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DOE OSTI2020

Materials Data on NaNiPO11 by Materials Project

NaNiO7PO4 crystallizes in the tetragonal P4_2/mmc space group. The structure is three-dimensional and consists of two phosphoric acid molecules and one NaNiO7 framework. In the NaNiO7 framework, Na is bonded to six O atoms to form NaO6 octahedra that share corners with two equivalent NaO6 octahedra and edges with two equivalent NiO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.28 Å) and two longer (2.44 Å) Na–O bond lengths. Ni is bonded to six O atoms to form NiO6 octahedra that share edges with two equivalent NaO6 octahedra. All Ni–O bond lengths are 1.83 Å. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Ni atom. In the second O site, O is bonded in a water-like geometry to one Na and one Ni atom. In the third O site, O is bonded in a linear geometry to two equivalent Na atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on P2O9 by Materials Project

P2O9 is Silicon tetrafluoride-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of eight phosphoric acid molecules and four water molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlPC4S4(N2O)4 by Materials Project

TlC4(N2S)4PO4 crystallizes in the orthorhombic Cccm space group. The structure is one-dimensional and consists of four phosphoric acid molecules and two TlC4(N2S)4 ribbons oriented in the (0, 0, 1) direction. In each TlC4(N2S)4 ribbon, Tl3+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are four shorter (3.03 Å) and four longer (3.05 Å) Tl–S bond lengths. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted trigonal planar geometry to two equivalent N1- and one S2- atom. Both C–N bond lengths are 1.31 Å. The C–S bond length is 1.83 Å. In the second C4+ site, C4+ is bonded in a distorted trigonal planar geometry to two equivalent N1- and one S2- atom. Both C–N bond lengths are 1.31 Å. The C–S bond length is 1.84 Å. There are two inequivalent N1- sites. In the first N1- site, N1- is bonded in a single-bond geometry to one C4+ and one S2- atom. The N–S bond length is 3.35 Å. In the second N1- site, N1- is bonded in a single-bond geometry to one C4+ atom. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to two equivalent Tl3+ and one C4+ atom. In the second S2- site, S2- is bonded in a 3-coordinate geometry to two equivalent Tl3+, one C4+, and two equivalent N1- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlP2O11 by Materials Project

Al2(PO6)3PO4 is Molybdenum Carbide MAX Phase-like structured and crystallizes in the trigonal R3 space group. The structure is zero-dimensional and consists of three phosphoric acid molecules and three Al2(PO6)3 clusters. In each Al2(PO6)3 cluster, there are two inequivalent Al sites. In the first Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with three equivalent PO4 tetrahedra. There is three shorter (1.82 Å) and three longer (1.94 Å) Al–O bond length. In the second Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with three equivalent PO4 tetrahedra. There is three shorter (1.86 Å) and three longer (1.93 Å) Al–O bond length. P is bonded to four O atoms to form PO4 tetrahedra that share corners with two AlO6 octahedra. The corner-sharing octahedra tilt angles range from 26–32°. There are a spread of P–O bond distances ranging from 1.52–1.57 Å. There are six inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Al atom. In the second O site, O is bonded in a single-bond geometry to one Al atom. In the third O site, O is bonded in a bent 150 degrees geometry to one Al and one P atom. In the fourth O site, O is bonded in a bent 150 degrees geometry to one Al and one P atom. In the fifth O site, O is bonded in a single-bond geometry to one P atom. In the sixth O site, O is bonded in a single-bond geometry to one P atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrPO10 by Materials Project

CrO6PO4 is Silicon tetrafluoride-derived structured and crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of eight phosphoric acid molecules and eight CrO6 clusters. In each CrO6 cluster, Cr is bonded in a tetrahedral geometry to four O atoms. There are a spread of Cr–O bond distances ranging from 1.62–1.75 Å. There are six inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Cr atom. In the second O site, O is bonded in a bent 120 degrees geometry to two O atoms. There is one shorter (1.21 Å) and one longer (1.77 Å) O–O bond length. In the third O site, O is bonded in a single-bond geometry to one Cr and one O atom. In the fourth O site, O is bonded in a single-bond geometry to one Cr atom. In the fifth O site, O is bonded in a single-bond geometry to one O atom. In the sixth O site, O is bonded in a single-bond geometry to one Cr atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KP4N3O16 by Materials Project

