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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Np(CuGe)2 by Materials Project

Np(CuGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded in a 8-coordinate geometry to eight equivalent Cu and eight equivalent Ge atoms. All Np–Cu bond lengths are 3.29 Å. All Np–Ge bond lengths are 3.08 Å. Cu is bonded to four equivalent Np and four equivalent Ge atoms to form a mixture of distorted corner, edge, and face-sharing CuNp4Ge4 tetrahedra. All Cu–Ge bond lengths are 2.43 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Np, four equivalent Cu, and one Ge atom. The Ge–Ge bond length is 2.45 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(MnGe)2 by Materials Project

Np(MnGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded in a 8-coordinate geometry to eight equivalent Mn and eight equivalent Ge atoms. All Np–Mn bond lengths are 3.24 Å. All Np–Ge bond lengths are 3.10 Å. Mn is bonded to four equivalent Np and four equivalent Ge atoms to form a mixture of edge, face, and corner-sharing MnNp4Ge4 tetrahedra. All Mn–Ge bond lengths are 2.37 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Np, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(CoGe)2 by Materials Project

Np(CoGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded in a 8-coordinate geometry to eight equivalent Co and eight equivalent Ge atoms. All Np–Co bond lengths are 3.15 Å. All Np–Ge bond lengths are 3.10 Å. Co is bonded to four equivalent Np and four equivalent Ge atoms to form a mixture of distorted corner, edge, and face-sharing CoNp4Ge4 tetrahedra. All Co–Ge bond lengths are 2.33 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Np, four equivalent Co, and one Ge atom. The Ge–Ge bond length is 2.47 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(SiIr)2 by Materials Project

Np(IrSi)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Np is bonded in a 4-coordinate geometry to eight Ir and eight Si atoms. There are four shorter (3.13 Å) and four longer (3.29 Å) Np–Ir bond lengths. There are four shorter (3.16 Å) and four longer (3.18 Å) Np–Si bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded to four equivalent Np and four equivalent Si atoms to form distorted IrNp4Si4 tetrahedra that share corners with twelve equivalent SiNp4Ir4 tetrahedra, edges with two equivalent SiNp4Ir4 tetrahedra, edges with four equivalent IrNp4Si4 tetrahedra, and faces with four equivalent IrNp4Si4 tetrahedra. All Ir–Si bond lengths are 2.44 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Np and five Si atoms. There are one shorter (2.38 Å) and four longer (2.43 Å) Ir–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded to four equivalent Np and four equivalent Ir atoms to form distorted SiNp4Ir4 tetrahedra that share corners with twelve equivalent IrNp4Si4 tetrahedra, edges with two equivalent IrNp4Si4 tetrahedra, edges with four equivalent SiNp4Ir4 tetrahedra, and faces with four equivalent SiNp4Ir4 tetrahedra. In the second Si site, Si is bonded in a 9-coordinate geometry to four equivalent Np and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(CrGe)2 by Materials Project

Np(CrGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Np–Ge bond lengths are 3.03 Å. Cr is bonded to four equivalent Ge atoms to form a mixture of edge and corner-sharing CrGe4 tetrahedra. All Cr–Ge bond lengths are 2.45 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Np, four equivalent Cr, and one Ge atom. The Ge–Ge bond length is 2.56 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(NiGe)2 by Materials Project

Np(NiGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded in a 8-coordinate geometry to eight equivalent Ni and eight equivalent Ge atoms. All Np–Ni bond lengths are 3.21 Å. All Np–Ge bond lengths are 3.12 Å. Ni is bonded to four equivalent Np and four equivalent Ge atoms to form a mixture of distorted edge, face, and corner-sharing NiNp4Ge4 tetrahedra. All Ni–Ge bond lengths are 2.36 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Np, four equivalent Ni, and one Ge atom. The Ge–Ge bond length is 2.52 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(FeGe)2 by Materials Project

Np(FeGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np is bonded in a 8-coordinate geometry to eight equivalent Fe and eight equivalent Ge atoms. All Np–Fe bond lengths are 3.13 Å. All Np–Ge bond lengths are 3.09 Å. Fe is bonded to four equivalent Np and four equivalent Ge atoms to form a mixture of distorted corner, edge, and face-sharing FeNp4Ge4 tetrahedra. All Fe–Ge bond lengths are 2.32 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Np, four equivalent Fe, and one Ge atom. The Ge–Ge bond length is 2.49 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(CrSi)2 by Materials Project

