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At least 667 records · Page 37

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DOE OSTI2019

Numerical Simulation of Thermodynamic Parameters of High-Porosity Copper

We propose that a modified equation of state be used for calculating the thermodynamically equilibrium TEC2 model for improving the reliability of description of thermodynamic parameters of shock loading of pure materials and heterogeneous mixtures of various porosities. For copper, the parameters of a thermally consistent equation of state have been determined. A reliable description of shock-wave loading of copper has been obtained using a small number of fitting parameters determined from the concordance with experimental data. Thermodynamic parameters have been simulated for copper with various porosities; the compression ratio and the temperature along the shock adiabat have been determined, and the value of heat capacity along the normal isobar has been calculated. The results of calculations are compared with available experimental results obtained by different authors.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2022

ATS (Advanced Terrestrial Simulator) integrated hydrology and reactive transport model output in Copper Creek, Colorado

This dataset is generated using the ATS (Advanced Terrestrial Simulator) model at Copper Creek, Colorado, the largest catchment in the East River watershed. ATS is an integrated hydrology and reactive transport model to simulate the Concentration-Discharge (C-Q) relationship, and is used to quantify the geochemical export and understand how watersheds respond to climate disturbances. Key hydrogeochemical variables, including discharge, precipitation, evapotranspiration, and geochemical concentrations, were simulated and output at a daily frequency at the Copper Creek outlet. A group of hydrology and geochemical model variables over the spatial domain are output at a bi-monthly frequency. The model used 1-km resolution daily frequency Daymet meteorological forcing, and mineral composition from previous studies. The simulations are performed on NERSC. The datasets include the input files for running the ATS (Advanced Terrestrial Simulator) simulation, including the mesh file, input script and geochemical model files. The output files from the ATS (Advanced Terrestrial Simulator) are the daily time-series discharge and geochemical concentration simulated at the outlet of Copper Creek, and the bi-monthly spatial output over the simulation domain.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2023

Microbial Competition for Copper: Impacts on Carbon and Nitrogen Cycling

Activities from this DOE sponsored project focused on two general questions: (1) how does competition between microbes for copper affect emissions of greenhouse gasses, especially methane and nitrous oxide? and (2) how does a novel copper-binding compound (methanobactin) made by some methane-oxidizing bacteria bind and reduce metals, as well as what are the regulatory elements involved in controlling methanobactin synthesis? From these efforts, we have conclusively shown that microbial competition for copper does indeed exert significant control on microbial community composition, as well as affects how microbes produce and consume nitrous oxide. We have also developed much better insights into the basis for methanobactin activity, as well as how methanotrophs control its production.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2026

Upstream Extraction of Tellurium from Copper Concentrates

A major barrier to increasing CdTe PV module production is the availability of tellurium (Te), an element necessary to manufacture CdTe PV cells that currently has a very limited supply. Most Te is obtained from ore extracted for copper mining, but the current processing methods only extract 3-4% of the available Te in this ore, with the rest being discarded during other processing steps. This project aims to increase Te supply by developing an innovative extraction method that will recover more Te from the copper ore earlier in the process. This method will also extract toxic elements like antimony and arsenic, making the copper mining process more environmentally friendly.

14 SOLAR ENERGY↗

DOE OSTI2022

Liquid Copper and Iron Production from Chalcopyrite, in the Absence of Oxygen

Clean energy infrastructure depends on chalcopyrite: the mineral that contains 70% of the world’s copper reserves, as well as a range of precious and critical metals. Smelting is the only commercially viable route to process chalcopyrite, where the oxygen-rich environment dictates the distribution of impurities and numerous upstream and downstream unit operations to manage noxious gases and by-products. However, unique opportunities to address urgent challenges faced by the copper industry arise by excluding oxygen and processing chalcopyrite in the native sulfide regime. Through electrochemical experiments and thermodynamic analysis, gaseous sulfur and electrochemical reduction in a molten sulfide electrolyte are shown to be effective levers to selectively extract the elements in chalcopyrite for the first time. We present a new process flow to supply the increasing demand for copper and byproduct metals using electricity and an inert anode, while decoupling metal production from fugitive gas emissions and oxidized by-products.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Wave speeds in single and polycrystalline copper

A novel technique was used to determine shock speeds in polycrystalline and single crystal copper that makes use of the ready availability of multiple velocimetry channels. Making use of a “top hat” design and five points of photonic Doppler velocimetry (PDV), which allows for accurate timing to determine wave arrival times, shock impacts were executed on [100], [110], and [111] single crystal copper, as well as polycrystalline copper at impact velocities ranging from 300 to 600 m/s. The data show that at these low velocities the [111] and [110] single crystal orientations have different shock speeds than the polycrystalline and [100] single crystal, but those differences may be within the apparent accuracy of the experimental technique.

