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Epitaxial Electrodeposition of Wide Bandgap Cuprous Bromide on Silver via a Silver Bromide Buffer Layer
Cuprous halides are an important class of wide bandgap p-type semiconductors used in opto-electronics. Cuprous bromide (CuBr) shows potential for short-wavelength devices due to a large exciton binding energy (108 meV) and near-ultraviolet bandgap (3.1 eV). However, the growth of high-quality epitaxial CuBr films by electrodeposition has remained a challenge. Here, we introduce a low-cost electrochemical procedure for producing epitaxial CuBr(111) on a Ag(111) substrate by a [111]-oriented silver bromide (AgBr) buffer layer. The AgBr buffer layer forms during the electrodeposition of the CuBr. The mismatch between CuBr(111) and AgBr(111) is –1.3%. A plausible mechanism for nucleation and growth of the epitaxial CuBr is proposed. X-ray techniques including high resolution X-ray diffraction and X-ray pole figures are used to determine the epitaxial relationship. CuBr(100) is also produced on a Ag(100) surface by a AgBr(100) buffer layer that is rotated in-plane 45° relative to the Ag(100) surface. In conclusion, this in-plane rotation reduces the lattice mismatch from +39.5% for an unrotated film to –1.4% for a 45° rotated film.
The reactions pertaining to zinc-silver and cadmium-silver batteries Final report
Electrochemical oxidation of zinc and cadmium in potassium hydroxide - thermal decomposition, and deposition of silver oxide on zinc anodes
Electron paramagnetic resonance studies of silver atom formation and enhancement by fluoride ions in gamma-irradiated frozen silver nitrate solutions
Trapped Ag atoms production in silver nitrate ice by gamma irradiation, discussing reaction enhancement by flouride ion
Multiscale, mechanistic calculation of the effective silver diffusion coefficient in polycrystalline silicon carbide: application to silver release in AGR-1 TRISO particles
The silicon carbide (SiC) layer in tristructural isotropic (TRISO) fuel particles serves as a barrier to prevent the escape of fission from the fuel kernel. The release of silver (Ag) is a concern due to the long half-life of the 110mAg isotope. In this study, the effective diffusion coefficient of the fission product Ag through the grain boundary (GB) network is calculated using a combination of atomistic and phase-field methods. Atomistic calculations of Ag diffusivity in SiC bulk and GBs are leveraged to develop a mesoscale effective Ag diffusion coefficient (Deff) in SiC. Since GBs serve as pathways for Ag diffusion, Deff is defined as a function of temperature, microstructure variables, and fluence. Deff is implemented in the fuel performance code Bison to predict Ag release from AGR-1 TRISO fuel particles. We hereby quantify the impact of SiC grain size and irradiation on Ag release and improve Bison's predictions.
Patterned nickel interlayers for enhanced silver wetting, spreading and adhesion on ceramic substrates
Not Available
Observations on the hardness, lattice parameter and microstructure of internally oxidized silver magnesium and silver aluminum alloys.
Hardness and lattice parameter increase effect on oxidation temperature of internally oxided Ag-Mg and Ag-Al alloys
The high-temperature steady-state creep of pure silver and internally oxidized silver-magnesium alloys.
High temperature steady state creep rate analysis of pure Ag and internally ionized Ag-Mg alloys
Quantitative measurements of density in shock-compressed silver up to 330 GPa using x-ray diffraction
This work presents a structural study of shock-compressed states in Ag to 331 GPa, accessed via laser shock compression. Structures of the resulting crystalline phases and the average atomic distribution of the liquid state are determined using in situ x-ray diffraction. We employ structure factor analysis, adapted for a non-monochromatic x-ray source, to determine the density of the liquid phase from analysis of x-ray diffraction data for the first time in shock compressed Ag. We also present a detailed analysis of the crystalline phases, which shows good agreement with the phase boundaries reported in previous experimental and theoretical works. We utilize the whole powder pattern fitting approach implemented in the MAUD package to constrain stacking faults in the face centered cubic structure. We observe the ambient fcc structure up to a stress of 146 GPa before a transition to a body-centered cubic structure and liquid phase at 179 GPa, with full melting above 212 GPa.
