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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

High resolution microstructural, chemical studies and localized burnup analysis in an irradiated U–10Zr metallic fuel

This study involves high resolution characterization of a sodium bonded solid uranium (U)-10 wt% zirconium (Zr) metallic fuel irradiated in Fast Flux Test Facility (FFTF). The fuel centerline temperature during irradiation was estimated to be around 675 °C with the peak burnup 13.1 atomic percent. Samples for transmission electron microscopy (TEM) and atom probe tomography (APT) were prepared from different regions/zones in the fuel cross section radially to elucidate the microstructural changes and chemical redistribution of solute elements as well as fission products during irradiation experiment. TEM results indicate the irradiation in fast flux testing leads to the formation of extensive Zr-rich precipitates with varying sizes in the U–Zr fuel matrix. APT analysis performed to investigate redistribution of Zr, U and fission products along the radial direction of fuel pin showed Zr-rich precipitates entrapping the fission products in higher concentration as compared to the α-U phases. Here, the local burnup ( 235 U depletion) is found to be consistent, calculated by quantification of 235 U, 236 U and 238 U isotopes from mass spectrum obtained from APT along the radial direction. Zr-rich precipitation and its implication on fuel constitutional redistribution are discussed based on SEM, TEM and APT results.

APT↗
DOE OSTI2026

Synthesis and Reactivity of Heteroleptic U 4+ Alkyl, Benzyl, and Hydride Imidophosphorane Complexes

A series of heteroleptic U 4+ benzyl, neopentyl, and methyl complexes supported by the imidophosphorane ligand, [N = P(N,N′-ditert-butylethylenediamide)(diethylamide)] 1− (NP*), were synthesized from the monoiodide precursor, [UI(NP*) 3 ]. These heteroleptic complexes were synthesized through the selective formation of [UI(NP*) 3 ] under transmetalation conditions in the reaction between [UI 4 (1,4-dioxane) 2 ] and K[NP*]. Formation of the homoleptic complex [U(NP*) 4 ] was not observed even in the presence of excess K[NP*]. The oxidation and hydrogenolysis reactivity of the neopentyl complex, [U(Npt)- (NP*) 3 ] (Npt = neopentyl) was explored. While cyclic voltammetry indicates a potentially isolable U5+ alkyl cation, chemical oxidation of the neopentyl complex results in the isolation of a cationic U 4+ complex with a bound diethyl ether in the primary coordination sphere, [U4+(NP*)) 3 (Et 2 O)][(BArF 24 )] (BArF 24 = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate). Notably, hydrogenolysis of [U(Npt)(NP*) 3 ] with H2 gas at −20 °C results in the formation of a terminal hydride intermediate confirmed by in situ NMR spectroscopy and deuterium labeling with D 2 . The connectivity and structural parameters of this hydride intermediate, [UH(NP*) 3 ], which rapidly thermally decomposes to the homoleptic complex, [U(NP*) 4 ], can be confirmed by single-crystal X-ray diffraction studies of a crystal grown by chilling the reaction mixture. The identity of [U(NP*) 4 ] was confirmed by its direct, bulk synthesis from [U(Me)(NP*) 3 ] and HNP* in a protonolysis reaction.

Alkyls↗
DOE OSTI2021

Effect of Diel Cycling Temperature, Relative Humidity, and Synthetic Route on the Surface Morphology and Hydrolysis of α -U 3 O 8

The speciation and morphological changes of α-U 3 O 8 following aging under diel cycling temperature and relative humidity (RH) have been examined. This work advances the knowledge of U-oxide hydration as a result of synthetic route and environmental conditions, ultimately giving novel insight into nuclear material provenance. α-U 3 O 8 was synthesized via the washed uranyl peroxide (UO 4 ) and ammonium uranyl carbonate (AUC) synthetic routes to produce unaged starting materials with different morphologies. α-U 3 O 8 from UO 4 is comprised of subrounded particles, while α-U 3 O 8 from AUC contains blocky, porous particles approximately an order of magnitude larger than particles from UO 4 . For aging, a humidity chamber was programmed for continuous daily cycles of 12 “high” hours of 45 °C and 90% RH, and 12 “low” hours of 25 °C and 20% RH. Samples were analyzed at varying intervals of 14, 24, 36, 43, and 54 days. At each aging interval, crystallographic changes were measured via powder X-ray diffraction coupled with whole pattern fitting for quantitative analysis. Morphologic effects were studied via scanning electron microscopy and 12-way classification via machine learning. While all samples were found to have distinguishing morphologic characteristics (93.2% classification accuracy), α-U 3 O 8 from UO 4 had more apparent change with increasing aging time. Nonetheless, α-U 3 O 8 from AUC was found to hydrate more quickly than α-U 3 O 8 from UO 4 , which can likely be attributed to its larger surface area and porous starting material morphology.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