36 MATERIALS SCIENCE↗

DOE OSTI2016

Development of Surface Grain Relief on Self-Ion Irradiated Copper

The development of surface grain relief has been observed on self-ion irradiated pure polycrystalline copper. However, the mechanistic origin of this feature has yet to be determined. Two possible mechanisms, anisotropic creep relaxation of void swelling induced stresses and crystallographic orientation-dependent sputtering rate differences, are being investigated as the cause of this evolution. This work focuses on characterizing the surface development and investigating the mechanism of orientation-dependent sputtering. Based on the conditions under which these specimens were irradiated, preferential sputtering is not likely to be the cause of the observed grain relief. Surface grain relief can greatly influence the ability to non-destructively detect irradiation-induced effects in polycrystalline metals. Determining the origin of grain relief development is necessary before this surface feature can be used an indicator of irradiation-induced effects in pure copper and other alloys. The development of surface grain relief has been observed on self-ion irradiated pure polycrystalline copper irradiated to 100 dpa. This surface feature was first noted by measuring samples using transient grating spectroscopy and later confirmed using scanning electron microscopy. Calculations of single-crystal sputtering rates show that the difference in sputtering yields between a randomly-oriented solid and a low-index plane is not sufficient to account for the observed height difference. SEM images appear to show a maximum step-height difference of around 100 nm and differential sputtering can only account for differences on the order of 10 nm at most. This determination indicates that anisotropic creep relaxation may be the mechanistic origin of the observed surface features. If this is the case, which will be confirmed by future work, then TG spectroscopy may be an effective tool for the determination of the onset of certain radiation-damage evolution. For example, if the onset of creep relaxation is strongly correlated to a specific level of void swelling and if the surface features present as a result of creep relaxation can be observed using TG spectroscopy, then accurate determinations of particular levels of void swelling may be made. (authors)

36 MATERIALS SCIENCE↗

DOE OSTI2019

Copper complexes: cytotoxicity and transport possibilities

A copper complex with N-(5,6-dihydro-4H-1,3-thiazin-2-yl)benzamide was synthesized for the first time and characterized by {sup 1}H NMR spectroscopy, LETDY mass spectrometry, and elemental analysis. A comparative study of the obtained complex and copper 2-aminopyrimidine complex was performed by flow cytometry on normal lymphocytes and Jurkat cells. Complexes with radionuclides {sup 64,67}Cu (with and wihout a carrier) were prepared, and distribution of the labeled complexes in the organs of mice was considered. Packing in carboxymethylcellulose-based microgels was proposed as a transport form for the complexes. The results show a promise of the obtained materials as potential radiopharmaceutical agents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2012

Progress in obtaining an absolute calibration of a total deuterium-tritium neutron yield diagnostic based on copper activation

The 350-keV Cockroft-Walton accelerator at Sandia National laboratory's Ion Beam facility is being used to calibrate absolutely a total DT neutron yield diagnostic based on the {sup 63}Cu(n,2n){sup 62}Cu({beta}+) reaction. These investigations have led to first-order uncertainties approaching 5% or better. The experiments employ the associated-particle technique. Deuterons at 175 keV impinge a 2.6 {mu}m thick erbium tritide target producing 14.1 MeV neutrons from the T(d,n){sup 4}He reaction. The alpha particles emitted are measured at two angles relative to the beam direction and used to infer the neutron flux on a copper sample. The induced {sup 62}Cu activity is then measured and related to the neutron flux. This method is known as the F-factor technique. Description of the associated-particle method, copper sample geometries employed, and the present estimates of the uncertainties to the F-factor obtained are given.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2012

Copper activation deuterium-tritium neutron yield measurements at the National Ignition Facility

