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DOE OSTI2020

Materials Data on OsPbO3 by Materials Project

OsPbO3 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Os4+ is bonded to six equivalent O2- atoms to form corner-sharing OsO6 octahedra. The corner-sharing octahedral tilt angles are 43°. All Os–O bond lengths are 1.98 Å. Pb2+ is bonded in a hexagonal planar geometry to six equivalent O2- atoms. All Pb–O bond lengths are 2.64 Å. O2- is bonded in a 2-coordinate geometry to two equivalent Os4+ and two equivalent Pb2+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr2MgOsO6 by Materials Project

Sr2MgOsO6 is (Cubic) Perovskite-derived structured and crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve equivalent SrO12 cuboctahedra, faces with six equivalent SrO12 cuboctahedra, faces with four equivalent MgO6 octahedra, and faces with four equivalent OsO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.70–2.94 Å. Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent OsO6 octahedra and faces with eight equivalent SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–10°. All Mg–O bond lengths are 2.05 Å. Os6+ is bonded to six O2- atoms to form OsO6 octahedra that share corners with six equivalent MgO6 octahedra and faces with eight equivalent SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–10°. There is four shorter (1.93 Å) and two longer (1.94 Å) Os–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to four equivalent Sr2+, one Mg2+, and one Os6+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to four equivalent Sr2+, one Mg2+, and one Os6+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Amorphizing noble metal chalcogenide catalysts at the single-layer limit towards hydrogen production

Rational design of noble metal catalysts with the potential to leverage efficiency is vital for industrial applications. Such an ultimate atom-utilization efficiency can be achieved when all noble metal atoms exclusively contribute to catalysis. In this work, we demonstrate the fabrication of a wafer-size amorphous PtSex film on a SiO 2 substate via a low-temperature amorphization strategy, which offers single-atom-layer Pt catalysts with high atom-utilization efficiency (~26 wt%). This amorphous PtSex (1.2 < x < 1.3) behaves as a fully activated surface, accessible to catalytic reactions, and features a nearly 100% current density relative to a pure Pt surface and reliable production of sustained high-flux hydrogen over a 2 inch wafer as a proof-of-concept. Furthermore, an electrolyser is demonstrated to generate a high current density of 1,000 mA cm –2 . Such an amorphization strategy is potentially extendable to other noble metals, including the Pd, Ir, Os, Rh and Ru elements, demonstrating the universality of single-atom-layer catalysts.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Pavilion 2 Feature Additions [Slides]

Pavilion 2 is a critical component of system testing for LANL HPC systems. Pavilion 2 is system independent, which allows for the creation of a large suite of generalized tests than can be applied to multiple systems. These additions to Pavilion 2 improve our ability to test systems and diagnose issues. With such a large suite, running the proper tests when diagnosing and fixing a system can be difficult, as well as locating old tests for reference. Test configurations may contain several permutations of a test, not all of which may apply to a given system. The ability to run sets of test permutations lets the tester focus on specific parts of the test without having to edit the test configurations or run extraneous tests. The addition of the filter argument improves the ability to find test results based on test attributes, including past tests. Pavilion 2's system independence is largely based on various layers of configuration files. Configuration files for the host, test, and modes exist to allow generalized testing. The operating system configuration layer can provide helpful OS defaults to a test. Survey, a collection and reporting tool, can help us gauge the performance of a system as well as diagnose issues. The addition of a Survey mode in Pavilion 2 makes running tests with Survey very straightforward. The Survey results are combined with Pavilion 2's test results to make it easy to access.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2023

Pavilion 2 Feature Additions [Slides]

