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DOE OSTI2020

Materials Data on Hg2Te4Kr3(O2F13)2 by Materials Project

(KrF2)3(HgTe2(OF5)2)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four HgTe2(OF5)2 clusters and six KrF2 clusters. In each HgTe2(OF5)2 cluster, Hg is bonded in a linear geometry to two O atoms. There are one shorter (2.06 Å) and one longer (2.08 Å) Hg–O bond lengths. There are two inequivalent Te sites. In the first Te site, Te is bonded in an octahedral geometry to one O and five F atoms. The Te–O bond length is 1.89 Å. There is three shorter (1.88 Å) and two longer (1.89 Å) Te–F bond length. In the second Te site, Te is bonded in an octahedral geometry to one O and five F atoms. The Te–O bond length is 1.88 Å. There are a spread of Te–F bond distances ranging from 1.87–1.89 Å. There are two inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to one Hg and one Te atom. In the second O site, O is bonded in a bent 120 degrees geometry to one Hg and one Te atom. There are ten inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Te atom. In the second F site, F is bonded in a single-bond geometry to one Te atom. In the third F site, F is bonded in a single-bond geometry to one Te atom. In the fourth F site, F is bonded in a single-bond geometry to one Te atom. In the fifth F site, F is bonded in a single-bond geometry to one Te atom. In the sixth F site, F is bonded in a single-bond geometry to one Te atom. In the seventh F site, F is bonded in a single-bond geometry to one Te atom. In the eighth F site, F is bonded in a single-bond geometry to one Te atom. In the ninth F site, F is bonded in a single-bond geometry to one Te atom. In the tenth F site, F is bonded in a single-bond geometry to one Te atom. In each KrF2 cluster, Kr is bonded in a linear geometry to two equivalent F atoms. Both Kr–F bond lengths are 1.94 Å. F is bonded in a single-bond geometry to one Kr atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Computational Chemistry-Based Evaluation of Metal Salts and Metal Oxides for Application in Mercury-Capture Technologies

Anthropogenic mercury emission to the atmosphere adversely affects the environment, wildlife, and human health. Accordingly, the design and implementation of improved mercury-capture technologies have received increased attention. We present a computational chemistry-based screening study to guide the development of mercury-capture materials. We use density functional theory (DFT) to probe the efficacy of metal salts and metal oxides (NaCl, NaBr, KCl, KBr, CaCl 2 , CaBr 2 , NaNO 3 , and MgO) toward mercury capture and their ability to be regenerated for continued use. We focus on three primary sources of mercury emission as elemental gaseous mercury (Hg(0)) or oxidized gaseous mercury species (Hg(II); HgCl 2 or HgBr 2 ): (i) Hg(0) emission from artisanal Au production; (ii) Hg(II)/Hg(0) emission from inlet/outlet streams for flue-gas desulfurization (FGD) operation; and (iii) Hg(0) and Hg(II) emission from cement production. Our results suggest that CaCl 2 and CaBr 2 are good candidates for capturing Hg(0) in artisanal Au production. For FGD operation, KBr, MgO, CaCl 2 , and CaBr 2 are good candidates for capturing HgCl 2 and HgBr 2 , while CaBr 2 is the only studied material that can capture Hg(0) from the outlet FGD stream. For cement production, CaBr 2 is the only material of those studied that can capture Hg(0), HgCl 2 , and HgBr 2 . Furthermore, our DFT results can accelerate the development of cheap and regenerable mercury-capture materials, as well as better prevent the release of mercury to the environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Preparation and Characterization of YBa 2 Cu 4 O 8 Superconductor

