bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Multiwavelength Pyrometry in Microwave Processing of Materials
Authors: Donnan R. S. , Samandi M. 
Published: April 2011

AbstractOver the past decade microwave energy has been increasingly used in materials processing, especially for sintering and more recently for the joining of advanced ceramics. However the hostile electromagnetic and plasma environment within a high power (1–6 kW) microwave applicator poses serious problems for very accurate high temperature measurement by precluding the use of existing classes of thermometry. For instance, conventional probe-based thermometry, multiple-wavelength ratio pyrometry and even the more recently developed technologies of optical fibre thermometry by fluoroptics and radiometry, are either incompatible or of restricted application. The main aim of this paper is to propose multiwavelength pyrometry as a viable technique for wide range (500–5000 K) thermometry in hostile electromagnetic and plasma environments. After briefly reviewing the physical basis of its operation, the experimental set up of the multiwavelength pyrometer is outlined, and consists of a comparatively inexpensive low resolving power grating monochromator and a PbS infrared single element detector. Results are presented that compare the measurements during conventional/microwave heating trials, from this multiwavelength pyrometer and from a K-type thermocouple, a double-wavelength ratio pyrometer and a single wavelength pyrometer aimed at a dummy target (carbon/metal).
Transient Temperature Distributions in a Cylinder Heated by Microwaves
Authors: Jackson H. W. , Barmatz M. , Wagner P. 
Published: April 2011

AbstractTransient temperature distributions were calculated for a lossy dielectric cylinder coaxially aligned in a cylindrical microwave cavity excited in a single mode. Results were obtained for sample sizes that range from fibers to large cylinders. Realistic values for temperature dependent complex dielectric constants and thermophysical properties of the samples were used. Losses in cavity walls were taken into account as were realistic thermal emissivities at all surfaces. For a fine mesh of points in time, normal mode properties and microwave power absorption profiles were evaluated using analytic expressions. Those expressions correspond to exact solutions of Maxwell's equations within the framework of a cylindrical shell model. Heating produced by the microwave absorption was included in self-consistent numerical solutions of thermal equations. In this model, both direct microwave heating and radiant heating of the sample (hybrid heating) were studied by including a lossy dielectric tube surrounding the sample. Calculated results are discussed within the context of two parametric studies. One is concerned with relative merits of microwave and hybrid heating of fibers, rods, and larger cylinders. The other is concerned with thermal runaway.
Mechanical Behavior of Microwave Processed Polymer Matrix Composites: the Effect Of The Temperature Increase Rate
Authors: Delmotte M. , Fitoussi J. , Toftegaard-Hansen J. , More C. , Jullien H. , Baptiste D. 
Published: April 2011

AbstractMicrowave processed glass reinforced epoxies or glass reinforced polyesters exhibit mechanical behaviors different from conventionally cured materials, relatively to tensile tests. The faster increases of temperature due to microwaves cause a competition between the matrix flow and the crosslinking reaction which can be estimated by porosity variations. Higher mechanical moduih are also obtained, because of both an effect on chemical kinetics and a more homogenous distribution of temperature in materials. Nevertheless, to provide such specific mechanical behaviors in microwave processed composite materials, a best control of the experimental pressure parameters is requested.
Microwave Annealing of Ion Implanted 6H-SiC
Authors: Gardner J. A. , Rao M. V. , Tian Y. L. , Holland O. W. , Kelner G. , Freitas J. A. , AIMAD I. 
Published: April 2011

AbstractMicrowave rapid thermal annealing has been utilized to remove the lattice damage caused by nitrogen (N) ion-implantation as well as to activate the dopant in 6H-SiC. Samples were annealed at temperatures as high as 1400 °C, for 10 min. Van der Pauw Hall measurements indicate an implant activation of 36%, which is similar to the value obtained for the conventional furnace annealing at 1600 °C. Good lattice quality restoration was observed in the Rutherford backscattering and photoluminescence spectra.
Deposition of Thin SiO2 Films on Polymers as a Hard – Coating using a Microwave – ECR Plasma
Authors: Sano K. , Tamamaki H. , Nomura M. , Wickramanayaka S. , Nakanishi Y. , Hatanaka Y. 
Published: April 2011