A DT neutron yield diagnostic based on the reactions, {sup 63}Cu(n,2n){sup 62}Cu({beta}{sup +}) and {sup 65}Cu(n,2n) {sup 64} Cu({beta}{sup +}), has been fielded at the National Ignition Facility (NIF). The induced copper activity is measured using a NaI {gamma}-{gamma} coincidence system. Uncertainties in the 14-MeV DT yield measurements are on the order of 7% to 8%. In addition to measuring yield, the ratio of activities induced in two, well-separated copper samples are used to measure the relative anisotropy of the fuel {rho}R to uncertainties as low as 5%.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2024

Copper‐Catalyzed C(sp 3 )−H α‐Acetylation: Generation of Quaternary Centers

Abstract α‐substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in natural products and pharmaceuticals. We report the α‐acetylation of C(sp 3 )−H substrates R−H with arylmethyl ketones ArC(O)Me to provide α‐alkylated ketones ArC(O)CH 2 R at RT with t BuOO t Bu as oxidant via copper(I) ‐diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α‐substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu II ](CH 2 C(O)Ar) that capture alkyl radicals R• to give R−CH 2 C(O)Ar outcompeting dimerization of the copper(II) enolate to give the 1,4‐diketone ArC(O)CH 2 CH 2 C(O)Ar.

Okoromoba, Otome E.↗

DOE OSTI2024

Copper‐Catalyzed C(sp 3 )−H α‐Acetylation: Generation of Quaternary Centers

Okoromoba, Otome E.↗

DOE OSTI2016

Electroreduction of carbon monoxide over a copper nanocube catalyst: Surface structure and pH dependence on selectivity

The activity and selectivity for CO 2 /CO reduction over copper electrodes is strongly dependent on the local surface structure of the catalyst and the pH of the electrolyte. Here we investigate a unique, copper nanocube surface (CuCube) as a CO reduction electrode under neutral and basic pH, using online electrochemical mass spectroscopy (OLEMS) to determine the onset potentials and relative intensities of methane and ethylene production. To relate the unique selectivity to the surface structure, the CuCube surface reactivity is compared to polycrystalline copper and three single crystals under the same reaction conditions. Here, we find that the high selectivity for ethylene over the CuCube surface is most comparable to the Cu(100) surface, which has the cubic unit cell. However, the suppression of methane production over CuCube is unique to that particular surface. Basic pH is also shown to enhance ethylene selectivity on all surfaces, again with the CuCube surface being unique.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2018

Calibration curves for commercial copper and aluminum alloys using handheld laser-induced breakdown spectroscopy

Handheld laser-induced breakdown spectroscopy (HH LIBS) was used to study the elemental composition of four copper alloys and four aluminum alloys to produce calibration curves. The HH LIBS instrument used is a SciAps Z-500, commercially available, that contains a class-1 solid-state laser with an output wavelength of 1532 nm, a laser energy of 5 mJ/pulse, and a pulse duration of 5 ns. Test samples were solid specimens comprising of copper and aluminum alloys and data were collected from the samples’ surface at three different locations, employing a 12-point-grid pattern for each data set. All three data sets of the spectra were averaged, and the intensity, corrected by subtraction of background, was used to produce the elemental calibration curves. Calibration curves are presented for the matrix elements, copper and aluminum, as well as several minor elements. The surface damage produced by the laser was examined by microscopy. The alloys were tested in air and in a glovebox to evaluate the instrument’s ability to identify the constituents within materials under different environmental conditions. The main objective of using this HH LIBS technology is to determine its capability to fingerprint the presence of certain elements related to subpercent level within materials in real time and in-situ, as a starting point for undertaking future complex material characterization work.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Mobility of twinning dislocations in copper up to supersonic speeds

Understanding the mobility of twinning dislocations is important for multiscale modeling of crystal plasticity, especially at high strain rates, where such dislocations may reach transonic or supersonic speeds. Here, we used molecular dynamics simulations to investigate the relationship between dislocation velocity and the applied resolved shear stress of an edge twinning dislocation in copper up to supersonic speeds. The twinning dislocation mobility relation is composed of two branches separated by a band of forbidden velocities. The lower velocity branch is limited by the first transverse sound speed ~2000 m/s while the upper branch stretches from ~3500 m/s in the transonic regime to supersonic velocities. Twinning dislocations cannot undergo uniform steady-state motion at velocities within the forbidden band. Our simulation results also reveal that edge twinning dislocation motion in copper is kink-mediated. We discuss the implications of our findings for the motion of twins, twinning dislocations, and twinning dislocation kinks in copper.

