bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colloid Investigations in the ‘Pocos De Caldas” Natural Analogue Project
Authors: Miekeley Norbert , Jesus H. C. , Silveira C.L.P. , Kuechler I. L. 
Published: March 2011

ABSTRACTPreliminary data are presented on colloids in groundwaters from two radioactive ore deposits (C-09 mine and Morro do Ferro) situated in the Pocos de Caldas plateau in the state of Minas Gerais, Brazil. Ultrafiltration with flat membranes of different nominal MW cutt-off limits (450 nm to 1, 000 dalton) was used to prepare colloid concentrates from 40 to 50 1 water samples. The colloidal retentates as well as the original groundwaters were analysed for relevant ‘major’ and trace element concentrations and for DOC. Distribution characteristics of elements like Si, Fe, Mn, DOC, U, Th and rare earths between colloidal phases and ‘solution’ as result of different groundwater chemistry will be discussed.
Modeling of Nickel Sorption and Speciation in a Natural Sediment-Groundwater System
Authors: Koss Volker 
Published: March 2011

ABSTRACTThe sorption of nickel in 15 natural sediment-groundwater systems from Gor leben has been modeled using a simple surface complexation model. An apparent constant of nickel sorption has been computed taking into account the bulk cation exchange capacity of the sediment, the analytical composition of the groundwater and experimental sorption data obtained from related systems. The method of determining the prevailing surface complex has been described in detail, using changing properties of the natural systems. Competition from natural groundwater components for sorption sites has been taken into account.The main parameters governing nickel sorption are cation exchange capacity of the sediment, together with ionic strength and pH of the groundwater. The model describes the influence of citrate on sorption and allows one to compare the varying sorption data of similar systems.Computations were performed using the geochemical code MINEQL.
Investigation into the Solubilities. Sorption and Migration Behaviour of Agl. CsNO3, Na2U2O7. NpO2OH and Pu(OH)4 in Near-Field-Systems
Authors: Marx G. , Keiling Ch. 
Published: March 2011

ABSTRACTResults are presented from investigations into the solubilities, sorption and migration behaviour of Agi. CsNO3, Na2U2O7. NpO2hOH and Pu(OH)4 in the near-field environment of an ILW repository located in a salt dome. Emphasis is placed on the synthetic complexing organics DBP, TBP, EDTA, citrate and oxalate, which influence the leaching and retardation of the above elements. Leachate data from real ILW forms, obtained from saturated salt solutions, have been compared with the results of the synthetic systems described.
Laboratory Investigation into the Radiolytic Gas Generation from Rock Salt. A Study Related to the Disposal of High Level Radioactive Waste
Authors: Jockwer Norbert , Monig Jörg 
Published: March 2011

ABSTRACTSalt samples of two different mineralogical compositions were subjected to 60Co-γ-irradiation under an air-atmosphere. The resulting gaseous products were analysed from the gas phase above the salt. Additionally, the salt was subsequently heated up to 300 °C in order to liberate adsorbed, less volatile, and polar compounds. The gases CO2, CO, N2O, H2S, SO2, and Cl2 were identified whereas H2 was notably absent. The influence of various parameters, i. e. the total absorbed dose, the dose rate, and the temperature, on the radiolytic gas production was studied in some detail, increasing dose leads to increasing yields in CO2 and N2O. Carbon monoxide is radiolytically destroyed. Since CO2 and CO occur naturally in rock salt, they desorb thermally to some extent during the irradiation. The dose rate does not affect the yields, while the temperature during irradiation has a big effect on the radiolytic CO2 yields. At 250 °C and a radiation dose of 1×106 Gy a maximum CO2 yield of 70 mg gas per kg irradiated salt was observed. Upon heating the sample to 300 °C for 30 min. 47 mg per kg salt are additionally released.
The Effect of Ground Water - Rock Interactions on the Migration of Redox Sensitive Radionuclides
Authors: Suksi Seija , Siitari-Kauppi M. , Kämäräinen E-L. , Lindberg A. 
Published: March 2011

