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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ag2S by Materials Project

Ag2S crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent S2- atoms. There are a spread of Ag–S bond distances ranging from 2.49–2.82 Å. In the second Ag1+ site, Ag1+ is bonded in a linear geometry to two equivalent S2- atoms. There are one shorter (2.42 Å) and one longer (2.43 Å) Ag–S bond lengths. S2- is bonded in a 5-coordinate geometry to five Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag2S by Materials Project

Ag2S crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are four inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a linear geometry to two S2- atoms. Both Ag–S bond lengths are 2.44 Å. In the second Ag1+ site, Ag1+ is bonded in a linear geometry to two S2- atoms. Both Ag–S bond lengths are 2.44 Å. In the third Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent S2- atoms. There are two shorter (2.51 Å) and one longer (2.75 Å) Ag–S bond lengths. In the fourth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent S2- atoms. There are two shorter (2.52 Å) and one longer (2.74 Å) Ag–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to five Ag1+ atoms. In the second S2- site, S2- is bonded in a 5-coordinate geometry to five Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag2S by Materials Project

Ag2S crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. Ag1+ is bonded in a 4-coordinate geometry to four equivalent S2- atoms. There are a spread of Ag–S bond distances ranging from 2.61–2.84 Å. S2- is bonded to eight equivalent Ag1+ atoms to form a mixture of distorted edge and corner-sharing SAg8 hexagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag2S by Materials Project

Ag2S crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a linear geometry to two equivalent S2- atoms. Both Ag–S bond lengths are 2.44 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent S2- atoms. There are two shorter (2.51 Å) and one longer (2.79 Å) Ag–S bond lengths. S2- is bonded in a 5-coordinate geometry to five Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag2S by Materials Project

Ag2S crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a trigonal planar geometry to three equivalent S2- atoms. There are a spread of Ag–S bond distances ranging from 2.54–2.60 Å. In the second Ag1+ site, Ag1+ is bonded in a distorted trigonal planar geometry to three equivalent S2- atoms. There are a spread of Ag–S bond distances ranging from 2.54–2.64 Å. S2- is bonded in a 6-coordinate geometry to six Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag2S by Materials Project

Ag2S crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent S2- atoms. There are a spread of Ag–S bond distances ranging from 2.51–2.75 Å. In the second Ag1+ site, Ag1+ is bonded in a linear geometry to two equivalent S2- atoms. Both Ag–S bond lengths are 2.44 Å. S2- is bonded in a 5-coordinate geometry to five Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag2S by Materials Project

Ag2S crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to two equivalent S2- atoms. Both Ag–S bond lengths are 2.47 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent S2- atoms. There are a spread of Ag–S bond distances ranging from 2.54–2.79 Å. S2- is bonded in a 5-coordinate geometry to five Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Long-term Accumulation, Depth Distribution, and Speciation of Silver Nanoparticles in Biosolids-Amended Soils

Biosolids, when applied to soil, can be a source of metals and metal nanoparticles. One of the metals that forms nanoparticles is silver (Ag), which is commonly used in elemental (Ag(0)) form as an engineered nanomaterial in industrial or consumer products. The objective of this study was to quantify and characterize the accumulation and transport of Ag in a natural soil that has received agronomically-recommended rates of biosolids as fertilizer for the past 23 years (1994{2017). Total Ag concentrations were measured in biosolids and soil samples collected from 0 to 10 cm between 1996 and 2017. In addition, the depth distribution of Ag in the soil down to 60-cm depth was measured in 2017. Electron microscopy, in combination with X-ray spectroscopy, and X-ray absorption spectroscopy were used to identify the elemental association and oxidation state of the Ag in the samples. The Ag concentrations in the biosolids-amended soil increased steadily from 1996 until 2007, after which the concentrations leveled off at about 1.25 mg Ag kg-1 soil. This corresponded with a decrease of Ag concentrations in the biosolids over time. The majority of the Ag (82%) was confined to the top 10 cm of the soil, small amounts (14%) were detected in 10 to 20-cm depth, and trace amounts (4%) in 30 to 40-cm depth. The Ag in the biosolids and soil was identified as Ag-containing nanoparticles with a diameter of 10 to 12 nm. Ag was associated with S suggest that these 19 nanoparticles are Ag2S. This could be corroborated in biosolids with X-ray absorption spectroscopy (XANES); however, the Ag concentrations in the soil samples were too low to allow identification with XANES. Biosolids, when applied at agronomic rates in dryland cropping systems, represent an economically viable source of crop nutrients. In our study, long-term application of biosolids did not increase the concentration of total Ag in soil above a maximum of 1.5 mg Ag kg-1, and the Ag is present in the sulfide form. This concentration is below ecotoxicity limits for Ag2S in soil.

