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At least 1,333 records · Page 74
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Li5Fe2(IrO5)2 by Materials Project

Li5Fe2(IrO5)2 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are five inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with four LiO6 octahedra, edges with two FeO6 octahedra, edges with four IrO6 octahedra, and edges with six LiO6 octahedra. The corner-sharing octahedra tilt angles range from 7–8°. There are a spread of Li–O bond distances ranging from 2.10–2.14 Å. In the second Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two equivalent LiO6 octahedra, corners with two equivalent FeO6 octahedra, corners with two equivalent IrO6 octahedra, edges with two equivalent IrO6 octahedra, edges with four LiO6 octahedra, and edges with four FeO6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are a spread of Li–O bond distances ranging from 2.15–2.18 Å. In the third Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with four IrO6 octahedra, edges with two equivalent FeO6 octahedra, edges with two equivalent IrO6 octahedra, and edges with seven LiO6 octahedra. The corner-sharing octahedra tilt angles range from 4–8°. There are a spread of Li–O bond distances ranging from 2.16–2.28 Å. In the fourth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two equivalent LiO6 octahedra, corners with four FeO6 octahedra, edges with four IrO6 octahedra, and edges with seven LiO6 octahedra. The corner-sharing octahedra tilt angles range from 6–8°. There are a spread of Li–O bond distances ranging from 2.08–2.28 Å. In the fifth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with four IrO6 octahedra, edges with two equivalent FeO6 octahedra, edges with two equivalent IrO6 octahedra, and edges with six LiO6 octahedra. The corner-sharing octahedra tilt angles range from 5–7°. There are two shorter (2.18 Å) and four longer (2.23 Å) Li–O bond lengths. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four LiO6 octahedra, edges with two equivalent FeO6 octahedra, edges with three IrO6 octahedra, and edges with five LiO6 octahedra. The corner-sharing octahedral tilt angles are 8°. There are a spread of Fe–O bond distances ranging from 2.00–2.11 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six LiO6 octahedra, edges with two equivalent FeO6 octahedra, edges with three IrO6 octahedra, and edges with five LiO6 octahedra. The corner-sharing octahedra tilt angles range from 6–7°. There are a spread of Fe–O bond distances ranging from 2.04–2.08 Å. There are two inequivalent Ir+4.50+ sites. In the first Ir+4.50+ site, Ir+4.50+ is bonded to six O2- atoms to form IrO6 octahedra that share corners with six LiO6 octahedra, an edgeedge with one IrO6 octahedra, edges with three FeO6 octahedra, and edges with six LiO6 octahedra. The corner-sharing octahedra tilt angles range from 4–7°. There are a spread of Ir–O bond distances ranging from 1.98–2.06 Å. In the second Ir+4.50+ site, Ir+4.50+ is bonded to six O2- atoms to form IrO6 octahedra that share corners with four LiO6 octahedra, an edgeedge with one IrO6 octahedra, edges with three FeO6 octahedra, and edges with eight LiO6 octahedra. The corner-sharing octahedra tilt angles range from 5–6°. There are a spread of Ir–O bond distances ranging from 2.01–2.05 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four Li1+, one Fe3+, and one Ir+4.50+ atom to form OLi4FeIr octahedra that share corners with two equivalent OLi4FeIr octahedra, corners with four OLi3FeIr square pyramids, edges with six OLi4FeIr octahedra, and edges with six OLi3FeIr square pyramids. The corner-sharing octahedra tilt angles range from 2–5°. In the second O2- site, O2- is bonded to four Li1+ and two Ir+4.50+ atoms to form OLi4Ir2 octahedra that share corners with two equivalent OLi4Ir2 octahedra, corners with four OLi2Fe2Ir square pyramids, edges with six OLi4FeIr octahedra, and edges with six OLi3FeIr square pyramids. The corner-sharing octahedra tilt angles range from 2–3°. In the third O2- site, O2- is bonded to three Li1+, one Fe3+, and one Ir+4.50+ atom to form OLi3FeIr square pyramids that share corners with two equivalent OLi4FeIr octahedra, corners with seven OLi3FeIr square pyramids, edges with five OLi4FeIr octahedra, and edges with three OLi3FeIr square pyramids. The corner-sharing octahedra tilt angles range from 1–4°. In the fourth O2- site, O2- is bonded to two Li1+, two Fe3+, and one Ir+4.50+ atom to form OLi2Fe2Ir square pyramids that share corners with four OLi4FeIr octahedra, corners with five OLi3FeIr square pyramids, edges with two OLi4FeIr octahedra, and edges with six OLi3FeIr square pyramids. The corner-sharing octahedra tilt angles range from 1–4°. In the fifth O2- site, O2- is bonded to two Li1+, two Fe3+, and one Ir+4.50+ atom to form OLi2Fe2Ir square pyramids that share corners with two equivalent OLi4Ir2 octahedra, corners with seven OLi3FeIr square pyramids, edges with five OLi4FeIr octahedra, and edges with three OLi2Fe2Ir square pyramids. The corner-sharing octahedral tilt angles are 3°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc2BeB2Ir5 by Materials Project

