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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Hydrogen Atom Abstraction from an Os II (NH 3 ) 2 Complex Generates an Os IV (NH 2 ) 2 Complex: Experimental and Computational Analysis of the N–H Bond Dissociation Free Energies and Reactivity

We report double hydrogen atom abstraction from (TMP)Os II (NH 3 ) 2 (TMP = tetramesitylporphyrin) with phenoxyl or nitroxyl radicals leads to (TMP)Os IV (NH 2 ) 2 . This unusual bis(amide) complex is diamagnetic and displays an N-H resonance at 12.0 ppm in its 1 H NMR spectrum. 1 H- 15 N correlation experiments identified a 15 N NMR spectroscopic resonance at –267 ppm. Experimental reactivity studies and density functional theory calculations support relatively weak N-H bonds of 73.3 kcal/mol for (TMP)Os II (NH 3 ) 2 and 74.2 kcal/mol for (TMP)Os III (NH 3 )(NH 2 ). Cyclic voltammetry experiments provide an estimate of the pK a of [(TMP)Os III (NH 3 ) 2 ] + . In the presence of Barton’s base, a current enhancement is observed at the Os(III/II) couple, consistent with an ECE event. Spectroscopic experiments confirmed (TMP)Os IV (NH 2 ) 2 as the product of bulk electrolysis. Double hydrogen atom abstraction is influenced by π donation from the amides of (TMP)Os IV (NH 2 ) 2 into the d orbitals of the Os center, favoring the formation of (TMP)Os IV (NH 2 ) 2 over N-N coupling. This π donation leads to a Jahn-Teller distortion that splits the energy levels of the d xz and d yz orbitals of Os, results in a low spin electron configuration, and leads to minimal aminyl character on the N atoms, rendering (TMP)Os IV (NH 2 ) 2 unreactive towards amide-amide coupling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Evaluation of the Radiological Characterization for Off-Site Source Recovery Program Waste Streams LA-OS-00-01.001, LA-OS-00-03, and LA-OS-00-04

The purpose of this memorandum is to satisfy the requirements of Section 4.4 of the CCP Acceptable Knowledge Documentation procedure CCP-TP-005 (Ref. 1). This evaluation is updating the previously issued memo NEN3:24-045 issued in August 2024. CCP-TP-005 requires an AK Expert and the OSRP group to evaluate the radionuclide characterization of a waste stream and prepare the NDA Memorandum (letter to CCP Records). This NDA memorandum was written with input from the OSRP group, as required by CCP-TP-005. This memo includes a discussion of the limitations for the radiological characterization and a description of the characterization method.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2023

Activity model for 36 elements in Fe-Ni-Si-S-C liquids with application to terrestrial planet accretion and mantle geochemistry: New data for Ru, Re, Pt, Os, Ti, Nb, and Ta

Understanding siderophile element partitioning between metal and silicate melts under diverse conditions can be used to place important constraints on the materials and conditions of planetary accretion and core formation, as well as post core formation processes. However, the effects of Si on the partitioning and activity coefficients for these elements are not well known, despite Si likely being one of the dominant light elements in Earth’s core. To address this gap in understanding, we have undertaken a systematic study of the highly siderophile elements Re, Pt, Os, and Ru, and the refractory lithophile elements Nb, Ta and Ti at 1600 °C and 1 GPa, to derive epsilon interaction parameters for these elements in FeSi metallic liquids. Positive epsilon interaction parameters were measured for Nb, Ta, Ti, Ru, Re, Pt, and Os, indicating that dissolved Si in Fe liquids causes a decrease in their metal/silicate partition coefficients (or ‘silicophobic’ behavior). Furthermore, ε$_{Re, Os, or Ru}^{Si}$ > ε$_{Re, Os, or Ru}^{S}$ which means Si causes a larger decrease in D(metal/silicate) than S, and the chalcophile behavior expected from some elements will be completely masked by the presence of Si in a metallic liquid. The new parameters are used to update an activity model that now includes 36 siderophile elements in Fe-Ni-Si-S-C liquids (27 trace elements considered here). Systematic assessment of these 27 elements shows which have the strongest affinity for Si, C, and S, and also how activity coefficients for these elements would vary during accretion and core formation in Earth, Mars, and Mercury of widely differing fO 2 and core compositional conditions. The activity model is combined with new partitioning expressions for Mo, W, Cr, Re Ru, Pt, and Os and applied to aspects of post core formation mantle geochemistry of Earth, Mars, and Mercury. Our updated expressions show that the BSE Mo/W ratio can easily be achieved with metal/silicate partitioning during growth of the Earth, whereas Re, Os and Ru become lower than and highly fractionated compared with BSE values during core formation and accretion, and thus nearly 99% of their BSE abundances are likely contributed by late accretion. Ru isotopes should be a very good indicator of the source material for the late accretion. The high Pt/Os and Re/Os developed in a deepening magma ocean during the growth of the Earth, indicates 186 Os and 187 Os isotopes could be coupled if this ancient material remained isolated and subsequently became entrained in mantle plumes and measured in surficial lavas. The extent to which this occurred will be limited by the low Os content of this ancient material, thus requiring mixing as a major component in plume sources. Martian mantle Hf/W ratio stays low during accretion and core formation modelling, suggesting that W isotope anomalies are more likely due to solid/liquid silicate fractionation than to core formation. Finally, Ti contents measured by MESSENGER at Mercury’s surface can be explained by segregation of either a metallic core (IW-6 to -8) or metallic core + sulfide (IW-4 to -7.5) followed by mantle melting.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