AbstractSiO2 thin films were deposited on automobile plastics at low temperatures using a microwave activated ECR plasma. Oxygen was used as the plasma gas while tetraethoxysilane (TEOS) was used as the source gas which was introduced into the downstream. In the present investigation high quality SiO2 films were deposited on polycarbonate (PC) and polypropylene (PP) substrates with and without a mesh and the characteristics of hard coating films were studied. The film growth rate increases with the decrease of substrate temperature when a mesh is inserted into the plasma. The irregularities of polymer surfaces could be planarized by the deposition of 1.0 μm thick SiO2 film. The dynamic hardness of PC and PP are increased by the deposition of SiO2 film, however, films deposited on PP is seen to be cracked while that of on PC is crack-free.
Materials Characterization and Diagnosis Using Variable Frequency Microwaves
Authors: Wei J. Billy , Fathi Zak , Tucker Denise A. , Hampton Michael L. , Garard Richard S. , Lauf Robert J. 
Published: April 2011

AbstractProduct quality control is a crucial part of manufacturing and usually involves materials characterization and diagnosis. Though various microwave assisted nondestructive evaluation (MA-NDE) systems have been fabricated for materials inspection, none of the systems can be applied to materials within a mold or reactor. A broadband variable frequency microwave based, resonant mode MA-NDE was studied as an alternative for characterization of materials within a cavity. The main advantage of the resonant mode MA-NDE are non-intrusive and volumetric diagnosis of the material inside a mold. The principles and possible applications of the resonant mode MA-NDE are discussed. Resonant mode MA-NDE was fully demonstrated by using Vani-Wave to trace material status during microwave curing of Diglycidyl Ether of Bisphenol A (DGEBA)/Diaminodiphenylsulphone (DDS) epoxy samples.
Microwave Separation Measurements of Bulk Lifetime and Surface Recombination Velocities in Si Wafers with Various Surface Properties
Authors: Ogita Y. , Minegishi M. , Higuma H. , Shigeto M. , Yakushiji K. 
Published: April 2011

AbstractThe separation measurements of a bulk lifetime υo, front and back surface recombination velocities S0, Sw have been investigated for both 620 μm and 1.08 mm thick Si wafers with various surface treatments. The separation was made by applying bisurface photocoductivity decay method to the photoconductivity decay curves measured by 500 MHz microwave reflection under the bias light illumination. The bulk lifetime and the surface recombination velocities have been determined, respectively, to be 624–659 μs and 18.4–66.1 cm/s for the oxidized sliced-surface and 6285 cm/s for the sliced surface. And they have been also determined, respectively, to be 412–422 μs and <1 cm/s for the oxidized mirror polished-surface or the oxidized etched surface, 565–626 μs and 1042–1112 cm/s for the oxidized sandblasted-surface. The noncontact microwave BSPCD method with bias lights makes it possible to determine separately the bulk lifetime and surface recombination velocities in the front surface and backsurface in Si wafers with the wafer thickness for the practical use.
Heat and Mass Transport Induced by Collision Cascades
Authors: Carol A. , Alurralde M. , Saliba R. , Caro M. 
Published: April 2011

AbstractIrradiation of materials with energetic particles produces changes in the microstructure that affect mechanical properties. In previous work we studied the thermal aspects of the quenching of collision cascades that involve nanoscale phase transitions between the solid and the liquid states of the target. In this work we present a rigorous treatment of these phenomena, including a detailed description of the Stefan problem in three dimensions and diffusion in thermal gradients. This approach is oriented to give a quantitative description of the influence of the primary knockon spectrum on the microstructure short after the quenching of the heat spike.
Charge State Defect Engineering of Silicon During Ion Implantation
Authors: Brown R. A. , Ravi J. , Erokhin Y. , Rozgonyi G. A. , White C. W. 
Published: April 2011

AbstractThe effects of in situ interventions which alter defect interactions during implantation, and thereby affect the final damage state, have been investigated. Specifically, we examined the effects of internal electric fields and charge carrier injection on damage accumulation in silicon. In the first part of this work, we implanted H or He ions into diode structures which were either reverse or forward biased during implantation. In the second part, we implanted B or Si ions into plain silicon wafers whilst illuminating them with UV light. In each case, the overall effect is one of damage reduction. Both the electric field and charge carrier injection effects may be understood as resulting from changes in defect interactions caused in part by changes to the charge state of defects formed during implantation.
Electronic Structure and Gate Capacitance-Voltage Characteristics of MBE Silicon δ-Fets
Authors: Manzoli J. E. , Hipólito O. 
Published: April 2011