Solid-state reaction of appropriate amounts of Y 2 O 3 , BaCOs, and CuO for 2 h at 800°C in flowing oxygen with a total pressure of 2.7 x 10 2 Pa (2 mm Hg), followed by cooling and annealing at 750°C for 10 h in oxygen at ambient pressure, has produced orthorhombic YBa 2 Cu 4 O 8 (124) as the main phase with YBa 2 Cu 3 O x (123) as an impurity phase. After the as-calcined powder was annealed in oxygen at 800°C for 24 h under ambient pressure, the phase purity improved considerably. Calcined 124 powder was pressed into pellets and rapidly annealed at temperatures from 870°C to 935°C. At these temperatures, the 124 decomposed into 123. The superconducting transition temperature, T c , of the annealed samples depended upon the annealing temperature and atmosphere. The decomposed samples have been characterized by low field RF SQUID magnetometer and high resolution transmission electron microscopy.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Mercury Reduction, Uptake, and Species Transformation by Freshwater Alga Chlorella vulgaris under Sunlit and Dark Conditions

As a major entry point of mercury (Hg) to aquatic food webs, algae play an important role in taking up and transforming Hg species in aquatic ecosystems. However, little is known how and to what extent Hg reduction, uptake, and species transformations are mediated by algal cells and their exudates, algal organic matter (AOM), under either sunlit or dark conditions. In this study, using Chlorella vulgaris (CV) as one of the most prevalent freshwater model algal species, we show that solar irradiation could enhance the reduction of mercuric Hg(II) to elemental Hg(0) by both CV cells and AOM. AOM reduced more Hg(II) than algal cells themselves due to cell surface adsorption and uptake of Hg(II) inside the cells under solar irradiation. Synchrotron radiation X-ray absorption near-edge spectroscopy (SR-XANES) analyses indicate that sunlight facilitated the transformation of Hg to less bioavailable species, such as β-HgS and Hg-phytochelatins, compared to Hg(Cysteine) 2 -like species formed in algal cells in the dark. These findings highlight important functional roles and potential mechanisms of algae in Hg reduction and immobilization under varying lighting conditions and how these processes may modulate Hg cycling and bioavailability in the aquatic environment.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Materials Data on Ga2CuCl8 by Materials Project

Cu(GaCl4)2 is Hg_xSn structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two Cu(GaCl4)2 clusters. Cu2+ is bonded in a distorted square co-planar geometry to four Cl1- atoms. All Cu–Cl bond lengths are 2.31 Å. Ga3+ is bonded in a tetrahedral geometry to four Cl1- atoms. There are a spread of Ga–Cl bond distances ranging from 2.13–2.29 Å. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Ga3+ atom. In the second Cl1- site, Cl1- is bonded in an L-shaped geometry to one Cu2+ and one Ga3+ atom. In the third Cl1- site, Cl1- is bonded in an L-shaped geometry to one Cu2+ and one Ga3+ atom. In the fourth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Ga3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TeC4(BrF3)2 by Materials Project

