bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Investigation of Metamict And Annealed Natural Pyrochlores by XRAY Absorption Spectroscopy
Authors: Greegor R. B. , Lytle F. W. , Chakoumakos B. C. , Lumpkin G. R. , Ewing R. C. 
Published: March 2011

AbstractThe pyrochlore structure type, A1−2 B2 O6 Y0−1, is a common phase in polycrystalline waste forms. A principal concern has been the effect of alpharecoil events on the longterm stability of these phases. Naturally occurring minerals of the pyrochlore group provide an example of the full range of radiation effects from fully crystalline to xray diffraction amorphous (the metamict state). Xray absorption spectroscopy is used to investigate the coordination geometry of Tisites in metamict and annealed (1,000°C) pyrochlores. The principal effects in the fullydamaged material (∼4026 alpha events/m3) compared to annealed samples include an increase in the asymmetry of the Tisite and a slight reduction in bond length and coordination number.
Irradiation-Induced Reduction of Microcracking in Zirconolite
Authors: Clinard F. W. , Tucker D. S. , Hurley G. F. , Kise C. D. , Rankin J. 
Published: March 2011

Abstract238Pu-substituted zirconolite (CaPuTi 2O7 ) was stored near ambient temnerature for 231 days, equivalent to an aipha decay dose of 3.1×1025 α/m3 or 3×105 years of storage time for SYNROC ceramic nuclear waste. Periodic indentation testing showed that hardness was decreased by alpha decay-induced conversion to the metamict state, while fracture toughness and resistance to cracking were increased, apparently as a consequence of the formation of a heterogeneous microstructure. These results imply improved stability of this nuclear waste phase as a result of self-irradiation damage.
Hot Cell Preparation of Tesiing Materials
Authors: Thornhill R. E. , Knox C. A. 
Published: March 2011

AbstractIt is important in nuclear waste repository development that testing be done with materials containing a radionuclide spectrum representative of actual wastes. To meet the need for such materials, the Materials Characterization Center (MCC) has prepared simulated high level waste (HLW) glasses with radionuclides representative of about 10-, 300-, and 1000-year-old waste. A quantity of well characterized spent fuel also has been acquired for the same purpose. Glasses containing 10- and 300-year-old wastes, and the spent fuel specimens, must be fabricated in a hot cell. Hot cell conditions (high radiation field, remote operation, and difficulty of repairs) require that procedures and equipment normally used in materials preparation out-of-cell be modified for hot cell applications.This paper discusses the fabrication of two glasses, and the preparation of test specimens of these glasses and spent fuel. One of the glasses is a 76–68 composition, which is fully loaded with actual commercial reactor fission product waste. The other glass contains simulated Barnwell Nuclear Fuel Plant waste, doped with different combinations of fission products and actinides. The spent fuel is a 10-year-old PWR material. Special techniques have been used to achieve high quality, well characterized testing materials, including specimens in the form of segments, wafers, cylinders, and powders of these materials.
The Role of Statistics in Characterizing Nuclear Waste Package Behavior
Authors: Bowen William M. 
Published: March 2011

AbstractThe characterization of nuclear waste package behavior is primarily based on the outcome of laboratory tests, where components of a proposed waste package are either individually or simultaneously subjected to simulated repository conditions. At each step of a testing method, both controllable and uncontrollable factors contribute to the overall uncertainty in the final outcome of the test. If not dealt with correctly, these sources of uncertainty could obscure or distort important information that might otherwise be gleaned form the test data. This could result in misleading or erroneous conclusions about the behavior characteristic being studied. It could also preclude estimation of the individual contributions of the major sources of uncertainty to the overall uncertainty. Statistically designed experiments and sampling plans, followed by correctly applied statistical analysis and estimation methods will yield the most information possible for the time and resources spent on experimentation, and they can eliminate the above concerns. Conclusions reached on the basis of such information will be sound and defensible. This presentation is intended to emphasize the importance of correctly applied, theoretically sound statistical methodology in characterizing nuclear waste package behavior.
Current Technical Issues Related to Near-Field Materials Testing
Authors: Shade John W. 
Published: March 2011

