 80°C and 95°C in the aqueous solutions. Surface analysis was also performed on a sample which had been exposed in water-saturated bentonite.It appears from the ESCA spectra that the oxide products formed on the surface consist of TiO The results also indicate that the thickness of the film formed at 60°C in water is in the range 50 Å to 100 Å. This is somewhat more than that obtained after exposure in water at room temperature. Exposure for 6 months increases the thickness of the oxide two to three times compared to that obtained during the short exposure at 60°C. The analyses of the samples that had been embedded in bentonite indicate that the surface reaction products are thinner than those found on the surface after exposure in an open vessel.
A Comparison of In-Situ Radionuclide Migration Studies in the Studsvik Area and Laboratory Measurements
Authors: LandstrÖm O. , Klockars C.E. , Persson O. , Andersson K. , Torstenfelt B. , Allard B. , Larsson S.Å. , Tullborg E.L. 
Published: March 2011

ABSTRACTA series of in-situ radionuclide migration tests are in progress in the Studsvik area on the Swedish east coast. Three well defined flowpaths have been located and characterized using non-sorbing tracers (I-131 and H-3), and one of these pathways have been used for a study of the migration of sorbing elements (Sr-85).Laboratory sorption studies with Sr-85 have been performed on materials (rock-water) from the same location as the field tests and with variation of parameters not easily varied in-situ (e.g. pH and nuclide concentration).A fairly good correlation was obtained between retention in natural fractures (field experiment) and laboratory column studies, although the latter were performed on crushed samples of whole rock (retention factors 15 – 30).
Estimating the Permittivity of Solids from Measurements on Granular or Pulverized Materials
Authors: Nelson Stuart O. 
Published: March 2011

ABSTRACTA procedure is outlined for determining the complex permittivity components of solid materials of known densities from those properties of granular or pulverized samples measured at a few different bulk densities. Properties of the solid are obtained by extrapolation of functions of the dielectric constant and loss factor that are linearly related to the bulk density of the air-particle mixture. Examples are given for whole-kernel wheat, ground white rice, and pulverized goethite.
Microwave Evidence for a Size-Induced Metal-Insulator Transition in Mesoscopic Conductors
Authors: Marquardt P. , Nimtz G. , Heite G. , Peters H. 
Published: March 2011

ABSTRACTMicrowave investigations on sub-pm (“mesoscopic”) metal crystals revealed a size-induced metal-insulator transition (SIMIT). The microwaves were applied to determine the sizedependent quasi-static conductivity of metal crystals dispersed in an insulating matrix. Choosing an indium colloid for a model system allowed an in-situ particle size variation from 10 nm up to about 1μm. The experiments were carried out in a microwave bridge at 10 GHz, a frequency where the oscillation time is much longer than the elastic scattering time of electrons in a metal (quasi-static limit). The conductivity of metal crystals was found to decrease approximately with their volumes in the above size range. The 3-dimensional confinement of the electron wave packets gives rise to quantum-mechanical interference effects leading to the SIMIT as the crystals become smaller than 1μm. Experimental details and results including the sizeaffected temperature dependence of the conductivity are presented. The universal significance of the SIMIT and its consequences for the engineering of novel materials and the ultimate size-reduction in microelectronic devices are discussed as well.,
Microwave Dielectric Properties of Metal Filled Particulate Composites
Authors: Ho Yung Shou , Kramer John J. 
Published: March 2011

ABSTRACTComposites of metal filled particulates, Al, Cu, Si(doped), Ag and Ni, up to 45 volume percent in a polyester or epoxy matrix were made and their dielectric properties measured between 8.5 and 11.5 GHz. The particulate size was small relative to the wavelength of the microwave radiation, but in general large compared to the skin depth. For all systems the real part of the dielectric constant increases rapidly with volume fraction filler. Some correlation was also found between the dielectric constant and the average aspect ratio of the particulates, based on the number of particulates in contact. In addition particle type and size was important. The imaginary part of the dielectric constant was small except for samples that appeared to be on the verge of percolation.
Pulsed Microwave Irradiation of Graphite/Epoxy Composites
Authors: James R. B. , Bolton P. R. , Alvarez R. A. 
Published: March 2011