USc 2 C 2 and USc 2 NC Clusters with U–C Triple Bond Character Stabilized Inside Fullerene Cages

The chemistry of f-block metal–carbon multiple bonds is underdeveloped compared to well-established carbene complexes of the d-block transition metals. Herein, we report two new actinide-rare earth mixed metal carbides and nitrogen carbide cluster fullerenes, USc 2 C 2 @D 5h (6)-C 80 and USc 2 NC@D 5h (6)-C 80 , which contain U–C bonds with triple bond character and were successfully synthesized and characterized by mass spectrometry, UV–vis–NIR spectroscopy, Fourier transform infrared spectroscopy, single crystal X-ray diffraction, and DFT calculations. Crystallographic studies show that the two previously unreported clusters, USc 2 C 2 and USc 2 NC, are stabilized in the D 5h (6)-C 80 carbon cage and adopt unique trifoliate configurations, in which C 2 /NC units are almost vertically inserted into the plane defined by the U and two Sc atoms. Combined experimental and theoretical studies further reveal the bonding structure of USc 2 C 2 and USc 2 NC, which contain C=U(VI)=C and C=U(V)=N bonding motifs. The electronic structures of the two compounds are determined as U 6+ (Sc 2 ) 6+ (C 4– ) 2 @D 5h (6)-C 80 4– and U 5+ (Sc 2 ) 6+ (N) 3– (C) 4– @D 5h (6)-C 80 4– , respectively. Quantum-chemical studies confirm that the U–C bonds in both molecules show unprecedented multicenter triple-bond character. Furthermore, the discovery of this unique U–C multiple bond offers a deeper understanding of the fundamentals of uranium chemistry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Accelerating phase field simulations through a hybrid adaptive Fourier neural operator with U-net backbone

Prolonged contact between a corrosive liquid and metal alloys can cause progressive dealloying. For one such process as liquid-metal dealloying (LMD), phase field models have been developed to understand the mechanisms leading to complex morphologies. However, the LMD governing equations in these models often involve coupled non-linear partial differential equations (PDE), which are challenging to solve numerically. In particular, numerical stiffness in the PDEs requires an extremely refined time step size (on the order of 10 -12 s or smaller). This computational bottleneck is especially problematic when running LMD simulation until a late time horizon is required. This motivates the development of surrogate models capable of leaping forward in time, by skipping several consecutive time steps at-once. In this paper, we propose a U-shaped adaptive Fourier neural operator (U-AFNO), a machine learning (ML) based model inspired by recent advances in neural operator learning. U-AFNO employs U-Nets for extracting and reconstructing local features within the physical fields, and passes the latent space through a vision transformer (ViT) implemented in the Fourier space (AFNO). We use U-AFNOs to learn the dynamics of mapping the field at a current time step into a later time step. We also identify global quantities of interest (QoI) describing the corrosion process (e.g., the deformation of the liquid-metal interface, lost metal, etc.) and show that our proposed U-AFNO model is able to accurately predict the field dynamics, in spite of the chaotic nature of LMD. Most notably, our model reproduces the key microstructure statistics and QoIs with a level of accuracy on par with the high-fidelity numerical solver, while achieving a significant 11, 200 × speed-up on a high-resolution grid when comparing the computational expense per time step. Finally, we also investigate the opportunity of using hybrid simulations, in which we alternate forward leaps in time using the U-AFNO with high-fidelity time stepping. We demonstrate that while advantageous for some surrogate model design choices, our proposed U-AFNO model in fully auto-regressive settings consistently outperforms hybrid schemes.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Oxidation kinetics of SPS-densified U 3 Si 2 fuels—Microstructure impact

