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Zinc and Its Alloys

Description: Report issued by the Bureau of Standards discussing world production of zinc and zinc alloys. History, metallurgy, and structural properties of zinc are presented. This report includes tables, illustrations, and photographs.
Date: November 6, 1931
Creator: United States. Bureau of Standards.
Partner: UNT Libraries Government Documents Department

The formation of metal/metal-matrix nano-composites by the ultrasonic dispersion of immiscible liquid metals

Description: Ultrasonic energy has been used to disperse one liquid metallic component in a second immiscible liquid metal, thereby producing a metallic emulsion. Upon lowering the temperature of this emulsion below the mp of the lowest-melting constituent, a metal/metal-matrix composite is formed. This composite consists of sub-micron-to-micron- sized particles of the minor metallic phase that are embedded in a matrix consisting of the major metallic phase. Zinc-bismuth was used as a model system, and ultrasonic dispersion of a minor Bi liquid phase was used to synthesize metal/metal-matrix composites. These materials were characterized using SEM and energy-dispersive x-ray analysis.
Date: December 1, 1996
Creator: Keppens, V.M.; Mandrus, D.; Boatner, L.A. & Rankin, J.
Partner: UNT Libraries Government Documents Department

Internal electric-field-lines distribution in CdZnTe detectors measured using X-ray mapping

Description: The ideal operation of CdZnTe devices entails having a uniformly distributed internal electric field. Such uniformity especially is critical for thick long-drift-length detectors, such as large-volume CPG and 3-D multi-pixel devices. Using a high-spatial resolution X-ray mapping technique, we investigated the distribution of the electric field in real devices. Our measurements demonstrate that in thin detectors, <5 mm, the electric field-lines tend to bend away from the side surfaces (i.e., a focusing effect). In thick detectors, 21 cm, with a large aspect ratio (thickness-to-width ratio), we observed two effects: the electric field lines bending away from or towards the side surfaces, which we called, respectively, the focusing field-line distribution and the defocusing field-line distribution. In addition to these large-scale variations, the field-line distributions were locally perturbed by the presence of extended defects and residual strains existing inside the crystals. We present our data clearly demonstrating the non-uniformity of the internal electric field.
Date: June 1, 2008
Creator: Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Hossain, A.; Yang, G.; Yao, H. W. et al.
Partner: UNT Libraries Government Documents Department

The development of lightweight hydride alloys based on magnesium

Description: The development of a magnesium based hydride material is explored for use as a lightweight hydrogen storage medium. It is found that the vapor transport of magnesium during hydrogen uptake greatly influences the surface and hydride reactions in these alloys. This is exploited by purposely forming near-surface phases of Mg{sub 2}Ni on bulk Mg-Al-Zn alloys which result in improved hydrogen adsorption and desorption behavior. Conditions were found where these near-surface reactions yielded a complex and heterogeneous microstructure that coincided with excellent bulk hydride behavior. A Mg-Al alloy hydride is reported with near atmospheric plateau pressures at temperatures below 200{degrees}C. Additionally, a scheme is described for low temperature in-situ fabrication of Mg{sub 2}Ni single phase alloys utilizing the high vapor pressure of Mg.
Date: February 1, 1996
Creator: Guthrie, S.E.; Thomas, G.J.; Yang, N.Y.C. & Bauer, W.
Partner: UNT Libraries Government Documents Department

Electrochemical Deposition of Zinc-Nickel Alloys in Alkaline Solution for Increased Corrosion Resistance.

