bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of the Surface of the HLW Glass R7T7 Reacted in Salt Brines
Authors: Roggendorf H. , Conradt R. , Schmidt H. 
Published: March 2011

ABSTRACTBorosilicate glasses are proposed as waste form for the final disposal of High Level Waste (HLW) in salt formations by the Federal Republic of Germany. To check the safety of this waste form the corrosion of the non-radioactive borosilicate glass R7T7 in salt brines has been studied in collaboration with the Hahn-Meitner-Institut, Berlin. Temperatures up to 190°C and S/V ratios (surface area to solution volume ratio) between 3.3 and 1000 m were applied. S/V was varied by the addition of glass powder. The results presented here concern the characterization of the surface composition of the corroded glass (corroded at 190°C in a brine containing high amounts of MgCl-, called Q brine in this paper) after removing the reaction product layer. The corrosion conditions were chosen to obtain samples typical of long term (silica saturation) corrosion. The surface composition was analyzed quantitatively by X-ray photoelectron spectroscopy (XPS) by using external standard glasses with a composition similar to R7T7. Additionally scanning electron microscopy (SEM) was employed.
Determination of Technetium and Selenium Transport Properties in Laboratory Soil Columns
Authors: Del Debbio J. A. , Thomas T. R. 
Published: March 2011

ABSTRACTLaboratory studies are being conducted to measure the transport properties of various radionuclide species through soil columns. The studies are being conducted to support evaluations for potential near-surface disposal of high-level radioactive waste (HLW) calcine stored at the Idaho National Engineering Laboratory. The data will be used to model radionuclide transport through the vadose (unsaturated) zone of the site under various water-contact scenarios. Retardation factors and dispersion coefficients for technetium and selenium species have been measured in water-saturated soil columns made up of sediments taken from 12 and 35 meters below the surface. A one-dimensional, convective-dispersive, solute-transport equation was fitted to column effluent data by optimizing three parameters (retardation factor, dispersion coefficient and pulse time) using a non-linear, least-squares fitting routine. The data indicated no retardation of the pertechnetate ion (TcO4-)and selenate ion (SeO4-) and a large retardation of the selenite ion (SeO3-) relative to water transport through the soil column.
Atomic-Scale Modeling of Low-Energy Ion-Solid Processes
Authors: Dodson Brian W. 
Published: March 2011

ABSTRACTVarious techniques which have been applied to modeling low-energy (<< 1 keV) ion-solid interactions on an atomistic scale are described. In addition to their individual strengths, all such methods also have a number of drawbacks, both fundamental and practical. The range of validity, and the problems encountered external to this range, will be outlined for the different approaches. Finally, examples of molecular dynamics simulations of low-energy ion-solid interactions will be presented.
Collision Cascade Densification of Materials
Authors: Bassel R. H. , Andreadis T. D. , Rosen M. , Mueller G. P. , Hubler G. K. 
Published: March 2011

ABSTRACTComputer simulations of the collision cascade process were used to investigate surface densification during ion beam assisted deposition (IBAD). The objective of the investigation was to see if densification resulted directly from the cascade, without any contribution from diffusion enhancement brought on by the bombardment. Calculations, using the computer code MARLOWE, were carried out for Ar bombardment of a crystalline Ge target, containing a void, using ion beam energies of 0.065, 0.5 and 1 keV. These results were used as data for a differential equation that describes the effect on void size of the simultaneous Ge atom deposition and Ar ion bombardment of a substrate containing voids. The present attempt examined the effects of irradiations on voids of 17 and 35 vacancies.
Stress Modification in Tungsten Films Deposited by Ion-Assisted Evaporation
Authors: Roy R. A. , Petkie R. , Yee D. S. , Karasinski J. , Boulding A. 
Published: March 2011

ABSTRACTThe modification of film stress in evaporated tungsten was studied as a function of deposition environment. Using concurrent ion bombardment of the growing film, the stress was seen to vary systematically with ion energy, ion flux, and substrate temperature. The qualitative behavior fits the model of stress modification developed for niobium films. X-ray diffraction was used to study the structure of the films, and a clear correlation between crystallographic texture and film stress is found. The original structure/impurity model for film stress modification due to ion bombardment has been modified to account for the relationship between film stress and texture.
Thermal Spike Related Nonlinear Effects in Ion Beam Mixing at Low Temperatures
Authors: Chen G-S. , Farkas D. , Rangaswamy M. 
Published: March 2011