Replication Data for: Hydrogen migration at restructuring palladium-silver oxide boundaries dramatically enhances reduction rate of silver oxide
The data underlying this published work have been made publicly available in this repository as part of the IMASC Data Management Plan. This work was supported as part of the Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0012573.
Using a Chromatographic Pseudophase Model To Elucidate the Mechanism of Olefin Separation by Silver(I) Ions in Ionic Liquids
Silver(I) ions undergo selective olefin complexation and have been utilized in various olefin/paraffin separation techniques such as argentation chromatography and facilitated transport membranes. Ionic liquids (ILs) are solvents known for their low vapor pressure, high thermal stability, low melting points, and ability to promote a favorable solvation environment for silver(I) ion–olefin interactions. To develop highly selective separation systems, a fundamental understanding of analyte partitioning to the stationary phase and the thermodynamic driving forces behind solvation is required. In this study, a chromatographic model treating silver(I) ions as a pseudophase is constructed and employed for the first time to investigate the olefin separation mechanism in silver(I) salt/IL mixtures. Stationary phases containing varying amounts of noncoordinated silver(I) salt ([Ag + ][NTf 2 – ]) dissolved in the 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C 10 MIM + ][NTf 2 – ]) IL are utilized to determine the partition coefficients of various analytes including alkanes, alkenes, alkynes, aromatics, aldehyde, esters, and ketones. As ligand coordination to silver(I) ions is known to lower its olefin complexation capability, this study also examines two different types of coordinated silver(I) ion pseudophases, namely, monocoordinated silver(I) salt ([Ag + (1-decyl-2-methylimidazole, DMIM)][NTf 2 – ]) and dicoordinated silver(I) salt ([Ag + (1-methylimidazole, MIM)(DMIM)][NTf 2 – ]). The extent of olefin partitioning to the coordinated silver(I) ion pseudophases over the carrier gas and IL decreased by up to two orders of magnitude. Values for enthalpy, entropy, and free energy of solvation were determined for the three silver(I) ion-containing systems. Olefin retention was observed to be enthalpically dominated, while ligand coordination to the silver(I) ion pseudophase resulted in variations for both enthalpic and entropic contributions to the free energy of solvation. Furthermore, the developed model can be used to study chemical changes that occur in silver(I) ions over time as well as identify optimal silver(I) salt/IL mixtures that yield high olefin selectivity.
Method for Reduction of Silver Biocide Plating on Metal Surfaces
Silver ions in aqueous solutions (0.05 to 1 ppm) are used for microbial control in water systems. The silver ions remain in solution when stored in plastic containers, but the concentration rapidly decreases to non-biocidal levels when stored in metal containers. The silver deposits onto the surface and is reduced to non-biocidal silver metal when it contacts less noble metal surfaces, including stainless steel, titanium, and nickel-based alloys. Five methods of treatment of contact metal surfaces to deter silver deposition and reduction are proposed: (1) High-temperature oxidation of the metal surface; (2) High-concentration silver solution pre-treatment; (3) Silver plating; (4) Teflon coat by vapor deposition (titanium only); and (5) A combination of methods (1) and (2), which proved to be the best method for the nickel-based alloy application. The mechanism associated with surface treatments (1), (2), and (5) is thought to be the development of a less active oxide layer that deters ionic silver deposition. Mechanism (3) is an attempt to develop an equilibrium ionic silver concentration via dissolution of metallic silver. Mechanism (4) provides a non-reactive barrier to deter ionic silver plating. Development testing has shown that ionic silver in aqueous solution was maintained at essentially the same level of addition (0.4 ppm) for up to 15 months with method (5) (a combination of methods (1) and (2)), before the test was discontinued for nickel-based alloys. Method (1) resulted in the maintenance of a biocidal level (approximately 0.05 ppm) for up to 10 months before that test was discontinued for nickel-based alloys. Methods (1) and (2) used separately were able to maintain ionic silver in aqueous solution at essentially the same level of addition (0.4 ppm) for up to 10 months before the test was discontinued for stainless steel alloys. Method (3) was only utilized for titanium alloys, and was successful at maintaining ionic silver in aqueous solution at essentially the same level of addition (0.4 ppm) for up to 10 months before the test was discontinued for simple flat geometries, but not for geometries that are difficult to Teflon coat.