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2020

Materials Data on YbB4Os by Materials Project

YbOsB4 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Yb2+ is bonded in a 2-coordinate geometry to four equivalent Os2- and fourteen B atoms. There are a spread of Yb–Os bond distances ranging from 3.02–3.10 Å. There are a spread of Yb–B bond distances ranging from 2.62–2.76 Å. Os2- is bonded in a 10-coordinate geometry to four equivalent Yb2+, one Os2-, and ten B atoms. The Os–Os bond length is 2.60 Å. There are a spread of Os–B bond distances ranging from 2.27–2.37 Å. There are four inequivalent B sites. In the first B site, B is bonded in a 3-coordinate geometry to four equivalent Yb2+, two equivalent Os2-, and three B atoms. There are a spread of B–B bond distances ranging from 1.75–1.85 Å. In the second B site, B is bonded in a 5-coordinate geometry to four equivalent Yb2+, two equivalent Os2-, and three B atoms. The B–B bond length is 1.84 Å. In the third B site, B is bonded in a 3-coordinate geometry to four equivalent Yb2+, two equivalent Os2-, and three B atoms. There is one shorter (1.74 Å) and one longer (1.77 Å) B–B bond length. In the fourth B site, B is bonded in a 9-coordinate geometry to two equivalent Yb2+, four equivalent Os2-, and three B atoms. The B–B bond length is 1.74 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on U2B6Os by Materials Project

U2OsB6 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. there are two inequivalent U4+ sites. In the first U4+ site, U4+ is bonded in a 2-coordinate geometry to three equivalent Os2- and fourteen B1- atoms. There are a spread of U–Os bond distances ranging from 3.03–3.15 Å. There are a spread of U–B bond distances ranging from 2.61–2.76 Å. In the second U4+ site, U4+ is bonded in a 12-coordinate geometry to one U4+, two equivalent Os2-, and twelve B1- atoms. The U–U bond length is 2.51 Å. There are one shorter (3.01 Å) and one longer (3.04 Å) U–Os bond lengths. There are a spread of U–B bond distances ranging from 2.61–2.71 Å. Os2- is bonded in a 10-coordinate geometry to five U4+ and ten B1- atoms. There are a spread of Os–B bond distances ranging from 2.33–2.40 Å. There are six inequivalent B1- sites. In the first B1- site, B1- is bonded in a 3-coordinate geometry to four equivalent U4+, two equivalent Os2-, and three B1- atoms. There are a spread of B–B bond distances ranging from 1.77–1.84 Å. In the second B1- site, B1- is bonded in a 3-coordinate geometry to four U4+, two equivalent Os2-, and three B1- atoms. There is one shorter (1.69 Å) and one longer (1.82 Å) B–B bond length. In the third B1- site, B1- is bonded in a 3-coordinate geometry to four U4+, two equivalent Os2-, and three B1- atoms. There is one shorter (1.77 Å) and one longer (1.78 Å) B–B bond length. In the fourth B1- site, B1- is bonded in a 3-coordinate geometry to four U4+, two equivalent Os2-, and three B1- atoms. There is one shorter (1.69 Å) and one longer (1.83 Å) B–B bond length. In the fifth B1- site, B1- is bonded in a 9-coordinate geometry to four U4+, two equivalent Os2-, and three B1- atoms. In the sixth B1- site, B1- is bonded in a 8-coordinate geometry to six U4+ and two B1- atoms.

36 MATERIALS SCIENCE↗

NASA NTRS2005

Re-187-Os-187, Pt-190-Os-186 Isotopic and Highly Siderophile Element Systematics of Group IVA Irons

We have recently completed Re-187-Os-187 and Pt-190-Os-186 isotopic and elemental studies of the two largest magmatic iron meteorite groups, IIAB and IIIAB [1]. These studies revealed closed-system behavior of both isotopic systems, but complex trace element behavior for Re, Pt and Os in group IIIAB. Here we examine isotopic and trace elemental systematics of group IVA irons. The IVA irons are not as extensively fractionated as IIAB and IIIAB and their apparently less complex crystallization history may make for more robust interpretation of the relative partitioning behavior of Re, Pt and Os, as well as the other highly siderophile elements (HSE) measured here; Pd, Ru and Ir [e.g. 2]. An additional goal of our continuing research plan for iron meteorites is to assess the possibility of relating certain ungrouped irons with major groups via trace element modeling. Here, the isotopic and trace element systematics of the ungrouped irons Nedagolla and EET 83230 are compared with the IVA irons.