AbstractSome test parameters have become issues in test development either because they are difficult to measure and control or because the significance of their effect on waste form dissolution and alteration is unknown. Issues identified by the MCC are Eh/pH system effects, SA/V effects, temperature effects on sampling, waste package composition effects, colloid formation and stability, radiolysis, and formation kinetics and stability of secondary reaction products. These issues are addressed by the MCC through literature reviews, workshops, and direct investigation with the objective of recommending methods for resolving them. This paper summarizes their status and attempts to identify needs required for their resolution.
Cleanout of Waste Storage Tanks at Oak Ridge National Laboratory
Authors: Weeren H. O. , Lasher L. C. , McDaniel E. W. 
Published: March 2011

AbstractIn 1943, six storage tanks were built at the Clinton Laboratories [later to become Oak Ridge National Laboratory (ORNL)] to contain wastes generated by wartime research and development operations. During the following years, these tanks became an integral part of the ORNL waste system and accumulated ∼1.5 × 106 L (400,000 gal) of sludge containing radioactive wastes. Recently, over a period of ∼18 months, these tanks were sluiced, the radioactive sludge resuspended, and the resuspended slurry pumped to the ORNL Hydrofracture Facility for underground disposal.In this paper, a summary of the development work is given, and the process design and constraints are described. The operating difficulties encountered and overcome included grinder blade erosion, malfunctioning instruments, pump suction plugging, and slurry settling. About 90% of the settled sludge (containing ∼715,000 Ci) was removed from the system.
Technetium Volatilization During HLLW Vitrification
Authors: Lammertz H. , Merz E. , Halaszovich S. T. 
Published: March 2011

AbstractThe volatilization of technetium in the course of high-level waste vitrification may be considerable, depending on process variations. A series of experiments has been performed in order to gain more insight into the vaporization behavior of Tc during HLLW vitrification. No losses have been observed during chemical denitration or drying of the solutions on a drum drier at moderate temperatures. However, substantial volatilization (40–60 %) occurred during high temperature processing which applied either liquid feeding or feeding as a dehydrated product into the glass melter. Details of parameters investigated are described, and consequences for technical process application are discussed.
Sorption of Cesium, Strontiuli, Iodine and Carbon in Concrete and Sand
Authors: Hietanfn Raija , Jaakkola Timo , Miettinen Jorma K. 
Published: March 2011

AbstractConcrete is a potential construction, waste package and backfill, material for disposal- of low and intermediate level nuclear wastes. Sorption of 90Sr, 137Cs, 129I and 14C in concrete and in sand ballast used as aggrepte of concrete was determined by measurement of 85Sr, 134Cs, 125I and 14C isotopes using the batch method. Natural ground waters from planned disposal sites were used, and for aggregate also ground water equilibrated with concrete. The sorption order of the different samples for cesium and strontium was Kd (aggregate + ground water) > Kd (concrete + ground water)> Kd (aggregace + ground water equilibrated with concrete). For iodine and carbon the order was Kd (concrete + ground water)> Kd (aggregate + ground water equilibrated with concrete)> K (aggregate + ground water). In the case of cesium the K -values were > 100 ml/g for all samples. The Kd -values of strontium were <25 ml/g and of iodine< 10 ml./g. The Kd -values of carbon were about 2 and 100 and 2 000 ml/g for aggregates with around water, aggregates with ground water equilibrated with concrete and concrete with ground water, respectively.
The Interaction of Bituminized Ion-Exchange Resins With Different Leachants
Authors: Valkiainen M. , Vuorinen Ulla , Uotila Paula 
Published: March 2011

AbstractLeaching tests on bituminized ion-exchange resins from Olkiluoto power plant were made according to ISO/DIS 6961 in deionized water and groundwater. Simulated waste products including Cs and Sr were leached in cement water. A clear difference is seen between the water types. With cobalt in granular resins the leach rate in groundwater is three orders of magnitude higher than in deionized water, the latter being in the order of 10–15 m/s.The bituminized cation exchanger is still operating and changing ions with the surrounding water. Bitumen provides a hindering diffusion barrier.Bituminized resin absorbs water from the surroundings and the weight (and volume) of the product increases 10–80 % in 898 days compared to the original value. The weight increase is slower with bituminized powdered resins than with granular resins.Due to differencies in densities between bitumen and both anion and cation ion-exchangers, a distinct sedimentation effect of granular mixed bed exchangers is observed. The cation exchanger is separated on the bottom of the 200 1 drum while the anion exchanger is separated in the upper part of the drum.
Oxygen Implanted Layers in Silicon Electrical and Microstructural Characterization
Authors: Varker C. J. , Wilson S. R. , Chan S. S. , Whitfield J. D. , Krause S. J. 
Published: March 2011