C4Te(BrF3)2 is Hg_xSn structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one C4Te(BrF3)2 cluster. there are eight inequivalent C+2.50+ sites. In the first C+2.50+ site, C+2.50+ is bonded in a water-like geometry to two F1- atoms. Both C–F bond lengths are 1.33 Å. In the second C+2.50+ site, C+2.50+ is bonded in a bent 120 degrees geometry to two F1- atoms. Both C–F bond lengths are 1.33 Å. In the third C+2.50+ site, C+2.50+ is bonded in a distorted single-bond geometry to one Te2- and one F1- atom. The C–Te bond length is 2.16 Å. The C–F bond length is 1.35 Å. In the fourth C+2.50+ site, C+2.50+ is bonded in a bent 120 degrees geometry to two F1- atoms. There is one shorter (1.32 Å) and one longer (1.33 Å) C–F bond length. In the fifth C+2.50+ site, C+2.50+ is bonded in a bent 120 degrees geometry to two F1- atoms. There is one shorter (1.32 Å) and one longer (1.33 Å) C–F bond length. In the sixth C+2.50+ site, C+2.50+ is bonded in a distorted single-bond geometry to one Te2- and one F1- atom. The C–Te bond length is 2.16 Å. The C–F bond length is 1.36 Å. In the seventh C+2.50+ site, C+2.50+ is bonded in a distorted single-bond geometry to one Te2- and one F1- atom. The C–Te bond length is 2.15 Å. The C–F bond length is 1.35 Å. In the eighth C+2.50+ site, C+2.50+ is bonded in a distorted single-bond geometry to one Te2- and one F1- atom. The C–Te bond length is 2.16 Å. The C–F bond length is 1.35 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 4-coordinate geometry to two C+2.50+ and four Br1- atoms. There are a spread of Te–Br bond distances ranging from 2.66–3.49 Å. In the second Te2- site, Te2- is bonded in a 5-coordinate geometry to two C+2.50+ and three Br1- atoms. There are a spread of Te–Br bond distances ranging from 2.62–3.26 Å. There are four inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 1-coordinate geometry to two Te2- and three F1- atoms. There are a spread of Br–F bond distances ranging from 3.35–3.47 Å. In the second Br1- site, Br1- is bonded in a distorted single-bond geometry to one Te2- atom. In the third Br1- site, Br1- is bonded in a distorted single-bond geometry to one Te2- atom. In the fourth Br1- site, Br1- is bonded in a 1-coordinate geometry to three Te2- and four F1- atoms. There are a spread of Br–F bond distances ranging from 3.34–3.56 Å. There are twelve inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ and one Br1- atom. In the second F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ and one Br1- atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ and one Br1- atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ atom. In the sixth F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ and one Br1- atom. In the seventh F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ atom. In the eighth F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ and one Br1- atom. In the ninth F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ atom. In the tenth F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ atom. In the eleventh F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ atom. In the twelfth F1- site, F1- is bonded in a single-bond geometry to one C+2.50+ and two Br1- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuH8C2(N6Cl)2 by Materials Project

CuC2H8(N6Cl)2 is Hg_xSn structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two CuC2H8(N6Cl)2 clusters. Cu2+ is bonded in a distorted square co-planar geometry to two equivalent N+1.33- and two equivalent Cl1- atoms. Both Cu–N bond lengths are 1.98 Å. Both Cu–Cl bond lengths are 2.34 Å. C4+ is bonded in a trigonal planar geometry to three N+1.33- atoms. There are a spread of C–N bond distances ranging from 1.33–1.36 Å. There are six inequivalent N+1.33- sites. In the first N+1.33- site, N+1.33- is bonded in a distorted trigonal planar geometry to one C4+ and two N+1.33- atoms. There is one shorter (1.37 Å) and one longer (1.39 Å) N–N bond length. In the second N+1.33- site, N+1.33- is bonded in a 3-coordinate geometry to one Cu2+, one C4+, and one N+1.33- atom. The N–N bond length is 1.36 Å. In the third N+1.33- site, N+1.33- is bonded in a water-like geometry to one N+1.33- and two H1+ atoms. Both N–H bond lengths are 1.03 Å. In the fourth N+1.33- site, N+1.33- is bonded in a water-like geometry to two N+1.33- atoms. The N–N bond length is 1.29 Å. In the fifth N+1.33- site, N+1.33- is bonded in a water-like geometry to two N+1.33- atoms. In the sixth N+1.33- site, N+1.33- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N+1.33- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N+1.33- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N+1.33- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.33- atom. Cl1- is bonded in a single-bond geometry to one Cu2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NiP2N2(O6F)2 by Materials Project

NiP2N2(O6F)2 is Hg_xSn structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two NiP2N2(O6F)2 clusters. Ni is bonded in an octahedral geometry to six O atoms. There are a spread of Ni–O bond distances ranging from 1.91–2.00 Å. P is bonded in a tetrahedral geometry to three O and one F atom. There are a spread of P–O bond distances ranging from 1.46–1.69 Å. The P–F bond length is 1.57 Å. N is bonded in a single-bond geometry to one O atom. The N–O bond length is 1.30 Å. There are six inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to one P and one O atom. The O–O bond length is 1.45 Å. In the second O site, O is bonded in a single-bond geometry to one P atom. In the third O site, O is bonded in a bent 120 degrees geometry to one P and one N atom. In the fourth O site, O is bonded in a distorted bent 120 degrees geometry to one Ni and one O atom. In the fifth O site, O is bonded in a 2-coordinate geometry to one Ni and one O atom. The O–O bond length is 1.30 Å. In the sixth O site, O is bonded in a 1-coordinate geometry to one Ni and one O atom. F is bonded in a single-bond geometry to one P atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H12C4Se(NO)2 by Materials Project