Description: The optimal conditions for deposition of zinc-nickel alloys onto stainless steel discs in alkaline solutions have been examined. In the past cadmium has been used because it shows good corrosion protection, but other methods are being examined due to the high toxicity and environmental threats posed by its use. Zinc has been found to provide good corrosion resistance, but the corrosion resistance is greatly increased when alloyed with nickel. The concentration of nickel in the deposit has long been a debated issue, but for basic solutions a nickel concentration of 8-15% appears optimal. However, deposition of zinc-nickel alloys from acidic solutions has average nickel concentrations of 12-15%. Alkaline conditions give a more uniform deposition layer, or better metal distribution, thereby a better corrosion resistance. Although TEA (triethanolamine) is most commonly used to complex the metals in solution, in this work I examined TEA along with other complexing agents. Although alkaline solutions have been examined, most research has been done in pH ≥ 12 solutions. However, there has been some work performed in the pH 9.3-9.5 range. This work examines different ligands in a pH 9.3-9.4 range. Direct potential plating and pulse potential plating methods are examined for optimal platings. The deposits were examined and characterized by XRD.
Date: December 2009
Creator: Conrad, Heidi A.
Partner: UNT Libraries

Distribution of zinc, resistivity, and photosensitivity in a Vertical Bridgman grown Cd1-xZnxTe ingot.

Description: We present the results of a comprehensive study of distribution of zinc, resistivity, and photosensitivity in a Cd{sub 1-x}Zn{sub x}Te ingot grown by the Vertical Bridgman method. We used several complementary methods, viz., glow discharge mass spectroscopy, photoluminescence-, resistivity-, and photosensitivity-mapping, along with photo-induced current transient spectroscopy to characterize the material. We identified electronic levels in the band-gap responsible for compensation, recombination, and photosensitivity.
Date: May 1, 2008
Creator: Babentsov, V.; Franc, J.; Fauler, A.; Fiederle, M. & James, R. B.
Partner: UNT Libraries Government Documents Department

Properties and processing of nanocrystalline materials. Quarterly report

Description: The present Report completes the investigations in the frame of the project for the first year. It is important to estimate our achievements in the investigation of properties of nanocrystalline materials obtained by severe plastic deformation and their production. We think that the main results obtained can be summarized as follows: (1) We performed an improvement of the die-set for equal channel (ECA) pressing and torsion under high pressure with the aim to increase dimensions of the samples produced and to conduct processing of low ductile materials. (2) It was established that in pure metals severe plastic deformation led to the formation of an ultra fine-grained structure with a mean grain size of 100-200 nm, while in alloys due to severe plastic deformation and/or special methods of treatment (a decrease in the temperature of deformation, an increase of the pressure applied etc.) the grain size could be decreased down to a few tens of manometers.
Date: January 22, 1996
Creator: Valiev, R.Z.
Partner: UNT Libraries Government Documents Department

Final disposal options for mercury/uranium mixed wastes from the Oak Ridge Reservation

Description: Laboratory testing was completed on chemical stabilization and physical encapsulation methods that are applicable (to comply with federal and state regulations) to the final disposal of both hazardous and mixed hazardous elemental mercury waste that is in either of the following categories: (1) waste generated during decontamination and decommissioning (D and D) activities on mercury-contaminated buildings, such as Building 9201-4 at the Oak Ridge Y-12 Plant, or (2) waste stored and regulated under either the Federal Facilities Compliance Agreement or the Federal Facilities Compliance Act. Methods were used that produced copper-mercury, zinc-mercury, and sulfur-mercury materials at room temperature by dry mixing techniques. Toxicity Characteristic Leaching Procedure (TCLP) results for mercury on batches of both the copper-mercury and the sulfur-mercury amalgams consistently produced leachates with less than the 0.2-mg/L Resource Conservation and Recovery Act (RCRA) regulatory limit for mercury. The results clearly showed that the reaction of mercury with sulfur at room temperature produces black mercuric sulfide, a material that is well suited for land disposal. The results also showed that the copper-mercury and zinc-mercury amalgams had major adverse properties that make them undesirable for land disposal. In particular, they reacted readily in air to form oxides and liberate elemental mercury. Another major finding of this study is that sulfur polymer cement is potentially useful as a physical encapsulating agent for mercuric sulfide. This material provides a barrier in addition to the chemical stabilization that further prevents mercury, in the form of mercuric sulfide, from migrating into the environment.
Date: August 29, 1994
Creator: Gorin, A.H.; Leckey, J.H. & Nulf, L.E.
Partner: UNT Libraries Government Documents Department