BeSc2Ir5B2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Be is bonded in a body-centered cubic geometry to eight equivalent Ir atoms. All Be–Ir bond lengths are 2.53 Å. Sc is bonded in a 1-coordinate geometry to ten Ir and three equivalent B atoms. There are a spread of Sc–Ir bond distances ranging from 2.76–2.93 Å. There are one shorter (2.58 Å) and two longer (2.87 Å) Sc–B bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to two equivalent Be, four equivalent Sc, and two equivalent B atoms. Both Ir–B bond lengths are 2.20 Å. In the second Ir site, Ir is bonded in a distorted body-centered cubic geometry to four equivalent Sc and four equivalent B atoms. All Ir–B bond lengths are 2.25 Å. B is bonded in a 7-coordinate geometry to three equivalent Sc and six Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr2Ge5Ir3 by Materials Project

Pr2Ir3Ge5 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. Pr is bonded in a 1-coordinate geometry to seven Ir and ten Ge atoms. There are a spread of Pr–Ir bond distances ranging from 3.19–3.59 Å. There are a spread of Pr–Ge bond distances ranging from 3.04–3.39 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 6-coordinate geometry to four equivalent Pr and six Ge atoms. There are four shorter (2.56 Å) and two longer (2.70 Å) Ir–Ge bond lengths. In the second Ir site, Ir is bonded in a 10-coordinate geometry to five equivalent Pr and five Ge atoms. There are a spread of Ir–Ge bond distances ranging from 2.44–2.55 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to four equivalent Pr and four equivalent Ir atoms. In the second Ge site, Ge is bonded in a 2-coordinate geometry to four equivalent Pr, three Ir, and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.71 Å. In the third Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Pr, three Ir, and two equivalent Ge atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NiIr3 by Materials Project

Ir3Ni is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Ir sites. In the first Ir site, Ir is bonded to eight Ir and four equivalent Ni atoms to form IrNi4Ir8 cuboctahedra that share corners with twelve equivalent IrNi4Ir8 cuboctahedra, edges with eight equivalent NiIr12 cuboctahedra, edges with sixteen IrNi4Ir8 cuboctahedra, faces with four equivalent NiIr12 cuboctahedra, and faces with fourteen IrNi4Ir8 cuboctahedra. There are four shorter (2.68 Å) and four longer (2.69 Å) Ir–Ir bond lengths. All Ir–Ni bond lengths are 2.69 Å. In the second Ir site, Ir is bonded to eight equivalent Ir and four equivalent Ni atoms to form IrNi4Ir8 cuboctahedra that share corners with four equivalent IrNi4Ir8 cuboctahedra, corners with eight equivalent NiIr12 cuboctahedra, edges with twenty-four IrNi4Ir8 cuboctahedra, faces with six equivalent NiIr12 cuboctahedra, and faces with twelve IrNi4Ir8 cuboctahedra. All Ir–Ni bond lengths are 2.68 Å. Ni is bonded to twelve Ir atoms to form NiIr12 cuboctahedra that share corners with four equivalent NiIr12 cuboctahedra, corners with eight equivalent IrNi4Ir8 cuboctahedra, edges with eight equivalent NiIr12 cuboctahedra, edges with sixteen equivalent IrNi4Ir8 cuboctahedra, faces with four equivalent NiIr12 cuboctahedra, and faces with fourteen IrNi4Ir8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc2AlB2Ir5 by Materials Project