C4H12Se(NO)2 is Hg_xSn-like structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four C4H12Se(NO)2 clusters. there are two inequivalent C sites. In the first C site, C is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one SeN2O2 tetrahedra. The C–N bond length is 1.47 Å. There is two shorter (1.10 Å) and one longer (1.11 Å) C–H bond length. In the second C site, C is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one CH3N tetrahedra and a cornercorner with one SeN2O2 tetrahedra. The C–N bond length is 1.47 Å. All C–H bond lengths are 1.10 Å. N3- is bonded in a trigonal non-coplanar geometry to two C and one Se2- atom. The N–Se bond length is 1.87 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C atom. Se2- is bonded to two equivalent N3- and two equivalent O2- atoms to form SeN2O2 tetrahedra that share corners with four CH3N tetrahedra. Both Se–O bond lengths are 1.65 Å. O2- is bonded in a single-bond geometry to one Se2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Screening two-dimensional materials with topological flat bands

The topological flat band (TFB) has been proposed theoretically in various lattice models, to exhibit a rich spectrum of intriguing physical behaviors. However, the experimental demonstration of flat band (FB) properties has been severely hindered by the lack of materials realization. In this study, by screening materials from a first-principles materials database, we identify a group of two-dimensional materials with TFBs near the Fermi level, covering some simple line-graph and generalized line-graph FB lattice models. These include the kagome sublattice of O in Ti O 2 yielding a spin-unpolarized TFB, and that of V in ferromagnetic V 3 F 8 yielding a spin-polarized TFB. The monolayer Nb 3 Te Cl 7 and its counterparts from element substitution are found to be breathing-kagome-lattice crystals. The family of monolayer II I 2 V I 3 compounds exhibit a TFB representing the coloring-triangle lattice model. Re F 3 , Mn F 3 , and Mn Br 3 are all predicted to be diatomic-kagome-lattice crystals, with TFB transitions induced by atomic substitution. Finally, Hg F 2 , Cd F 2 , and Zn F 2 are discovered to host dual TFBs in the diamond-octagon lattice. Our findings pave the way to further experimental exploration of eluding FB materials and properties.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrHg8 by Materials Project