Monte Carlo study of neutronics properties of the modular storage geometry

Description: The modular storage vault (MSV) geometry was investigated for its effects on the spectrum of neutrons from the spontaneous and induced fission of plutonium. Zinc alloy and aluminum alloy plates that will house neutron detectors and weight sensors were included. It was found that because of the large number of captures by plutonium and the steel and concrete MSV structure, only 12% of the neutron spectrum in the vicinity of the detector position was thermalized and over half of the neutrons incident on the detector position have energy in excess of 100 keV. Based on this, it is recommended that both fast and slow neutron detectors be included in the instrumentation package if plutonium is to be stored an MSV structure. No differences in the neutron spectra were found with different zinc alloys. In addition, insufficient differences in the spectra were found when aluminum was substituted for zinc to warrant any recommendation for one material over the other.
Date: September 1995
Creator: Bell, Z. W.
Partner: UNT Libraries Government Documents Department

Constant Q measurements of collective modes in Mg{sub 70}Zn{sub 30} glass

Description: In this study the Neutron Brillouin Scattering technique has been used to measure longitudinal excitations in a magnesium-zinc glass at momentum transfers within the first pseudo-Brillouin zone. The measurements were performed at room temperature and constant momentum transfer, which enables the data to be readily and reliably compared with theory. The experimental results taken down to Q = 6.2 nm{sup {minus}1} and E = 27 meV show a 5 meV downward shift in the dispersion energy of the longitudinal optic mode of the glass when compared to theoretical predictions.
Date: November 1, 1997
Creator: Benmore, C.J.; Sweeney, S.; Robinson, R.A.; Egelstaff, P.A. & Suck, J.B.
Partner: UNT Libraries Government Documents Department

Argonne National Laboratory Chemical Engineering Division Summary Report: July, August, September 1960

Description: 9 : : 7 : 7 9 : 5 5 ? 5 9 G -- 8 ; 8 ; = -activity levels of the melt-refining process for EBR-II core fuel was completed. An experiment was also completed on the evolution of fission- product krypton and xenon from an irradiated fuel pim as it was heat to a temperature above the melting point. In tests of alternate materials for use in a meltrefining furnace, a fibrous potassium titanate grain retainer was found to be a very effective heat insulator, but to have less strength than nigid Fibenfrax retainers. The skull remaining in the zirconia crucible after a meltrefining operation must be processed to recover, as partially purified metal, the fissionable material for return to the fuel cycle. Several essentially quantitative reductions of uranium dioxide and skull oxides were achieved in times of less than 8 hr at 800 deg C in dilute magnesium-zinc solutions and in magnesium containing a small percentage (0.5 to 2) of sodium as a wetting agent. Data and equations for solubilities of other elements in liquid cadmium are included. The partition coefficients of a numbsr of representative fissile and fission product elements between the two immiscible liquids, lead and zinc, at about 735 deg C were measured. The free energy of formation of the uraniumthallium intermetallic compound UTl/sub 3/ was measured, using a galvanic cell method. Galvanic cell measurements with the cerium-zinc system at 443 to 742 deg C were also made. The determination of the heat of formation of zirconium tetrafluoride by combustions of zirconium in fluonine was completed. A valus of -372.44 kcal/mole was obtained for the heat of formation of molybdenum hexafluoride. Calorimetric oombustions of boron in fluorine are being continued. Exploratory combustions of magnesium, aluminum, zinc, and cadmium are being carried out. Fuel ...
Date: October 1961
Creator: Argonne National Laboratory. Chemical Engineering Division.
Partner: UNT Libraries Government Documents Department