ABSTRACTA semi-empirical model for ion mixing at low temperatures was developed taking into account collisional mixing and thermal spike effects, as well as the thermal spike shape. The collisional mixing part was accounted for by the Kinchin-Pease model, or, alternatively dynamic Monte Carlo simulation. For the thermal spike, the ion beam mixing parameter Dt/Φ is derived as being proportional to χ2+μ, where the damage parameter is defined as, χ = − F0/ΔHcoh, F0 is the damage energy deposited per unit path length, and μ is a constant dependent on the thermal spike shape and point defect density in the thermal spike regions. The shape of the thermal spike that best fit the experimental results depends on the magnitude of the cascade density. For relatively high density collisional cascades, where thermal spikes start to be important, it was found that a spherical thermal spike model was more consistent with experimental measurements at low temperatures. However, for extremely high density collisional cascade regions, a cylindrical thermal spike gave better results. Finally, three different regions of ion beam induced mixing were recognized according to different density levels of damage energy scaled by the damage parameter χ.
A Comparison of the Mixing Rates for Fe-Ti and Ni-Ti Bilayers
Authors: Børgesen P. , Lilienfeld D. A. , Wistrom R. E. , Johnson H. H. 
Published: March 2011

ABSTRACTPrevious comparisons of the room temperature mixing of Ni-Ti and Fe-Ti multilayers have shown significant differences in the mixing rates in spite of closely similar heats of mixing as well as ballistic properties. This result suggests contributions from mechanisms other than ballistic and thermal spike effects, or a break-down of present thermal spike models for these materials. In order to identify the mixing mechanisms involved, quantitative measurements were made at various temperatures between 80K and 350K using bilayer samples. Surprisingly, the mixing rates were found to disagree significantly with those estimated for multilayer samples.
Ion-Beam Mixing in Amorphous and Crystalline Fe-Ti
Authors: Scheuer Udo , Rehn Lynn E. , Baldo Pete 
Published: March 2011

ABSTRACTCrystalline Fe and Fe-10at.%Ti and amorphous Fe-37at.%Ti films with Ag and Hf markers were produced by vapor deposition. Marker spreading during ion-beam mixing between 77 K and 580 K was measured using Rutherford Back-scattering (RBS). Marker spreading was also measured between temperatures of 300 K to 700 K after full crystallization of the Fe-37at.%Ti films. Microstructural changes during ion-beam mixing were studied in situ, in a High-Voltage Electron Microscope. Homogeneous nucleation of a metastable bcc phase, was observed at high temperatures. The results are discussed in terms of their relevance to “radiation-enhanced” diffusion in amorphous materials.
The Effect of Hydrogen Content on Ion Beam Mixing
Authors: Wistrom R. E. , Børgesen P. , Johnson H. H. , Lilienfeld D. A. 
Published: March 2011

ABSTRACTA qualitative study of ion beam mixing of multilayers has shown that the presence of hydrogen in the sample slows mixing considerably for Fe/Ti, and slightly for Ni/Ti. We have quantified this effect and extended the study to four more systems (Co/Ti, Pd/Ti, Ti/Cu, and Ti/Al) and to lower temperatures. The degree to which H charging reduced the mixing rate varied substantially with multilayer system. H was lost during mixing. H was lost fastest from those films for which the H effect was the smallest. Our data are consistent with a model that relates mixing inhibition to H-vacancy binding energy in the non-Ti component.
Ion Beam Induced Intermixing of Wsi0.45 on GaAs
Authors: Pearton S. J. , Short K. T. , Jones K. S. , Baca A. G. , Wu C. S. 
Published: March 2011

