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Thermodynamic ground states of platinum metal nitrides

Description: We have systematically studied the thermodynamic stabilities of various phases of the nitrides of the platinum metal elements using density functional theory. We show that for the nitrides of Rh, Pd, Ir and Pt two new crystal structures, in which the metal ions occupy simple tetragonal lattice sites, have lower formation enthalpies at ambient conditions than any previously proposed structures. The region of stability can extend up to 17 GPa for PtN{sub 2}. Furthermore, we show that according to calculations using the local density approximation, these new compounds are also thermodynamically stable at ambient pressure and thus may be the ground state phases for these materials. We further discuss the fact that the local density and generalized gradient approximations predict different values of the absolute formation enthalpies as well different relative stabilities between simple tetragonal and the pyrite or marcasite structures.
Date: October 9, 2007
Creator: Aberg, D; Sadigh, B; Crowhurst, J & Goncharov, A
Partner: UNT Libraries Government Documents Department

FreedomCAR - Aftertreatment Subsystem Development

Description: The primary objective of this program was to develop generic aftertreatment technologies applicable for LDV and LDT engines ranging from 55 kW to 200kW, to develop an optimized and integrated aftertreatment system for a LDT (Light Duty Truck) type vehicle, and to demonstrate the technology which will enable light duty diesel engines to meet Federal Tier II regulation with minimum impact on fuel economy. Specifically, the development targets for emissions reduction and fuel injection penalty are given below: (1) NOx conversion efficiency > 90% (hot), > 84% (combined); (2) PM conversion efficiency > 90% (hot), > 84% (combined); (3) Fuel penalty over FTP-75 Less than 5%; and (4) Fuel penalty at Cruise condition Less than 3%. Development of cost-effective, highly efficient diesel exhaust aftertreatment systems in combination with very low engine out emission combustion development are essential elements for realization of Federal Tier II emission standards for Light Duty Trucks and Vehicles. Evaluation of several aftertreatment technologies was completed as part of this program. A combination of Diesel Oxidation Catalyst, NOx Adsorbing Catalyst and Catalyzed Soot Filter was found to provide the levels of conversion efficiency required to achieve the emission targets. While early systems required relatively large catalyst volumes, external dosing, sulfur traps, full bypass configurations and high levels of Platinum metals; the final system is a compact, scalable, flow-through, fully-integrated and engine-managed aftertreatment system capable of commercial application for Light Duty Vehicles and Trucks. NOx adsorber/particulate filter technology is particularly attractive for Light Duty applications due to the lower exhaust flow and temperature requirements as compared to Heavy Duty engines. Despite these strong positive aspects, NOx Adsorbers are challenged by their regeneration requirements and susceptibility to sulfur poisoning and thermal degradation. Capability was developed to regenerate the NOx Adsorber for NOx and SOx as well as the Particulate ...
Date: September 30, 2005
Creator: Prentiss, Lisa A.
Partner: UNT Libraries Government Documents Department

Selection of replacement material for the failed surface level gauge wire in Hanford waste tanks

Description: Surface level gauges fabricated from AISI Type 316 stainless steel (316) wire failed after only a few weeks of operation in underground storage tanks at the Hanford Site. The wire failure was determined to be due to chloride ion assisted corrosion of the 316 wire. Radiation-induced breakdown of the polyvinyl chloride (PVC) riser liners is suspected to be the primary source of the chloride ions. An extensive literature search followed by expert concurrence was undertaken to select a replacement material for the wire. Platinum (Pt){minus}20 % Iridium (Ir) alloy was selected as the replacement material from tile candidate materials, P-20% Ir, Pt-1O% Rhodium (Rh), Pt-20%Rh and Hastelloy C-22. The selection was made on the basis of the alloy`s immunity towards acidic and basic environments as well as its adequate tensile properties in the fully annealed state.
Date: October 1, 1995
Creator: Anantatmula, R.P.; Pitman, S.G. & Lund, A.L.
Partner: UNT Libraries Government Documents Department

Vitrification of noble metals containing NCAW simulant with an engineering scale melter (ESM): Campaign report