ABSTRACTInteractions of redox sensitive elements with common Finnish rocks were studied in the laboratory under oxic and anoxic conditions. Sorption and diffusion of technetium, uranium, plutonium and neptunium were studied in drill cores of granites and gneiss. Cylindrical drill core cup samples and plane surfaces sawed from drill cores were exposed for periods from six to eighteen months to synthetic ground water to which Tc-99, U-233, Pu-236 or Np-237 had been added. Identification of the sorption and the diffusion pathways were discovered by qualitative autora-diography. The concentrations of elements versus depth in the drill core were measured radiometrically, by quantitative autoradio-graphy or by both methods. The migration of plutonium was slow in all samples. Technetium, uranium and neptunium were transported effectively under both oxic and anoxic conditions. Transported species of these elements were found throughout the rock matrices investigated - in microfissures, along mineral grain boundaries and in the minerals themselves. The ranges of the measured apparent diffusivities for neptunium were (2.7 – 30) × 10−14 m2/s under oxic conditions and (1.4 – 4.3) × 10−14 m2/s under anoxic conditions. For uranium the range of Da-values under oxic conditions was (3.6 – 5.7) × 10−14 m2/s under anoxic conditions it was (1.1 × 4.3) × 10−14 m2/s in granitic ground water and (1.8 – 5.3) × 10−14 m2/s in bentonite water.
Speciation of Transuranic Ions in Groundwater by Laser-Induced Photoacoustic Spectroscopy (LPAS)
Authors: Klenze R. , Kim J. I. 
Published: March 2011

ABSTRACTThe speciation of the Am(III) ion in various chemical states is illustrated using laser-induced photoacoustic spectroscopy (LPAS). Based on these reference LPAS spectra, the actual chemical states of Am(III) in one of Gorleben groundwaters are systematically verified. The a-radiolytic oxidation of Am(III) to Am(V) in the concentrated NaCl solution and their carbonate complexation are also speciated for the purpose of demonstration.
In Situ Parametric Investigation of the Mechanism of Diamond Film Deposition from Low Energy Ion Beams
Authors: Lifshitz Y. , Kasi S. R. , Rabalais J. W. 
Published: March 2011

ABSTRACTA general scheme for the analysis of deposition from hyperthermal (10–5000 eV) species is presented. Successful deposition involves consideration of species range, maximum local concentration obtainable, trapping efficiency, radiation damage, and sputtering efficiency. Examples of in situ parametric investigations of carbon deposition performed with a controlled mass selected UHV ion beam facility are presented. A subplantation model for diamond film deposition is discussed. XRD evidence for epitaxial growth of diamond(111) on Si(111) is provided.
Effects of Ionized Cluster Beam Bombardment on Epitaxial Metal Film Deposition on Silicon Substrates
Authors: Yamada Isao 
Published: March 2011

ABSTRACTThe effects of ion beam bombardment during ionized cluster beam (ICB) deposition of metal films on Si(111) and Si(100) substrates have been discussed. In the case of Al deposition, films have been epitaxially deposited on Si(lll) and Si(100) substrates at near room temperature. On Si(111) substrates, nearly perfect Al single crystal films could be formed. On Si(100) substrates, Al bicrystals have been grown epitaxially. A remarkable fact concerning these results is that the epitaxial films could be formed at nearly room temperature and on a large lattice mismatch (25%) substrate surface. Atomic resolution TEM analysis suggests that the epitaxy of Al occurs not only on Si surfaces but also at Al/Al grain boundaries. These epitaxial films exhibit extremely high thermal stability and long electromigration life time. To understand the deposition features and film characteristics, the effects of ICB bombardment on the film growth at the initial stage of the deposition and the resultant film structure have been studied. The results show that the role of very low energy ion bombardment is especially important in forming epitaxial metal films. Depositions of Au and Cu on Si substrates have also been made to understand whether ICB deposition may improve the characteristics of other metal films. Preliminary results of these film depositions are also obtained.
A Thermal Spike Analysis of Low Energy Ion Activated Surface Processes
Authors: Gilmore C. M. , Haeri A. , Sprague J. A. 
Published: March 2011

ABSTRACTA thermal spike analysis was utilized to predict the time evolution of energy propagation through a solid resulting from energetic particle impact. An analytical solution was developed that can predict the number of surface excitations such as desorption, diffusion or chemical reaction activated by an energetic particle. The analytical solution is limited to substrates at zero Kelvin and to materials with constant thermal diffusivities. These limitations were removed by developing a computer numerical integration of the propagation of the thermal spike through the solid and the subsequent activation of surface processes.
A Model of a Combined Film Deposition and Ion Bombardment for Coatings Formation
Authors: Iskanderova Z. A. , Radjabov T. D. , Leiderman R. Yu. , Tukfatullin F. K. 
Published: March 2011

