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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ag3SI by Materials Project

Ag3SI is (Cubic) Perovskite structured and crystallizes in the trigonal R32 space group. The structure is three-dimensional. Ag1+ is bonded in a 3-coordinate geometry to two equivalent S2- and three equivalent I1- atoms. Both Ag–S bond lengths are 2.56 Å. There are one shorter (3.01 Å) and two longer (3.55 Å) Ag–I bond lengths. S2- is bonded to six equivalent Ag1+ atoms to form distorted corner-sharing SAg6 octahedra. The corner-sharing octahedral tilt angles are 25°. I1- is bonded in a 3-coordinate geometry to nine equivalent Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AgSbS2 by Materials Project

AgSbS2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a distorted square co-planar geometry to four S2- atoms. There are two shorter (2.41 Å) and two longer (3.07 Å) Ag–S bond lengths. In the second Ag1+ site, Ag1+ is bonded in a distorted tetrahedral geometry to four S2- atoms. There are two shorter (2.58 Å) and two longer (2.64 Å) Ag–S bond lengths. Sb3+ is bonded in a 3-coordinate geometry to three S2- atoms. There are a spread of Sb–S bond distances ranging from 2.48–2.56 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to two Ag1+ and one Sb3+ atom. In the second S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to two Ag1+ and two equivalent Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag4S(NO)2 by Materials Project

Ag4(NSO2N) crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are four inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a distorted linear geometry to two N1+ atoms. There are one shorter (2.15 Å) and one longer (2.20 Å) Ag–N bond lengths. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to two N1+ and one O2- atom. There are one shorter (2.19 Å) and one longer (2.21 Å) Ag–N bond lengths. The Ag–O bond length is 2.80 Å. In the third Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to two N1+ atoms. There are one shorter (2.15 Å) and one longer (2.22 Å) Ag–N bond lengths. In the fourth Ag1+ site, Ag1+ is bonded in a distorted linear geometry to one N1+ and one O2- atom. The Ag–N bond length is 2.23 Å. The Ag–O bond length is 2.19 Å. There are two inequivalent N1+ sites. In the first N1+ site, N1+ is bonded in a 5-coordinate geometry to four Ag1+ and one S2- atom. The N–S bond length is 1.66 Å. In the second N1+ site, N1+ is bonded in a distorted tetrahedral geometry to three Ag1+ and one S2- atom. The N–S bond length is 1.60 Å. S2- is bonded in a tetrahedral geometry to two N1+ and two O2- atoms. There is one shorter (1.47 Å) and one longer (1.52 Å) S–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ag1+ and one S2- atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Ag1+ and one S2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Availability and reactivity of N 2 ( v ) for NH 3 synthesis by plasma catalysis

Production of vibrationally excited N 2 (N 2 (v)) in atmospheric pressure nonthermal plasma and loss of N 2 (v) by gas-phase reactions and reactions on catalytic surfaces are analyzed to examine the role of N 2 (v) in NH 3 formation by plasma catalysis. Vibrational state-to-state kinetic models complemented with molecular beam mass spectrometry (MBMS) measurements demonstrate that N 2 (v> 0) is produced with densities 100× greater than the density of N radicals by a radiofrequency atmospheric pressure plasma jet. The experimentally measured loss of N 2 (v) corresponds with a state-to-state kinetic model that describes loss of N 2 (v) by surface-mediated vibrational relaxation without consideration of reactions that convert N 2 (v) to NH 3 over the catalyst surface. Rate constants for vibrational relaxation of N 2 (v) on catalyst surfaces exceed upper bounds on proposed rate constants for NH 3 formation reactions from N 2 (v) over Fe when v < 9, Ni when v < 18, and Ag when v < 39, which indicates that only higher vibrational levels can possibly contribute to catalytic NH 3 formation faster than they undergo vibrational relaxation on the surface. Densities of N 2 (v> 8), vibrational levels that can possibly react over Fe to form NH 3 faster than they undergo vibrational relaxation, are less than or similar to N densities at the inlet of the catalyst bed and measured NH 3 formation for the investigated conditions in this work, while densities of N 2 (v> 17) and N 2 (v> 38) are orders of magnitude below the N density at the inlet of the catalyst bed and the measured NH 3 formation. The loss of N 2 (v) by vibrational relaxation on the surface limits the ability of N 2 (v) to contribute to catalytic NH 3 formation and explains why N 2 (v) does not produce NH 3 in quantities that are comparable to NH 3 formation from N even though N 2 (v > 0) is more abundantly produced by the plasma.