Walker, R. J.↗

DOE OSTI2020

Materials Data on Th2Si3Os by Materials Project

Th2OsSi3 crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. there are two inequivalent Th4+ sites. In the first Th4+ site, Th4+ is bonded in a 8-coordinate geometry to eight Si4- atoms. There are a spread of Th–Si bond distances ranging from 3.14–3.24 Å. In the second Th4+ site, Th4+ is bonded in a 10-coordinate geometry to ten Si4- atoms. There are a spread of Th–Si bond distances ranging from 3.16–3.24 Å. Os4+ is bonded in a trigonal planar geometry to three Si4- atoms. There are one shorter (2.38 Å) and two longer (2.43 Å) Os–Si bond lengths. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 2-coordinate geometry to six Th4+, two equivalent Os4+, and one Si4- atom. The Si–Si bond length is 2.38 Å. In the second Si4- site, Si4- is bonded in a 1-coordinate geometry to six Th4+, one Os4+, and two equivalent Si4- atoms. Both Si–Si bond lengths are 2.40 Å. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to six Th4+ and three Si4- atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Structure and magnetism across the Sr 2- x Ba x NiOsO 6 phase diagram: Understanding magnetic superexchange between first and third row transition metal ions

The crystal chemistry and magnetism of compositions in the Sr 2-x Ba x NiOsO 6 phase diagram have been investigated to better understand the superexchange interactions between 3d and 5d transition metal ions. Compositions with x < 1.35 crystallize with the double perovskite structure, while those with x > 1.83 crystallize in a trigonal structure that is a cation ordered variant of the 6H hexagonal perovskite structure. The Sr-rich double perovskites undergo a cubic to tetragonal distortion upon cooling that is driven by out-of-phase octahedral tilting. The tetragonal distortion occurs upon cooling below 650 K in Sr 2 NiOsO 6 . The temperature of this transition decreases as the barium content increases and is completely suppressed for x ≥ 1.2. All compositions in the double perovskite region become spin glasses below T g ≈ 40 K, due to the competition between ferromagnetic Ni–Os and antiferromagnetic Ni–Ni and Os–Os superexchange interactions. The double perovskite compositions that are rich in barium, like Sr 0.8 Ba 1.2 NiOsO 6 show some signs of magnetic ordering in small clusters, but the presence of Ba/Sr disorder inhibits long-range magnetic order. Trigonal Ba 2 NiOsO 6 orders ferrimagnetically below T C = 108 K. In conclusion, the magnetic structure of this compound contains ferromagnetic ~180° Ni–O–Os interactions and antiferromagnetic ~90° Ni–O–Os interactions, both in agreement with the Goodenough-Kanamori rules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1975

History of Boulder 1 at Station 2, Apollo 17 based on trace element interrelationships

Correlations among the trace and minor element pairs Cl and Br, Cl and P2O5, and Ru and Os, present in parent igneous rocks, generally survived the processes of boulder breccia formation. Fractions of Cl, Br, and Hg that are mobilized by water leaching or volatilization at moderate temperatures place constraints on the thermal history of Boulder 1 and its component breccias. Since, and possibly during, consolidation, the boulder has probably not been subjected to temperatures in excess of 450 C. The parent rocks of the Apollo 17 boulder and breccia samples studied could have been derived from two initial magmas. Vapor clouds from apparently external sources permeated the source regions of the boulders.