ABSTRACTThe systematics of ion beam induced intermixing of WSi0.45 on GaAs have been studied after through-implantation of Si or O in the dose range 1013 − 5 × 1016 cm−2. SIMS profiling shows significant knock-on of Si and W into the GaAs at the high dose range in accordance with Monte Carlo simulations, but there is virtually no electrical activation (≤0.1%) of this Si after normal implant annealing (900°C, 10 sec). This appears to be a result of the high level of disorder near the metal-semiconductor interface, which is not repaired by annealing. This damage consists primarily of dislocation loops extending a few hundred angstroms below the end of range of the implanted ions. Extrapolation of the ion doses used in this work to the usual doses used in GaAs device fabrication would imply that ion-induced intermixing of WSix will not be significant in through-implantation processes.
Ion Beam Mixing of High-Tc Superconductor Components.
Authors: Borgesen P. , Lilienfeld D. A. 
Published: March 2011

ABSTRACTThe design of the necessary multilayer structures for producing superconducting thin films by ion beam mixing methods requires, among others, the knowledge of the individual (binary) mixing rates. In order to measure these, various combinations of Y, Ba, Cu, and Bi were irradiated with 600 keV Xe-ions at 80K and 300K. The systems exhibited a wide range of mixing behaviors which are also of fundamental interest. Ba and Cu readily formed the BaCu phase, and further mixing with Cu progressed only via binary collision mechanisms. At 80K Cu and Y were rapidly mixed in any ratio by thermal spikes, whereas a Cu rich sample rapidly formed the Cu6Y phase at 300K. Ba could not be mixed into Y or a Y-Cu mixture. Finally, irradiation of polycrystalline layers of Cu and Bi apparently lead to rapid motion of Bi along grainboundaries at both temperatures.
Angle of Incidence Effects in Ion Beam Processing
Authors: Harper J. M. E. , Hörnström S. E. , Rudeck P. J. , Bradley R. M. 
Published: March 2011

ABSTRACTThe angle of incidence of ion bombardment is an important processing parameter, which can strongly affect the shape, composition and microstructure of bombarded surfaces. We describe several phenomena directly related to the angle of ion incidence during ion beam etching and ion beam assisted deposition. First, the development of surface ripple topography during ion beam etching is modeled. Surface perturbations are shown to grow under ion bombardment, while surface selfdiffusion acts to select a characteristic wavelength. The orientation of these characteristic ripples changes by 90° as the angle of ion incidence is varied from near-normal to near-glancing angle. The second example is the effect of angle of incidence on the etching rate of Ta under mixed Ar-O2 ion bombardment. For pure Ar bombardment, the sputtering yield of Ta increases with angle of ion incidence slower than secθ, producing a maximum etch rate at normal incidence. Above a critical pressure of O2, however, the yield increases faster than secθ dependence, producing a maximum etch rate at a non-normal angle of incidence. The third example is the effect of angle of incidence on the preferential sputtering of Al relative to Cu in Al-5% Cu thin films. Films deposited by evaporation with simultaneous Ar ion bombardment at 500 eV show a depletion of Al relative to Cu. This composition change is enhanced by increasing the angle of incidence away from normal, resulting in a higher Cu concentration in a film deposited on a tilted surface. Finally, a mechanism is described for the generation of oriented microstructure in films deposited under simultaneous glancing-angle ion bombardment, demonstrated previously for Nb. Grain orientations are selected which allow channelling of the ion beam. These results show that the shape, composition and microstructure of films deposited under ion bombardment respond to changes in angle of incidence, and that these effects need further study and modeling.
Epitaxial Growth of Ni on Si by Ion Beam Assisted Deposition
Authors: Grabowski K. S. , Kant R. A. , Qadr S. B. 
Published: March 2011

ABSTRACTEpitaxial Ni films were grown on Si(111) substrates to a thickness of about 500 nm by ion beam assisted deposition at room temperature. The films were grown using 25-keV-Ni ions and electron-beam evaporation of Ni at a relative arrival ratio of one ion for every 100 Ni vapor atoms. The ion beam and evaporant flux were both incident at 45° to the sample surface. Standard θ-2θ X-ray diffraction scans revealed the extent of crystallographic texture, while Ni {220} pole figure measurements identified the azimuthal orientation of Ni in the plane of the film. Films grown without the ion beam consisted of nearly randomly oriented fine grains of Ni whereas with bombardment the Ni (111) plane was found parallel to the Si (111) plane. In all the epitaxial cases the Ni [110] direction was perpendicular to the axis of the ion beam, suggesting that the azimuthal orientation of the film was determined by channeling of the ion beam down {110} planar channels in the Ni film. Additional experiments with different ions, energies, and substrates revealed their influence on the degree of epitaxy obtained.
Soft Magnetism and Morphology of Fe Films by Dual Ion Beam Sputtering
Authors: Nagakubo M. , Yamamoto T. , Naoe M. 
Published: March 2011