SrHg8 is Magnesium tetraboride-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Sr sites. In the first Sr site, Sr is bonded in a 11-coordinate geometry to fourteen Hg atoms. There are a spread of Sr–Hg bond distances ranging from 3.67–3.88 Å. In the second Sr site, Sr is bonded in a 1-coordinate geometry to sixteen Hg atoms. There are a spread of Sr–Hg bond distances ranging from 3.42–3.99 Å. There are sixteen inequivalent Hg sites. In the first Hg site, Hg is bonded in a 9-coordinate geometry to two equivalent Sr and seven Hg atoms. There are a spread of Hg–Hg bond distances ranging from 3.01–3.36 Å. In the second Hg site, Hg is bonded in a 8-coordinate geometry to two equivalent Sr and six Hg atoms. There are a spread of Hg–Hg bond distances ranging from 2.98–3.31 Å. In the third Hg site, Hg is bonded in a 8-coordinate geometry to three Sr and five Hg atoms. There are a spread of Hg–Hg bond distances ranging from 2.96–3.27 Å. In the fourth Hg site, Hg is bonded in a 8-coordinate geometry to three equivalent Sr and five Hg atoms. There are a spread of Hg–Hg bond distances ranging from 3.03–3.20 Å. In the fifth Hg site, Hg is bonded in a 5-coordinate geometry to seven Hg atoms. There are a spread of Hg–Hg bond distances ranging from 3.03–3.37 Å. In the sixth Hg site, Hg is bonded in a 1-coordinate geometry to one Sr and four Hg atoms. Both Hg–Hg bond lengths are 3.28 Å. In the seventh Hg site, Hg is bonded in a 6-coordinate geometry to three Sr and five Hg atoms. There are one shorter (3.00 Å) and two longer (3.29 Å) Hg–Hg bond lengths. In the eighth Hg site, Hg is bonded in a 2-coordinate geometry to six Hg atoms. There are two shorter (3.31 Å) and two longer (3.37 Å) Hg–Hg bond lengths. In the ninth Hg site, Hg is bonded in a 7-coordinate geometry to three equivalent Sr and five Hg atoms. There are one shorter (3.05 Å) and one longer (3.18 Å) Hg–Hg bond lengths. In the tenth Hg site, Hg is bonded in a 8-coordinate geometry to three Sr and five Hg atoms. There are a spread of Hg–Hg bond distances ranging from 2.95–3.19 Å. In the eleventh Hg site, Hg is bonded in a 1-coordinate geometry to one Sr and four Hg atoms. There are a spread of Hg–Hg bond distances ranging from 3.03–3.20 Å. In the twelfth Hg site, Hg is bonded in a 10-coordinate geometry to two equivalent Sr and eight Hg atoms. The Hg–Hg bond length is 3.33 Å. In the thirteenth Hg site, Hg is bonded in a 9-coordinate geometry to two equivalent Sr and seven Hg atoms. The Hg–Hg bond length is 3.00 Å. In the fourteenth Hg site, Hg is bonded in a 2-coordinate geometry to nine Hg atoms. In the fifteenth Hg site, Hg is bonded in a 10-coordinate geometry to two equivalent Sr and eight Hg atoms. In the sixteenth Hg site, Hg is bonded in a 6-coordinate geometry to three Sr and three Hg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Roadmap to Iodine and Mercury Abatement Materials Selection in Nuclear Waste Processing Off-Gas Streams

This work provides a guide for candidate mercury (Hg) and iodine-129 (129I) abatement material identification, screening, evaluation, technical gap identification, and bench-scale testing prioritization while also conceptualizing a materials deployment roadmap for implementation of new materials in the Hanford Waste Treatment and Immobilization Plant (WTP) Low-Activity Waste (LAW) Facility at Hanford in Richland, Washington, and elsewhere in the U.S. Department of Energy (DOE) complex for similar applications. The study was prompted by the need to replace the Kombisorb BAT-37 due to uncertainties in Hg and 129I capture performance and future availability for use in the WTP LAW Facility secondary off-gas system, specifically the Carbon Adsorber units. However, replacement of this material could also mitigate two other issues with Kombisorb BAT-37 (and its successor BAT II 37): (1) fire safety risk due to exothermic heat generated by adsorption reactions between the carbon material and Hg and (2) the risk of low retention of 129I in glass and subsequent downstream impacts on secondary liquid waste treatment at the Effluent Treatment Facility.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Materials Data on Hg3S2BrCl by Materials Project