(K(PO4)3)2(N2)3(PO4)2 crystallizes in the tetragonal P-4 space group. The structure is three-dimensional and consists of three ammonia molecules, one phosphoric acid molecule, and one K(PO4)3 framework. In the K(PO4)3 framework, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.89 Å) and four longer (2.98 Å) K–O bond lengths. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All P–O bond lengths are 1.54 Å. In the second P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.53 Å) and two longer (1.55 Å) P–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one K1+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one P5+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PO4 by Materials Project

PO4 is Silicon tetrafluoride-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four phosphoric acid molecules. P is bonded in a tetrahedral geometry to four O atoms. All P–O bond lengths are 1.54 Å. There are four inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one P atom. 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 single-bond geometry to one P atom. In the fourth O site, O is bonded in a single-bond geometry to one P atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PRhO10 by Materials Project

RhO6PO4 crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of eight phosphoric acid molecules and eight RhO6 clusters. In each RhO6 cluster, Rh is bonded in a distorted octahedral geometry to six O atoms. All Rh–O bond lengths are 1.93 Å. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Rh atom. In the second O site, O is bonded in a single-bond geometry to one Rh atom. In the third O site, O is bonded in a single-bond geometry to one Rh atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mo8P9Br(N3O14)4 by Materials Project

(Mo2P2O13)4(N2)4PO4N4Br crystallizes in the tetragonal P-4 space group. The structure is two-dimensional and consists of eight ammonia molecules; one phosphoric acid molecule; one N4Br cluster; and two Mo2P2O13 sheets oriented in the (0, 0, 1) direction. In the N4Br cluster, N is bonded in a single-bond geometry to one Br atom. The N–Br bond length is 2.17 Å. Br is bonded in a rectangular see-saw-like geometry to four equivalent N atoms. In each Mo2P2O13 sheet, there are two inequivalent Mo sites. In the first Mo site, Mo is bonded to six O atoms to form distorted MoO6 octahedra that share a cornercorner with one MoO6 octahedra and corners with three PO4 tetrahedra. The corner-sharing octahedral tilt angles are 26°. There are a spread of Mo–O bond distances ranging from 1.73–2.24 Å. In the second Mo site, Mo is bonded to six O atoms to form distorted MoO6 octahedra that share a cornercorner with one MoO6 octahedra and corners with three PO4 tetrahedra. The corner-sharing octahedral tilt angles are 27°. There are a spread of Mo–O bond distances ranging from 1.75–2.32 Å. There are two inequivalent P sites. In the first P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with three MoO6 octahedra. The corner-sharing octahedra tilt angles range from 17–48°. There is two shorter (1.54 Å) and two longer (1.55 Å) P–O bond length. In the second P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with three MoO6 octahedra. The corner-sharing octahedra tilt angles range from 34–48°. There are a spread of P–O bond distances ranging from 1.53–1.55 Å. There are fourteen inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to two equivalent Mo atoms. In the second O site, O is bonded in a single-bond geometry to one Mo atom. In the third O site, O is bonded in a distorted single-bond geometry to one Mo and one P atom. In the fourth O site, O is bonded in a distorted bent 150 degrees geometry to one Mo and one P atom. In the fifth O site, O is bonded in a distorted linear geometry to one Mo and one P atom. In the sixth O site, O is bonded in a distorted single-bond geometry to one Mo and one P atom. In the seventh O site, O is bonded in a single-bond geometry to one Mo atom. In the eighth O site, O is bonded in a bent 150 degrees geometry to one Mo and one P atom. In the ninth O site, O is bonded in a single-bond geometry to one Mo atom. In the tenth O site, O is bonded in a bent 150 degrees geometry to two equivalent Mo atoms. In the eleventh O site, O is bonded in a 1-coordinate geometry to one Mo and one P atom. In the twelfth O site, O is bonded in a single-bond geometry to one P atom. In the thirteenth O site, O is bonded in a single-bond geometry to one Mo atom. In the fourteenth O site, O is bonded in a single-bond geometry to one P atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrPO10 by Materials Project