Olefin Coupling Catalyzed by (Pybox)Os Complexes via Osmacyclopentane Intermediates: Comparison with Isoelectronic (Phebox)Ir

(Pybox)Os is found to catalyze alkene hydrovinylation, effecting the dimerization of ethylene, tail-to-tail coupling of propene and 1-butene, and cross-coupling of ethylene with higher α-olefins. This reactivity contrasts with the previously reported dehydrogenative coupling of ethylene to give butadiene catalyzed by the isoelectronic fragment (Phebox)Ir. The reaction mechanism was investigated through computational and experimental means. Both the Os- and Ir-catalyzed reactions proceed through a [2 + 2 + 1] cyclization of the corresponding bis-olefin complex to yield an experimentally observed metallacyclopentane intermediate. In both cases, the metallacyclopentane undergoes β- H elimination, via a dechelated κ 2 -pincer-ligated intermediate, to yield a σ−π-but-3-enyl hydride complex or derivative. Both the greater reactivity and the distinct chemoselectivity of the Os system relative to the Ir system are attributable to C−H reductive elimination by the σ−π-but-3-enyl hydride having a barrier for Os much lower than that for Ir. This lower barrier to C−H elimination for Os is unexpected given that the thermodynamic driving force for elimination is much less for Os than for Ir. Computational studies of model complexes were conducted, comparing (Pybox)Os(L)(CH 3 )(H) with the isoelectronic (Phebox)Ir(L)(CH 3 )(H). The results indicate that the more facile kinetics with Os relative to Ir may be general for C−H elimination from six-coordinate d 6 complexes of the two metals, as well as for the microscopic reverse, i.e., C−H addition to the corresponding four-coordinate d 8 species.

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

Materials Data on Os(CO)4 by Materials Project

Os(CO)4 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of twelve Os(CO)4 clusters. In four of the Os(CO)4 clusters, Os2- is bonded in a see-saw-like geometry to four C+2.50+ atoms. There is two shorter (1.91 Å) and two longer (1.96 Å) Os–C bond length. There are four inequivalent C+2.50+ sites. In the first C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.50+ site, C+2.50+ is bonded in a linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the third C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In eight of the Os(CO)4 clusters, Os2- is bonded in a see-saw-like geometry to four C+2.50+ atoms. There are a spread of Os–C bond distances ranging from 1.90–1.96 Å. There are four inequivalent C+2.50+ sites. In the first C+2.50+ site, C+2.50+ is bonded in a linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the third C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.50+ site, C+2.50+ is bonded in a linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Os(OF)2 by Materials Project

OsF4(OsO3F)2Os(OF)2 is Iron carbide-derived structured and crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of two tetrafluoroosmium molecules, two Os(OF)2 clusters, and four OsO3F clusters. In each Os(OF)2 cluster, Os6+ is bonded in a tetrahedral geometry to two O2- and two F1- atoms. Both Os–O bond lengths are 1.70 Å. Both Os–F bond lengths are 1.90 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Os6+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Os6+ atom. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Os6+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Os6+ atom. In each OsO3F cluster, Os6+ is bonded in a tetrahedral geometry to three O2- and one F1- atom. There are a spread of Os–O bond distances ranging from 1.72–1.75 Å. The Os–F bond length is 1.88 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Os6+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Os6+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one Os6+ atom. F1- is bonded in a single-bond geometry to one Os6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Os(CO)4 by Materials Project

