Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Pt(NO)6”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Theoretical search for possible Li–Ni–B crystal structures using an adaptive genetic algorithm

The structural diversity of rare-earth and transition metal borides indicates that alkali-transition metal borides (A-T-B) show tremendous promise in exhibiting a variety of crystal structures with different dimensionalities of T-B frameworks. On the other hand, the A-T-B ternary systems are severely underexplored because of the synthetic challenges associated with their preparation. Accurate and efficient computational predictions of low-energy stable and metastable phases can identify the optimal compositions of the hypothetical compounds in the A-T-B systems to guide the synthesis. As such, in this work, we have computationally discovered several new phases in the Li–Ni–B ternary system. The newly discovered LiNiB, Li 2 Ni 3 B, and Li 2 NiB phases expand the existing theoretical database, and the convex-hull surface of Li–Ni–B has been re-constructed. The lowest energy structure of the LiNiB compound has been found by an adaptive genetic algorithm with layered motif, which matches with the experimentally determined structure. According to our electrochemical calculations, LiNiB and another predicted layered Li 2 NiB compounds have great potential as anode materials for lithium batteries. The Li 2 Ni 3 B compound with the space group P4 3 32 was predicted to crystallize in a cubic structure composed of distorted octahedral units of BNi 6 , which is isostructural to two noncentrosymmetric superconductors Li 2 Pd 3 B and Li 2 Pt 3 B. While we were unable to experimentally confirm the Li 2 Ni 3 B compound utilizing the hydride synthetic route, attempts to synthesize this compound by alternate methods remain highly desirable, considering its potential superconducting properties.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NiGePt2 by Materials Project

Pt2NiGe crystallizes in the orthorhombic Fmmm space group. The structure is three-dimensional. there are two inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in a 6-coordinate geometry to four equivalent Pt2-, four equivalent Ni2+, and four equivalent Ge2+ atoms. All Pt–Pt bond lengths are 2.80 Å. There are two shorter (2.73 Å) and two longer (2.75 Å) Pt–Ni bond lengths. There are two shorter (2.58 Å) and two longer (2.90 Å) Pt–Ge bond lengths. In the second Pt2- site, Pt2- is bonded in a 12-coordinate geometry to four equivalent Pt2-, four equivalent Ni2+, and four equivalent Ge2+ atoms. All Pt–Ni bond lengths are 2.74 Å. All Pt–Ge bond lengths are 2.69 Å. Ni2+ is bonded in a 8-coordinate geometry to eight Pt2- and two equivalent Ge2+ atoms. Both Ni–Ge bond lengths are 2.42 Å. Ge2+ is bonded in a 10-coordinate geometry to eight Pt2- and two equivalent Ni2+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

A Transmission Electron Microscopy Study of a Refractory Metal Grain from a Calcium-Aluminum-Rich Inclusion in the Leoville CV3 Chondrite