Here, U 3 Si 2 is a potential candidate for accident tolerant fuels because of its high uranium density and excellent thermal conductivity in comparison to UO 2 . However, U 3 Si 2 suffers from oxidation, steam corrosion, and subsequent disintegration/pulverization. The detailed investigation of kinetics that incorporates fundamental treatment of oxidation of U 3 Si 2 is scarcely reported, and the oxidation mechanisms have not been fully elucidated. In this paper, the oxidation behavior of microcrystalline (mc - ) and nanocrystalline (nc - ) U 3 Si 2 have been systematically investigated using a thermogravimetric analysis (TGA) apparatus through a series of isothermal and non-isothermal kinetic studies. The isothermal kinetic study with a model-fitting approach indicates oxidation activation energy of 85 kJ/mol for dense mc - U 3 Si 2 and 96.4 kJ/mol for nc - U 3 Si 2 pellets, while the isoconversional approach leads to an activation energy in the range of 70–85 kJ/mol for mc - U 3 Si 2 and 75–86 kJ/mol for nc - U 3 Si 2 with three most common model-free methods, including Kissinger–Akahira–Sunose, Flynn–Wall–Ozawa, and Friedman methods. The derivation of oxidation activation energies using both isothermal and isoconversional methods highlights the approach to evaluate the oxidation resistance of nuclear materials using TGA quantitatively and makes it possible to compare among various nuclear fuels.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

A guided ion beam investigation of UO 2 + thermodynamics and f orbital participation: Reactions of U + + CO 2 , UO + + O 2 , and UO + + CO

A guided ion beam tandem mass spectrometer was employed to study the reactions of U + + CO 2 , UO + + O 2 , and the reverse of the former, UO + + CO. Reaction cross sections as a function of kinetic energy over about a three order of magnitude range were studied for all systems. The reaction of U + + CO 2 proceeds to form UO + + CO with an efficiency of 118% ± 24% as well as generating UO 2 + + C and UCO + + O. The reaction of UO + + O 2 forms UO 2 + in an exothermic, barrierless process and also results in the collision-induced dissociation of UO + to yield U + . In the UO + + CO reaction, the formation of UO 2 + in an endothermic process is the dominant reaction, but minor products of UCO + + O and U + + (O + CO) are also observed. Analysis of the kinetic energy dependences observed provides the bond energies, D 0 (U + –O) = 7.98 ± 0.22 and 8.05 ± 0.14 eV, D 0 (U + –CO) = 0.73 ± 0.13 eV, and D 0 (OU + –O) = 7.56 ± 0.12 eV. The values obtained for D 0 (U + –O) and D 0 (OU + –O) agree well with the previously reported literature values. To our knowledge, this is the first experimental measurement of D 0 (U + –CO). Furthermore, an analysis of the oxide bond energies shows that participation of 5f orbitals leads to a substantial increase in the thermodynamic stability of UO 2 + relative to ThO 2 + and especially transition metal dioxide cations.

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

From antiferromagnetic and hidden order to Pauli paramagnetism in U M 2 Si 2 compounds with 5 f electron duality

Using inelastic X-ray scattering beyond the dipole limit and hard X-ray photoelectron spectroscopy we establish the dual nature of the U 5 f electrons in U M 2 Si 2 ( M = Pd, Ni, Ru, Fe), regardless of their degree of delocalization. We have observed that the compounds have in common a local atomic-like state that is well described by the U 5 f 2 configuration with the $Γ^{(1)}_1$ and $Γ_2$ quasi-doublet symmetry. The amount of the U 5 f 3 configuration, however, varies considerably across the U M 2 Si 2 series, indicating an increase of U 5 f itineracy in going from M = Pd to Ni to Ru and to the Fe compound. The identified electronic states explain the formation of the very large ordered magnetic moments in UPd 2 Si 2 and UNi 2 Si 2 , the availability of orbital degrees of freedom needed for the hidden order in URu 2 Si 2 to occur, as well as the appearance of Pauli paramagnetism in UFe 2 Si 2 . A unified and systematic picture of the U M 2 Si 2 compounds may now be drawn, thereby providing suggestions for additional experiments to induce hidden order and/or superconductivity in U compounds with the tetragonal body-centered ThCr 2 Si 2 structure.