Description: ESM has been designed as a 10th-scale model of the DWPF-type melter, currently the reference melter for nitrification of Hanford double shell tankwaste. ESM and related equipment have been integrated to the existing mockup vitrification plant VA-WAK at KfK. On June 2-July 10, 1992, a shakedown test using 2.61 m{sup 3} of NCAW (neutralized current acid waste) simulant without noble metals was performed. On July 11-Aug. 30, 1992, 14.23 m{sup 3} of the same simulant with nominal concentrations of Ru, Rh, and Pd were vitrified. Objective was to investigate the behavior of such a melter with respect to discharge of noble metals with routine glass pouring via glass overflow. Results indicate an accumulation of noble metals in the bottom area of the flat-bottomed ESM. About 65 wt% of the noble metals fed to the melter could be drained out, whereas 35 wt% accumulated in the melter, based on analysis of glass samples from glass pouring stream in to the canisters. After the melter was drained at the end of the campaign through a bottom drain valve, glass samples were taken from the residual bottom layer. The samples had significantly increased noble metals content (factor of 20-45 to target loading). They showed also a significant decrease of the specific electric resistance compared to bulk glass (factor of 10). A decrease of 10- 15% of the resistance between he power electrodes could be seen at the run end, but the total amount of noble metals accumulated was not yet sufficient enough to disturb the Joule heating of the glass tank severely.
Date: March 1, 1996
Creator: Grunewald, W.; Roth, G.; Tobie, W.; Weisenburger, S.; Weiss, K.; Elliott, M. et al.
Partner: UNT Libraries Government Documents Department

Solid state device for two-wire downhole temperature measurement as a function of current. Final performance technical report

Description: Several metals systems were reviewed for their potential to act as resistive temperature devices. Platinum metal was selected as the metal of choice. Platinum was plated onto 5 mil copper wire, and then subsequently coated with Accusol's proprietary ceramic coating. The copper was etched out in an attempt to make a pure platinum, high resistive, resistive-temperature device. The platinum plating on the wire cracked during processing, resulting in a discontinuous layer of platinum, and the element could not be formed in this way.
Date: January 15, 2002
Creator: Anderson, Roger & Anderson, David
Partner: UNT Libraries Government Documents Department

Initial calorimetry experiments in the Physics Division, ORNL (Oak Ridge National Laboratory)

Description: Four calorimetry experiments were performed with palladium cathode electrolysis cells to investigate the possibility of cold fusion heat production based on the reported results of Fleischmann and Pons. Two of the cells contained 6.35-mm-diam {times} 10-cm-long palladium cathodes in a 0.2-M {sup 6}LiOD electrolyte; one cell contained a similar cathode in a 0.1-M {sup 6}LiOD electrolyte solution; and one cell used a cast 1.27-cm-diam {times} 10-cm long palladium rod in a 0.2-M electrolyte. All four cells were constructed with platinum wire anodes. One of the cells exhibited an apparent 2-3 W power excess for a period of approximately 300 hours of a total operating time of 1800 hours; each of the remaining cells remained in power balance for the 1800 hour period. 2 refs., 5 figs.
Date: January 1, 1989
Creator: Hutchinson, D.P.; Bennett, C.A.; Richards, R.K.; Bullock, J. IV. & Powell, G.L.
Partner: UNT Libraries Government Documents Department

Recovery of deformed and hydrogen-charge palladium

Description: Positron lifetime and Doppler-broadening studies made at 300 K have been used to investigate the interaction between interstitial hydrogen and lattice defects in deformed Pd. Specimens were charged with hydrogen at 300 K to levels up to 0.1%. The presence of hydrogen was found to have no effect on the recovery curves of Pd upon annealing to 400/sup 0/C. By 400/sup 0/C the values for both lifetime and Doppler-broadening for both cold worked and cold worked plus hydrogen were below the values obtained for annealed pure Pd. This can be interpreted as gaseous-impurity-trapped vacancies being present after the 1200/sup 0/C anneal, but being swept away by the dislocation microstructure recovery between 200 to 400/sup 0/C.
Date: January 1, 1982
Creator: Snead, C.L. Jr.; Lynn, K.G. & Lynch, J.F.
Partner: UNT Libraries Government Documents Department

Controlled-potential-coulometric determination of uranium at a platinum electrode

Description: A controlled-potential-coulometric method has been developed for determining uranium at a solid electrode which features high specificity and a precision of 0.1% relative standard deviation at the 5 mg uranium level. Uranium and added iron, necessary for the electrolytic oxidation of uranium, are reduced to U(IV) and Fe(II) with excess Cr(II). At a sequence of controlled potentials, the excess Cr(II) is oxidized to Cr(III), Fe(II) and U(IV) are oxidized to Fe(III) and U(VI), then the Fe(III) is reduced to Fe(II). The difference in the measured number of coulombs for the oxidation of Fe(II) and U(IV) and for the reduction of Fe(III) to Fe(II) is proportional to the quantity of uranium.
Date: January 1, 1983
Creator: Saponara, N.M. & Jackson, D.D.
Partner: UNT Libraries Government Documents Department

