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9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on As2O3 by Materials Project

As2O3 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of two As2O3 sheets oriented in the (0, 0, 1) direction. there are two inequivalent As3+ sites. In the first As3+ site, As3+ is bonded in a distorted T-shaped geometry to three O2- atoms. There is two shorter (1.82 Å) and one longer (1.85 Å) As–O bond length. In the second As3+ site, As3+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of As–O bond distances ranging from 1.82–1.84 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two As3+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent As3+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent As3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on As2O3 by Materials Project

As2O3 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of two As2O3 sheets oriented in the (0, 1, 0) direction. there are two inequivalent As3+ sites. In the first As3+ site, As3+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of As–O bond distances ranging from 1.82–1.84 Å. In the second As3+ site, As3+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of As–O bond distances ranging from 1.81–1.83 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two As3+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two As3+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two As3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on As2O3 by Materials Project

As2O3 is diamond structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight chebi:30621 molecules. As3+ is bonded in a distorted trigonal non-coplanar geometry to three equivalent O2- atoms. All As–O bond lengths are 1.83 Å. O2- is bonded in a bent 120 degrees geometry to two equivalent As3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KAs4BrO6 by Materials Project

K(As2O3)2Br crystallizes in the hexagonal P6/mmm space group. The structure is two-dimensional and consists of one hydrobromic acid molecule and one K(As2O3)2 sheet oriented in the (0, 0, 1) direction. In the K(As2O3)2 sheet, K1+ is bonded to twelve equivalent O2- atoms to form edge-sharing KO12 cuboctahedra. All K–O bond lengths are 3.17 Å. As3+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. All As–O bond lengths are 1.84 Å. O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two equivalent As3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KAs4IO6 by Materials Project

K(As2O3)2I crystallizes in the hexagonal P6/mmm space group. The structure is two-dimensional and consists of one hydriodic acid molecule and one K(As2O3)2 sheet oriented in the (0, 0, 1) direction. In the K(As2O3)2 sheet, K1+ is bonded to twelve equivalent O2- atoms to form edge-sharing KO12 cuboctahedra. All K–O bond lengths are 3.19 Å. As3+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. All As–O bond lengths are 1.84 Å. O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two equivalent As3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KAs4ClO6 by Materials Project

(K(As2O3)2)2Cl2 crystallizes in the hexagonal P6/mmm space group. The structure is two-dimensional and consists of one hydrochloric acid molecule and one K(As2O3)2 sheet oriented in the (0, 0, 1) direction. In the K(As2O3)2 sheet, K1+ is bonded to twelve equivalent O2- atoms to form edge-sharing KO12 cuboctahedra. All K–O bond lengths are 3.17 Å. As3+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. All As–O bond lengths are 1.84 Å. O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two equivalent As3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Geogenic, Anthropogenic, and Authigenic Minerals Hosting Arsenic and Antimony in Yellowknife Bay Sediments

Abstract Yellowknife Bay (Great Slave Lake, Northwest Territories, Canada) is a water body valued by surrounding communities for its subsistence, recreational, and cultural use. Located directly downstream of the former Giant Mine and Con Mine, Yellowknife Bay has received inputs from mine waste streams enriched in arsenic (As), antimony (Sb), and metals since the late 1930s. Lake sediments in Yellowknife Bay provide a record of metal(loid) contamination from aerially deposited roaster stack emissions, mine effluent, and Giant Mine tailings. A sediment sampling program was conducted in Yellowknife Bay to characterize As and Sb mineralogy using scanning electron microscopy-mineral liberation analysis. Mineralogical analysis of As- and Sb-hosted minerals in nine sediment cores suggests that arsenic trioxide (As2O3), originally deposited during the period of peak-mining emissions, has since been transformed into authigenic sulfides (interpreted to be realgar) down core from peak-mining emissions. Arsenic has also been attenuated by iron (Fe)-oxyhydroxides and roaster-generated iron oxides up-core from peak-mining emissions, near the sediment–water interface. The Sb-bearing minerals appear to be stable in Yellowknife Bay sediments, with no conclusive evidence of post-depositional mobility having been identified. The observed prevalence of arsenic trioxide in surface sediments proximal to Giant Mine suggests that As and Sb contamination is ongoing, likely from terrestrial weathering of contaminated soils and shoreline outcrops. Arsenic-bearing oxide minerals prevalent in surface sediments may become unstable should redox conditions in the hypolimnion change; prolonged anoxia could destabilize the As hosting minerals and release As to bottom waters. Therefore, long-term monitoring of the water column, including hypolimnion conditions, in Yellowknife Bay is recommended.

Mineralogy↗
NASA NTRS1980

Chemical depth profiles of the GaAs/native oxide interface

The final-state oxidation products and their distribution in thin native oxides (30-40 A) on GaAs have been studied using X-ray photoelectron spectroscopy in conjunction with chemical depth profiling. Extended room-temperature-oxidation conditions have been chosen to allow the native oxide to attain its equilibrium composition and structure. The work emphasizes the use of chemical depth-profiling methods which make it possible to examine the variation in chemical reactivity of the oxide structure. A minimum of two distinct regions of Ga2O3 with differing chemical reactivity is observed. Chemical shift data indicate the presence of As2O3 in the oxide together with an elemental As overlayer at the interface. A change in relative charge transfer between oxygen and both arsenic and gallium-oxide species is observed in the region of the interface.

Grunthaner, P. J.↗
NASA NTRS1990

Deformation and fracture of aluminum-lithium alloys: The effect of dissolved hydrogen

The effects of dissolved hydrogen on the mechanical properties of 2090 and 2219 alloys are studied. The work done during this semi-annual period consists of the hydrogen charging study and some preliminary mechanical tests. Prior to SIMS analysis, several potentiostatic and galvanostatic experiments were performed for various times (going from 10 minutes to several hours) in the cathodic zone, and for the two aqueous solutions: 0.04N of HCl and 0.1N NaOH both combined with a small amount of As2O3. A study of the surface damage was conducted in parallel with the charging experiments. Those tests were performed to choose the best charging conditions without surface damage. Disk rupture tests and tensile tests are part of the study designed to investigate the effect of temperature, surface roughness, strain rate, and environment on the fracture behavior. The importance of the roughness and environment were shown using the disk rupture test as well as the importance of the strain rate under hydrogen environment. The tensile tests, without hydrogen effects, have not shown significant differences between low and room temperature.

Rivet, F. C.↗