36 MATERIALS SCIENCE↗
DOE OSTI2024

High-throughput determination of Hubbard $U$ and Hund $J$ values for transition metal oxides via the linear response formalism

DFT+U provides a convenient, cost-effective correction for the self-interaction error (SIE) that arises when describing correlated electronic states using conventional approximate density functional theory (DFT). The success of a DFT+U(+J) calculation hinges on the accurate determination of its Hubbard U and Hund J parameters, and the linear response (LR) methodology has proven to be computationally effective and accurate for calculating these parameters. This study provides a high-throughput computational analysis of the U and J values for transition metal d-electron states in a representative set of over 1000 magnetic transition metal oxides (TMOs), providing a frame of reference for researchers who use DFT+U to study transition metal oxides. In order to perform this high-throughput study, an ATOMATE workflow is developed for calculating U and J values automatically on massively parallel supercomputing architectures. Here, to demonstrate an application of this workflow, the spin-canting magnetic structure and unit cell parameters of the multiferroic olivine LiNiPO4 are calculated using the computed Hubbard U and Hund J values for Ni-d and O-p states, and are compared with experiment. Both the Ni-d U and J corrections have a strong effect on the Ni-moment canting angle. Additionally, including a O-pU value results in a significantly improved agreement between the computed lattice parameters and experiment

36 MATERIALS SCIENCE↗
DOE OSTI2021

Combined Technologies for In Situ Remediation of Tc-99 and U in Subsurface Sediments

In this study, combinations of chemical remedies were tested in bench-scale batch experiments to evaluate a two-step reduction-sequestration approach to effectively stabilize high concentrations of inorganic contaminant mixtures. Bench tests simulated contaminant and geochemical conditions of a perched aquifer located within the Central Plateau at the Hanford Site, located in southeastern Washington State (USA). Pairwise combinations of a reductant [e.g., zero valent iron, sulfur modified iron (SMI), or calcium polysulfide] and a sequestering agent [e.g., calcite, apatite, or dilute alkaline solution (e.g., NaOH)] were evaluated for immobilization and stabilization of technetium (Tc) (50,000 pCi/L), uranium (U) (150 mg/L), and nitrate (NO 3 ) (200 mg/L) in high ionic strength groundwater. The results of these batch studies demonstrated that reduction by SMI and sequestration in apatite or calcite are the most effective combination for these contaminant mixtures and conditions. Aqueous concentrations of Tc and U decreased by 95.6% ± 2.5% and 101.1% ± 5.2%, respectively, with SMI-apatite and 98.3% ± 0.0% and 101.2% ± 5.2%, respectively, with SMI-calcite. Sequential extractions showed that sequestered contaminants had limited capacity for re-oxidation; in fact, less than 10% of immobilized Tc and U was recovered by selective extraction of mineral phases most susceptible to oxidation. In addition, X-ray absorption near edge structure analysis of the sediment samples treated with SMI-calcite showed the presence of only U(IV), while both U(IV) and U(VI) were present in the SMI apatite combination [ratio of 0.43 U(IV):0.59 U(VI)].This study describes preliminary results that a two-step approach for stabilizing contaminant mixtures of long-lived radionuclides can be effective at reducing contaminant fluxes to groundwater from vadose and perched water zones.

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

Materials Data on U(SiIr)2 by Materials Project

UIr2Si2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. U is bonded in a 8-coordinate geometry to eight Ir and eight Si atoms. There are four shorter (3.11 Å) and four longer (3.25 Å) U–Ir bond lengths. There are four shorter (3.14 Å) and four longer (3.17 Å) U–Si bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent U and five Si atoms. There are one shorter (2.35 Å) and four longer (2.41 Å) Ir–Si bond lengths. In the second Ir site, Ir is bonded to four equivalent U and four equivalent Si atoms to form distorted IrU4Si4 tetrahedra that share corners with twelve equivalent SiU4Ir4 tetrahedra, edges with two equivalent SiU4Ir4 tetrahedra, edges with four equivalent IrU4Si4 tetrahedra, and faces with four equivalent IrU4Si4 tetrahedra. All Ir–Si bond lengths are 2.44 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to four equivalent U and five Ir atoms. In the second Si site, Si is bonded to four equivalent U and four equivalent Ir atoms to form distorted SiU4Ir4 tetrahedra that share corners with twelve equivalent IrU4Si4 tetrahedra, edges with two equivalent IrU4Si4 tetrahedra, edges with four equivalent SiU4Ir4 tetrahedra, and faces with four equivalent SiU4Ir4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(AlAu)2 by Materials Project