Np(CrSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Np–Si bond lengths are 3.01 Å. Cr+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing CrSi4 tetrahedra. All Cr–Si bond lengths are 2.38 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Np3+, four equivalent Cr+2.50+, and one Si4- atom. The Si–Si bond length is 2.34 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(FeSi)2 by Materials Project

Np(FeSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Np–Si bond lengths are 3.05 Å. Fe+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing FeSi4 tetrahedra. All Fe–Si bond lengths are 2.28 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Np3+, four equivalent Fe+2.50+, and one Si4- atom. The Si–Si bond length is 2.47 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(SiNi)2 by Materials Project

Np(NiSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Np–Si bond lengths are 3.00 Å. Ni2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.31 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Np4+, four equivalent Ni2+, and one Si4- atom. The Si–Si bond length is 2.33 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(SiAu)2 by Materials Project

Np(AuSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np7+ is bonded to eight equivalent Si4- atoms to form NpSi8 hexagonal bipyramids that share corners with sixteen equivalent AuSi4 tetrahedra, edges with four equivalent NpSi8 hexagonal bipyramids, edges with eight equivalent AuSi4 tetrahedra, and faces with four equivalent NpSi8 hexagonal bipyramids. All Np–Si bond lengths are 3.18 Å. Au+0.50+ is bonded to four equivalent Si4- atoms to form AuSi4 tetrahedra that share corners with eight equivalent NpSi8 hexagonal bipyramids, corners with four equivalent AuSi4 tetrahedra, edges with four equivalent NpSi8 hexagonal bipyramids, and edges with four equivalent AuSi4 tetrahedra. All Au–Si bond lengths are 2.57 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Np7+, four equivalent Au+0.50+, and one Si4- atom. The Si–Si bond length is 2.27 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(MoO4)2 by Materials Project

Np(MoO4)2 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Np4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Np–O bond distances ranging from 2.30–2.40 Å. There are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 1.79–1.82 Å. In the second Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.79 Å) and two longer (1.80 Å) Mo–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Np4+ and one Mo6+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Np4+ and one Mo6+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Np4+ and one Mo6+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Np4+ and one Mo6+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Np4+ and one Mo6+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Np4+ and one Mo6+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Np4+ and one Mo6+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Np4+ and one Mo6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Two Neptunium(III) Mellitate Coordination Polymers: Completing the Series Np–Cf of Trans-Uranic An(III) Mellitates

For this work, two neptunium(III) mellitates, 237 Np 2 (mell)(H 2 O) 9 ·1.5H 2 O (Np-1α) and 237 Np 2 (mell)(H 2 O) 8 ·2H 2 O (Np-1β), have been synthesized from 237 NpCl 4 (dme) 2 by reduction with KC 8 and subsequent reaction with an aqueous solution of mellitic acid (H 6 mell). Characterization by single-crystal X-ray crystallography and UV–vis–NIR spectroscopy confirms that the neptunium is in its +3 oxidation state and both polymorphs are isostructural to the previously reported plutonium mellitates. Of the two morphologies, Np-1α is indefinitely stable in air, while Np-1β slowly oxidizes over several months. This is due to the change in the energy of the metal-ligand charge-transfer absorption exhibited by these compounds attributed to differing numbers of carboxylate bonds to Np(III), where in Np-1β the energy is low enough to result in spontaneous oxidation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Coupled Cluster Study of the Interactions of AnO 2 , AnO 2 + , and AnO 2 2+ (An = U, Np) with N 2 and CO

We report thermochemical and spectroscopic properties for actinyl complexes involving UO 2 2+/1+/0 and NpO 2 2+/1+/0 with N 2 and CO, together with the UO 2 -O 2 , UO 2 + -O 2 , and UO 2 + -NO complexes, have been studied for the first time using an accurate composite coupled cluster approach. Two general bonding motifs were investigated, end-on (η 1 ) and side-on (η 2 ) relative to the metal center of the actinyls. For end-on CO complexes, both C-coordinated (An-C) and O-coordinated (An-O) structures were examined, with the former always being lower in energy. All of the η 1 complexes were calculated to be stable, with dissociation energies ranging from 2 to 36 kcal/mol, except for that of UO 2 + -O 2 (the η 1 orientation for UO 2 + -NO was not amenable to single reference coupled cluster). In agreement with a previous study, the η 2 structure for UO 2 + -O 2 was calculated to be relatively strongly bound, by 22.3 kcal/mol in this work. The closely related NO complex, however, had a calculated dissociation energy of just 4.0 kcal/mol. The binding energy of O 2 to neutral UO 2 in a η 2 orientation was calculated to be very strong, 75.4 kcal/mol, and strongly resembled a UO 2 + (O 2 – ) complex at equilibrium. The N–N and C–O bonds were found to be somewhat activated for all the side-on (η 2 ) neutral An(IV) complexes, with stretching frequencies of N 2 or CO being red-shifted by as much as 480 cm –1 with a 0.06 Å bond length elongation. Dissociation energies for the η 1 complexes are strongly correlated with the extent of electron transfer from ligand to actinyl. The nature of bonding in the actinyl complexes is examined using natural resonance theory (NRT). The correlation between bonding motif and small molecule activation is in agreement with experiments in condensed phases.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1982