ABSTRACTWe have measured the microwave-induced damage to the near-surface region of a graphite/epoxy composite material for 1.1-μs pulses at a frequency of 2.856 GHz and a pulse power of up to 8 MW. Rectangular samples were irradiated by single-pass TE10 traveling wave pulses inside a WR-284 waveguide, and in situ and post irradiation studies were performed to characterize the material modifications induced by the microwave pulses. The results of the time-resolved optical measurements in vacuo show that surface decomposition of the epoxy resin occurs for incident pulse powers exceeding 1.1 MW, and that the surface damage is accompanied by a large increase in the reflected microwave power. Simultaneous with the onset of surface decomposition, significant light emission from the sample and a large enhancement of the gas pressure in the test cell were observed. The large increments in both the reflected power and light emission are attributed to the formation of a plasma due to electrical breakdown of the gas at (or near) the sample surface.
Rapid Heating of Ion-Implanted Silicon by High-Power Pulsed Microwave Radiation
Authors: James R. B. , Bolton P. R. , Alvarez R. A. , Christie W. H. 
Published: March 2011

ABSTRACTWe have used 1.1-μs microwave pulses at a frequency of 2.856 GHz to rapidly heat the near-surface region of arsenic-implanted silicon. The samples were irradiated inside a WR-284 waveguide by single-pass TE10 traveling wave pulses. Post-irradiation studies show that surface melting occurs for incident pulse powers exceeding about 3 MW. Time-resolved measurements of the microwave reflectivity (R) show that there is an abrupt and large increase in R for microwave pulse powers greater than the melt threshold. Significant light emission was also observed from the test cell, which is most likely due to the relaxation of a microwave-induced plasma formed by electrical breakdown of gas. Using secondary ion mass spectrometry, we measured the depth profile of the implanted arsenic and found that the penetration of the melt front in the near-surface region is not spatially homogeneous over the silicon surface.
Microwave Sintering of Boron Carbide
Authors: Katz J. D. , Blake R. D. , Petrovic J. J. , Sheinberg H. 
Published: March 2011

ABSTRACTBoron carbide has been sintered to 95% of theoretical density in less than 12 minutes without the use of sintering aides by heating to 2000°C with 2.45 GHz microwave radiation. An average grain size of about 20 μm resulted. Twins and microcracking were present in the microstructure. Energy usage for microwave sintering was found to be 18% less than for inductive hot-pressing.
Microwave Processing and Sintering of PZT and PLZT Ceramics
Authors: Harrison W. B. , Hanson M. R. B. , Koepke B. G. 
Published: March 2011

ABSTRACTMicrowave processing techniques were established for all of the thermal treatment steps necessary to prepare high density PZT and PLZT. The microstructure and ferroelectric properties of the microwave processed materials were compared to conventionally sintered and fast fired PZT. Unique high density, small grain size, PZT and PLZT were obtained by microwave sintering either conventionally or fully microwave processed powders. It was estimated that microwave sintering would use only five percent of the energy used by conventional sintering.The suitability of microwave processing for the production of two modifications (Sr and La) of lead zirconate - lead titanate (PZT) ceramics was investigated in this program. A commercial microwave oven was used to evaluate drying, calcining, binder burnoff, and sintering. These materials were then compared to those produced by fast-firing and conventional sintering methods.
Microwave Firing of High Alumina Castables
Authors: Sutton Willard H. 
Published: March 2011

ABSTRACTThe potential for the microwave processing of high alumina castables was investigated*. Originally a study was conducted on the removal of the physical water from cast shapes. However, it was observed that the refractory castable material (alumina plus calcium aluminate phases) would also interact with the 2.45 GHz M/W radiation, and with proper thermal insulation it could be heated to well above 1427°C (2600°F). Full size production shapes, weighing up to 62 kg (136 lb) were heated in a 13.5 kW oven to these high temperatures. Over 1360 kg (3000 lb) of production shapes were successfully fired using M/W energy. The results of these studies are discussed along with several of the benefits which were made possible by microwave processing.
New Frontiers in the Use of Microwave Energy: Power and Metrology
Authors: Bruce Ralph W. 
Published: March 2011

ABSTRACTThe Microwave/Radio Frequency portion of the electromagnetic spectrum has been used principally for the transmission and reception of information in communications and radar. With the advent of low cost commercial and consumer items (satellite downlinks and microwave ovens) has also come a resurgence of interest in using the energy and properties of these frequencies for other important tasks.The purpose of this paper is to give a short review of the basics of electromagnetic heating and an overview of new trends in this use of microwave/RF energy. These trends can be divided into two broad categories: power and metrology.
Design Principles for High-Frequency Microwave Cavities
Authors: Kimrey H. D. , Janney M. A. 
Published: March 2011

ABSTRACTThe characteristics of untuned cavities are determined for microwave processing of alumina. Alumina is a low-loss ceramic that is difficult to heat in the lower microwave region. System efficiency is determined as a function of cavity and workpiece size, frequency, and temperature. With operation at 28 GHz, a cavity applicator can be designed which is capable of generating uniform fields at high efficiency and with a reasonable size.
Temperature Characterization of Pulsed Laser Annealing of Semiconductors
Authors: Kwong D.L. , Kim D.M. 
Published: March 2011