state-to-state kinetic modeling↗
DOE OSTI2024

Upcycling linear low-density polyethylene waste to turbostratic graphene for high mass loading supercapacitors

Linear low-density polyethylene (LLDPE) waste is difficult to upcycle into more valuable carbon materials because it tends to completely decompose into small molecules during thermal processing. In this work, LLDPE is upcycled into a high quality turbostratic graphene using a pre-treatment step to oxidatively crosslink the polymer with the assistance of solid additives (KCl and K 2 CO 3 ) that improve crosslinking by increasing the effective surface area of the polymer melt during processing. After this pretreatment step, the crosslinked polymer could then be carbonized and catalytically graphenized between 400–950°C without decomposition of the polymer feedstock. The LLDPE derived graphene (LLDPE-G) obtained from this process has a Brunauer–Emmett–Teller (BET) specific surface area, up to 1800m 2 g -1 and average Raman I D /I G and I 2D /I G ratios of 0.85 and 0.57, respectively, indicating high quality graphene. When used as an electrode material in symmetric supercapacitors, LLDPE-G possesses a specific capacitance up to 175Fg -1 at a mass loading of 20mgcm -2 , which is two times the commercial requirement, yielding an areal capacitance of 3.5 Fcm -2 . Moreover, LLDPE-G exhibits exceptional cycling stability with a capacitance retention of 95.8 % after 100,000 cycles at a current density of 4.0 Ag -1 . Additionally, the KCl and K 2 CO 3 solids are recycled and reused over 3 complete reaction cycles to make new LLDPE-G with the material quality and electrocapacitive performance retained and verified after each cycle. Our approach creates new opportunities for upcycling waste LLDPE and other varieties of polyethylene into a higher value graphene used for electrochemical energy storage applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Ag25(BiO6)3 by Materials Project

Ag25(BiO6)3 is Potassium Silver Cyanide-derived structured and crystallizes in the trigonal P-3 space group. The structure is three-dimensional. there are six inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a distorted linear geometry to two O2- atoms. There are one shorter (2.16 Å) and one longer (2.21 Å) Ag–O bond lengths. In the second Ag1+ site, Ag1+ is bonded in a linear geometry to two O2- atoms. There are one shorter (2.14 Å) and one longer (2.15 Å) Ag–O bond lengths. In the third Ag1+ site, Ag1+ is bonded in a linear geometry to two equivalent O2- atoms. Both Ag–O bond lengths are 2.13 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All Ag–O bond lengths are 2.58 Å. In the fifth Ag1+ site, Ag1+ is bonded in a linear geometry to two O2- atoms. Both Ag–O bond lengths are 2.17 Å. In the sixth Ag1+ site, Ag1+ is bonded in a linear geometry to two equivalent O2- atoms. Both Ag–O bond lengths are 2.11 Å. There are two inequivalent Bi+3.67+ sites. In the first Bi+3.67+ site, Bi+3.67+ is bonded in an octahedral geometry to six equivalent O2- atoms. All Bi–O bond lengths are 2.20 Å. In the second Bi+3.67+ site, Bi+3.67+ is bonded in an octahedral geometry to six O2- atoms. There are three shorter (2.27 Å) and three longer (2.46 Å) Bi–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Bi+3.67+ atom. In the second O2- site, O2- is bonded to three Ag1+ and one Bi+3.67+ atom to form distorted corner-sharing OAg3Bi tetrahedra. In the third O2- site, O2- is bonded to three Ag1+ and one Bi+3.67+ atom to form corner-sharing OAg3Bi tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag13As3(IO3)4 by Materials Project