Geochemical anomalies near the Eocene-Oligocene and Permian-Triassic boundaries

Description: Evidence is presented to support the theory that several mass extinctions, i.e., those that define the Permian-Triassic boundary, the Cretaceous-Tertiary boundary, and the Eocene-1 Oligocene boundary, were caused by impact on the earth of extraterrestrial objects having the composition of carbonaceous chondrites and diameters of about 10 km. The evidence consists of anomalously high concentrations of iridium and other siderophile elements at the stratigraphic levels defining the extinctions. (ACR)
Date: October 1, 1981
Creator: Asaro, F.; Alvarez, L.W.; Alvarez, W. & Michel, H.V.
Partner: UNT Libraries Government Documents Department

Study of mechanisms of hydrogen diffusion in separation devices. Third annual report, 1979-1980

Description: The main results are in the following three areas: (1) examination of a diffusion model for PdH system, (2) connection between the diffusion model and other physical models, (3) related problems. Advances made during the third year of this project, particularly in understanding the physical model for hydrogen diffusion, make it possible to begin to meet some of the long-range objectives described in the initial proposals of 1977-1978.
Date: April 5, 1980
Creator: Lee, M.H.
Partner: UNT Libraries Government Documents Department

Mass spectrometric analysis of nanogram levels of ruthenium

Description: Previous investigations have demonstrated the possibility of using ruthenium originating from the spontaneous fission of /sup 238/U for geochronological purposes. Because the abundance of ruthenium is low in geologic specimens and isotopic data are required, an indepth study of the production of steady mass spectrometer ion beams from nanogram amounts of ruthenium was undertaken. The results of this continuing mass spectrometric investigation are presented with some illustrative data.
Date: January 1, 1979
Creator: Delmore, J.E.
Partner: UNT Libraries Government Documents Department

A Frontier Molecular Orbital determination of the active sites on dispersed metal catalysts

Description: An angular overlap calculation has been used to determine the s, p and d orbital energy levels of the different types of surface sites present on a dispersed metal catalysts. The basis for these calculations is the reported finding that a large number of catalyzed reactions take place on single atom active sites on the metal surface. Thus, these sites can be considered as surface complexes made up of the central active atom surrounded by near-neighbor metal atom ligands'' with localized surface orbitals perturbed only by these ligands''. These complexes'' are based on a twelve coordinate species with the ligands'' attached to the t{sub 2g} orbitals and the coordinate axes coincident with the direction of the e{sub g} orbitals on the central atom. These data can permit a Frontier Molecular Orbital treatment of specific site activities as long as the surface orbital availability for overlap with adsorbed substrates is considered along with its energy value and symmetry.
Date: January 1, 1992
Creator: Augustine, R.L. & Lahanas, K.M.
Partner: UNT Libraries Government Documents Department

On the Hardening and Softening of Nanocrystalline Materials

Description: Nanocrystalline Pd and Cu samples have been thermally treated to determine whether the relation between hardness and grain size depend on the method used to vary the grain sizes. Previous reports indicate that hardening with decreasing grain size resulted from data obtained using individual samples, while softening with decreasing grain size resulted from data from a given sample that had been thermally treated. Hardening and softening regimes were evident for the nanocrystalline cu, and the hardness improvements over the original as-consolidated state were maintained throughout the thermal treatments. This review examines our hardness results for Cu and Pd and those for other nanocrystalline materials.
Date: April 1, 1993
Creator: Fougere, G. E.; Weertman, J. R. & Siegel, R. W.
Partner: UNT Libraries Government Documents Department

Catalytic oxidation of secondary alcohols

Description: The dioxygen oxidation of alcohols over platinum catalysts has been known for a long time. While of potential importance in synthetic procedures, this process has never found extensive use except in carbohydrate oxidations. Some reasons for this is the fact that this reaction only appears to work well in an aqueous medium in the presence of rather large amounts of a Pt black catalyst. Results obtained here show that supported Pt catalysts can be used to promote this oxidation in organic solvents provided a small amount of water is added to the reaction medium. It was also estabilished that the reaction takes place on the more coordinately unsaturated corner atoms on the Pt surface.
Date: January 1, 1992
Creator: Augustine, R.L. & Doyle, L.K.
Partner: UNT Libraries Government Documents Department