Introduction: Calcium-aluminum-rich inclusions (CAIs) are an important component of chondritic meteorites. They can contain materials that are thermodynamically predicted and isotopically age dated to be among the first-formed solids in our solar system [1-5]. Observed in some CAIs are micron to sub-micron sized inclusions rich in Fe, Ni, and high-Z elements such as Pt, Os, Ir and W, in the form of refractory metal nuggets (RMNs), fremdlinges, and ‘nugget like objects’ (NLOs) [1,6]. Refractory siderophile elements such as Os, Ir and Ru are thermodynamically predicted to condense at temperatures well in excess of the major CAI phases such as melilite, perovskite, spinel and hibonite [2,7-9]. These refractory metal inclusions in CAIs can therefore serve as probes into the thermodynamic landscape of the early solar protoplanetary disk. Here we report on a refractory grain identified in a CAI of the Leoville CV3 chondrite. This work is part of an ongoing effort to gain insight into the thermochemistry of the early solar system through systematic analyses of the structure and chemistry of various components in CAIs [10-13]. Sample and Analytical Techniques: A fluffy type A CAI (Fig. 1A) was identified in a section of the Leoville, CV3 chondrite (Center for Meteorite Studies, Arizona State University collection, #821_C_3) using a JOEL-JXA 8530F electron microprobe at Arizona State University. Backscattered electron (BSE) imaging and energy-dispersive X-ray spectroscopy (EDS) were used to identify refractory metal grains in the CAI using a Thermo Fisher (formerly FEI) Helios NanoLab 660 G3 focused-ion-beam scanning-electron microscope (FIBSEM) located at the Kuiper Materials Imaging and Characterization Facility (KMICF) at the Lunar and Planetary Laboratory, University of Arizona. The FIB is equipped with an EDAX EDS system. We selected one of the larger (micron-sized) refractory metal grains, designated as ‘Spud’ (Fig. 1B) for further analysis. ‘Spud’ was extracted and thinned to electron transparency (<100 nm) using the FIB-SEM located in KMICF, following methods described by [14- 15]. The FIB section was analyzed using a 200 keV Hitachi HF5000 scanning transmission electron microscope (S/TEM) located at KMICF. The HF5000 is equipped with cold-field emission gun, 3rd-order spherical aberration corrector for STEM imaging, and an Oxford Instruments X-Max N 100 TLE energydispersive spectroscopy (EDS) system with dual 100 mm2 windowless silicon-drift detectors (Ω = 2.0 sr). Selected-area electron-diffraction (SAED) patterns were acquired to aid in determination of crystallinity and phase. Results: The mineralogy, texture, and morphology of the CAI are consistent with that of a fluffy type A (FTA) CAI [16]. BSE imaging at high magnifications revealed grains with high contrast, indicative of compositions rich in elements of higher atomic number relative to surrounding material. These high-Z grains have sizes that range from ∼250 nm to 4 µm. EDS analyses confirm that the bright grains are metal-rich inclusions. A minor fraction of the grains are composed of only Fe and Ni, but the majority (∼60%) of the identified inclusions also contained various refractory siderophiles including Os, Ru, Zr, Ir and Mo. EDS analysis on the FIB-SEM of Spud shows that it contains Fe, Ni, Mo and Ru. High-angle annular dark-field (HAAFD) imaging and EDS mapping in the TEM (Fig. 2) show that Spud occurs in melilite (Ca1.9Al1.99Si1.06O7). Spud contains a subhedral to anhedral morphology and is compositionally heterogenous (polyphasic, Fig. 2). Local spatial correlation occurs among Fe, Ni, and Pt, and also among Os, Ru, and Mo. SAED patterns show that the Fe-Ni-Pt, Fe-Os-Mo-Ru and Fe-Pt regions are crystalline. Discussion: CAIs can contain various types of inclusions rich in Fe, Ni and refractory siderophiles such as Os, Ru, W and Pt [1]. RMNs are micron-sized, single phase alloy grains and can contain Os, Ir, Ru and Rh [1,7,17]. NLOs are also micron-sized inclusions, but contain two phases, a refractory metal, and an oxide [6]. Fremdlinge are the largest of such inclusions (tens of microns in size) and are complex aggregates of Fe-Ni alloy, silicates, oxides, and sulfides [1,17]. While the size of Spud matches previous descriptions of RMNs and NLOs, Spud is neither a single-phase alloy like RMNs, nor does it contain one metal phase and one oxide like NLOs. Spud does not match the above described categories of refractory metal inclusions. The presence of refractory siderophiles such as Mo, Os, Ru, and Pt suggests a high-temperature origin. Thermodynamic modelling by [7] indicates condensation temperatures of 1917 K, 1693 K, 1613 K and 1415 K for Os, Mo, Ru and Pt respectively. These models also show that following the initial condensation of a refractory metal, alloying of solutes such as Fe, Ni and W, occurs in levels proportional to their partial pressures in the surrounding gas. Such alloying occurs at temperatures above the condensation temperatures of common CAI phases such as melilite (1529 K), perovskite (1441 K), spinel (197 K) and forsterite (1354 K) [2]. The polyphasic nature of Spud could be the result of such high-temperature alloying, possibly shortly after the condensation of Mo and Ru at 1693 K and 1613 K respectively. That Spud occurs as an inclusion is consistent with it having formed prior to and at temperature above that of its host melilite in this FTA CAI, which is qualitatively consistent with such prior thermodynamic modeling. Further, the polyphasic nature of Spud is similar to refractory grains from a FTA CAI in the Northwest Africa (NWA) 8323, CV3 chondrite [11-13]. These data suggest that such refractory metal grains could have been widespread in the inner and early solar protoplanetary disk and represent some of the earliest formed solids to have condensed. Acknowledgments: Research and instrumentation supported by NASA grants #NNX12AL47G, #NNX15AJ22G and #80NSSC19K0509, and NSF grants #1531243 and #0619599. Fig 2. STEM data on ‘Spud’. HAADF Image (Top) False-color EDS Maps (Bottom) References: [1] MacPherson G. J. (2014) T. of Geochem. Vol I: Met. And Cosmochem. Processes, 139-179. [2] Lodders K. (2003) ApJ, 591, 1220-1247. [3] Ebel D. S. (2006) Met. & the Early S. Sys. II., 253- 277. [4] Amelin Y. (2002) Science, 297, 1678-1683. [5] Connelly J.N. et.al. (2012) Science, 338, 651-655. [6] Schwander D. et al. (2015) GCA, 18, 70-87. [7] Palme H. and Wlotzka F. (1976) EPSL, 33, 45-60. [8] Berg T. et al. (2009) ApJ, 702, 172-176. [9] Liffman K. et al. (2021) Icarus, 221, 89-105. [10] Zega T.J. et al. (2021) PSJ, 2, 115. [11] Ramprasad T. et al. (2020) LPSC LI, Abstract #2472. [12] Ramprasad T. et al. (2021) Microscopy & Microanalysis, S1, 2792-2794. [13] Ramprasad T. et al. (2021) 84th MetSoc, Abstract #6123. [14] Zega T.J. et al. (2007) MAPS, 42, 1373-1386. [15] Ramprasad T. et al. (2022) MAPS, in revision. [16] Grossman L. (1975), GCA, 39, 433-454. [17] El Goresy A. et al. (1978) LPSC IX, Abstract#1100