ABSTRACTThe mathematical model of a combined film deposition and and high dose ion implantation for coating formation has been developed. Calculations of concentration profiles of implanted element in the film and substrate depending on different parameters of the model have been carried out.
Silicon Homoepitaxy at Low Temperature Using Microwave Multipolar Plasma for Cleaning and Deposition
Authors: Burke R. , Guillermet M. , Vallier L. , Voisin E. 
Published: March 2011

ABSTRACTThe Microwave Multipolar Plasma (MMP) offers unique features for plasma assisted deposition by combining multipolar magnetic confinement and microwave excitation. Independent control of the plasma-surface interaction parameters (neutral flux, ion flux and ion impact energy) has led to low temperature (400–800°C) silicon epitaxial growth in pure or H2 diluted silane MMPs.Prior to the epitaxial growth of Si, a plasma cleaning is applied to remove 0 and C atoms contaminant from the substrate surface. Ar and H2 were tested on 2 and 4 inch, (100) oriented, silicon wafers loaded “as received” and heated at the deposition temperature. The cleaning is effective in both cases giving a pure Si Auger spectrum. However, a LEED signature is only observed when operating at very low bias of the sample (low energy ions) and the lower the substrate temperature, the lower the energy allowed to obtain a LEED pattern. The cleaning process is also checked and inspected by post-deposition analyses, including TEM, RBS, SIMS and Secco etch.Various layer thicknesses were grown according to the characterization method. Specular epitaxial films are obtained for a large range of plasma and substrate parameters. The temperature may be as low as 400°C but the best results are obtained in the 600–700°C range. Interestingly, epitaxy is lost when the ion energy is increased. These results show a compromise between ion energy and substrate temperature. One needs to work at low ion energy to enhance the surface reaction while avoiding surface damage, but the temperature has to be sufficiently high to restructure the surface. Preliminary results on intentional doping reveal further potentialities of this low energy controlled interaction for low temperature plasma processing.
Deuterium Interactions with Ion-Implanted Oxygen in Cu and Au
Authors: Myers S. M. , Swansiger W. A. , Follstaedt D. M. 
Published: March 2011

ABSTRACTThe interactions of deuterium (D) with oxygen in Cu and Au were examined using ion implantation, nuclear-reaction analysis, and transmission electron microscopy. In Cu, the reduction of Cu2O precipitates by D to produce D20 was shown to occur readily down to room temperature, at a rate limited by the transport of D to the oxides. The reverse process of D2O dissociation was characterized for the first time below the temperature range of steam blistering. The evolution of the Cu(D)-Cu2O-D2O system was shown to be predicted by a newly extended transport formalism encompassing phase changes, trapping, diffusion, and surface release. In Au, buried 0 sinks were used to measure the permeability of D at 573 and 373 K, thereby extending the range of measured permeabilities downward by about six orders or magnitude.
Phases and Microstructures of Carbon-Implanted Niobium
Authors: Huang J. S. , Musket R. G. , Wall M. A. 
Published: March 2011

ABSTRACTPolycrystalline niobium was implanted with 200, 100, and 50 keV carbon ions to create a uniform distribution of carbon over a thickness of about 0.25 μm. Samples implanted with calculated carbon content of 0.6, 1.9, 5.8, and 16 atomic percent were prepared, and the uniformity of the carbon distribution with depth was confirmed by Auger electron spectroscopy analysis. Glancing-angle X-ray diffraction analysis and transmission electron microscopy were used to characterize the phases and microstructures formed. The results indicated that no detectable second phases were present except on the surfaces where an amorphous phase and many particles were formed from contamination. Despite the low equilibrium solubility limit of carbon in Nb, we have created metastable solid solutions of Nb and C with carbon contents as high as 16 at.%.
Ion Beam Analysis of O, N, and B Compositions in Materials Using Non-Rutherford Scattering of Protons
Authors: Parikh N. R. , Zhang Z. H. , Swanson M. L. , Yu N. , Chu W. K. 
Published: March 2011