Jovanovic, S.↗

DOE OSTI2020

Materials Data on OsC3IO3 by Materials Project

IOs(CO)3 crystallizes in the monoclinic P2_1/m space group. The structure is zero-dimensional and consists of twelve formaldehyde molecules and two IOs clusters. In each IOs cluster, Os3+ is bonded in a 2-coordinate geometry to two I1- atoms. There are one shorter (2.78 Å) and one longer (2.80 Å) Os–I bond lengths. There are two inequivalent I1- sites. In the first I1- site, I1- is bonded in a 6-coordinate geometry to two equivalent Os3+ atoms. In the second I1- site, I1- is bonded in a 4-coordinate geometry to two equivalent Os3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Os3W3C2 by Materials Project

WOs3(WC)2 crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one tungsten molecule and one Os3(WC)2 sheet oriented in the (0, 0, 1) direction. In the Os3(WC)2 sheet, W+4.67+ is bonded in a 3-coordinate geometry to three equivalent Os2- atoms. All W–Os bond lengths are 2.75 Å. There are two inequivalent Os2- sites. In the first Os2- site, Os2- is bonded in a 3-coordinate geometry to three equivalent W+4.67+ and three equivalent C4- atoms. All Os–C bond lengths are 2.12 Å. In the second Os2- site, Os2- is bonded to six equivalent C4- atoms to form distorted edge-sharing OsC6 octahedra. All Os–C bond lengths are 2.22 Å. C4- is bonded to six Os2- atoms to form a mixture of corner and edge-sharing COs6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗

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 OSTI2023

Observationally Constrained Modeling of the Reactive Uptake of Isoprene-Derived Epoxydiols under Elevated Relative Humidity and Varying Acidity of Seed Aerosol Conditions

Isoprene is the non-methane volatile organic compound (VOC) emitted in largest amounts to the atmosphere, and it is a significant source of secondary organic aerosol (SOA) mass. The uptake of isoprene oxidation products followed by multiphase chemistry in fine particles is the key pathway to form isoprene epoxydiol-derived SOA (IEPOX-SOA). However, many parameters that relate to diffusion and reaction of IEPOX in the particle phase remain uncertain, since reaction kinetics previously measured in bulk aqueous phase solutions might be different from atmospheric aerosols. Here, we use simultaneous environmental chamber measurements of multiple parameters governing IEPOX-SOA formation at timescales of ~hours: particle size distribution, composition, and volatility of IEPOX-SOA to constrain the key parameters governing IE-POX-SOA formation under humid (i.e., 50% relative humidity, RH) and varying seed aerosol acidity conditions. Reducing the 2-methyltetrol (tetrol) reaction rate constants by a factor of 4 brings the model predictions in agreement with the IEPOX-SOA measurements with acidified ammonium bisulfate seed aerosols. For less acidic ammonium sulfate aerosols both the organo-sulfate (OS) and tetrol reaction rate constants need to be reduced to bring model predictions closer to chamber observations. Using the measured non-volatile content of IEPOX-SOA we constrain the oligomerization timescale of 2-methyltetrols. We find that the oligomerization timescale is 4 hours with acidified seed aerosols, but a much longer time scale of 24 hours is needed for non-acidified seed aerosols, indicating that the aerosol acidity greatly affects the oligomerization rate of tetrols. Here we show that the actual kinetics of IEPOX-SOA formation rate on aerosol seeds consisting of both ammonium bisulfate and ammonium sulfate are a factor of 4~5 slower under 50-60% RH conditions compared to their application in previous models, which were based on bulk aqueous solution measurements.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Isoelectronic perturbations to f - d -electron hybridization and the enhancement of hidden order in URu 2 Si 2

Significance Phase transitions often manifest themselves in characteristic signatures in the electrical resistivity. Here, we track the temperature increase of the resistive signature of the hidden-order (HO) phase transition in URu 2 Si 2 , a mysterious phase with unknown order parameter. The application of pressure and the isoelectronic substitutions of Fe and Os ions for Ru are the only known perturbations to favor the HO phase. These perturbations are likely to cause increases in f - d -electron hybridization that lead to degeneracy and instabilities in the electronic band structure. The degeneracy is lifted by partial gapping of electronic states over the Fermi surface during the transition to HO. This and related investigations point to the importance of isoelectronic perturbations in generating emergent electronic phases.