Direct observations of the primary state of radiation damage of ion-irradiated tungsten and platinum

Description: A brief summary was presented of all the Cornell work on the primary state of radiation damage in ion-irradiated tungsten and platinum. The primary research tool for all this research was the field-ion microscope (FIM); the FIM was ideally suited for this research because of its excellent atomic resolution and the ability to examine the interior of the specimens, as a result of the field-evaporation effect. This paper summarized, in outline form, the following items: (1) the principal experimental quantities determined from the analyses performed on all the individual depleted zones (DZs) observed; (2) the main experimental programs; (3) a number of the more important results and conclusions concerning the vacancy structure of DZs; and (4) the three-dimensional spatial distribution of self-interstitial atoms around DZs in tungsten which had been irradiated and examined in situ at 10/sup 0/K.
Date: July 1, 1980
Creator: Seidman, D. N.; Current, M. I.; Pramanik, D. & Wei, C. Y.
Partner: UNT Libraries Government Documents Department

Development of highly polished, grazing incidence mirrors for synchrotron radiation beam lines at SSRL

Description: New platinum-coated grazing incidence mirrors with low surface roughnesses have been developed to focus bending magnet radiation from the SSRL/SLAC SPEAR storage ring on the entrance slits of two Beam Line VIII grating monochromators. The first mirror in the toroidal grating monochromator (TGM) branch is a cooled SiC cylinder capable of absorbing synchrotron radiation power levels of up to 260 watts without excessive distortion. This mirror deflects the beam vertically through a 12/degree/ angle and focuses it sagitally on the TGM entrance slit plane. The second TGM optical element is a fused-silica spherical mirror with a large radius of curvature that deflects the beam vertically through an additional 12/degree/ and focuses it tangentially with 3/1 demagnification. The first mirror in our spherical grating branch is a 5/degree/-vertically deflecting, cooled SiC toroid designed to focus tangentially on the monochromator entrance slits and sagitally in the exit slits. A 4/degree/-deflecting fused silica mirror is used after the exit sites in each beam line to refocus on to the sample. For this application a thin cylinder is bent to approximate an ellipsoid. The mirrors are now installed at SSRL and performance measurements are planned. Qualitatively the focus of the TGM optics at the entrance slit plane appears very good. In this paper we discuss considerations leading to the choice of SiC for each of the two first mirrors. We present highlights of the development of these mirrors with some emphasis on SiC polishing techniques. In addition, the specialized metrology developed to produce the more difficult figure of the toroid will be described. Measured surface roughness and figure results will be presented. 19 refs., 11 figs.
Date: August 1, 1987
Creator: Tirsell, K.G.; Berglin, E.J.; Fuchs, B.A.; Holdener, F.R.; Humpal, H.H.; Karpenko, V.P. et al.
Partner: UNT Libraries Government Documents Department

Fermi surface of platinum

Description: The two high-mass (epsilon,..beta..) orbits on the open hole surface of platinum predicted by band structure calculations but not observed in previous de Haas--van Alphen studies were measured; a complete set of area data for this transition metal is thus provided. A phase-shift fit to these area data using a nonmuffin-tin relativistic KKR formalism was calculated, with an rms error of about 0.2%. From this fit the Fermi radii were determined for all surfaces. As a check, the total volume of the hole surfaces was calculated and compared with that of the electron surface; agreement to within 1% was found. Effective mass data were also fit, with an rms error of 3.4%; the density of states calculated from the fit was constrained to agree with the specific heat value; Fermi velocities were determined for all surfaces. 2 figures, 3 tables.
Date: January 1, 1977
Creator: Dye, D. H. & Ketterson, J. B.
Partner: UNT Libraries Government Documents Department

Secondary defects in quenched platinum

Description: The structure of secondary defects in two different platinum purities quenched under ultra high vacuum, has been studied by transmission electron microscopy. Faulted loops on (100) planes have been observed in both materials. In the less pure platinum, Pt B (but purer in terms of carbon content), the defects were observed after quenching, whereas in the purest one, Pt A (but less pure in terms of carbon content), the defects were formed after a long annealing. The Burgers vector of the loops formed after the quenching was a/3 <100> and for loops formed during long annealings, was a/2 <100>, apparently. It was found that in Pt B the loop density increased and the loop size decreased as the quenching temperature was lowered.The same effect was produced by increasing the carbon content by a small amount. The loop formation was totally inhibited by adding a larger amount of carbon and also when the quenching was performed in poor vacuum (approx. 0.01 torr) or in air. The defects can be interpreted as pure vacancy loops heterogeneously nucleated at carbon atom clusters or, as plate like precipitates of carbon atoms and vacancies formed by a co-precipitation mechanism. The discussion of the experimental results obtained is based upon these two models.
Date: November 1, 1979
Creator: Perez, M.I.
Partner: UNT Libraries Government Documents Department