ABSTRACTElastic scattering of protons with energies from 1.5 MeV to 2 MeV was used to determine the concentration of oxygen in Y-Ba-Cu-O compound, nitrogen in GaN films, and boron in B-Si glass and other materials. Proton scattering from light elements in this energy range exhibits non-Rutherford scattering cross section, which are enhanced by a factor of 3 to 6 or more relative to the Rutherford scattering cross sections. Thus the sensitivity for the light clement detection is considerably larger than that obtained by He ion scattering.Quantitative analysis by proton scattering is discussed and compared with other methods.
Effects of Sputtered Particle Energy on the Properties of SiO2 Films
Authors: Taga Yasunori , Ohwaki Takeshi 
Published: March 2011

ABSTRACTThe secondary ion energy distributions (SIED) emitted from Si under various conditions of targets (Si, SiO2) and primary ions (Ar+, O+) were measured and the thin SiO2 films were deposited by magnetron sputtering techniques under the corresponding conditions to the SIED experiments. The most probable energies of silicon oxygen cluster ions of SimOn+ (m, n=l, 2,…) are equal to those of Al+ thermal ions, while those of Siℓ+ (ℓ=l, 2,…) remain unchanged with the introduction of oxygen in chamber during Ar+ ion bombardment. The currentvoltage plots of SiO2 films are also measured and found to be influenced by the deposition conditions.It is concluded that the differences in current-voltage characteristics of SiO2 films prepared under various sputtering conditions can be reasonably explained in terms of the changes in the most probable energy of the sputtered particles.
Friction Characteristics of B+- and N2+-Implanted Fe-Cr Alloys
Authors: Sasaki Jun , Iwaki Masaya 
Published: March 2011

ABSTRACTA study has been made on friction and hardness of boron and nitrogen ion implanted Fe-Cr alloys. Ion implantation has been carried out with doses ranging from 5 wt% up to 20 wt% at energies of 50, 100 and 150 keY at room temperature. Reciprocal traces for friction coefficient measurements were performed by using a Bowden-Leben tester at a low speed without lubricant. Hardness was measured by using a micro-Vickers tester at a load of 2gf. Hardness of the specimen increases after the implantation with either of ion species. Friction measurements with reciprocal sliding show that a life-time of decreased friction coefficient depends on implanted ion species, Cr concentrations and acceleration energies. For B+- implantation, the lower the chromium contents are, the longer a decreased friction coefficient lasts. Meanwhile, the friction reduced by nitrogen implantation lasts longer for higher chromium content substrates. Dependence of friction coefficient on an acceleration energy is discussed for B+-implantation.
The Friction and Wear Behavior of Ion Beam Assisted Nitride Coatings
Authors: Tetreault Thomas G. , Hirvonen J. K. , Parker G. , Hirvonen J. P. 
Published: March 2011

ABSTRACTThe method of Ion Beam Enhanced Deposition, (IBED), was used to produce hard films of i-BN, i-SixNy and i-TixNy. The friction, hardness, adhesion, and wear behavior of these nitride coalings were examined using a ball-ondisc Friction/wear tester. The friction and wear results were sensitive to stoichiometry and the presence of impurities (e.g., hydrogen) in the film as well as the choice of ball material (400C stainless steel or silicon nitride).
Surface Mechanical Properties of Ti Alloys Produced by Excimer Laser Mixing of Ti on AISI 304 Stainless Steel
Authors: Jervis T. R. , Hirvonen J-P. , Nastasi M. , Zocco T. G. , Martin J. A. , Pharr G. M. , Oliver W. C. 
Published: March 2011

ABSTRACTWe have investigated the properties of surface alloys of Ti formed by excimer laser melting and mixing of Ti overlayers on AISI 304 stainless steel substrates.The thickness of the initial Ti surface layers and the fluence and number of pulses used to mix the surface were varied to investigate a broad range of processing conditions. Samples were uniformly translated at different speeds under repetitive pulses of homogenized laser radiation at 308 nm to vary the number of pulses incident on the sample. We investigated the surface structure and composition, the wear and friction behavior, and the surface hardness of the resulting alloys.The extent of mixing is observed by Rutherford backscattering spectroscopy to be proportional to the number of pulses incident on the sample. Amorphous surface layers are formed at some mixing levels with a composition which indicates that Ti substitutes for Fe in the stainless steel on a one to one basis. Incorporation of C from surface and interface contamination is observed but at a level much below that found in comparable ion implanted materials.Friction coefficient measurements indicate that there exists an optimum level of mixing for each layer thickness. Excessive mixing degrades both the coefficient of friction and the wear performance in dry sliding tests.As with the tribological measurements, the surface hardness showed a dependence on amount of mixing. The surface hardness of the as deposited samples was higher than that of the laser mixed samples, initially decreased with mixing, and finally increased with further mixing.
Combined Oxygen - Nitrogen Ion Implants Into Ti6A14V
Authors: Greenwald Anton , Daly James , Meroth John , Oliver Richard , Sioshansi Piran , Clayton Clive 
Published: March 2011