Wolowiec, Christian T.↗

DOE OSTI2022

Phase IB study of ziv-aflibercept plus pembrolizumab in patients with advanced solid tumors

Background The combination of antiangiogenic agents with immune checkpoint inhibitors could potentially overcome immune suppression driven by tumor angiogenesis. We report results from a phase IB study of ziv-aflibercept plus pembrolizumab in patients with advanced solid tumors. Methods This is a multicenter phase IB dose-escalation study of the combination of ziv-aflibercept (at 2–4 mg/kg) plus pembrolizumab (at 2 mg/kg) administered intravenously every 2 weeks with expansion cohorts in programmed cell death protein 1 (PD-1)/programmed death-ligand 1(PD-L1)-naïve melanoma, renal cell carcinoma (RCC), microsatellite stable colorectal cancer (CRC), and ovarian cancer. The primary objective was to determine maximum tolerated dose (MTD) and recommended dose of the combination. Secondary endpoints included overall response rate (ORR) and overall survival (OS). Exploratory objectives included correlation of clinical efficacy with tumor and peripheral immune population densities. Results Overall, 33 patients were enrolled during dose escalation (n=3) and dose expansion (n=30). No dose-limiting toxicities were reported in the initial dose level. Ziv-aflibercept 4 mg/kg plus pembrolizumab 2 mg/kg every 2 weeks was established as the MTD. Grade ≥3 adverse events occurred in 19/33 patients (58%), the most common being hypertension (36%) and proteinuria (18%). ORR in the dose-expansion cohort was 16.7% (5/30, 90% CI 7% to 32%). Complete responses occurred in melanoma (n=2); partial responses occurred in RCC (n=1), mesothelioma (n=1), and melanoma (n=1). Median OS was as follows: melanoma, not reached (NR); RCC, 15.7 months (90% CI 2.5 to 15.7); CRC, 3.3 months (90% CI 0.6 to 3.4); ovarian, 12.5 months (90% CI 3.8 to 13.6); other solid tumors, NR. Activated tumor-infiltrating CD8 T cells at baseline (CD8+PD1+), high CD40L expression, and increased peripheral memory CD8 T cells correlated with clinical response. Conclusion The combination of ziv-aflibercept and pembrolizumab demonstrated an acceptable safety profile with antitumor activity in solid tumors. The combination is currently being studied in sarcoma and anti-PD-1-resistant melanoma. Trial registration number NCT02298959 .

Rahma, Osama E.↗

DOE OSTI2022

$\textit{J}$ = 0 nonmagnetic insulating state in K 2 OsX 6 ($\textit{X}$ = F, Cl, and Br)

In 4$\textit{d}$ /5$\textit{d}$ transition-metal systems, many interesting physical properties arise from the interplay of bandwidth, electronic correlations, and spin-orbit interactions. Here, using ab initio density functional theory, we systematically study the double-perovskite-like system K 2 OsX6 ($\textit{X}$ = F, Cl, and Br) with a $5d^4$ electronic configuration. In this work, our main result is that the $\textit{J}$ = 0 nonmagnetic insulating state develops in this system, induced by strong spin-orbit coupling (SOC). Specifically, the well-separated OsX 6 octahedra lead to the cubic crystal-field limit and result in dramatically decreasing hoppings among nearest neighbor Os-Os sites. In this case, the three degenerate $t_{2g}$ orbitals are reconstructed into two “effective” $j_{\text{eff}}$ ($j_{\text{eff}}$ = 1/2 and $j_{\text{eff}}$ = 3/2 states) states separated by the strong SOC, opening a gap with four electrons occupying the$j_{\text{eff}}$ = 3/2 orbitals. Furthermore, the hybridization between the Os 5$\textit{d}$ orbitals and the $\textit{X}$ ($\textit{X}$ = F, Cl, and Br) $\textit{p}$ orbitals increases from F to Br, leading the electrons in K 2 OsF 6 to be more localized than in K 2 OsCl 6 and K 2 OsBr 6 , resulting in a smaller bandwidth for K 2 OsF 6 than in the Cl- or Br-cases. Our results provide guidance to experimentalists and theorists working on this interesting family of osmium halides.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