UAu2Al2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to eight Au and eight Al atoms. There are four shorter (3.31 Å) and four longer (3.38 Å) U–Au bond lengths. There are four shorter (3.29 Å) and four longer (3.41 Å) U–Al bond lengths. There are two inequivalent Au sites. In the first Au site, Au is bonded to four equivalent U and four equivalent Al atoms to form distorted AuU4Al4 tetrahedra that share corners with twelve equivalent AlU4Au4 tetrahedra, edges with two equivalent AlU4Au4 tetrahedra, edges with four equivalent AuU4Al4 tetrahedra, and faces with four equivalent AuU4Al4 tetrahedra. All Au–Al bond lengths are 2.58 Å. In the second Au site, Au is bonded in a 5-coordinate geometry to four equivalent U and five Al atoms. There are one shorter (2.44 Å) and four longer (2.57 Å) Au–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent U and four equivalent Au atoms to form AlU4Au4 tetrahedra that share corners with twelve equivalent AuU4Al4 tetrahedra, edges with two equivalent AuU4Al4 tetrahedra, edges with four equivalent AlU4Au4 tetrahedra, and faces with four equivalent AlU4Au4 tetrahedra. In the second Al site, Al is bonded in a 5-coordinate geometry to four equivalent U and five Au atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(MoO5)12 by Materials Project

U(MoO4)12(O2)6 crystallizes in the trigonal R-3 space group. The structure is zero-dimensional and consists of three hexaoxane molecules, six trioxirane molecules, and three U(MoO4)12 clusters. In each U(MoO4)12 cluster, U is bonded in a cuboctahedral geometry to twelve O atoms. There are six shorter (2.40 Å) and six longer (2.51 Å) U–O bond lengths. There are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.72–2.32 Å. In the second Mo site, Mo is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mo–O bond distances ranging from 1.73–2.35 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Mo atom. 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 single-bond geometry to one Mo atom. In the fourth O site, O is bonded in a single-bond geometry to one Mo atom. In the fifth O site, O is bonded in a single-bond geometry to one O atom. The O–O bond length is 2.04 Å. In the sixth O site, O is bonded in a distorted rectangular see-saw-like geometry to one U and three Mo atoms. In the seventh O site, O is bonded in a water-like geometry to two Mo and one O atom. In the eighth O site, O is bonded in a distorted rectangular see-saw-like geometry to one U and three Mo atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(Fe5Si)2 by Materials Project

UFe10Si2 crystallizes in the orthorhombic Fmmm space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to sixteen Fe and four equivalent Si atoms. There are a spread of U–Fe bond distances ranging from 2.92–3.14 Å. All U–Si bond lengths are 3.14 Å. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded in a 10-coordinate geometry to one U, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.37–2.93 Å. Both Fe–Si bond lengths are 2.51 Å. In the second Fe site, Fe is bonded to two equivalent U and ten Fe atoms to form FeU2Fe10 cuboctahedra that share corners with four equivalent SiU2Fe8Si2 cuboctahedra, corners with six equivalent FeU2Fe10 cuboctahedra, edges with four equivalent SiU2Fe8Si2 cuboctahedra, faces with two equivalent FeU2Fe10 cuboctahedra, and faces with four equivalent SiU2Fe8Si2 cuboctahedra. There are two shorter (2.38 Å) and four longer (2.41 Å) Fe–Fe bond lengths. In the third Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent U, eight Fe, and two equivalent Si atoms. There are one shorter (2.52 Å) and one longer (2.58 Å) Fe–Fe bond lengths. Both Fe–Si bond lengths are 2.37 Å. Si is bonded to two equivalent U, eight Fe, and two equivalent Si atoms to form distorted SiU2Fe8Si2 cuboctahedra that share corners with four equivalent FeU2Fe10 cuboctahedra, corners with six equivalent SiU2Fe8Si2 cuboctahedra, edges with four equivalent FeU2Fe10 cuboctahedra, faces with two equivalent SiU2Fe8Si2 cuboctahedra, and faces with four equivalent FeU2Fe10 cuboctahedra. Both Si–Si bond lengths are 2.38 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(GeRh)2 by Materials Project