Os(CO)4 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of eight Os(CO)4 clusters. In four of the Os(CO)4 clusters, Os2- is bonded in a rectangular see-saw-like geometry to four C+2.50+ atoms. There are a spread of Os–C bond distances ranging from 1.91–1.96 Å. There are four inequivalent C+2.50+ sites. In the first C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.50+ site, C+2.50+ is bonded in a linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.17 Å. In the third C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In four of the Os(CO)4 clusters, Os2- is bonded in a rectangular see-saw-like geometry to four C+2.50+ atoms. There are a spread of Os–C bond distances ranging from 1.90–1.96 Å. There are four inequivalent C+2.50+ sites. In the first C+2.50+ site, C+2.50+ is bonded in a linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the third C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Os by Materials Project

Os is Magnesium structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Os is bonded to twelve equivalent Os atoms to form a mixture of edge, face, and corner-sharing OsOs12 cuboctahedra. There are six shorter (2.70 Å) and six longer (2.76 Å) Os–Os bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Os by Materials Project

Os is Copper structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Os is bonded to twelve equivalent Os atoms to form a mixture of edge, face, and corner-sharing OsOs12 cuboctahedra. All Os–Os bond lengths are 2.73 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Local site behavior of the 5$d$ and 4$f$ ions in the frustrated pyrochlore Ho 2 Os 2 O 7

The pyrochlore osmate Ho 2 Os 2 O 7 is a candidate material for a fragile J=0 local singlet ground state, however little is known regarding the single-ion behavior of either the Os or Ho ions. To address this we present polarized neutron powder diffraction (PNPD) and resonant inelastic x-ray scattering (RIXS) measurements that separately probe the local site behavior of the Os and Ho ions. The PNPD results are dominated by Ho 3+ scattering and the analysis reveals local site susceptibility behavior consistent with spin ice materials. Complimentary unpolarized neutron powder diffraction show an ordered spin ice ground state in an applied magnetic field. To isolate the Os 4+ single-ion behavior we present resonant inelastic x-ray scattering (RIXS) measurements at the osmium L-edge. Analysis of the RIXS spectra parameterize the spin-orbit coupling (0.35 eV), Hund’s coupling (0.27 eV) and trigonal distortion (-0.17 eV). Here, the results are considered within the context of a J=0 model and possible departures from this through structural distortions, excitonic interactions and 5d-4f interactions between the Os ion and the surrounding Ho lattice. The experimental methodology employed highlights the complimentary information available in rare earth based 5d pyrochlores from distinct neutron and x-ray scattering techniques that allow for the isolation and determination of the behavior of the different ions.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on Os(OF2)2 by Materials Project

Os(OF2)2 is Protactinium-like structured and crystallizes in the hexagonal P6_1 space group. The structure is zero-dimensional and consists of six Os(OF2)2 clusters. Os8+ is bonded in an octahedral geometry to two O2- and four F1- atoms. There is one shorter (1.71 Å) and one longer (1.72 Å) Os–O bond length. There is two shorter (1.88 Å) and two longer (1.94 Å) Os–F bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Os8+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Os8+ atom. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Os8+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Os8+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Os8+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one Os8+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Os(OF2)2 by Materials Project

Os(OF2)2 crystallizes in the hexagonal P6_1 space group. The structure is zero-dimensional and consists of six Os(OF2)2 clusters. Os8+ is bonded in an octahedral geometry to two O2- and four F1- atoms. There is one shorter (1.71 Å) and one longer (1.72 Å) Os–O bond length. There are a spread of Os–F bond distances ranging from 1.89–1.93 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Os8+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Os8+ atom. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Os8+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Os8+ atom. In the third F1- site, F1- is bonded in a distorted single-bond geometry to one Os8+ atom. In the fourth F1- site, F1- is bonded in a distorted single-bond geometry to one Os8+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Os(OF)2 by Materials Project

Os(OF)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one Os(OF)2 cluster. Os6+ is bonded in a T-shaped geometry to one O2- and two F1- atoms. The Os–O bond length is 1.85 Å. There is one shorter (1.87 Å) and one longer (1.88 Å) Os–F bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Os6+ and one O2- atom. The O–O bond length is 1.33 Å. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one O2- and one F1- atom. The O–F bond length is 2.72 Å. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to one Os6+ and one O2- atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Os6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Decay spectroscopy at the two-proton drip line: Radioactivity of the new nuclides 160 Os and 156 W