CrO6PO4 is Silicon tetrafluoride-derived structured and crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of eight phosphoric acid molecules and eight CrO6 clusters. In each CrO6 cluster, Cr is bonded in a distorted tetrahedral geometry to six O atoms. There are a spread of Cr–O bond distances ranging from 1.61–2.39 Å. There are six inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Cr atom. In the second O site, O is bonded in a single-bond geometry to one Cr atom. In the third O site, O is bonded in a distorted single-bond geometry to one Cr atom. In the fourth O site, O is bonded in a single-bond geometry to one Cr atom. In the fifth O site, O is bonded in a single-bond geometry to one Cr atom. In the sixth O site, O is bonded in a single-bond geometry to one Cr atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on P(HO)3 by Materials Project

H3PO3 crystallizes in the monoclinic P2_1 space group. The structure is one-dimensional and consists of four phosphorous acid molecules and two H3PO3 ribbons oriented in the (0, 1, 0) direction. In each H3PO3 ribbon, P5+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.61 Å) and two longer (1.64 Å) P–O bond length. There are three inequivalent H+0.33+ sites. In the first H+0.33+ site, H+0.33+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H+0.33+ site, H+0.33+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.70 Å) H–O bond length. In the third H+0.33+ site, H+0.33+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one P5+ and one H+0.33+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one P5+ and one H+0.33+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one P5+ and two H+0.33+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na4AsP(H15O11)2 by Materials Project

Na4AsH29O18HPO4 crystallizes in the monoclinic Pc space group. The structure is one-dimensional and consists of two phosphoric acid molecules and two Na4AsH29O18 ribbons oriented in the (0, 1, 0) direction. In each Na4AsH29O18 ribbon, there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form a mixture of edge and face-sharing NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.38–2.47 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form a mixture of edge and face-sharing NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.39–2.46 Å. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form a mixture of edge and face-sharing NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.34–2.48 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form a mixture of edge and face-sharing NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.34–2.48 Å. As5+ is bonded in a tetrahedral geometry to four O2- atoms. There is three shorter (1.71 Å) and one longer (1.78 Å) As–O bond length. There are twenty-nine inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the ninth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.60 Å) H–O bond length. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eighteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the nineteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twentieth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twenty-first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twenty-second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twenty-third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twenty-fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twenty-fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twenty-sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the twenty-seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the twenty-eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twenty-ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one As5+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Na1+ and two H1+ atoms. In the third O2- site, O2- is bonded in a distorted water-like geometry to one Na1+ and two H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one Na1+ and three H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted water-like geometry to one Na1+ and two H1+ atoms. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to one As5+ atom. In the ninth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the tenth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the eleventh O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the twelfth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to one As5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the sixteenth O2- site, O2- is bonded in a 2-coordinate geometry to one As5+ and one H1+ atom. In the seventeenth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlP3(NO6)2 by Materials Project

TlP2(NO4)2PO4 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional and consists of four phosphoric acid molecules and one TlP2(NO4)2 framework. In the TlP2(NO4)2 framework, Tl1+ is bonded to eight O2- atoms to form distorted TlO8 hexagonal bipyramids that share corners with four equivalent PO4 tetrahedra and edges with two equivalent PO4 tetrahedra. There are four shorter (2.99 Å) and four longer (3.02 Å) Tl–O bond lengths. P5+ is bonded to four O2- atoms to form distorted PO4 tetrahedra that share corners with two equivalent TlO8 hexagonal bipyramids and an edgeedge with one TlO8 hexagonal bipyramid. There is two shorter (1.47 Å) and two longer (1.82 Å) P–O bond length. N4+ is bonded in a water-like geometry to two equivalent O2- atoms. Both N–O bond lengths are 1.31 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Tl1+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted L-shaped geometry to one Tl1+, one P5+, and one N4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PH24W12C6N3O40 by Materials Project

(WO3)12((CH3)2NH2)3PO4 crystallizes in the trigonal R-3m space group. The structure is zero-dimensional and consists of eighteen dimethylazanium molecules, six phosphoric acid molecules, and six WO3 clusters. In each WO3 cluster, there are three inequivalent W sites. In the first W site, W is bonded in a 5-coordinate geometry to five O atoms. There is one shorter (1.73 Å) and four longer (1.95 Å) W–O bond length. In the second W site, W is bonded in a 5-coordinate geometry to five O atoms. There are a spread of W–O bond distances ranging from 1.74–1.95 Å. In the third W site, W is bonded in a 5-coordinate geometry to five O atoms. There are a spread of W–O bond distances ranging from 1.74–1.95 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to two equivalent W atoms. In the second O site, O is bonded in a bent 150 degrees geometry to two equivalent W atoms. In the third O site, O is bonded in a bent 120 degrees geometry to two equivalent W atoms. In the fourth O site, O is bonded in a bent 150 degrees geometry to two W atoms. In the fifth O site, O is bonded in a single-bond geometry to one W atom. In the sixth O site, O is bonded in a single-bond geometry to one W atom. In the seventh O site, O is bonded in a bent 120 degrees geometry to two W atoms. In the eighth O site, O is bonded in a bent 150 degrees geometry to two equivalent W atoms. In the ninth O site, O is bonded in a single-bond geometry to one W atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrPO10 by Materials Project