Sc2Ir5AlB2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Sc is bonded in a 11-coordinate geometry to ten Ir and three equivalent B atoms. There are a spread of Sc–Ir bond distances ranging from 2.79–2.96 Å. There are one shorter (2.66 Å) and two longer (2.88 Å) Sc–B bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to four equivalent Sc, two equivalent Al, and two equivalent B atoms. Both Ir–Al bond lengths are 2.62 Å. Both Ir–B bond lengths are 2.20 Å. In the second Ir site, Ir is bonded in a distorted body-centered cubic geometry to four equivalent Sc and four equivalent B atoms. All Ir–B bond lengths are 2.25 Å. Al is bonded in a body-centered cubic geometry to eight equivalent Ir atoms. B is bonded in a 9-coordinate geometry to three equivalent Sc and six Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce2Ge5Ir3 by Materials Project

Ce2Ir3Ge5 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. Ce is bonded in a 1-coordinate geometry to seven Ir and ten Ge atoms. There are a spread of Ce–Ir bond distances ranging from 3.14–3.57 Å. There are a spread of Ce–Ge bond distances ranging from 3.01–3.36 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 6-coordinate geometry to four equivalent Ce and six Ge atoms. There are four shorter (2.54 Å) and two longer (2.65 Å) Ir–Ge bond lengths. In the second Ir site, Ir is bonded in a 10-coordinate geometry to five equivalent Ce and five Ge atoms. There are a spread of Ir–Ge bond distances ranging from 2.41–2.54 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to four equivalent Ce and four equivalent Ir atoms. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Ce, three Ir, and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.69 Å. In the third Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Ce, three Ir, and two equivalent Ge atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Caffeic acid attenuates irradiation-induced hematopoietic stem cell apoptosis through inhibiting mitochondrial damage

Highlights: • IR-induced mitochondrial damage accelerates HSC apoptosis. • CA attenuates mitochondrial damage and apoptosis of HSCs induced by IR. • CA protects against BM hematopoietic failure in mice after IR exposure. Hematopoietic stem cells (HSCs) are sensitive to ionizing radiation (IR) damage, and its injury is the primary cause of bone marrow (BM) hematopoietic failure and even death after exposure to a certain dose of IR. However, the underlying mechanisms remain incompletely understood. Here we show that mitochondrial oxidative damage, which is characterized by mitochondrial reactive oxygen species overproduction, mitochondrial membrane potential reduction and mitochondrial permeability transition pore opening, is rapidly induced in both human and mouse HSCs and directly accelerates HSC apoptosis after IR exposure. Mechanistically, 5-lipoxygenase (5-LOX) is induced by IR exposure and contributes to IR-induced mitochondrial oxidative damage through inducing lipid peroxidation. Intriguingly, a natural antioxidant, caffeic acid (CA), can attenuate IR-induced HSC apoptosis through suppressing 5-LOX-mediated mitochondrial oxidative damage, thus protecting against BM hematopoietic failure after IR exposure. These findings uncover a critical role for mitochondria in IR-induced HSC injury and highlight the therapeutic potential of CA in BM hematopoietic failure induced by IR.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Broadband Fourier-Transform Optical Photothermal Infrared Spectroscopy and Imaging

Infrared (IR) spectroscopy is a powerful method for mapping chemical heterogeneity on the microscale. Synchrotron IR radiation uniquely provides a high brightness and broad bandwidth to further extend the capabilities of IR spectroscopic imaging. However, the diffraction-limited spatial resolution of IR spectroscopy is insufficient for studies requiring submicrometer spatial differentiation. Optical photothermal IR (O-PTIR) microscopy is a powerful, emerging method that overcomes the IR diffraction limit in IR hyperspectral imaging by employing a modulated IR beam and a visible probe laser beam to detect local temperature-induced modulation at the visible diffraction limit. In this work, we extend the spectral range of photothermal infrared measurements by incorporating a synchrotron IR source, demonstrating a combined synchrotron-based O-PTIR modality that enables high spatial resolution far-field chemical imaging spanning the entire mid-IR range. Both optical- and fluorescence-detected photothermal modalities were performed using a step-scan interferometer, demonstrating improved spectral range (541-4000 cm-1) when compared to optical photothermal microscopy with commercial laser sources (800-1800 cm-1 for this particular source) and improved spatial resolution, when compared to synchrotron microspectroscopy measurements. Following these initial validation studies, synchrotron Fourier-transform fluorescence-detected photothermal IR spectroscopy in combination with synchrotron microspectroscopy measurements was used to differentiate cells in mouse brain tissue sections, which requires submicron spatial resolutions beyond those accessible by IR spectroscopy alone.