Ag13As3(O3I)4 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are eight inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to three O2- and one I1- atom. There are two shorter (2.44 Å) and one longer (2.48 Å) Ag–O bond lengths. The Ag–I bond length is 2.79 Å. In the second Ag1+ site, Ag1+ is bonded to four O2- atoms to form distorted AgO4 trigonal pyramids that share corners with four AsO4 tetrahedra. There are three shorter (2.44 Å) and one longer (2.68 Å) Ag–O bond lengths. In the third Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to three O2- and one I1- atom. There are a spread of Ag–O bond distances ranging from 2.38–2.51 Å. The Ag–I bond length is 2.74 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to two O2- and two I1- atoms. There are one shorter (2.35 Å) and one longer (2.41 Å) Ag–O bond lengths. There are one shorter (2.95 Å) and one longer (2.98 Å) Ag–I bond lengths. In the fifth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three O2- and two equivalent I1- atoms. There are one shorter (2.35 Å) and two longer (2.42 Å) Ag–O bond lengths. There are one shorter (2.86 Å) and one longer (3.57 Å) Ag–I bond lengths. In the sixth Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to two O2- and two I1- atoms. There are one shorter (2.38 Å) and one longer (2.39 Å) Ag–O bond lengths. Both Ag–I bond lengths are 2.83 Å. In the seventh Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.29–2.77 Å. In the eighth Ag1+ site, Ag1+ is bonded in a distorted water-like geometry to two O2- and three I1- atoms. There are one shorter (2.36 Å) and one longer (2.37 Å) Ag–O bond lengths. There are a spread of Ag–I bond distances ranging from 3.08–3.28 Å. There are three inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share a cornercorner with one AgO4 trigonal pyramid. There is one shorter (1.72 Å) and three longer (1.74 Å) As–O bond length. In the second As5+ site, As5+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.73 Å) and two longer (1.74 Å) As–O bond length. In the third As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with three equivalent AgO4 trigonal pyramids. There are a spread of As–O bond distances ranging from 1.73–1.75 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded to three Ag1+ and one As5+ atom to form a mixture of distorted edge and corner-sharing OAg3As tetrahedra. In the second O2- site, O2- is bonded to three Ag1+ and one As5+ atom to form distorted corner-sharing OAg3As tetrahedra. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ag1+, one As5+, and one I1- atom. The O–I bond length is 3.63 Å. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Ag1+ and one As5+ atom. In the fifth O2- site, O2- is bonded in a distorted tetrahedral geometry to three Ag1+ and one As5+ atom. In the sixth O2- site, O2- is bonded to three Ag1+ and one As5+ atom to form distorted corner-sharing OAg3As tetrahedra. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Ag1+ and one As5+ atom. In the eighth O2- site, O2- is bonded to three Ag1+ and one As5+ atom to form a mixture of distorted edge and corner-sharing OAg3As tetrahedra. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one As5+ atom. There are four inequivalent I1- sites. In the first I1- site, I1- is bonded in a 7-coordinate geometry to two equivalent Ag1+ atoms. In the second I1- site, I1- is bonded in a 5-coordinate geometry to seven Ag1+ and one O2- atom. In the third I1- site, I1- is bonded in a 6-coordinate geometry to six Ag1+ atoms. In the fourth I1- site, I1- is bonded in a 6-coordinate geometry to six Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag32Te20As3 by Materials Project

Ag32As3Te20 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. there are four inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 6-coordinate geometry to two equivalent Ag1+ and four equivalent Te2- atoms. Both Ag–Ag bond lengths are 2.94 Å. All Ag–Te bond lengths are 3.31 Å. In the second Ag1+ site, Ag1+ is bonded in a 8-coordinate geometry to five Ag1+ and three Te2- atoms. There are a spread of Ag–Ag bond distances ranging from 2.86–3.05 Å. There are two shorter (2.97 Å) and one longer (3.21 Å) Ag–Te bond lengths. In the third Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to two equivalent Ag1+ and three Te2- atoms. There are one shorter (2.86 Å) and two longer (2.90 Å) Ag–Te bond lengths. In the fourth Ag1+ site, Ag1+ is bonded in a distorted single-bond geometry to one Ag1+ and six equivalent Te2- atoms. The Ag–Ag bond length is 2.69 Å. All Ag–Te bond lengths are 4.03 Å. As+2.67+ is bonded in a square co-planar geometry to four equivalent Te2- atoms. All As–Te bond lengths are 2.80 Å. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a distorted pentagonal pyramidal geometry to six equivalent Ag1+ atoms. In the second Te2- site, Te2- is bonded in a 8-coordinate geometry to four Ag1+ and four Te2- atoms. There are two shorter (2.75 Å) and two longer (3.26 Å) Te–Te bond lengths. In the third Te2- site, Te2- is bonded in a 8-coordinate geometry to six Ag1+, one As+2.67+, and one Te2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag2TeO3 by Materials Project