AbstractNew implementations in MBE growth techniques allow high accuracy in δ-doping profiles in Silicon crystals. In this work we present a self-consistent numerical calculations of the electronic structure of δ-FETs, field effect transistors where electric transport channel is a quasi-two-dimensional plan of Antimonide doping in a Silicon crystal. We made the calculations to the heavy and light electrons at 77 and 300K varying the gate voltage in devices with one to three coupled deltas. We obtain the effective potential, the sub-bands and respective electronic densities, basic calculations to point at optimization of the device. We made considerations on theirs DC - capacitances and free electron density spreadings to achieve the gate-voltage best performance.
Vacancy-Type Defects in Electron and Proton Irradiated II- VI Compounds
Authors: Brunner S. , Puff W. , Mascher P. , Balogh A. G. , Baumann H. 
Published: April 2011

AbstractIn this contribution, we present a study aimed at investigating the basic properties of radiation induced defects in ZnS and ZnO and the influence of the atmosphere on the annealing characteristics of the defects. Positron annihilation experiments (both lifetime and Dopplerbroadening measurements) were performed on both single- and polycrystalline samples, irradiated with 3 MeV protons or 1 MeV electrons. For ZnS it was found that both electron and proton irradiation caused significant changes in the positron annihilation characteristics. The annealing of proton irradiated ZnS in air leads to significant oxidation and eventual transformation into ZnO.
Elevated Temperature Implantation of GaAs With Si Ions
Authors: Bhown R. A. , Williams J. S. 
Published: April 2011

AbstbactThe formation of amnorphous layers in GaAs during ion bombardment at elevated temperatures, where dynamic annealing of radiation-induced defects is substantial, is shown to be extremely sensitive to the ion flux. fluence. and implantation temperature. For example. with increasing fluence. damage can first build up extremely slowly. then suddenly collapse to the amorphous phase. Alternatively. for a constant ion fluence, a change in flux by one order of magnitude can change the critical temperature for amorphisation by 27°C. and at constant flux and fluence. a change of only 6°C can alter the residual damage from small clusters barely visible by conventional transmission electron microscopy and Rutherlord backscattering to a thick amorphous layer. The temperature at which this occurs is strongly dependent upon the ion flux and fluence.
Interaction of Cavities and Dislocations in Semiconductors
Authors: Follstaedt D. M. , Myers S. M. , Lee S. R. , Reno J. L. , Dawson R. L. , Han J. 
Published: April 2011

AbstractTransmission electron microscopy of He-implanted Si-Ge and InGaAs shows an attractive interaction between cavities and dislocations. Calculation indicates that cavities are attracted to dislocations through surrounding strain fields, and strong binding (100s of eV) occurs when a cavity intersects the core. In a strained SiGe/Si heterostructure, He implantation enhances relaxation rates, and cavities bound to misfit dislocations show evidence of increasing relaxation at equilibrium by lowering dislocation energies. The interaction is expected for all crystalline solids, and gives insight into voids in GaN/sapphire and bubbles in He-implanted metals.
Growth of Ge1−xCx, Alloys on Si by Combined Low-Energy Ion Beam and Molecular Beam Epitaxy Method
Authors: Shibata H. , Kimura S. , Fons P. , Yamada A. , Makita Y. , Obara A. , Kobayashi N. , Takahashi H. , Katsumata H. , Tanabe J. , Uekusa S. 
Published: April 2011

AbstractA combined ion beam and molecular beam epitaxy (CIBMBE) method was applied for the deposition of a Ge1−x, Cx, alloy on Si(100) using a low-energy ( 50 – 100 eV ) C+ ion beam and a Ge molecular beam. Metastable Ge1−xCx solid solutions were formed up to x= 0.047, and the CIBMBE method was shown to have a very high potential to grow metastable Ge1−xCx alloys. It was also revealed that the sticking coefficient of C+ ions into Ge was ˜28% for Ei = 100 eV and ˜18% for Ei. = 50 eV. Structural characterization suggests that the deposited films are single crystals grown epitaxially on the substrate with twins on {111} planes. Characterization of lattice dynamics using Raman spectroscopy suggested that the deposited layers have a small amount of ion irradiation damage.
Effects of the Surface on Displacement Cascades Produced by Heavy-Ion Irradiation of Ni3Al and Cu3Au
Authors: Müller S. , Jenkins M. L. , Abromeit C. , Wollenberger H. 
Published: April 2011