Hg3S2BrCl crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are five inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 5-coordinate geometry to two S2-, one Br1-, and two Cl1- atoms. There are one shorter (2.46 Å) and one longer (2.47 Å) Hg–S bond lengths. The Hg–Br bond length is 3.44 Å. There are one shorter (2.81 Å) and one longer (3.06 Å) Hg–Cl bond lengths. In the second Hg2+ site, Hg2+ is bonded in a 5-coordinate geometry to two equivalent S2-, one Br1-, and two equivalent Cl1- atoms. Both Hg–S bond lengths are 2.45 Å. The Hg–Br bond length is 3.33 Å. There are one shorter (2.87 Å) and one longer (3.08 Å) Hg–Cl bond lengths. In the third Hg2+ site, Hg2+ is bonded to two equivalent S2- and four Br1- atoms to form a mixture of edge and corner-sharing HgS2Br4 octahedra. The corner-sharing octahedra tilt angles range from 2–7°. Both Hg–S bond lengths are 2.45 Å. There are two shorter (3.29 Å) and two longer (3.30 Å) Hg–Br bond lengths. In the fourth Hg2+ site, Hg2+ is bonded in a 5-coordinate geometry to two equivalent S2-, one Br1-, and two Cl1- atoms. Both Hg–S bond lengths are 2.44 Å. The Hg–Br bond length is 3.49 Å. There are one shorter (2.85 Å) and one longer (3.29 Å) Hg–Cl bond lengths. In the fifth Hg2+ site, Hg2+ is bonded to two equivalent S2- and four Br1- atoms to form a mixture of edge and corner-sharing HgS2Br4 octahedra. The corner-sharing octahedra tilt angles range from 2–7°. Both Hg–S bond lengths are 2.44 Å. There are two shorter (3.27 Å) and two longer (3.33 Å) Hg–Br bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 7-coordinate geometry to seven Hg2+ atoms. In the second Br1- site, Br1- is bonded in a 5-coordinate geometry to five Hg2+ atoms. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 5-coordinate geometry to five Hg2+ atoms. In the second Cl1- site, Cl1- is bonded in a distorted trigonal planar geometry to three Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hg8Br3O4 by Materials Project

HgHgBrHg4O3BrHg2OBr crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of four mercury molecules; four Hg2OBr clusters; two HgBr ribbons oriented in the (0, 1, 0) direction; and two Hg4O3Br sheets oriented in the (0, 0, 1) direction. In each Hg2OBr cluster, there are two inequivalent Hg+1.38+ sites. In the first Hg+1.38+ site, Hg+1.38+ is bonded in a 1-coordinate geometry to one Br1- atom. The Hg–Br bond length is 3.10 Å. In the second Hg+1.38+ site, Hg+1.38+ is bonded in a single-bond geometry to one O2- atom. The Hg–O bond length is 2.29 Å. O2- is bonded in a bent 120 degrees geometry to one Hg+1.38+ and one Br1- atom. The O–Br bond length is 1.79 Å. Br1- is bonded in a distorted L-shaped geometry to one Hg+1.38+ and one O2- atom. In each HgBr ribbon, Hg+1.38+ is bonded in a 2-coordinate geometry to one Hg+1.38+ and two equivalent Br1- atoms. The Hg–Hg bond length is 2.63 Å. There are one shorter (2.55 Å) and one longer (3.14 Å) Hg–Br bond lengths. Br1- is bonded in an L-shaped geometry to two equivalent Hg+1.38+ atoms. In each Hg4O3Br sheet, there are four inequivalent Hg+1.38+ sites. In the first Hg+1.38+ site, Hg+1.38+ is bonded in a distorted linear geometry to two O2- and three equivalent Br1- atoms. Both Hg–O bond lengths are 2.11 Å. There are a spread of Hg–Br bond distances ranging from 3.21–3.27 Å. In the second Hg+1.38+ site, Hg+1.38+ is bonded in a 2-coordinate geometry to two O2- and one Br1- atom. Both Hg–O bond lengths are 2.47 Å. The Hg–Br bond length is 3.02 Å. In the third Hg+1.38+ site, Hg+1.38+ is bonded in a distorted single-bond geometry to one O2- atom. The Hg–O bond length is 2.90 Å. In the fourth Hg+1.38+ site, Hg+1.38+ is bonded to three O2- and one Br1- atom to form distorted corner-sharing HgBrO3 trigonal pyramids. There are a spread of Hg–O bond distances ranging from 2.29–2.34 Å. The Hg–Br bond length is 2.92 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hg+1.38+ atoms to form corner-sharing OHg4 tetrahedra. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Hg+1.38+ and one O2- atom. The O–O bond length is 1.40 Å. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Hg+1.38+ and one O2- atom. Br1- is bonded in a 5-coordinate geometry to five Hg+1.38+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb6Hg(Br8O9)2 by Materials Project