ABSTRACTFe films have been deposited by using dual ion beam sputtering apparatus under various conditions, and the dependence of their magnetic properties and morphology on preparation parameters such as film thickness, δt, and argon gas pressure, PAr, have been investigated in detail.
The saturation magnetiza ion 4πMs of the specimen films did not change remarkably with 6t in the range of 50 ∼1000nm. However, with decrease of 6t below 50 nm, 4πMs decreased to less than 20 kG and coercivity Hc increased to more than 16 Oe. As PAr increased from 0.5 to 1.6 mTorr without ion bombardment, 4πMs decreased to less than 20 kG and Hc increased to about 20 Oe. The SEM micrographs of these films deposited at higher PAr showed the columnar structure. On the other hand, the films deposited at Yower PAr and ones bombarded by argon ions with proper kinetic energy during deposition did not present any texture and exhibited better soft magnetism. Such a morphology may be attributed to the difference in arrival energy of sputtered Fe particles to film surface and related closely to soft magnetism. It has been found that the dual ion beam sputtering method can control 4πMs and Hc with changing PAr and so prepare Fe films with superior soft magnetism by adjusting the kinetic energy of bombarding argon ions at lower PAr.
The Effect of Simultaneous Electron and Kr+ Irradiation on Amorphization of CuTi
Authors: Koike J. , Okamoto P. R. , Rehn L. E. , Meshii M. 
Published: March 2011

ABSTRACTCuTi was irradiated with 1-MeV electrons and Kr+ ions simultaneously at temperatures from 10 to 423 K. Retardation of Kr+-induced amorphization was observed with simultaneous electron irradiation at 295 and 423 K. The retardation effect increased with increasing irradiation temperature and relative electron-to-Kr dose rate. In contrast, simultaneous irradiation below 100 K showed an additive effect of electron- and Kr+-induced amorphization. The results can be explained by the mobility point defects introduced by electron irradiation interacting with Kr+-induced displacement cascades.
Argon Ion Bombardment During Molecular Beam Epitaxy of Ge (001)
Authors: Chason Eric , Horn K. M. , Tsao J. Y. , Picraux S. T. 
Published: March 2011

ABSTRACTUsing in situ, real-time reflection high energy electron diffraction (RHEED), we have measured the evolution of Ge (001) surface morphology during simultaneous molecular beam epitaxy and Ar ion beam bombardment. Surprisingly, low-energy Ar ions during growth tend to smoothen the surface. Bombardment by the ion beam without growth roughens the surface, but the surface can be reversibly smoothened by restoring the growth beam. We have measured the effect of such “ion beam growth smoothening” above and below the critical temperature for intrinsic growth roughening. At all measured growth temperatures the surface initially smoothens, but below the critical roughening temperature the final surface morphology is rough whereas above this temperature the final morphology is smooth.
Tribological and Mossbauer Studies of Ion-Implanted Iron
Authors: Williamson D. L. , Qu Yi , Wei Ronghua , Sampath W. S. , Wilbur P. J. 
Published: March 2011

ABSTRACTA modified pin-on-disc wear test technique and conversion electron Mössbauer spectroscopy (CEMS) have been used to characterize the tribological and microstructural properties, respectively, of pure Fe implanted with N and Ar ions at high current densities. CEMS measurements were made before and after wear testing. For the lubricated, mild adhesive wear conditions used here, no evidence was found for iron-nitride dissolution or N atom migration. Disordering of γ'-Fe4N did occur as a result of the wear process. All Nimplanted surfaces were tribologically superior to the Ar-implanted surface and an extremely wear-resistant surface layer about 30–50 nm thick was produced with a dose of 8×1016 N atoms/cm2, at a dose rate of 100 μA/cm2. However, once this layer was worn away the wear rate returned sharply to that of unimplanted pure Fe. A high retained N dose has been observed even for a dose rate of 750 μA/cm2 during which the sample reached 280°C.
Characterization of TiN Films Prepared by Ion Beam Assisted Deposition
Authors: Chang Albert L. , Kant R. A. 
Published: March 2011