Taylor, Stephen E.↗
DOE OSTI2024

Evaluating Iodine Immobilization Technologies: Cermets, Polycermets, and Polyhalmets

The work in this report documents the efforts conducted to assess the feasibility of some of the ideas documented in Pacific Northwest National Laboratory invention disclosure reports (IDRs) including: 1) Iodine capture in polyacrylonitrile (PAN)-containing composite sorbents (32451-E). In this work, the composites evaluated included Ag0, Bi0, Cu0, Bi2S3, and Cu2S embedded in PAN. 2) Metal iodide removal from these sorbents through dissolution in dimethyl sulfoxide (DMSO) (32729-E). In this work, PAN dissolution was evaluated for multiple types of sorbents including Ag-Pan, Bi-PAN, Cu-PAN, Bi2S3-PAN, and Cu2S-PAN. 3) Using metal-sulfide sorbents for iodine capture (32647-E). In this work, the composites evaluated under this IDR included Ag2S, Bi2S3, and Cu2S embedded in PAN. 4) Using low-melting metals to immobilize (encapsulate) iodine-loaded and polymer-containing sorbents into polymer-ceramic-metal (called polycermet) or polymer-halide-metal (called polyhalmet) composite waste forms (32625-E). In this work, the iodine-loaded PAN composites included AgI-PAN, BiI-PAN, and CuI-PAN. 5) Ceramic-metal composite waste form synthesis of polymer-containing materials using low-melting metals like bismuth, tin, or bismuth-tin alloys (32537-E). In this work, the metals evaluated included Bi, 58Bi-42Sn eutectic. 6) Cermets for immobilizing commercial sorbents loaded with radioiodine (32806-E). In this work, AgIX (iodine-loaded silver faujasite zeolite) was evaluated in cermet form.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Microwave-Assisted Solution Synthesis of Metastable Intergrowth of AgInS2 Polymorphs

The intergrowth of stable and metastable AgInS2 polymorphs was synthesized using a microwave-assisted synthesis. The samples were synthesized in water and in a deep eutectic solvent (DES) consisting of choline chloride and thiourea. An increase in the metal precursor concentration improved the crystallinity of the synthesized samples and affected the particle size. AgInS2 cannot be synthesized from crystalline binary Ag2S or In2S3 via this route. The solution synthesis reported here results in the intergrowth of the thermodynamically stable polymorph (space group I4¯2d, chalcopyrite structure) and the high-temperature polymorph (space group Pna21, wurtzite-like structure) that is metastable at room temperature. A scanning transmission microscopy (STEM) study revealed the intergrowth of tetragonal and orthorhombic polymorphs in a single particle and unambiguously established that the long-thought hexagonal wurtzite polymorph has pseudo-hexagonal symmetry and is best described with the orthorhombic unit cell. The solution-synthesized AgInS2 polymorphs intergrowth has slightly lower bandgap values in the range of 1.73 eV–1.91 eV compared to the previously reported values for tetragonal I4¯2d (1.86 eV) and orthorhombic Pna21 (1.98 eV) polymorphs.

Adeyemi, Adedoyin N. (ORCID:0000000340096150)↗