AFM CHARACTERIZATION OF LASER INDUCED DAMAGE ON CDZNTE CRYSTAL SURFACES

Description: Semi-conducting CdZnTe (or CZT) crystals can be used in a variety of detector-type applications. CZT shows great promise for use as a gamma radiation spectrometer. However, its performance is adversely affected by point defects, structural and compositional heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity), secondary phases and in some cases, damage caused by external forces. One example is damage that occurs during characterization of the surface by a laser during Raman spectroscopy. Even minimal laser power can cause Te enriched areas on the surface to appear. The Raman spectra resulting from measurements at moderate intensity laser power show large increases in peak intensity that is attributed to Te. Atomic Force Microscopy (AFM) was used to characterize the extent of damage to the CZT crystal surface following exposure to the Raman laser. AFM data reveal localized surface damage in the areas exposed to the Raman laser beam. The degree of surface damage to the crystal is dependent on the laser power, with the most observable damage occurring at high laser power. Moreover, intensity increases in the Te peaks of the Raman spectra are observed even at low laser power with little to no visible damage observed by AFM. AFM results also suggest that exposure to the same amount of laser power yields different amounts of surface damage depending on whether the exposed surface is the Te terminating face or the Cd terminating face of CZT.
Date: June 10, 2008
Creator: Hawkins, S; Lucile Teague, L; Martine Duff, M & Eliel Villa-Aleman, E
Partner: UNT Libraries Government Documents Department

EFFECTIVENESS OF ELECTROSTATIC SHIELDING AND ELECTRONIC SUBTRACTION TO CORRECT FOR THE HOLE TRAPPING IN CDZNTE SEMICONDUCTOR DETECTORS.

Description: CdZnTe (CZT) is a very promising material for nuclear-radiation detectors. CZT detectors operate at ambient temperatures and offer high detection efficiency and excellent energy resolution, placing them ahead of high-purity Ge for those applications where cryogenic cooling is problematic. The progress achieved in CZT detectors over the past decade is founded on the developments of robust detector designs and readout electronics, both of which helped to overcome the effects of carrier trapping. Because the holes have low mobility, only electrons can be used to generate signals in thick CZT detectors, so one must account for the variation of the output signal versus the locations of the interaction points. To obtain high spectral resolution, the detector's design should provide a means to eliminate this dependence throughout the entire volume of the device. In reality, the sensitive volume of any ionization detector invariably has two regions. In the first, adjacent to the collecting electrode, the amplitude of the output signal rapidly increases almost to its maximum as the interaction point is located farther from the anode; in the rest of the volume, the output signal remains nearly constant. Thus, the quality of CZT detector designs can be characterized based on the magnitude of the signals variations in the drift region and the ratio between the volumes of the driR and induction regions. The former determines the ''geometrical'' width of the photopeak i.e., the line width that affects the total energy resolution and is attributed to the device's geometry when all other factors are neglected. The latter determines the photopeak efficiency and the area under the continuum in the pulse-height spectra. In this work, we describe our findings from systematizing different designs of CZT detectors and evaluating their performance based on these two criteria.
Date: August 26, 2007
Creator: BOLOTNIKOV,A.E.; CAMARDA, G.S.; HOSSAIN, A.; CUI, Y. & JAMES, R.B.
Partner: UNT Libraries Government Documents Department

Predicting Low Energy Dopant Implant Profiles in Semiconductors using Molecular Dynamics