CrO6CrO4(PO4)2O2 is Silicon tetrafluoride-derived structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four cq4 molecules, four oxygen molecules, eight phosphoric acid molecules, and four CrO6 clusters. In each CrO6 cluster, Cr is bonded in an octahedral geometry to six O atoms. There is four shorter (1.81 Å) and two longer (1.83 Å) Cr–O bond length. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Cr atom. In the second O site, O is bonded in a single-bond geometry to one Cr atom. In the third O site, O is bonded in a single-bond geometry to one Cr atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

A short tutorial on uranium electropolishing

Electropolishing of uranium metal is best performed in a simple aqueous solution of phosphoric acid. With +3 to +10 volts of bias potential applied to the uranium (anode) relative to a Pt counter electrode (cathode). As summarized in a Pourbaix stability diagram, these conditions yield dissolution of the U surface as UOX containing solution species without the possibility of injecting hydrogen into the metal surface. However, if the uranium is biased to negative potentials relative to the counter electrode then water may be reduced at the U surface and hydrogen gas becomes available for reaction with the U metal. The stability diagram may be modified if there are other complexing species present in solution and the potential scale shifted if a different metal is use for the counter electrode. These effects can be understood in a known way as long as solution and electrochemical cell conditions are recognized.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

Research tool development for catalyst, catalyst/ionomer, and ionomer characterization above 100°C (CRADA Final Report)

There is a need to develop experimental tools that address the catalyst and ionomer interface under high-temperature proton-exchange-membrane (HT-PEM) operating conditions (dry, >100°C). These conditions mean traditional water-based measurements for membrane and ionomer properties are insufficient; new ex-situ techniques are required to address and characterize expected novel materials. In this project we develop a microelectrode cell for high temperature kinetics and gas transport properties and ex-situ ionomer thin-film characterization under these conditions. We use baseline Nafion and phosphoric-acid imbibed membranes as prototype materials for measuring the membrane/acid/ionomer systems with Pt microelectrodes and demonstrate feasibility of the tools.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Dehalogenation reactions between halide salts and phosphate compounds

Reactions between phosphoric acid [H 3 PO 4 ] or ammonium hydrogen phosphates [i.e., NH 4 H 2 PO 4 , (NH 4 ) 2 HPO 4 ] and halide salts can be used to dehalogenate (remove halides from) salt-based waste streams, where the process of removing halides yields products that have more efficient disposal pathways for repository storage. In this context, the term efficiency is defined as higher waste loadings and simplified immobilization processes with potential for recycle of certain salt components (e.g., 37 Cl as H 37 Cl or NH 4 37 Cl). The main streams identified for these processes are nuclear wastes generated during electrochemical reprocessing of used nuclear fuel as well as used halide salts from molten salt reactor operation. The potential byproducts of these reactions are fairly consistent across the range of halide species (i.e., F, Cl, Br, I) where the most common are hydrogen halides [e.g., HCl (g) ] or ammonium halides (e.g., NH 4 Cl). However, trihalide compounds (e.g., NCl 3 ), nitrogen triiodide ammine adducts [NI 3 ·(NH 3 ) x ], and ammonium triiodide (NH 4 I 3 ) are also possible. Several of these byproducts (i.e., NCl 3 , NBr 3 , NI 3 , and NH 4 I 3 ) are shock-sensitive contact explosives so their production in these processes must be tracked and carefully controlled, which includes methods of immediate neutralization upon production such as direct transport to a caustic scrubber for dissolution. Several benefits arise from utilizing H 3 PO 4 as the phosphate additive during dehalogenation reactions for making iron phosphate waste forms including more oxidized iron (higher Fe 3+ :Fe 2+ ratios), higher chemical durabilities, and the avoidance of trihalides, but the byproducts are hydrogen halides, which are corrosive and require special handling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