AbstractStereo transmission electron microscopy has been used to characterise the distribution in depth of disordered zones and associated dislocation loops in the ordered alloys Ni3Al and Cu3Au after heavy ion irradiation, most extensively for Ni3Al irradiated with 50 keV Ta+ ions at a temperature of 573 K. The Cu3Au specimen was irradiated with 50 keV Ni+ ions at an incident angle of 45° at a temperature of 373 K. In Ni3Al the defect yield, i.e. the probability for a disordered zone to contain a loop was found to be strongly dependent on the depth of the zone in the foil, varying from about 0.7 for near-surface zones to about 0.2 in the bulk. The sizes and shapes of disordered zones were only weakly dependent on depth, except for a small population of zones very near the surface which were strongly elongated parallel to the incident ion beam. In Cu3Au the surface had a smaller but still significant effect on the defect yield. The dependence of the tranverse disordered zone diameter d on ion energy E for Ta+ irradiation of NiA was found to follow a relationship d = k1, E1/α with k, = 2.4 ± 0.4 and α = 3.3 ± 0.4. A similar relationship with the same value of α is valid for a wide variety of incident ion/target combinations found in the literature.
Surface Topography of Thin Au and Pd Films After Ion Bombardment Studied With STM
Authors: Reimann K. P. , Rehmet A. , Bolse W. , Geyer U. 
Published: April 2011

AbstractThe changes in surface topography of thin metallic films during ion bombardment were investigated with STM. Pd and Au thin films, having defect-free, atomically flat areas over at least 300×300Å2 were bombarded with Ar+, Kr+, Xe+ ions. Ion energies and target temperatures were varied. The roughening after high fluence irradiation shows scaling with a roughness exponent 0.84. For 300 K target temperature we observe, both for Au and Pd, 3 D erosion, for 700 K, on the contrary, layer-by-layer erosion. The differences in erosion morphologies between Au and Pd surfaces are supposed to stem from differences in surface mobility of adatoms.
Molecular Dynamics Simulation of Cascade Damage in Gold
Authors: Alonso E. , Caturla M. J. , Tang M. , Huang H. , Rubia T. Diaz de ia 
Published: April 2011

AbstractHigh-energy cascades have been simulated in gold using molecular dynamics with a modified embedded atom method potential. The results show that both vacancy and interstitial clusters form with high probability as a result of intracascade processes. The formation of clusters has been interpreted in terms of the high pressures generated in the core of the cascade during the early stages. We provide evidence that correlation between interstitial and vacancy clustering exists.
Short and Long-Range Ordering of (Ni0.67Cr0.33)1-xFex Alloys Under Electron Irradiation
Authors: Frely E. , Beuneu B. , Barbu A. , Jaskierowicz G. 
Published: April 2011

Abstract(Ni0.67Cr0.33)1-xFex alloys with x = 0, 5 and 10 at.%, have been irradiated at temperatures between 300°C and 500°C with the electrons of a 2.5MeV Van de Graaff accelerator and of a 1MeV High Voltage Electron Microscope (HVEM). All of them have been successively ordered at short and at long range under irradiation. The transition temperature is 525°C for Ni0.61Cr0.34Fe0.05 and 445°C for Ni0.59Cr0.31Fe0.10. An Inconel sample irradiated up to 1 d.p.a. in the 1MeV microscope did not show any superlattice peak although its composition is very close to the 10% iron model alloy. The kinetics of ordering has been followed by resistivity measurements and fitted by the Dienes kinetic model.
Atom Transport in Nickel by Displacement Cascades for Spatially Dependent Displacement Rate and Sink Strength
Authors: Wollenberger H. , Fielitz P. , Macht M.-P. , Naundorf V. 
Published: April 2011

AbstractAtom transport under irradiation is determined by the concentration of freely migrating defects, which depends on the dynamical equilibrium between production and annihilation rates. In order to determine effective values of both of these quantities for the case of ion irradiation, spatially resolved self-diffusion measurements were performed on single crystals of nickel which contained several thin tracer layers at different depths. By fitting the solution of a diffusion equation to the depth dependent measurements effective fractional production rates of freely migrating defects and effective sink strengths have been obtained.
Boron Transient Enhanced Diffusion in Heavily Phosphorus Doped Silicon
Authors: Huang M. B. , Myler U. , Simpson T. W. , Simpson P. J. , Mitchell I. V. 
Published: April 2011