Hg(NbO)6(O2)6(Br)16 crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of sixteen hexaoxane molecules, one hundred and twenty-eight hydrobromic acid molecules, eight mercury molecules, and forty-eight niobium(ii) oxide molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta6Hg(Br8O9)2 by Materials Project

Hg(TaO)6(O2)6(Br)16 crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of sixteen hexaoxane molecules, one hundred and twenty-eight hydrobromic acid molecules, eight mercury molecules, and forty-eight oxotantalum molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Removable, Sequestration Coatings for Mitigating Hazardous Contaminants Related to Deactivation and Decommissioning Activities

This project is a collaborative effort between InnoSense LLC (ISL) and Oak Ridge National Laboratory (ORNL) aimed at mitigating the mercury (Hg) contamination problem at the Y-12 National Security Complex (NSC). The report summarizes the research and technology development work of the Phase IIB Project, led by Dr. Uma Sampathkumaran at ISL for the period of July 31, 2017–October 31, 2021. The Y-12 site cleanup includes technologies for safe and cost-effective facility demolition, soil remediation, and on-site treatment and disposal of mercury bearing wastes. One of the technology demonstration goals was a reactive strippable coating for targeted pre-demolition and de-contamination to limit Hg mobilization and the volume of debris requiring treatment for disposal. Toward this, ISL has developed a water-based reactive strippable coating (Trap & See-Hg™) to sequester elemental Hg(0) and mercuric Hg(II) species in the coating. The coating provides multiple benefits including (1) Hg vapor suppression, (2) sealing in the hazardous contaminants, (3) visually locating the contaminant through color changes, and (4) remediating the contaminated surfaces upon coating removal. Through collaboration between ORNL and ISL in Phase II work, the team successfully demonstrated the Trap & See-Hg technology to (1) visually locate the presence of Hg on concrete, soil and drywall surfaces, (2) effectively sequester all mercury species (elemental, soluble and insoluble Hg) from lab-generated and ex-situ soil and brick/rubble samples collected from the Y 12 site with 80 to 95% efficiency to capture/reduce Hg vapor concentration, (3) be applied by manual and robotic spray applicators and cure at room ambient, (4) remain a cohesive and peelable coating upon drying, and (5) sequester Hg0 from walls in the alpha-2 building basement at Y-12 during a small scale in-situ field trial. In Phase IIB, ISL’s effort was focused on refining the coating formulations with additives containing passive and reactive sorbents, colorimetric indicator, and thixotropic agents to achieve the desired performance. The paints were then evaluated at ORNL for applicability to metal and concrete surfaces of different sizes and shapes, and soil rubble, Hg-sorption capacity and achieving sag-free coating on surfaces when applied by a manual spray applicator. Ambient cure of the coating resulted in a dry thickness of 16–20 mil. The coatings were removed from smooth or rough surfaces with low to moderate force. Both lab-generated Hg-contaminated samples and soil and brick/rubble samples containing a range of Hg concentrations (collected from the Y-12 site by UCOR) were used in this project. Optimized formulations were applied to these samples and evaluated for ability to suppress Hg vapors, sequester Hg 0 and Hg(II) species and color mapping of mercury species on the test surface. The ORNL team initially identified three to four potential sites at Y-12 and ORNL for potential demonstration. However, the pandemic closed any possible avenues for on-site demonstration of the robotic spray applicator. The metal and concrete samples with low to high Hg content provided by UCOR from an ongoing demolition were subsequently used for ex-situ sample characterization and analysis at ORNL over a period of 25 days. The coatings suppressed Hg vapors with an efficiency of 95–99% from heavily contaminated metal and 60% from concrete substrate. Analysis of total Hg in the peeled paints indicates sorption capacities ranging from 12 µg Hg/g of paint from concrete to 1.2 mg Hg/g of paint from the metal substrates while peeled paints from soil samples could capture a total Hg from 2.3 mg Hg/g to 66 mg/g paint. Toxicity characteristic leaching procedure (TCLP) tests recovered total mercury leached at 0.15±0.0008 µg/L for concrete to 126.81±0.67 µg/L and 377.25±5.67 µg/L for the two metal substrates, to allow for informed decisions on downstream disposal considerations. Together, this Phase IIB demonstrated the potential value of the Trap & See-Hg for Hg uptake, vapor suppression, and color mapping, and may thus be used to enhance worker safety during site cleanup, facility demolition, and downstream waste disposal at Y-12 NSC.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Materials Data on Sr11Hg54 by Materials Project