Ag2TeO3 is Krennerite-derived structured and 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 6-coordinate geometry to six O2- atoms. There are a spread of Ag–O bond distances ranging from 2.36–2.97 Å. In the second Ag1+ site, Ag1+ is bonded to five O2- atoms to form distorted corner-sharing AgO5 square pyramids. There are a spread of Ag–O bond distances ranging from 2.37–2.71 Å. Te4+ is bonded in a 3-coordinate geometry to four O2- atoms. There are a spread of Te–O bond distances ranging from 1.91–3.00 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to three Ag1+ and one Te4+ atom. In the second O2- site, O2- is bonded in a 5-coordinate geometry to four Ag1+ and one Te4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to four Ag1+ and two equivalent Te4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Destructive PIE and Safety Testing of Six AGR-2 UO 2 Capsule 3 Compacts

The Advanced Gas Reactor (AGR) Fuel Development and Qualification Program’s second irradiation experiment (AGR-2) was irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) from June 2010 to October 2013 (Collin 2014). The fuel compacts in this experiment held either tristructural isotropic (TRISO)-coated spherical kernels of uranium oxide (UO2) or TRISO-coated kernels containing both uranium carbide and uranium oxide phases (UCO). There were six separately monitored and controlled capsules in the AGR-2 test train. Capsule 3 held twelve compacts containing UO2-TRISO particles fabricated by BWX Technologies Nuclear Operations Group. The AGR-2 TRISO particles were fabricated in a pilot-scale fluidized-bed chemical vapor deposition (FB-CVD) furnace with a coating chamber inner diameter of 150 mm (Phillips, Barnes, and Hunn 2010), which was a change from the first irradiation experiment (AGR-1) particles that had been coated in a lab-scale FB-CVD coating system with a chamber inner diameter of 50 mm (Lowden 2006). The TRISO particles were overcoated with resinated graphite flake at Oak Ridge National Laboratory (ORNL), and the overcoated particles were pressed into one-inch-long, half-inch-diameter cylinders (Hunn, Montgomery, and Pappano 2010). Each cylindrical compact held an average of 1,543 TRISO particles with 9.6% enriched UO2 kernels that had a nominal diameter of 500 μm (Hunn, Savage, and Silva 2012). Capsule 3 compacts were irradiated to average calculated burnups of 9.01–10.69% fissions per initial metal atom (FIMA), and the average calculated fluences of fast neutrons with energies E n > 0.18 MeV were 3.05–3.53×10 25 n/m 2 (Sterbentz 2014). The calculated time-average, volume-average Capsule 3 compact temperatures were 996–1,062°C. However, Capsule 3 compact temperatures varied several hundred degrees across each compact, and the timeaverage minimum (TA min ) and time-average maximum (TA max ) temperatures were between 889–999°C and 1,072–1,105°C, respectively (Hawkes 2014). After irradiation, the AGR-2 test train was transferred from ATR to the INL Materials and Fuels Complex for inspection and disassembly (Ploger, Demkowicz, and Harp 2015). The initial inspection included dimensional metrology of the compacts and graphite fuel holders. Like all the AGR-2 compacts, the compacts in Capsule 3 shrank slightly during irradiation, as expected, with an average length reduction of 1.07–1.24% and an average diameter reduction of 0.13–0.41%. Post-irradiation examination (PIE) of the capsule components was completed to measure select fission products ( 90 Sr, 110m Ag, 134 Cs, 137 Cs, 144 Ce, and 154 Eu) outside the compacts (Stempien and Demkowicz 2020). This involved gamma counting of the graphite and graphoil spacers at the top and bottom of each capsule, acid leaching for radiochemical analysis of fission products on the metallic capsule components, and burn-leach analysis of the graphite holders. The total amount of 110mAg measured on the Capsule 3 components was 13% of the calculated capsule inventory. This was significantly lower than the amount of 110m Ag measured on the three UCO capsule components, which ranged from 32–70%. The lower 110m Ag release in Capsule 3 was likely due to lower peak temperatures compared with the UCO fuel capsules (Hawkes 2014). Measured inventories of the other select fission products were also lower in Capsule 3.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Materials Data on Ag4PIO4 by Materials Project