ABSTRACTThe dynamic characteristics of lattice temperature, T attained in Si under the influence of a high power laser beam irradiation are examined analytically over a wide range of laser wavelengths, pulse intensities and durations. The strongly temperature-dependent material parameters, such as optical absorption coefficient α(T) and thermal diffusivity D(T) are incorporated in heat diffusion equation, and their nonlinear coupling effect on the ensuing temperature in laser-processed semiconductors are examined. Specifically, the threshold pulse energy for surface melting is characterized as a function of both material and annealing laser beam parameters. This analytic description of pulsed laser heating of semiconductors should provide considerable insight into the transient heating phenomena and localized material modifications.
Substrate Latent Heat Effects in The Calculations for Pulsed Laser Irradiated Thin Films
Authors: Cao J.J. , Rose K. , Aina O. , Katz W. , Norton J. 
Published: March 2011

ABSTRACTWe present a numerical model for the calculation of the temperature rise caused by pulsed laser irradiation of a thin film/substrate structure. This model includes phase changes in both the thin film and the substrate. The inclusion of phase changes results in more complex thermal behavior and significantly affects melt durations. This model was applied to the AuGe/GaAs system. Morphological observation using the scanning electron microscope and SIMS profiles provides experimental verification for the numerical calculations.
Solid-Phase-Epitaxial Growth of Ion Implanted Silicon Using CW Laser and Electron Beam Annealing
Authors: Narayan J. , Holland O. W. , Olson G. L. 
Published: March 2011

ABSTRACTThe nature of residual damage in As+, Sb+, and In+ implanted silicon after CW laser and e− beam annealing has been studied using plan-view and cross-section electron microscopy. Lattice location of implanted atoms and their concentrations were determined by Rutherford backscattering and channeling techniques. Maximum substitutional concentrations achieved by furnace annealing in a temperature range of 500–600°C have been previously reported [1] and greatly exceeded the retrograde solubility limits for all dopants studied. Higher temperatures and SPE growth rates characteristic of electron or cw laser annealing did not lead to greater incorporation of dopant within the lattice and often resulted in dopant precipitation. Dopant segregation at the surface was sometimes observed at higher temperatures.
Raman Scattering with Nanosecond Resolution During Pulsed Laser Heating of Silicon
Authors: Von Der Linde D. , Wartmann G. , Ozols A. 
Published: March 2011

ABSTRACTWe present time-resolved measurements of spontaneous anti-Stokes and Stokes Raman scattering during pulsed laser heating of crystalline silicon. The time-evolution of the lattice temperature is determined from the measured anti-Stokes/Stokes intensity ratio. In a separate calibration experiment we measure the temperature dependence of the anti-Stokes/Stokes ratio of an oven-heated silicon crystal from 300 K up to 900 K. The phase transition occuring during laser heating is detected by monitoring the changes of the optical reflectivity during laser irradiation. Our data suggest that the phase transition occurs at a lattice temperature of ∼600 K.
Explosive Recrystallization Of Ion Implantation Amorphous Silicon Layers
Authors: Narayan J. , Rozgonyi G. R. , Bensahel D. , Auvert G. , Nguyen V. T. , Rai A. K. 
Published: March 2011

ABSTRACTExplosive recrystallization of amorphous layers, induced by scanned electron or CW Ar+ laser beams, has been investigated in arsenic implanted (100) specimens. We have studied the microstructural changes using plan-view and crosssection electron microscopy to obtain the mechanism of explosive recrystallization phenomenon. The confinement of heat in the amorphous layers during laser irradiation and the nature of amorphous silicon determine the modes of explosive recrystallization. We indicate that, depending upon the degree of undercooling, two distinct modes of liquid-phase recrystallization are observed: one occurring at a velocity of, ∼2 ms−1 and the other at ∼10ms−1. Explosively recrystallized grains contain <110> and <110> as surface normal and growth direction respectively. We present a model for unseeded crystallization to explain the <110> texture observed in diamond cubic lattices.
Visualization of Temperature Profiles in a-Si Crystallized in the Explosive Mode by Ow Laser.
Authors: Rivier Michel , Cserhati Andras , Goetz George 
Published: March 2011

ABSTRACTWe present an experimental method, based on the isothermal nature of the boundaries of explosively crystallized silicon, to display instantaneous isotherms produced by fast scanning laser beams. This method is especially useful for the case of multilayer structures or complex geometries, where thermal profiles simulation is a difficult problem. We can also obtain directly a measure of the spatial intensity distribution in the laser beam.
Picosecond Laser-Induced Surface Transformations in Solids
Authors: Fauchet P.M. , Guosheng Zhou , Siegman A.E. 
Published: March 2011