ABSTRACTWe report on an investigation of ‘buried’ oxygen implants formed by 0+ implantation at 400 KeV and 3.5 MeV into p-type CZ (100) wafers with a dopant density NA 1015 cm−3. Peak concentrations of 1 × 1019 cm−3 to 2 × 1020 cm−3. were investigated. Test devices were fabricated on implanted and annealed wafers using conventional wafer processing. For the 400 keV implants, a 4 µm epitaxial buffer layer was grown subsequent to the 0+ implant. For a dose of 3 × 1015 cm−2 the lifetime reduction ratio for the effective generation lifetime τg at the implant peak is greater than 103 relative to an unimplanted region where τg = 150 µS. C-V and SRP profiles show evidence for oxygen donor compensation. TEM analysis reveals a well defined layer at 1 µm with respect to the original implant surface containing a relatively high density of small precipitates and dislocation loops. DLTS measurements on diodes reveal 2 electron traps designated as E1 and E2. The trap energy ∆E and capture cross section σ are (EC-ET)1 = 0.41 ± 0.020 eV and (EC-ET)2 = 0.22 ± 0.030 eV with σ 1019 cm-3. The estimated trap density NT for the dominant trap is 8.2 × 1013 cm−3 for a calculated peak 0+ implant concentration of 6.8 × 1019 cm−3. The values of ∆E are in good agreement with values for unimplanted CZ wafers subjected to 2-step precipitation anneals. The experimental results provide direct evidence that ion implantation provides an effective method of introducing atomic oxygen in silicon at concentration exceeding its solid solubility during processing to produce a buried low lifetime region.
The Effect of Incomplete Collision Cascades on The Angle of Ion Incidence Behaviour of Interface Mixing
Authors: Webb R.P. , Wilson I.H. 
Published: March 2011

ABSTRACTA new geometrical theory of sputtering is extended to investigate the behaviour of interface mixing as a function of the angle of ion incidence. It is found that the amount of mixing peaks with the angle of incidence at different angles depending upon the depth of the interface. When the interface is at the surface the mixing parameter behaves as the sputtering yield and maximises around 70°, whilst deeper interfaces, around the damage range, have maximum mixing at normal incidence.
A Self-Annealing Technique for Simultaneous Titanium Silicide and N+/P Junction Formation
Authors: Finetti Manuela , Gabilli E. , Lotti R. , Lulli G. , Merli P.G. , Nipoti R. , Antisari M. Vittori 
Published: March 2011

ABSTRACT- P+ self-annnealing implantations through evaporated Ti is performed to simultaneously form the silicide and the junction underneath, avoiding the need for further post-implantation thermal treatments. The formation of the TiSi2, phase and the good quality of the silicon-silicide interface are observed, when operating at power densities ≤ 16 W/cm2. Deep phosphorus distributions extending below the silicide down to 480÷600 nm are obtained.
Boltzmann Transport Equation Analysis of Ion Implantation Range and Damage Distributions
Authors: Gibbons James F. , Christel Lee A. , Giles Martin D. 
Published: March 2011

ABSTRACTThe Boltzmann transport equation has been used to calculate range anddamage distributions in multilayer targets of general interest for semiconductor fabrication. A comprehensive review of the calculations will be presented, with particular emphasis on how large angle scattering events and channeling phenomena may be included. Examples of the quality of fit between the theory and experiment show that difficult phenomena (such as residual channeling) can be reasonable modelled.
Line-Shaped Electron Beam System and Soi Films Prepared by The System
Authors: Hayafuji Y. , Shibata A. , Yanada T. , Sawada A. , Usui S. , Kawado S. , Hayashi H. 
Published: March 2011