ABSTRACTOne of the advantages of the ion beam assisted deposition process is its controllability of the processing parameters such as: ion-to-atom arrival ratio and the ion energy. In this study, the effects of the nitrogen ion energy (from 1 KV to 30KV) on the TiN film morphology and microstructures were systematically investigated as a function of ion-to-atom arrival ratios, using TEM, XTEM, SEM, ESCA and other analytical techniques.
A Study of the Anodic Oxidation on Aluminium by Ion-Implanted Xe Ions Marker and RBS Analysis Techniques
Authors: Chen Hemting , Bai Xinde , Li Wangpei , Dai Mingjiang 
Published: March 2011

ABSTRACTThis paper presents the results on the mechanism of the anodic oxidation on Al by means of ion–implanted marker Layer of xenon and RBS analysis techniques. ExperimentaLly, it has been shown that the mechanisms of anoulic oxidation on Al are different in the different elctrolytes. In the solution of 15%.wt sulphuric-acid, the anodic oxide film is formed by the react ion be tweeit metal rations at the metal/oxide interface and continuously migrated oxygen anions. While in the solution of 5%wt ammonium citrate, both tie migration of the metal cations and that of the oxygen anions contribute to the formation of the anodic flim, and the oxidization takes place in internal region of the oxide ftim or at lhe interface. The transport numbers for Al in 5%.wt ammonium citrate were found to vary with the voltage or current density front 44% to 64∼
High Dose Implantation of Nitrogen and Phosphor into Silica Glass
Authors: Tagami Takashi , Oyoshi Keiji , Tanaka Shuhei 
Published: March 2011

ABSTRACTThe surface chemistry of silica glass implanted with N+ or P+ ions has been studied. The X-ray photoelectron spectroscopy (XPS) spectra of N(1s) for silica glass implanted with N+ shows the possibility of the formation of oxynitride glass. For the first time, the effect of the implantation of N+ and additional Si+ on the surface chemistry of silica glass has been studied and found to be significant in increasing the nitrogen concentration in the silica glass. The peak concentration of N increases several times, and does not change even if the sample is annealed at 900°C. The XPS spectra of P(2p) for silica glass implanted with P+ ions shows two interactions, both P-O and P-P. Therefore, the XPS spectra shows the possibility for the formation of phosphosilicate glass using P+ implantation into silica glass.
Damage Formation in Semiconductors During Mev Ion Implantation
Authors: Sjoreen T. P. , Holland O. W. , El-Ghor M. K. , White C. W. 
Published: March 2011

ABSTRACTDamage produced by 1.0-2.5 MeV self-ion and O-ion implantation into Si and Ge single crystals has been characterized by cross-sectional electron microscopy and ion channeling. In Si, it is observed that the damage morphology varies substantially along the ion's track. Near the end-of-range of the ion, damage accumulation is very similar to that which occurs during medium- to low-energy implantation (i.e., damage increases monotonically with dose until the lattice is made completely amorphous). In front of this end-of-range region, however, damage saturates at a very low level for moderate implantation fluences. A model based on homogeneous damage nucleation in Si is discussed. For Ge, damage accumulation is very different; a monotonic increase of damage with dose is observed over the entire range of the ion. Possible mechanisms responsible for the differences between Si and Ge are discussed.
Properties of Silicon Oxynitride and Aluminum Oxynitride Coatings Deposited Using Ion Assisted Deposition
Authors: Al-Jumaily G. A. , Mooney T. A. , Spurgeon W. A. , Dauplaise H. M. 
Published: March 2011

ABSTRACTOptical thin films of nitrides, oxynitrides and oxides of aluminum and silicon were deposited using ion assisted deposition. Coatings were deposited by thermal evaporation of AlN and e-beam evaporation of Si with simultaneous bombardment with 300 eV ions of nitrogen, a mixture of nitrogen and oxygen or oxygen. The chemical composition and the index of refraction of the coating was varied by varying the gas mixture in the ion beam. Optical properties of and environmental stability of coatings were examined. Results indicated that coatings are stable even under severe conditions of humidity and temperature.