36 MATERIALS SCIENCE↗

DOE OSTI2017

Thermal conductance characterization of a pressed copper rope strap between 0.13 K and 10 K

Mechanically pressing the ends of a copper braid in solid copper is an effective way of constructing solderless conductive straps for cryogenic applications. In this paper we present thermal conductance data of such a copper strap measured using the two-heater one-thermometer method. The measurements span a wide temperature range of 0.13–10 K applicable to a variety of cryogenic systems employing liquid helium, pulse tube coolers, adiabatic demagnetization refrigerators, and others. Above ≈1.5 K, the braid thermal conductivity dominates the strap conductance resulting in a near-linear dependence with temperature. The variation with temperature below ≈1.5 K is near-quadratic indicating dominance of the pressed contact conductance at the strap ends. In conclusion, electron-beam welding the braid to the strap ends is shown to be a promising solution for improving sub-Kelvin thermal conductance of the strap.

43 PARTICLE ACCELERATORS↗

DOE OSTI2022

Robust silane self-assembled monolayer coatings on plasma-engineered copper surfaces promoting dropwise condensation

Dropwise condensation is well known to result in better heat transfer performance owing to efficient condensate/droplet removal, which can be harnessed in various industrial heat/mass transfer applications such as power generation and conversion, water harvesting/desalination, and electronics thermal management. The key to enhancing condensation via the dropwise mode is thin low surface energy coatings (<100 nm) with low contact angle hysteresis. Ultrathin (<5 nm) silane self-assembled monolayers (or SAMs) have been widely studied to promote dropwise condensation due to their minimal thermal resistance and scalable integration processes. Such thin coatings typically degrade within an hour during condensation of water vapor. After coating failure, water vapor condensation transitions to the inefficient filmwise mode with poor heat transfer performance. We enhance silane SAM quality and durability during water vapor condensation on copper compared to state-of-the-art silane coatings on metal surfaces. We achieve this via (i) surface polishing to sub-10 nm levels, (ii) pure oxygen plasma surface treatment, and (iii) silane coating integration with the copper substrate in an anhydrous/moisture-free environment. The resulting silane SAM has low contact angle hysteresis (≈20°) and promotes efficient dropwise condensation of water for >360 hours without any visible sign of coating failure/degradation in the absence of non-condensable gases. We further demonstrate enhanced heat transfer performance (≈5-7× increase over filmwise condensation) over an extended period of time. Surface characterization data post-condensation leads us to propose that in the absence of non-condensable gases in the vapor environment, the silane SAM degrades due to reduction and subsequent dissolution of copper oxide at the oligomer-substrate interface. The experiments also indicate that the magnitude of surface subcooling (or condensation rate) affects the rate of coating degradation. Finally, this work identifies a pathway to durable dropwise promoter coatings that will enable efficient heat transfer in industrial applications.

42 ENGINEERING↗

DOE OSTI2021

Chemical upgrade of carbon monoxide to acetate on an atomically dispersed copper catalyst via CO-insertion

Electrochemical conversion of small molecules such as carbon dioxide (CO 2 ) and carbon monoxide (CO) to high-value multi-carbon products (C 2+ ) offers a chemical upgrade approach for fuels and chemical feedstock production using renewable energy, in the possible absence of the petrochemical industry under the new energy system such as hydrogen economy. Identifying robust and efficient electrocatalysts to selectively produce C 2+ products remains a challenge. In this study, we report a synthetic strategy of atomically dispersing copper atoms on nitrogen-rich porous carbon (Cu–N–C) through pyrolysis of a supramolecular assembly. Benefitting from the unsaturated coordination structure, in KOH electrolyte, the Cu–N–C with a Cu content of 6.9 wt% exhibits a maximum acetate Faradaic efficiency (FE) of 30% with an acetate partial current density as high as 48 mA cm –2 in electrochemical CO reduction. Different from the C–C coupling mechanism on metallic copper, we propose a CO insertion mechanism for the acetate production on the single site copper catalyst.

36 MATERIALS SCIENCE↗