Characterizing Olefin Selectivity and Stability of Silver Salts in Ionic Liquids Using Inverse Gas Chromatography
Separation systems utilizing silver(I) ion-olefin complexation have limitations since silver(I) ions can be poisoned or reduced to metallic silver. Ionic liquids (ILs) are used as solvents for silver(I) ions to facilitate separations since their physico-chemical properties can be easily tuned. To develop separation systems with sustainable olefin selectivity, factors that affect silver(I) ion stability need to be understood. In this study, a total of 13 silver salt/IL mixtures were examined by inverse gas chromatography to identify the effects of silver salt anion and IL cation/anion combination on silver(I) ion stability. The effects of temperature and three different exposure gases on silver(I) ion stability were systematically studied. Exposing silver salt/IL mixtures to hydrogen at high temperatures had a greater effect on decreasing silver(I) ion-olefin complexation. Silver(I) ions from the silver bis[(trifluoromethyl)sulfonyl]imide ([NTf 2 – ]) salt were more stable in [NTf 2 – ]-containing ILs than in [BF 4 – ]-containing ILs. Optimum mixtures exhibited high olefin selectivity and were stable beyond 90 h when exposed to hydrogen gas.
Material Compatibility Study of Coated Metals to Maintain Biocidal Silver in a Spacecraft Potable Water System
Ionic silver-based biocide remains an option of choice for microbial control in spacecraft potable water systems. However, depletion of silver ions by wetted materials readily reduces ionic silver to nonbiocidal levels. This phenomenon occurs via various transport mechanisms at the liquid-solid interfaces between the silver-containing water and adjacent surfaces. Consequently, challenges remain in the design and/or selection of materials that can be used for the wetted system components that will help ensure silver is maintained at biocidal levels. Since silver has been baselined, and/or remains, as a potable water biocide option for several future spacecraft potable water systems, a multitiered approach is being investigated, looking at heritage materials, new processes, and/or alterative materials. This study conducted the application of eleven chemically-resistant coatings onto coupons that were cut out from three types of spacecraft-grade metals (Titanium Grade 2, Inconel 718, and 316L Stainless Steel) to investigate the performance of this material strategy as a barrier against silver depletion. In this investigation, the coated metals were immersed in a static 400 parts per billion silver biocide solution at a surface-area-to-volume ratio of 2.0 cm^(-1) and left to soak for predefined time periods. The concentration of the solution in contact with the coated samples was analyzed at various points via inductively coupled plasma mass spectrometry, and the measurements were interpreted as silver retention percentages over time. This paper summarizes the coating selection process, the configuration of the test, and the performance of each coating-metal combination at diminishing silver depletion. The preliminary results demonstrate that some of the selected coatings succeeded at maintaining biocidal silver concentrations far beyond the corresponding base metal in a similar test. The knowledge acquired through this investigation supports the deploying of coatings on plumbing lines for the integration of biocidal silver in the water system architecture of a spacecraft. Nevertheless, further testing must be continued to assess the performance of these coatings on other wetted geometries and any implications of unifying this material strategy with traditional and developmental engineering design processes for spacecraft potable water systems.
Assessment of Silver Based Disinfection Technology for CEV and Future US Spacecraft
Silver biocide offers a potential advantage over iodine, the current state-of-the-art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. As such, silver may reduce the overall complexity and mass of future spacecraft potable water systems, particularly those used to support long duration missions. A primary technology gap identified for the use of silver biocide is one of material compatibility. Wetted materials of construction are required to be selected such that silver ion concentrations can be maintained at biocidally effective levels. Preliminary data on silver biocide depletion rates in heritage spacecraft potable water system wetted-materials of construction has been gathered as part of a multi-phase test project aimed at the characterization of silver based biocide technology through: development of preferred materials lists, investigation of silver biocide forms and delivery methods, down-selection of silver biocide technologies, and integrated testing. A 10% - 20% loss in silver ion concentration per day was observed for acid passivated Nitronic 40 tubing with surface area to volume (S/V) ratios of approximately 4.59 cm-1. The Nitronic 40 tubes were tested both with and without biocide pretreatment. Silver biocide depletion was also observed at approximately 0.1% per day for the first 35 days of exposure to acid passivated Inconel 718 coupon, S/V of approximately 0.14 cm-1. Surface analysis by scanning election microscopy (SEM) suggested deposition of silver metal on both test materials. SEM analysis also provided evidence of potential variability in the passivation process for tube configuration of the Nitronic 40 test apparatus. These preliminary results are presented and discussed herein, along with the current project status.