Ag4I(PO4) crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are five inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to three O2- and one I1- atom. There are a spread of Ag–O bond distances ranging from 2.38–2.44 Å. The Ag–I bond length is 2.75 Å. In the second Ag1+ site, Ag1+ is bonded in a distorted bent 120 degrees geometry to two O2- and three I1- atoms. There are one shorter (2.34 Å) and one longer (2.45 Å) Ag–O bond lengths. There are a spread of Ag–I bond distances ranging from 2.95–3.32 Å. In the third Ag1+ site, Ag1+ is bonded to four O2- atoms to form distorted AgO4 trigonal pyramids that share corners with four PO4 tetrahedra. There are a spread of Ag–O bond distances ranging from 2.45–2.70 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three O2- and two equivalent I1- atoms. There are a spread of Ag–O bond distances ranging from 2.36–2.45 Å. There are one shorter (2.85 Å) and one longer (3.56 Å) Ag–I bond lengths. In the fifth Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to three O2- and one I1- atom. There are two shorter (2.42 Å) and one longer (2.53 Å) Ag–O bond lengths. The Ag–I bond length is 2.81 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent AgO4 trigonal pyramids. There are a spread of P–O bond distances ranging from 1.56–1.58 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one AgO4 trigonal pyramid. There are a spread of P–O bond distances ranging from 1.55–1.58 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to three Ag1+ and one P5+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to three Ag1+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to three Ag1+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ag1+, one P5+, and one I1- atom. The O–I bond length is 3.69 Å. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to three Ag1+ and one P5+ atom. There are two inequivalent I1- sites. In the first I1- site, I1- is bonded in a 5-coordinate geometry to seven Ag1+ and one O2- atom. In the second I1- site, I1- is bonded in a 6-coordinate geometry to six Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AgTe by Materials Project

AgTe crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to three Ag1+ and four Te1- atoms. There are a spread of Ag–Ag bond distances ranging from 3.01–3.09 Å. There are a spread of Ag–Te bond distances ranging from 2.83–3.14 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to two equivalent Ag1+ and four Te1- atoms. There are a spread of Ag–Te bond distances ranging from 2.83–3.23 Å. In the third Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to two equivalent Ag1+ and four Te1- atoms. There are a spread of Ag–Te bond distances ranging from 2.87–2.98 Å. There are three inequivalent Te1- sites. In the first Te1- site, Te1- is bonded in a 5-coordinate geometry to four Ag1+ and one Te1- atom. The Te–Te bond length is 2.90 Å. In the second Te1- site, Te1- is bonded in a 1-coordinate geometry to one Ag1+ and two equivalent Te1- atoms. In the third Te1- site, Te1- is bonded in a 7-coordinate geometry to seven Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsAg5Te3 by Materials Project

CsAg5Te3 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Cs1+ is bonded in a body-centered cubic geometry to eight Te2- atoms. There are four shorter (3.96 Å) and four longer (3.98 Å) Cs–Te bond lengths. There are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded to four equivalent Ag1+ and four Te2- atoms to form distorted face-sharing AgAg4Te4 tetrahedra. All Ag–Ag bond lengths are 3.20 Å. There are two shorter (2.83 Å) and two longer (3.06 Å) Ag–Te bond lengths. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three equivalent Ag1+ and three equivalent Te2- atoms. There are one shorter (2.93 Å) and two longer (3.18 Å) Ag–Ag bond lengths. There are one shorter (2.82 Å) and two longer (2.94 Å) Ag–Te bond lengths. In the third Ag1+ site, Ag1+ is bonded in a 9-coordinate geometry to five Ag1+ and four Te2- atoms. There are a spread of Ag–Te bond distances ranging from 2.79–3.05 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 8-coordinate geometry to four equivalent Cs1+ and four Ag1+ atoms. In the second Te2- site, Te2- is bonded in a 9-coordinate geometry to two equivalent Cs1+ and seven Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Adsorption of molecular iodine and alkyl iodides from spent-nuclear-fuel-reprocessing off-gas using reduced silver mordenite