ABSTRACTThe line-shaped electron beam annealing system which generates an electron beam of a length of 4 cm and a width af less than 100 um with a high energy density exceeding well over 100 kW/cm2 was developed for the first time with a purpose of SOI processing as its primary application. An pccelaration voltage of up to 20 kV can be used in this system. Seeded single crystalline islands with areas several mm long and 30 to 100 um in width were obtained by a single scan of the electron beam. The electron beam is generated in a pulsed way in the system due to the power restriction of the power supplies. An area of 4×5 cm2 was processed by a single scan of an electron beam at a sample speed of 530 cm/sec and a beam duration of 9.5 msec. The scanning area for one scan is determined by the beam length and the duration of the beam and sample speed.The present system could give single crystalline silicon films without any grain boundaries. The electron mobility of the electron beam recrystallized films, obtained from FETs made as a vehicle to test the electrical properties of the films, was comparable to that of the bulk silicon. A very rapid migration of silicon atoms in solid polycrystalline silicon films, which is controllable by process parameters, was also found with a migration speed of the order of 1 m/sec in a capped structure. The present electron beam system is useful in studying basic mechanisms of crystal growth in thin films. The system can have a very high throughput, a desirable feature in semiconductor industry. The present system can also be used to study the rapid thermal treatment of materials other than semiconductors including rapidly solidified materials.
Determination of Optimal Rapid Thermal Annealing Exposure Time and Pulse Rising Rate for Minimum Impurity Redistribution
Authors: de Araujo Carlos A. Paz , Ting-Ao Tang 
Published: March 2011

ABSTRACTA simple relationship for rapid thermal annealing exposure time for the case of annealing of boron and arsenic high dose shallow implants is found from first principles. The percentage of redistribution is found to be intrinsically dependent on exposure time and rate of temperature rise in the heat pulse. An upper bound of pulse rising rate for a given percentage tolerance in redistribution is also found. Extensive SIMS analysis shows very good agreement of these formulae with experimental data.
A Model of Amorphous Silicon Layer Regrowth
Authors: Ling P. , Washburn J. 
Published: March 2011

ABSTRACTA new model which combines heterogenous nucleation and growth process to explain the mechanism of the crystal regrowth of amorphous silicon, in contact with a Si single crystal substrate, is presented. This model explains the effects of substrate orientation and impurity concentration on the kinetics of crystal regrowth. A comparison of experimental results with the predictions of the model is also included.
Prediction of High Dose Ion Implantation Profiles as Influenced by Radiation Induced Transport and Sputtering
Authors: Rangaswamy M. , Farkas D. 
Published: March 2011

ABSTRACTVarious models for predicting high fluence ion collection profiles are reviewed. Recent calculations based on the diffusion approximation are described. The solute and defect probability distributions are calculated by a MONTECARLO code, TRIM. The method takes into account the effects of sputtering, including preferential sputtering of one of the components, and lattice dilation. In addition, the effects of radiation enhanced diffusion and radiation induced segregation are also considered. The calculations include the coupling of solute and defect fluxes. The described formalism can account for observed maximum attainable concentrations and distributions in high fluence implantation conditions of practical interest.
Electronic-Structure Calculation of 3d Transition-Metal Point Defects in Silicon
Authors: Beeler Franz , Andersen Ole K. , Scheffler Matthias 
Published: March 2011

AbstractThe states of lowest energy have been calculated for iron-group (3d) transition-metal impurities in silicon. The donor and acceptor levels reproduce all experimentally observed transitions and trends. The theory predicts that the ground states of the early 3d interstitials and late 3d substitutionals have low spin. This is in conflict with the generally accepted model of Ludwig and Woodbury, if applied to these impurities, but not with existing experiments.
Detailed Analysis of DLTS Signal of EL2 in LEC n-GaAs Crystals
Authors: Yahata A. , Sato T. , Kikjta T. , Ishida K. 
Published: March 2011

AbstractDetailed DLTS measurements have revealed the presence of threedifferent midgap levels, labeled EOI, EO2 and EO3, in LEC n-GaAs. The variations of EOl and EO2 concentrations, which are EL2 and ELO in Lagowski's terminology, do not correlate with the distributions of the optical absorption coefficient across wafers, while that of EO3 exhibits good correlation. This suggests that EO3 is the optically detected midgap level. Furthermore, preliminary charged particle activation analysis of oxygen content in GaAs shows that the presence of EO2 (ELO) is not attributed to oxygen. Concentrations of these levels all increase with arsenic mole fraction in the melt.
Electron Paramagnetic Resonance of Intrinsic Defects in III-V Semiconductors
Authors: Wilsey N. D. , Kennedy T. A. 
Published: March 2011