AbstractA study has been made of B transient enhanced diffusion (TED) in heavily P-doped Si using secondary ion mass spectroscopy (SIMS) and positron annihilation spectroscopy (PAS). The Pdoped silicon was implanted with boron ions of 40 keV energy to a dose of 3 x 1014 cm-2, and then annealed at temperatures ranging from 700–1000°C in a N2 ambient for varying durations. As P doping concentration increased from 3 x 1019 to 1 x 1020 cm-3, boron diffusivity and the immobile boron fraction decreased. Our experimental results are inconsistent with the predictions of the Fermi-level model and suggest that the clustering between B atoms and Si interstitials should be invoked in order to explain the immobile portion of the B peak during TED.
Neutron Damage in Reactor Pressure-Vessel Steel Examined with Positron Annihilation Lifetime Spectroscopy
Authors: Cumblidge Stephen E. , Motta Arthur T. , Catchen Gary L. 
Published: April 2011

AbstractWe have used positron annihilation lifetime spectroscopy to study the development of damage and annealing behavior of neutron-irradiated reactor pressure-vessel steels. We irradiated samples of ASTM A508 nuclear reactor pressure-vessel steel to fast neutron 172 fluences of up to 1017 n/cm2, and we examined these samples using positron annihilation lifetime spectroscopy (PALS) to study the effects of neutron damage in the steels on positron lifetimes. Non-irradiated samples show two positron lifetimes: a 110 ps component corresponding to annihilations in the bulk material, and a 165 ps lifetime corresponding to annihilations in dislocation defects. The irradiated samples show an additional lifetime component of 300 ps in the PAL spectra and an increase in the proportion of annihilations with a 165 ps lifetime, suggesting that vacancies and vacancy clusters are present in the material after room temperature irradiation. The samples were then annealed to temperatures ranging from 210° C to 450° C. The positron lifetimes introduced by neutron damage disappear after annealing the samples at 280° C.
Radiation-Induced Segregation in Alloy X-750
Authors: Kenik E. A. 
Published: April 2011

AbstractThe microstructural and microchemical evolution of an Alloy X-750 heat under neutron irradiation has been studied in order to understand the origin of irradiation-assisted stress corrosion cracking. Both clustering of point defects and radiation-induced segregation (RIS) at interfaces and boundaries have been observed. Although no significant changes in the precipitate structure were observed, boundaries exhibited additional depletion of Cr and Fe and enrichment of Ni.
Defect Diffusion During Annealing of Low-Energy Ion-Implanted Silicon
Authors: Bedrossian P. J. , Caturla M -J. , Diaz De La Rubia T. 
Published: April 2011

AbstractWe present a new approach for investigating the kinetics of defect migration during annealing of low-energy, ion-implanted silicon, employing a combination of computer simulations and atomic-resolution tunneling microscopy. Using atomically-clean Si(111)-7×7 as a sink for bulk point defects created by 5 keV Xe and Ar irradiation, we observe distinct, temperature-dependent surface arrival rates for vacancies and interstitials. A combination of simulation tools provides a detailed description of the processes that underdy the observed temperature-dependence of defect segregation, and the predictions of the simulations agree closely with the experimental observations.
Radiation Effects in Glass Waste Forms for High-Level Waste and Plutonium Disposal
Authors: Weber W. J. , Ewing R. C. 
Published: April 2011

AbstractA key challenge in the permanent disposal of high-level waste (HLW), plutonium residues/scraps, and excess weapons plutonium in glass waste forms is the development of predictive models of long-term performance that are based on a sound scientific understanding of relevant phenomena. Radiation effects from β-decay and α-decay can impact the performance of glasses for HLW and Pu disposition through the interactions of the α-particles, β-particles, recoil nuclei, and γ-rays with the atoms in the glass. Recently, a scientific panel convened under the auspices of the DOE Council on Materials Science to assess the current state of understanding, identify important scientific issues, and recommend directions for research in the area of radiation effects in glasses for HLW and Pu disposition. The overall finding of the panel was that there is a critical lack of systematic understanding on radiation effects in glasses at the atomic, microscopic, and macroscopic levels. The current state of understanding on radiation effects in glass waste forms and critical scientific issues are presented.