Feasibility Testing of Silver Electrolysis for Disinfection of Spacecraft Potable Water Systems
Anodic dissolution of silver electrodes, or “silver electrolysis,” is being investigated as a means of introducing biocidal silver into potable water on exploration spacecraft. A proof-of-concept prototype of a silver electrolysis reactor was developed, and feasibility was demonstrated for imparting a target silver concentration into a spacecraft water system. Prototype testing showed that the primary initial concerns related to the technology - inefficiencies of electrolysis in low conductivity water, the potential formation of resistive oxides on the electrode surfaces, and the potential for release of electrolytically-generated silver particles to the effluent water - were not problematic over the duration of the feasibility testing. The testing also demonstrated advantages of the technology, including the ability to consistently deliver silver at targeted concentrations and the ability to directly correlate the silver concentration to measurements of water conductivity. On the other hand, the reliability of the system has not yet been demonstrated. During prototype testing, intermittent periods of poor reactor performance manifested as a decrease in voltage accompanied by a decrease in silver output. It was determined that the cause of this behavior was silver-based deposits on inter-electrode wetted surfaces forming a conductive “bridge” between electrodes. Ongoing testing and refinement of the prototype reactor design seek to elucidate the root cause the bridging phenomenon and identify associated mitigation strategies. Once resolved, long-term performance testing is planned as part of continued development of the electrolytic silver dosing system.
Substrate Matters: Ionic Silver Alters Lettuce Growth, Nutrient Uptake, and Root Microbiome in a Hydroponics System
Ionic silver (Ag+) is being investigated as a residual biocide for use in NASA spacecraft potable water systems on future crewed missions. This water will be used to irrigate future spaceflight crop production systems. We have evaluated the impact of three concentrations (31 ppb, 125 ppb, and 500 ppb) of ionic silver biocide solutions on lettuce in an arcillite (calcinated clay particle substrate) and hydroponic (substrate-less) growth setup after 28 days. Lettuce plant growth was reduced in the hydroponic samples treated with 31 ppb silver and severely stunted for samples treated at 125 ppb and 500 ppb silver. No growth defects were observed in arcillite-grown lettuce. Silver was detectable in the hydroponic-grown lettuce leaves at each concentration but was not detected in the arcillite-grown lettuce leaves. Specifically, when 125 ppb silver water was applied to a hydroponics tray, Ag+ was detected at an average amount of 7 μg/g (dry weight) in lettuce leaves. The increase in Ag+ corresponded with a decrease in several essential elements in the lettuce tissue (Ca, K, P, S). In the arcillite growth setup, silver did not impact the plant root zone microbiome in terms of alpha diversity and relative abundance between treatments and control. However, with increasing silver concentration, the alpha diversity increased in lettuce root samples and in the water from the hydroponics tray samples. The genera in the hydroponic root and water samples were similar across the silver concentrations but displayed different relative abundances. This suggests that ionic silver was acting as a selective pressure for the microbes that colonize the hydroponic water. The surviving microbes likely utilized exudates from the stunted plant roots as a carbon source. Analysis of the root-associated microbiomes in response to silver showed enrichment of metagenomic pathways associated with alternate carbon source utilization, fatty-acid synthesis, and the ppGpp (guanosine 3′-diphosphate 5′-diphosphate) stringent response global regulatory system that operates under conditions of environmental stress. Nutrient solutions containing Ag+ in concentrations greater than 31 ppb in hydroponic systems lacking cation-exchange capacity can severely impact crop production due to stunting of plant growth.