AbstractThe use of electron paramagnetic resonance to investigate intrinsic defects in the III-V semiconductors is reviewed. Particular attention is given to lattice vacancies, antisites and their complexes in GaP, GaAs, and InP. The role of EPR in arriving at an understanding of these defects is emphasized and the interplay between experiment and theory is discussed.
An ODMR Study of The Killer Center Fe in GaP:O
Authors: Lee K. M. , Kimerling L. C. , Sturge M. D. 
Published: March 2011

AbstractThe role of the luminescence killer center iron in GaP has been studied by the optically detected magnetic resonance technique. Observations of strong Fe°(3d5) and O0 resonance in the (Zn,O) donor-acceptor pair (DAP) and the 0.841 eV electron capture (EC) luminescence bands show that the luminescence killing action is via (Fe,O) DAP recombination.Two distinct but similar (Fe,O) DAP processes were detected: The (Fe0,O0) process with a slower recombination rate and (Fe0,O0*) process, with a faster effective relaxation rate, involving the oxygen excited state.
Absolute Photoionization Cross Sections of the Acceptor State Level of Chromium in Indium Phosphide
Authors: Bremond Georges , Guillot G. , Nouailhat A. , Picoli G. 
Published: March 2011

AbstractWe have analyzed the photoionization of Cr2+ in InP by the Deep Level Optical Spectroscopy (D.L.O.S.). The σ°n cross section exhibits both a resonant and non resonant character. The former corresponds to the internal transition 5T2-5E of Cr2+ while the threshold of the second allows us to locate the Cr2+/Cr3+ level below the conduction band. The absolute photoionization cross sections towards the two bands are very similar. In particular no selection rule seems to work.
Electronic Defect Characterization
Authors: Grimmeiss H.G. 
Published: March 2011

AbstractKnowledge concerning the electronic properties of defects is crucial for the understanding of the behaviour of these defects in semiconductors. Considering the important role defects play in most currently used devices it is not surprising that a great number of different measurement techniques have been developed with the aim of not only quantitatively determining the electronic parameters but also of identifying the defect chemically and evaluating the local environment of such defects. In most cases this goal can not be achieved by applying only a single (defect property) measuring technique.In this paper an attempt is made, using two different examples, to show what achievements in defect characterization and identification can be obtained by combining two or more different measurement techniques. The first example is a single substitutional impurity, sulfur in silicon, while the second example deals with a more complex defect, the oxygen-vacancy center in silicon. In both cases a number of techniques such as different junction space charge measurements, Hall effect, absorption, ESR, photo-ESR, ENDOR photoconductivity, irradiation and annealing processes, and even theory were used to study the defect. The advantages and limitations of various methodologies will be discussed.
Luminescence and Tem-Investigation of Laser Induced Defects in (AI,Ga)As Heterostructures
Authors: Zysset B. , Salathe R.P. , Martin J.L. , Gotthardt R. , Reinhart F.K. 
Published: March 2011

AbstractLaser induced defects in (AI,Ga)As heterostructures have been investigated. Luminescencetopography reveals three different defects, a luminescent B, a nonradiative D as well asdark line defects (DLD). Luminescence and excitation spectra together with TEM measurements indicate a point defect or point defect complex for B and D. Defect B is described by a configuration coordinate (CC-) model with low vibrational energies. Defect DLD consists of extended dislocations.
Defect Scattering of Phonons in Phoiopcited GaAs
Authors: Culbertson J.C. , Klein P.B. , Wolf S.A. , Strom U. 
Published: March 2011

AbstractThe time resolved heat pulse generated by above band gap light is studied at 2 K in undoped, semi—insulating GaAs. The phonon lineshape changes with irradiation by 1.1 micron below gap light. The changes in phonon lineshape are reversed by raising the sanple teaperature to 130 K and recooling to 2M. The results provide strong evidence for the change in acoustic phonon scattering when the defect EL2 is transferred to its metastable state. The phonon scattering anisotropies observed for the [100] and [111] directions is indicative of an anisotropic phonon—defect interaction.
Defects in CZ—Silicon Investigated by the Positron Annihilation Techniques
Authors: Dannefaer S. , Kerr D. 
Published: March 2011

AbstractPositron measurements on boron doped CZ—silicon show that clusters of oxygen interstitials trap positrons. Depending on whether a vacancy is associated to this cluster or not, the positron lifetimes exhibit changes from 240 to 100 ps. The positron data indicate the nature of the initial —or precursor — stages for thermal donor formation.