Recent advances in Pt coating of microspheres by a batch magnetron sputtering process

Description: Some proposed inertial confinement fusion targets require high-Z, high density metal coatings on glass microspheres. Platinum, which satisfies the high-Z and density requirements, can be coated onto microspheres with a batch magnetron sputtering process incorporating oxygen as a dopant gas to prevent the microspheres from sticking. This paper outlines recent progress in three areas: First, the coating process has been improved; second, the oxygen content and resistivity of the oxygen doped platinum films are analyzed; and third, the roles oxygen may play in reducing microsphere sticking during sputtering are discussed in regard to cold welding, Van der Waals bonding, electrostatic sticking, and sintering.
Date: August 29, 1980
Creator: Hsieh, E.J. & Meyer, S.F.
Partner: UNT Libraries Government Documents Department

Evidence of surface migration and formation of catalytically inactive Pt in corrosion studies of Pt/sup +/ implanted Ti

Description: This investigation is part of an ongoing research project directed at applying the techniques of ion implantation doping and ion scattering analysis to identify the mechanisms associated with the anodic dissolution of Ti-Pt alloys. The Ti-Pt alloys produced by ion implantation were electrochemically examined in hydrogen saturated 1 N H/sub 2/SO/sub 4/ by both potentiostatic polarization and open-circuit potential methods. In this study, Ti samples implanted to relatively high doses (5.4 x 10/sup 15/ to 2.9 x 10/sup 16/ atoms/cm/sup 2/) were examined by ion scattering analysis at various stages in the electrochemical measurements. Quantitative measurements showed that the majority of the implanted Pt accumulated on the surface during anodic dissolution and underwent large scale surface migration. Evidence is also presented for the transition of the Pt on the surface from a catalytically active to inactive state. Possible mechanisms for the observed catalytically inactive Pt are discussed.
Date: August 1, 1980
Creator: Appleton, B.R.; Kelly, E.J.; White, C.W.; Thompson, N.G. & Lichter, B.D.
Partner: UNT Libraries Government Documents Department

Current operations and experiments at the Tritium Systems Test Assembly

Description: The Tritium Systems Test Assembly (TSTA) has continued to move toward operation of a fully-integrated, full-sized, computer-controlled fusion fuel processing loop. Concurrent, nonloop experiments have answered important questions on new components and issues such as palladium diffusion membranes, ceramic electrolysis cells, regenerable tritium getters, laser Raman spectroscopy, unregenerable tritium inventory on molecular sieves, tritium contamination problems and decontamination methods, and operating data on reliability, emissions, doses, and wastes generated. 4 refs., 2 figs.
Date: January 1, 1985
Creator: Bartlit, J.R. & Anderson, J.L.
Partner: UNT Libraries Government Documents Department

Some considerations of cold fusion including the calculation of fusion rates in molecules of hydrogen isotopes

Description: We calculate the fusion reaction rates in molecules of hydrogen isotopes. The rates are calculated analytically (for the first time) as an asymptotic expansion in the ratio of the electron mass to the reduced mass of the nucleii. The fusion rates of the P-D, D-D, and D-T reactions are given for a variable electron mass by a simple analytic formula. However, we do not know any mechanism by which a sufficiently localized electron in solid can have an effective mass' large enough to explain the result of Fleischman and Pons (FP). This calculation indicates that P-D rates should exceed D-D rates for D-D fusion rates less than approximately 10{sup {minus}23} per molecule per second. The D-D fusion rate is enhanced by a factor of 10{sup 5} at 10,000{degree}K if the excited vibrational states are populated with a Boltzmann distribution and the rotational excitations suppressed. The suggestion that experimental results could be explained by bombardment of cold deuterons by kilovolt deuterons is shown to be an unlikely from an energetic point of view. 12 refs., 3 figs., 1 tab.
Date: November 1, 1989
Creator: Cowley, S.C. & Kulsrud, R.M.
Partner: UNT Libraries Government Documents Department