Razumtcev, Aleksandr↗
DOE OSTI2026

Impact of Porous Transport Layer Morphology on the Performance of Proton Exchange Membrane Water Electrolyzers with Ultra-Low Iridium Loadings

Reducing Ir loadings in proton exchange membrane water electrolyzer anodes is critical for lowering capital expenses. Loading reduction could be achieved by improving the Ir activity via doping/alloying and/or the development of advanced microstructures. However, the anode porous transport layer (PTL) is a comparatively simple component whose properties also impact Ir utilization. Therefore, well-designed PTLs may also enable reduced Ir loadings. In this work, we survey eight PTLs from various manufacturers to observe their impact on cell performance at low (0.4 mg Ir cm -2 ) and ultralow (0.1 mg Ir cm -2 ) Ir loadings. The PTLs were characterized by their microstructural properties, including porosity, particle size distribution, and pore size distribution. Electrochemical cell performance was correlated to PTL morphology, and it was found that PTLs with lower porosities and smaller particle and pore radii enabled good performance even at ultralow Ir loadings. 1000-h durability testing indicated that using lower porosity PTLs can significantly improve durability behavior. A runaway voltage phenomenon was observed during durability testing of cells with ultralow Ir loadings, which was caused by increases in both anode and cathode overpotentials. Furthermore, we observed that the beginning of test performance of 0.1 mg Ir cm -2 cells correlates to the 1000-h degradation rates of 0.4 mg Ir cm -2 cells, suggesting that for the Ir catalyst used in this work, short-term testing at ultralow loadings can be used as an indicator of long-term degradation at higher loadings.

08 HYDROGEN↗
DOE OSTI2024

High-Performance Iridium–Molybdenum Oxide Electrocatalysts for Water Oxidation in Acid: Bayesian Optimization Discovery and Experimental Testing

Ir oxides are costly and scarce catalysts for oxygen evolution reaction (OER) in acid. There has been extensive interest in developing alternatives that are either Ir-free or require smaller amounts of Ir to drive the reactions at acceptable rates. One design strategy is to identify Ir-based mixed oxides that achieve similar performance while requiring smaller amounts of Ir. The obstacle to this strategy has been a very large phase space of the Ir-based mixed metal oxides, in terms of the metals combined with Ir and the different crystallographic structures of the mixed oxides, which prevents a thorough exploration of possible materials. In this work, we developed a workflow that uses machine-learning-aided Bayesian optimization in combination with density functional theory to make the exploration of this phase space plausible. This screening identified Mo as a promising dopant for forming acid-tolerant Ir-based oxides for the OER. We synthesized and characterized the Ir–Mo mixed oxides in the form of thin-film electrocatalysts with a known surface area. We show that these mixed oxides exhibited overpotentials ~30 mV lower than a pure Ir control while maintaining 24% lower Ir dissolution rates than the Ir control. Furthermore, these findings suggest that Mo is a promising dopant and highlight the promise of machine learning to guide the experimental exploration and optimization of catalytic materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Long-Term Effects of Very Low Dose Particle Radiation on Gene Expression in the Heart: Degenerative Disease Risks