ABSTRACTWe report the results of a study of surface transformations in semiconductors (Si, GaAs) and metals (Cu) produced by 100 ps long pulses from a Nd:YAG laser system. We present and outline the conclusions of our model for growth of spontaneous periodic surface structures or ripples often associated with laser damage and annealing. The effect of repetitive subthreshold illumination is also examined. Theoretical analysis is presented to support time-resolved experiments performed with two excitation pulses at different wavelengths.
Aligned, Coexisting Liquid and Solid Regions in Pulsed and CW Laser Annealing of Si
Authors: Nemanich R. J. , Biegelsen D. K. , Hawkins W. G. 
Published: March 2011

ABSTRACTAligned, coexisting liquid and solid regions are observed in cw laser annealing of polycrystalline Si films on quartz substrates. These stripe patterns are the precursors of surface topography that exists after cooling. It is proposed that a similar situation exists in the pulse annealing process. A calculation of the temperature evolution which assumes stripe symmetry and kinetic restraints of the crystallization process has been carried out. These calculations indicate a lattice temperature of between 1100 and 1300 K, 10 nsec after the sample has fully solidified.
Interferometric Measurements of Surface Properties During Laser Annealing
Authors: Bertolotti Mario , Ferrari Aldo , Sibilia Concetta , Jani Peter 
Published: March 2011

ABSTRACTA simple interferometric method is presented which allows measurement of small vertical displacement of a surface heated by a laser beam. Calculations applied to a silicon crystal in the case of a c.w. laser show reasonable agreement with experiment. The method can be applied to assess surface temperature and thermal constants.
Pulsed Raman Measurements of Phonon Populations: Time Reversal, Correction Factors, and All That
Authors: Compaan A. , Lo H.W. , Aydinli A. , Lee M.C. 
Published: March 2011

ABSTRACTTransient optic phonon populations are measured in crystalline Si as a function of 532 nm laser energy density. The use of a continuously tunable pulsed dye laser as the Raman probe allows us to obtain, under exact experimental conditions, all correction factors necessary to extract the phonon population without the necessity of relying on room temperature or oven-heated conditions. We find the shift of the 520 cm−1 Raman-line to be consistent with the observed Stokes/anti-Stokes ratios indicating a maximum optic phonon temperature of 450 ± 100°C. A discussion is also given of the errors in several recent criticisms of the Raman results.
Coherent Precipitate Formation In Pulsed-Laser And Thermally-Annealed,
Ion-Implanted Si.*
Authors: Appleton B. R. , Narayan J. , Holland O. W. , Pennycook S. J. 
Published: March 2011

AbstractIt Will be shown that under suitable conditions ion implanted impurities in Si can precipitate and grow coherently within the single crystal lattice during recrystallization induced by pulsed laser or thermal annealing. Ion channeling and transmission electron microscopy (Tem) were used to characterize such precipitates in Si implanted with Sb and B and thermally annealed, and in Si implanted with Tl and annealed with a pulsed ruby laser.The orientations of these precipitates were determined from TEM and detailed angular scans using ion scattering channeling.The nucleation and precipitation processes will be discussed in terms of differences in the liquid and solid phase regrowth mechanisms.
Pulsed Laser Annealing of Ion Implanted Ge
Authors: Holland O. W. , Arayan J. , White C. W. , Appleton B. R. 
Published: March 2011

ABSTRACTIon backscattering/channeling and transmission electron microscopy (TEM) were used to investigate the annealing behavior of ion implanted Ge single crystals using a Q-switched ruby laser. The impurities studied were Bi, In, Sb and Pb, which were implanted at liquid nitrogen temperature into both (100) and (111) crystal orientations. A rather unique damage structure which can form during room temperature implantation of Ge is discussed. Maximum substitutional concentrations, which far exceed the retrograde maxima, are reported for all the dopants studied in (100)Ge. The maximum concentrations were limited by an interfacial instability during epitaxial growth following laser irradiation which led to the formation of a well-defined cellular structure.
Picosecond Time-Resolved Detection of Plasma Formation and Phase Transitions in Silicon
Authors: Liu J. M. , Kurz H. , Bloembergen N. 
Published: March 2011

ABSTRACTPicosecond time-resolved reflectivity and transmission changes of bulk silicon and silicon-on-sapphire have been measured to study the electron-hole plasma formation and phase transitions in silicon, induced by picosecond green or ultraviolet pulses. The results provide direct evidence of ultrafast energy transfer to the lattice and ultrafast phase transitions in silicon. Lattice heating up to the melting point and overheating of the melt or boiling have been observed during the picosecond pulse duration.