ABSTRACTThe alloy preferred for medical protheses, Ti6A14V, was ion implanted with oxygen and nitrogen alone and in combination at varying energies, 25 to 120 keV, and varying dose levels, 1017 to 1018 ions/cm2. Measurements were made of microhardness, corrosion resistance, chemical bonding of implanted species, and (with UHMWpo lyethylene) pin-on-disk wear and friction. The addition of oxygen to nitrogen implants now used in production was found to have little effect on wear or any other parameter.
Metal Silicides Formed by Direct Ion Beam Deposition
Authors: Zuhr R. A. , Pennycook S. J. , Haynes T. E. , Holland O. W. 
Published: March 2011

ABSTRACTThin films of transition metal silicides have been produced at low temperatures on Si substrates by direct ion beam deposition (IBD) of the metal ion. Using a mass-analyzed beam of metallic ions rastered over the target at energies on the order of 100 eV and at substrate temperatures near 500°C, stoichiometric silicide films of varying thicknesses up to 300 nm have been formed on both n- and p-type Si. The advantages of this technique over other methods for silicide formation include good control of thickness by current integration, high purity due to the mass analysis, and control of incident ion energy which permits formation of the disilicide phase at low temperatures, thereby minimizing the thermal budget and the associated dopant diffusion in the underlying substrate. Films were characterized by Rutherford backscattering, transmission electron microscopy, and electrical measurements. Co, Fe, Ni, Ti, and W silicides have been formed by this direct deposition process. The effectiveness of the technique has been found to be dependent upon the diffusion characteristics of the particular metal/Si couple involved, with systems in which Si is the dominant diffuser, such as Ti/Si, giving the best results. Stoichiometric TiSi2 films produced at 550°C by this process show low bulk-like resistivity (15 μΩ-cm) without subsequent high-temperature annealing. All of these characteristics make silicide formation by IBD attractive for integrated circuit fabrication and shallow junction technology.
Ion Beam Processing of Optical Materials
Authors: Williams F. L. , Boyer L. L. , Reicher D W. , McNally J. J. , Al-Jumaily G. A. , McNeil J. R. 
Published: March 2011

ABSTRACTWe have deposited thin films of optical materials using ion beam sputtering and ion assisted deposition techniques. It is possible to obtain good quality film material deposited on substrates at temperatures lower than normally required. Ion assisted deposition influences film stoichiometry and packing density, which in turn determine optical and mechanical properties of the film material. We discuss two general indicators which appear helpful in predicting the degree to which these occur.
Thermal Annealing Investigation of the Optical Properties of Si1-xNx Films Fabricated by Ion Beam Assisted Deposition
Authors: Donovan E. P. , Carosella C. A. , Vechten D. Van 
Published: March 2011

ABSTRACTThe annealing behavior of the optical properties of silicon nitride films (Si1-xNx) is described for films fabricated by ion beam assisted deposition. The data are needed for the precise manufacture of optical filters, where the index of refraction must be predicted from deposition parameters and film annealing history.The reflection of homogeneous, amorphous samples deposited on (100) silicon substrates was measured from 500 to 3120 nm. Fits to the interference spectra were obtained over the range 1000 to 3120 nm to obtain the index of refraction vs wavelength as a function of film nitrogen content. Nitrogen atom fraction was varied from.2 to.58 by variation of the incident relative fluxes of nitrogen ion beam current to evaporant silicon flux. The films were annealed in argon at 450 C, 600 C, 750 C, and 1100 C and the measurements repeated. The systematic shifts in index of refraction with annealing temperature are described.