The radioactivity of $^{160}_{76}$Os 84 and $^{156}_{74}$W 82 that lie at the two-proton drip line has been measured in an experiment performed at the Accelerator Laboratory of the University of Jyväskylä. The 160 Os nuclei were produced using fusion-evaporation reactions induced by a beam of 310 MeV 58 Ni ions bombarding a 106 Cd target. The 160 Os ions were separated in flight using the recoil separator MARA and implanted into a double-sided silicon strip detector, which was used to measure their decays. The α decays of the ground state of 160 Os (Ε α = 7092(15) keV, t 1/2 = 97$^{+97}_{-32}$ μs) and its isomeric state (Ε α = 8890(10) keV, t 1/2 = 41$^{+15}_{-9}$ μs) were measured, allowing the excitation energy of the isomer to be determined as 1844(18) keV. These α-decay properties and the excitation energy of the isomer are compared with systematics. The α decays were correlated with subsequent decays to investigate the β decays of the ground state of 156 W, revealing that unlike its isotones, both low-lying isomers were populated in its daughter nuclide, 156 Ta. An improved value for the half-life of the proton-decaying high-spin isomeric state in $^{156}_{73}$Ta 83 of 333$^{+25}_{-22}$ ms was obtained in a separate experiment using the same experimental systems with a 102 Pd target. This result was employed to improve the precision of the half-life determined for 156 W, which was measured as 157$^{+57}_{-34}$ ms.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

High-efficiency purification of CH 4 and H 2 energy sources enabled by a phosphotungstic acid-supported Os single-atom catalyst

Methane (CH 4 ) and hydrogen (H 2 ) show promise as low-carbon energy sources, but their impurities, including H 2 and CO, pose challenges for storage and use. To address these challenges, a robust purification protocol for CH 4 and/or H 2 , combined with the catalytic conversion of impurities into CO 2 and H 2 O, is a compelling solution. Here, in this work, we investigated 11 phosphotungstic acid (PTA)-supported single-atom catalysts (SACs) by density functional theory (DFT) computations. Os 1 /PTA SACs exhibited superior catalytic activity, and the ease of oxidation follows the CO > H 2 > CH 4 order. It facilitated efficient purification of CH 4 in solvents such as water, MeOH, and various others. For H 2 purification, Os 1 /PTA SACs demonstrated excellent performance in gas, water, and MeOH. Notably, in water and MeOH, it selectively removed CO without consuming H 2 with low free energy barriers. The strong Os-PTA interactions and charge transfer mechanism contributed to its exceptional catalytic activity. Our findings shed light on SAC behavior and their potential for efficient CH 4 and H 2 purification. By addressing impurity challenges and improving clean energy utilization, these findings contribute to the development of sustainable energy technologies.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2022

Terahertz nano-imaging of metal-insulator transition in Cd 2 Os 2 O 7

The osmate pyrochlore Cd 2 Os 2 O 7 supports an antiferromagnet insulator ground state with an all-in/all-out (AIAO) spin ordering at low temperature. Above 225 K, Cd 2 Os 2 O 7 becomes a paramagnetic metal whereas the mechanism of this metal-to-insulator transition (MIT) remains elusive. In this letter, we use cryogenic near-field technique operating at terahertz frequencies to study the evolution of low-energy response across the MIT. We observed a systematic variation of the magnitude of nano-THz signal across the transition, consistent with the trend in the direct-current conductivity. Conducting domain walls that dominate the nano-scale landscape of the conductivity of a closely related AIAO system Nd 2 Ir 2 O 7 are not apparent in Cd 2 Os 2 O 7

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Os(SeCl6)2 by Materials Project

Os(SeCl6)2 crystallizes in the orthorhombic Fdd2 space group. The structure is three-dimensional. Os8+ is bonded in an octahedral geometry to six Cl1- atoms. There are a spread of Os–Cl bond distances ranging from 2.33–2.36 Å. Se2+ is bonded in a 6-coordinate geometry to six Cl1- atoms. There are a spread of Se–Cl bond distances ranging from 2.20–3.00 Å. There are six inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Se2+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Se2+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Os8+ and one Se2+ atom. In the fourth Cl1- site, Cl1- is bonded in a distorted water-like geometry to one Os8+ and one Se2+ atom. In the fifth Cl1- site, Cl1- is bonded in a single-bond geometry to one Se2+ atom. In the sixth Cl1- site, Cl1- is bonded in a distorted water-like geometry to one Os8+ and one Se2+ atom.

36 MATERIALS SCIENCE↗