URh2Ge2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. U is bonded in a 8-coordinate geometry to eight Rh and eight Ge atoms. There are four shorter (3.19 Å) and four longer (3.35 Å) U–Rh bond lengths. There are four shorter (3.23 Å) and four longer (3.25 Å) U–Ge bond lengths. There are two inequivalent Rh sites. In the first Rh site, Rh is bonded to four equivalent U and four equivalent Ge atoms to form distorted RhU4Ge4 tetrahedra that share corners with twelve equivalent GeU4Rh4 tetrahedra, edges with two equivalent GeU4Rh4 tetrahedra, edges with four equivalent RhU4Ge4 tetrahedra, and faces with four equivalent RhU4Ge4 tetrahedra. All Rh–Ge bond lengths are 2.49 Å. In the second Rh site, Rh is bonded in a 9-coordinate geometry to four equivalent U and five Ge atoms. There are one shorter (2.42 Å) and four longer (2.49 Å) Rh–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded to four equivalent U and four equivalent Rh atoms to form distorted GeU4Rh4 tetrahedra that share corners with twelve equivalent RhU4Ge4 tetrahedra, edges with two equivalent RhU4Ge4 tetrahedra, edges with four equivalent GeU4Rh4 tetrahedra, and faces with four equivalent GeU4Rh4 tetrahedra. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent U and five Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(CuSn)2 by Materials Project

UCu2Sn2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to eight Cu and eight Sn atoms. There are four shorter (3.35 Å) and four longer (3.38 Å) U–Cu bond lengths. There are four shorter (3.32 Å) and four longer (3.50 Å) U–Sn bond lengths. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to four equivalent U and four equivalent Sn atoms. All Cu–Sn bond lengths are 2.59 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to four equivalent U and five Sn atoms. There are one shorter (2.47 Å) and four longer (2.61 Å) Cu–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 4-coordinate geometry to four equivalent U and four equivalent Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent U and five Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(GeIr)2 by Materials Project

UIr2Ge2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to eight Ir and eight Ge atoms. There are four shorter (3.18 Å) and four longer (3.36 Å) U–Ir bond lengths. There are four shorter (3.23 Å) and four longer (3.24 Å) U–Ge bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded to four equivalent U and four equivalent Ge atoms to form distorted IrU4Ge4 tetrahedra that share corners with twelve equivalent GeU4Ir4 tetrahedra, edges with two equivalent GeU4Ir4 tetrahedra, edges with four equivalent IrU4Ge4 tetrahedra, and faces with four equivalent IrU4Ge4 tetrahedra. All Ir–Ge bond lengths are 2.50 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent U and five Ge atoms. There are one shorter (2.40 Å) and four longer (2.49 Å) Ir–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded to four equivalent U and four equivalent Ir atoms to form distorted GeU4Ir4 tetrahedra that share corners with twelve equivalent IrU4Ge4 tetrahedra, edges with two equivalent IrU4Ge4 tetrahedra, edges with four equivalent GeU4Ir4 tetrahedra, and faces with four equivalent GeU4Ir4 tetrahedra. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent U and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U(AlCu)6 by Materials Project

UCu6Al6 crystallizes in the orthorhombic Fmmm space group. The structure is three-dimensional. U is bonded in a 4-coordinate geometry to eight Cu and twelve Al atoms. There are four shorter (3.04 Å) and four longer (3.31 Å) U–Cu bond lengths. There are eight shorter (3.23 Å) and four longer (3.36 Å) U–Al bond lengths. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to two equivalent U, four equivalent Cu, and four equivalent Al atoms. All Cu–Cu bond lengths are 2.70 Å. All Cu–Al bond lengths are 2.43 Å. In the second Cu site, Cu is bonded in a 10-coordinate geometry to one U, three Cu, and six Al atoms. The Cu–Cu bond length is 2.64 Å. There are a spread of Cu–Al bond distances ranging from 2.62–2.73 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 12-coordinate geometry to two equivalent U, four equivalent Cu, and six Al atoms. There are two shorter (2.51 Å) and four longer (2.61 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 12-coordinate geometry to two equivalent U, six Cu, and four Al atoms. There are one shorter (2.76 Å) and one longer (3.00 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