Radioactive iodine is a hazardous byproduct of spent-nuclear-fuel reprocessing that must be removed from the off-gas stream before it can be discharged. Reduced silver mordenite (Ag 0 Z) is currently the baseline material for iodine capture in the U.S. Although the performance characteristics and capture mechanisms of I 2 and CH 3 I have been established, similar investigations into long-chain organic iodides have yet to be performed. In this study, thin beds of Ag 0 Z were loaded with I 2 , CH 3 I, C 4 H 9 I, and C 12 H 25 I (5 ppm to 50 ppm) carried in a dry air stream at 150°C. The maximum iodine capacity was 105 ± 5 mg I/g Ag 0 Z for all species. Saturated Ag 0 Z samples were characterized using scanning electron microscopy, X-ray fluorescence, X-ray photoelectron spectroscopy, diffuse reflectance UV–visible spectroscopy, pair distribution function analysis, and thermogravimetric analysis. Further, near-complete Ag utilization and similar physical/chemical properties were observed for all samples. Through a comparison with previous studies and an investigation of aged Ag 0 Z, we propose that iodine species react with Ag + at exchange sites, forming α-AgI within the mordenite channels, and with surface Ag 0 nanoparticles, yielding β-/γ-AgI. The available Ag sites in the interior (Ag + ) and exterior (Ag 0 ) of mordenite determine the adsorption capacity since α-AgI formation is limited by the total pore volume. Potential iodine uptake routes were summarized for aging and non-aging environments. A scalable predictive model was implemented for deep-bed iodine removal, and predictions were in good agreement with experimental data. Sensitivity analysis suggests that iodine uptake kinetics is governed by pore diffusion.

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

Materials Data on Ag3Sn2(GeP2)3 by Materials Project

Ag3Sn2(GeP2)3 crystallizes in the cubic I-43m space group. The structure is three-dimensional. Ag1+ is bonded in a distorted L-shaped geometry to two equivalent P3- atoms. Both Ag–P bond lengths are 2.60 Å. Sn2+ is bonded in a distorted T-shaped geometry to three equivalent P3- atoms. All Sn–P bond lengths are 2.65 Å. Ge+3.67+ is bonded to four equivalent P3- atoms to form corner-sharing GeP4 tetrahedra. All Ge–P bond lengths are 2.36 Å. P3- is bonded to one Ag1+, one Sn2+, and two equivalent Ge+3.67+ atoms to form corner-sharing PAgSnGe2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Models to Incorporate Reaction Mechanisms into DG-OSPREY: Fixed-Bed Simulations for Organic Iodides Capture Using Ag 0 Z

As one of the most potent radioisotopes released during spent nuclear fuel reprocessing, 129 I is strictly regulated and must be removed before discharge. Organic iodides (primarily alkyl iodides with different chain lengths, i.e., CH 3 I, C 4 H 9 I, and C 12 H 25 I) comprise ~2% of the total iodine in the reprocessing off-gases and are primarily present in vessel off-gas (VOG). Reduced silver mordenite (Ag 0 Z) is predominantly considered for the removal of radioiodine; however, its capture performance and underlying interaction processes with long-chain organic iodides are not fully understood. Two major tasks were accomplished in this study. First, to improve upon the previous experimental studies where Ag 0 Z was used to capture CH 3 I, C 4 H 9 I, and C 12 H 25 I at different concentrations, we comprehensively investigated the corresponding capture mechanisms by characterizing fully loaded Ag 0 Z samples. Second, computational codes were implemented to perform fixed-bed simulations that account for transport and reaction mechanisms. Scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), powder X-ray diffraction (PXRD), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), and thermogravimetric analysis (TGA) were conducted on Ag 0 Z samples that are saturated with I 2 , CH 3 I, C 4 H 9 I, and C 12 H 25 I), respectively. Results indicate that AgI is the predominant adsorption product regardless of the adsorbed iodine species, yet alkyl iodides with different carbon chain lengths may have different compositions of α- and γ-AgI. Synchrotron pair distribution function (PDF) measurements and TGA coupled with a Fourier transformed infrared detector (TGA FTIR) have been performed, and experimental data are currently analyzed. Results are expected to provide further insights into the adsorption mechanisms. The fixed-bed capture performance for CH 3 I was successfully simulated by solving mathematical equations that describe the underlying transport processes and adsorption reactions. The computational framework, Catalytic After Treatment System (CATS), that was originated in our research group, was used to solve the governing equations. Kinetic parameters, including the pore diffusivity and reaction rate constant were obtained by optimization techniques using data from thin-bed experiments performed at Oak Ridge National Laboratory. The performance of a deep bed predicted using the optimized parameters showed promising agreement with the experimental data.