Oscillator strengths and collision strengths for some ions of oxygen and sulphur

Collision strengths for electron impact excitation of the O II, O III, S II and S III for some transitions in the ultraviolet of the type ns(sup 2) np(sup q) yields ns np(sup q +1), ns(sup 2) np(sup q) yields ns(sup 2) np(sup q-1) (n+1)s and 3s2 3p(sup q) yields 352 3p(sup q -1) 3d are calculated in a close coupling approximation for an energy rate up to one million K. Configuration interaction target wave functions which give oscillator strengths accurate to 10% for O II and O III, and 20-30% for S II and S III, are used in the expansion. Accurate knowledge of the electron impact excitation cross sections is particularly significant for a proper interpretation of the combined ultraviolet observations of the Voyager UVS and IUE results on properties of the Io plasma torus.

Ho, Y. K.↗
DOE OSTI2026

Ion-Specific Effects on PuO 2 Nanoparticle Aggregation and Dissolution in Concentrated Electrolytes

Hydrolytic PuO 2 nanoparticles (NPs) are a dominant aqueous Pu-bearing phase in high ionic strength nuclear wastes, yet their reactivity in nonideal brines remains poorly constrained. We quantify how electrolyte identity and concentration control PuO 2 NP aggregation and ligand-assisted dissolution in acidic, high salinity solutions (NaCl, NaNO 3 , NaClO 4 , Na 2 SO 4 , Na 2 C 2 O 4 up to 5 M). A multitechnique workflow combining liquid scintillation counting (operationally defined aqueous [Pu]), scattering/electrokinetic measurements (aggregate size and zeta potential), and spectroscopy (UV–vis, XPS, Raman) resolves electrolyte-dependent partitioning between colloidal and molecular Pu species. Weakly coordinating anions (ClO 4 – , Cl – , NO 3 – ) largely preserve the (aggregated) nanoparticulate fraction but generate distinct dissolved species at high concentration, i.e., Pu(IV)–nitrato complexes in NaNO 3 and Pu(VI)–chloro complexes in NaCl. In contrast, stronger ligands substantially perturb PuO 2 NP stability: sulfate promotes partial dissolution to Pu(IV)–sulfate complexes at low concentration but reduces aqueous [Pu] at higher sulfate levels via secondary Pu(IV) sulfate formation, whereas oxalate drives strong dissolution to aqueous Pu–oxalate complexes. Aged NPs show similar trends with reduced aqueous fractions and more dominant aggregation mechanisms. In conclusion, these spectroscopically constrained speciation data provide a foundation for incorporating PuO 2 NP reactivity into thermodynamic and reactive transport models for high salinity waste and brine environments.

Aggregation↗
DOE OSTI2020

Materials Data on Np(SiRu)2 by Materials Project

NpRu2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np3+ is bonded to eight equivalent Si4- atoms to form NpSi8 hexagonal bipyramids that share corners with sixteen equivalent RuSi4 tetrahedra, edges with four equivalent NpSi8 hexagonal bipyramids, edges with eight equivalent RuSi4 tetrahedra, and faces with four equivalent NpSi8 hexagonal bipyramids. All Np–Si bond lengths are 3.15 Å. Ru+2.50+ is bonded to four equivalent Si4- atoms to form RuSi4 tetrahedra that share corners with eight equivalent NpSi8 hexagonal bipyramids, corners with four equivalent RuSi4 tetrahedra, edges with four equivalent NpSi8 hexagonal bipyramids, and edges with four equivalent RuSi4 tetrahedra. All Ru–Si bond lengths are 2.38 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Np3+, four equivalent Ru+2.50+, and one Si4- atom. The Si–Si bond length is 2.38 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Np(CoSi)2 by Materials Project

NpCo2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Np4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Np–Si bond lengths are 2.96 Å. Co2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing CoSi4 tetrahedra. All Co–Si bond lengths are 2.28 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Np4+, four equivalent Co2+, and one Si4- atom. The Si–Si bond length is 2.36 Å.

36 MATERIALS SCIENCE↗