Compared to low doses of gamma irradiation (γ-IR), high-charge-and-energy (HZE) particle IR may have different biological response thresholds in cardiac tissue at lower doses, and these effects may be IR type and dose dependent. Three- to four-month-old female CB6F1/Hsd mice were exposed once to one of four different doses of the following types of radiation: γ-IR 137Cs (40-160 cGy, 0.662 MeV), 14Si-IR (4-32 cGy, 260 MeV/n), or 22Ti-IR (3-26 cGy, 1 GeV/n). At 16 months post-exposure, animals were sacrificed and hearts were harvested and archived as part of the NASA Space Radiation Tissue Sharing Forum. These heart tissue samples were used in our study for RNA isolation and microarray hybridization. Functional annotation of twofold up/down differentially expressed genes (DEGs) and bioinformatics analyses revealed the following: (i) there were no clear lower IR thresholds for HZE- or γ-IR; (ii) there were 12 common DEGs across all 3 IR types; (iii) these 12 overlapping genes predicted various degrees of cardiovascular, pulmonary, and metabolic diseases, cancer, and aging; and (iv) these 12 genes revealed an exclusive non-linear DEG pattern in 14Si- and 22Ti-IR-exposed hearts, whereas two-thirds of γ-IR-exposed hearts revealed a linear pattern of DEGs. Thus, our study may provide experimental evidence of excess relative risk (ERR) quantification of low/very low doses of full-body space-type IR-associated degenerative disease development.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
NASA NTRS2003

Platinum-group elements (PGE) and Rhenium in Marine Sediments across the Cretaceous-Tertiary Boundary: Constraints on Re-PGE Transport in the Marine Environment

The nature of Re-platinum-group element (PGE; Pt, Pd, Ir, Os, Ru) transport in the marine environment was investigated by means of marine sediments at and across the Cretaceous-Tertiary boundary (KTB) at two hemipelagic sites in Europe and two pelagic sites in the North and South Pacific. A traverse across the KTB in the South Pacific pelagic clay core found elevated levels of Re, Pt, Ir, Os, and Ru, each of which is approximately symmetrically distributed over a distance of approx. 1.8 m across the KTB. The Re-PGE abundance patterns are fractionated from chondritic relative abundances: Ru, Pt, Pd, and Re contents are slightly subchondritic relative to Ir, and Os is depleted by approx. 95% relative to chondritic Ir proportions. A similar depletion in Os (approx. 90%) was found in a sample of the pelagic KTB in the North Pacific, but it is enriched in Ru, Pt, Pd, and Re relative to Ir. The two hemipelagic KTB clays have near-chondritic abundance patterns. The approx. 1.8-m-wide Re-PGE peak in the pelagic South Pacific section cannot be reconciled with the fallout of a single impactor, indicating that postdepositional redistribution has occurred. The elemental profiles appear to fit diffusion profiles, although bioturbation could have also played a role. If diffusion had occurred over approx. 65 Ma, the effective diffusivities are approx. 10(exp -13)sq cm/s, much smaller than that of soluble cations in pore waters (approx. 10(exp -5) sq cm/s). The coupling of Re and the PGEs during redistribution indicates that postdepositional processes did not significantly fractionate their relative abundances. If redistribution was caused by diffusion, then the effective diffusivities are the same. Fractionation of Os from Ir during the KTB interval must therefore have occurred during aqueous transport in the marine environment. Distinctly subchondritic Os/Ir ratios throughout the Cenozoic in the South Pacific core further suggest that fractionation of Os from Ir in the marine environment is a general process throughout geologic time because most of the inputs of Os and Ir into the ocean have OsAr ratios greater than or = 1. Mass balance calculations show that Os and Re burial fluxes in pelagic sediments account for only a small fraction of the riverine Os (less than 10%) and Re (less than 0.1%) inputs into the oceans. In contrast, burial of Ir in pelagic sediments is similar to the riverine Ir input, indicating that pelagic sediments are a much larger repository for Ir than for Os and Re. If all of the missing Os and Re is assumed to reside in anoxic sediments in oceanic margins, the calculated burial fluxes in anoxic sediments are similar to observed burial fluxes. However, putting all of the missing Os and Re into estuarine sediments would require high concentrations to balance the riverine input and would also fail to explain the depletion of Os at pelagic KTB sites, where at most approx. 25% of the K-T impactor's Os could have passed through estuaries. If Os is preferentially sequestered in anoxic marine environments, it follows that the OsAr ratio of pelagic sediments should be sensitive to changes in the rates of anoxic sediment deposition. There is thus a clear fractionation of Os and Re from Ir in precipitation out of sea water in pelagic sections. Accordingly, it is inferred here that Re and Os are removed from sea water in anoxic marine depositional regimes.