Sr11Hg54 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. there are four inequivalent Sr sites. In the first Sr site, Sr is bonded in a 1-coordinate geometry to thirteen Hg atoms. There are a spread of Sr–Hg bond distances ranging from 3.32–3.74 Å. In the second Sr site, Sr is bonded in a 9-coordinate geometry to nine Hg atoms. There are a spread of Sr–Hg bond distances ranging from 3.26–3.52 Å. In the third Sr site, Sr is bonded in a 1-coordinate geometry to fourteen Hg atoms. There are a spread of Sr–Hg bond distances ranging from 3.34–3.71 Å. In the fourth Sr site, Sr is bonded in a 1-coordinate geometry to fifteen Hg atoms. There are a spread of Sr–Hg bond distances ranging from 3.46–3.76 Å. There are fourteen inequivalent Hg sites. In the first Hg site, Hg is bonded in a 9-coordinate geometry to three equivalent Sr and six equivalent Hg atoms. All Hg–Hg bond lengths are 3.11 Å. In the second Hg site, Hg is bonded in a 1-coordinate geometry to three Sr and three Hg atoms. There are a spread of Hg–Hg bond distances ranging from 2.98–3.29 Å. In the third Hg site, Hg is bonded in a 2-coordinate geometry to two Sr and three Hg atoms. There are a spread of Hg–Hg bond distances ranging from 3.18–3.28 Å. In the fourth Hg site, Hg is bonded in a 9-coordinate geometry to three Sr and six Hg atoms. There are a spread of Hg–Hg bond distances ranging from 3.02–3.36 Å. In the fifth Hg site, Hg is bonded in a 10-coordinate geometry to three equivalent Sr and seven Hg atoms. The Hg–Hg bond length is 3.26 Å. In the sixth Hg site, Hg is bonded in a 7-coordinate geometry to three Sr and four Hg atoms. There are a spread of Hg–Hg bond distances ranging from 2.95–3.19 Å. In the seventh Hg site, Hg is bonded in a 1-coordinate geometry to one Sr and three Hg atoms. There are one shorter (3.09 Å) and two longer (3.35 Å) Hg–Hg bond lengths. In the eighth Hg site, Hg is bonded in a 2-coordinate geometry to two Sr and two equivalent Hg atoms. Both Hg–Hg bond lengths are 3.15 Å. In the ninth Hg site, Hg is bonded in a distorted hexagonal planar geometry to three equivalent Sr and three equivalent Hg atoms. All Hg–Hg bond lengths are 3.04 Å. In the tenth Hg site, Hg is bonded in a 1-coordinate geometry to one Sr and two equivalent Hg atoms. In the eleventh Hg site, Hg is bonded in a 8-coordinate geometry to four Sr and four Hg atoms. There are one shorter (3.04 Å) and one longer (3.15 Å) Hg–Hg bond lengths. In the twelfth Hg site, Hg is bonded in a 9-coordinate geometry to nine Hg atoms. In the thirteenth Hg site, Hg is bonded in a 9-coordinate geometry to three Sr and four Hg atoms. The Hg–Hg bond length is 3.18 Å. In the fourteenth Hg site, Hg is bonded in a 10-coordinate geometry to three Sr and seven Hg atoms.

36 MATERIALS SCIENCE↗