Description: The authors present a highly efficient molecular dynamics scheme for calculating dopant density profiles in group-IV alloy, and III-V zinc blende structure materials. Their scheme incorporates several necessary methods for reducing computational overhead, plus a rare event algorithm to give statistical accuracy over several orders of magnitude change in the dopant concentration. The code uses a molecular dynamics (MD) model to describe ion-target interactions. Atomic interactions are described by a combination of 'many-body' and pair specific screened Coulomb potentials. Accumulative damage is accounted for using a Kinchin-Pease type model, inelastic energy loss is represented by a Firsov expression, and electronic stopping is described by a modified Brandt-Kitagawa model which contains a single adjustable ion-target dependent parameter. Thus, the program is easily extensible beyond a given validation range, and is therefore truly predictive over a wide range of implant energies and angles. The scheme is especially suited for calculating profiles due to low energy and to situations where a predictive capability is required with the minimum of experimental validation. They give examples of using the code to calculate concentration profiles and 2D 'point response' profiles of dopants in crystalline silicon and gallium-arsenide. Here they can predict the experimental profile over five orders of magnitude for <100> and <110> channeling and for non-channeling implants at energies up to hundreds of keV.
Date: May 2, 1999
Creator: Beardmore, K.M. & Gronbech-Jensen, N.
Partner: UNT Libraries Government Documents Department

Thermoelectric properties of ZnSb films grown by MOCVD

Description: The thermoelectric properties of metallorganic chemical vapor deposited (MOCVD) ZnSb films are reported. The growth conditions necessary to obtain stoichiometric ZnSb films and the effects of various growth parameters on the electrical conductivity and Seebeck coefficients of the films are described. The as-grown ZnSb films are p-type. It was observed that the growth of thicker ZnSb films lead to improved carrier mobilities and lower free-carrier concentrations. The Seebeck coefficient of ZnSb films was found to rise rapidly at approximately 160 to 170 C, with peak Seebeck coefficients as high as 470 {micro}V/K at 220 C. The various growth conditions, including the use of intentional dopants, to improve the Seebeck coefficients at room temperature and above, are discussed. A short annealing of the ZnSb films at temperatures of {approximately} 200 C resulted in reduced free-carrier levels and higher Seebeck coefficients at 300 K. Finally, ZT values based on preliminary thermal conductivity measurements using the 3-{omega} method are reported.
Date: April 1, 1997
Creator: Venkatasubramanian, R.; Watko, E. & Colpitts, T.
Partner: UNT Libraries Government Documents Department

Competing mechanisms for ordering tendencies in BCC CuAuZn{sub 2} and FCC AuFe alloys

Description: We have briefly discussed the ASRO (atomic short-range order) in AuFe and CuAuZn{sub 2}. General points are that (1) we have implemented a first-principles theory of ASRO in N-component alloys which allows determination of the electronic origins of said ASRO; (2) such calculations can provide much information on the high- and (sometimes) low-temperature alloys; and (3) this approach has identified the origin for the novel special-point ASRO in AuFe. Displacement effects, i.e., non-rigid lattice effects, as well as the other contributions beyond band-energy, are being incorporated into the multicomponent alloy calculations. Such improvements will allow us to investigate other alloys, where charge effects may play a role, to ``design`, for example, higher temperature intermetallics through alloying.
Date: July 1, 1995
Creator: Johnson, D.D.; Althoff, J.D.; Staunton, J.B.; Ling, M.F. & Pinski, F.J.
Partner: UNT Libraries Government Documents Department

Liquid-metal-cooled, curved-crystal monochromator for Advanced Photon Source bending-magnet beamline 1-BM

Description: The authors describe a horizontally focusing curved-crystal monochromator that invokes a 4-point bending scheme and a liquid-metal cooling bath. The device has been designed for dispersive diffraction and spectroscopy in the 5--20 keV range, with a predicted focal spot size of {le} 100 {micro}m. To minimize thermal distortions and thermal equilibration time, the 355 x 32 x 0.8 mm crystal will be nearly half submerged in a bath of Ga-In-Sn-Zn alloy. The liquid metal thermally couples the crystal to the water-cooled Cu frame, while permitting the required crystal bending. Calculated thermal profiles and anticipated focusing properties are discussed.
Date: June 1, 1996
Creator: Brauer, S.; Rodricks, B.; Assoufid, L.; Beno, M.A. & Knapp, G.S.
Partner: UNT Libraries Government Documents Department