Lee, Cin-Ty Aeolus↗
DOE OSTI2020

Materials Data on LaPIr by Materials Project

LaIrP is hexagonal omega structure-derived structured and crystallizes in the tetragonal I4_1md space group. The structure is three-dimensional. La is bonded to six equivalent Ir and six equivalent P atoms to form a mixture of edge and face-sharing LaP6Ir6 cuboctahedra. There are two shorter (3.12 Å) and four longer (3.21 Å) La–Ir bond lengths. There are four shorter (3.16 Å) and two longer (3.23 Å) La–P bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent La and three equivalent P atoms. All Ir–P bond lengths are 2.40 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent La and three equivalent P atoms. There are two shorter (3.12 Å) and four longer (3.21 Å) Ir–La bond lengths. All Ir–P bond lengths are 2.40 Å. P is bonded in a 9-coordinate geometry to six equivalent La and three equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NdPIr by Materials Project

NdIrP is hexagonal omega structure-derived structured and crystallizes in the tetragonal I4_1md space group. The structure is three-dimensional. Nd is bonded to six equivalent Ir and six equivalent P atoms to form a mixture of edge and face-sharing NdP6Ir6 cuboctahedra. There are two shorter (3.09 Å) and four longer (3.17 Å) Nd–Ir bond lengths. There are four shorter (3.12 Å) and two longer (3.20 Å) Nd–P bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Nd and three equivalent P atoms. There are two shorter (2.37 Å) and one longer (2.38 Å) Ir–P bond lengths. In the second Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Nd and three equivalent P atoms. There are two shorter (3.09 Å) and four longer (3.17 Å) Ir–Nd bond lengths. There are two shorter (2.37 Å) and one longer (2.38 Å) Ir–P bond lengths. P is bonded in a 9-coordinate geometry to six equivalent Nd and three equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SnIr)2 by Materials Project

Ce(IrSn)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight Ir and eight Sn atoms. There are four shorter (3.40 Å) and four longer (3.50 Å) Ce–Ir bond lengths. There are four shorter (3.38 Å) and four longer (3.56 Å) Ce–Sn bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Ce and five Sn atoms. There are one shorter (2.59 Å) and four longer (2.66 Å) Ir–Sn bond lengths. In the second Ir site, Ir is bonded to four equivalent Ce and four equivalent Sn atoms to form distorted IrCe4Sn4 tetrahedra that share corners with twelve equivalent SnCe4Ir4 tetrahedra, edges with two equivalent SnCe4Ir4 tetrahedra, edges with four equivalent IrCe4Sn4 tetrahedra, and faces with four equivalent IrCe4Sn4 tetrahedra. All Ir–Sn bond lengths are 2.64 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ce and five Ir atoms. In the second Sn site, Sn is bonded to four equivalent Ce and four equivalent Ir atoms to form distorted SnCe4Ir4 tetrahedra that share corners with twelve equivalent IrCe4Sn4 tetrahedra, edges with two equivalent IrCe4Sn4 tetrahedra, edges with four equivalent SnCe4Ir4 tetrahedra, and faces with four equivalent SnCe4Ir4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SiIr)2 by Materials Project

CeIr2Si2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 4-coordinate geometry to eight Ir and eight Si atoms. There are four shorter (3.16 Å) and four longer (3.29 Å) Ce–Ir bond lengths. There are four shorter (3.19 Å) and four longer (3.20 Å) Ce–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 Ce and five Si atoms. There are one shorter (2.41 Å) and four longer (2.43 Å) Ir–Si bond lengths. In the second Ir site, Ir is bonded to four equivalent Ce and four equivalent Si atoms to form a mixture of distorted edge and face-sharing IrCe4Si4 tetrahedra. All Ir–Si bond lengths are 2.45 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to four equivalent Ce and five Ir atoms. In the second Si site, Si is bonded in a 4-coordinate geometry to four equivalent Ce and four equivalent Ir atoms.

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 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↗