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

Materials Data on Ag8GeTe6 by Materials Project

Ag8GeTe6 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 8-coordinate geometry to four Ag1+ and four Te2- atoms. There are a spread of Ag–Ag bond distances ranging from 2.87–3.01 Å. There are a spread of Ag–Te bond distances ranging from 2.95–3.13 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three Ag1+ and three Te2- atoms. There are one shorter (2.92 Å) and one longer (3.03 Å) Ag–Ag bond lengths. There are a spread of Ag–Te bond distances ranging from 2.84–2.94 Å. In the third Ag1+ site, Ag1+ is bonded in a 5-coordinate geometry to one Ag1+ and four Te2- atoms. The Ag–Ag bond length is 2.94 Å. There are a spread of Ag–Te bond distances ranging from 2.83–3.06 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to three Ag1+ and four Te2- atoms. There are one shorter (2.82 Å) and one longer (2.90 Å) Ag–Ag bond lengths. There are a spread of Ag–Te bond distances ranging from 2.78–3.21 Å. In the fifth Ag1+ site, Ag1+ is bonded in a 7-coordinate geometry to three Ag1+ and four Te2- atoms. The Ag–Ag bond length is 2.89 Å. There are a spread of Ag–Te bond distances ranging from 2.84–3.16 Å. In the sixth Ag1+ site, Ag1+ is bonded in a 7-coordinate geometry to three Ag1+ and four Te2- atoms. There are a spread of Ag–Te bond distances ranging from 2.89–3.21 Å. In the seventh Ag1+ site, Ag1+ is bonded in a 5-coordinate geometry to one Ag1+ and four Te2- atoms. There are a spread of Ag–Te bond distances ranging from 2.86–3.17 Å. In the eighth Ag1+ site, Ag1+ is bonded in a 6-coordinate geometry to two Ag1+ and four Te2- atoms. There are a spread of Ag–Te bond distances ranging from 2.78–3.23 Å. Ge4+ is bonded in a tetrahedral geometry to four Te2- atoms. There are a spread of Ge–Te bond distances ranging from 2.59–2.65 Å. There are six inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 8-coordinate geometry to eight Ag1+ atoms. In the second Te2- site, Te2- is bonded in a 7-coordinate geometry to seven Ag1+ atoms. In the third Te2- site, Te2- is bonded in a 7-coordinate geometry to six Ag1+ and one Ge4+ atom. In the fourth Te2- site, Te2- is bonded in a 5-coordinate geometry to four Ag1+ and one Ge4+ atom. In the fifth Te2- site, Te2- is bonded in a 5-coordinate geometry to four Ag1+ and one Ge4+ atom. In the sixth Te2- site, Te2- is bonded in a 3-coordinate geometry to two Ag1+ and one Ge4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2026

The Cascade Effectiveness of 3-Terminal Tandem Photocathode Architectures as Applied to CO 2 Reduction

Cascade catalysis for photoelectrochemical CO 2 reduction (CO 2 R) decouples the overall reaction into sequential steps occurring on separately optimized catalysts (for example, Ag and Cu) between which an intermediate species such as CO is transferred. A 3-terminal tandem (3TT) photovoltaic architecture advantageously holds two different catalytic regions at different potentials under a single illumination source, but its overall efficiency is low. Using a stochastic reaction-diffusion model, we have examined 3TT photocathode design principles, focusing on the coupling of surface chemistry and transport of CO both inside the boundary layer and outward, into the bulk electrolyte. We find that ensuring that the lateral diffusion distance within the boundary layer is short compared to the boundary layer thickness and controlling bulk flow are key, with interdigitated designs showing an overall conversion efficiency improvement by 2 orders of magnitude compared to the side-by-side case without flow. These findings can be adapted for other cascaded architectures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