T. Ramprasad↗
DOE OSTI2020

Materials Data on In2Pt3 by Materials Project

Pt3In2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in a 5-coordinate geometry to six Pt2- and five In3+ atoms. There are a spread of Pt–Pt bond distances ranging from 2.82–2.98 Å. There are a spread of Pt–In bond distances ranging from 2.77–2.96 Å. In the second Pt2- site, Pt2- is bonded in a 5-coordinate geometry to six equivalent Pt2- and five In3+ atoms. There are a spread of Pt–In bond distances ranging from 2.77–2.96 Å. There are three inequivalent In3+ sites. In the first In3+ site, In3+ is bonded in a 6-coordinate geometry to six Pt2- atoms. In the second In3+ site, In3+ is bonded in a 6-coordinate geometry to six Pt2- atoms. In the third In3+ site, In3+ is bonded in a distorted q6 geometry to nine Pt2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Solution-Phase Synthesis of Platinum-Decorated Hydrogen Tungsten Bronzes for Hydrogen Atom Transfer from Oxides to Molecules

Hydrogen bronzes can be used as hydrogen donors for the broad class of reactions involving proton-coupled electron transfer (PCET). Here, in this work, we describe a method to prepare platinum-decorated hydrogen tungsten bronzes, Pt@H x WO 3 · n H 2 O with n = 0, 1, and 2, by reacting the pristine oxides at modest temperatures with a mild reducing agent, H 3 PO 2 , and H 2 PtCl 6 in an aqueous solution. We explored the tunability and kinetics of this reaction and compared it with that of archetypal gas–solid hydrogen spillover. We demonstrate that the identity of the noble metal affects the extent of bronze reduction. This suggests that the mechanism proceeds via the adsorption of a hydrogen-atom species on the noble metal. Finally, we explored the ability of the Pt-decorated hydrogen tungsten bronzes to hydrogenate a model H + /e – acceptor, 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO). The bronze phases return to their fully oxidized states along with the subsequent reduction of TEMPO to TEMPOH. Overall, this work demonstrates a solution-phase method to obtain hydrogen bronzes, which can then be used to perform hydrogen transfer reactions, providing a pathway for the use of extended transition metal oxides as stoichiometric reagents for broad classes of hydrogenation reactions.

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

Thermally induced PtOx interfacial layer enhances stability of Pt/β-Ga2O3 vertical Schottky diodes

This study investigates the long-term stability of Pt/β-Ga2O3 field-plated Schottky barrier diodes at high temperatures, with extended thermal cycling and soaking stress. The device characteristics reveal a strong dependence on operating temperature, leading to an ON/OFF current ratio of ∼10× at ±3 V and 600 °C. Extensive thermal cycling (25 cycles over 100 h) between room temperature and 350 °C shows that leakage currents stabilize after the initial ten cycles. This stabilization is likely due to the formation of a thin PtOx layer at the Pt/β-Ga2O3 interface, as confirmed by high-resolution scanning transmission electron microscopy. Further exposure to a constant 350 °C environment for 10 h reveals a slight increase in the leakage current from 10−7 to 10−6 A at −5 V and degradation of the forward current, due to potential thermodynamic instability of the Ohmic contacts. This study provides insights into the changes in the Pt/β-Ga2O3 diode performance with thermal stress, offering a basis for predicting the device’s operational reliability at high temperatures for sensing and power applications.

08 HYDROGEN↗
DOE OSTI2020

Enhanced NO, CO and C 3 H 6 conversion on Pt/Pd catalysts: Impact of oxygen storage material and catalyst architecture

Simultaneous conversion of NO, CO and C 3 H 6 under stoichiometric conditions was carried out on washcoated monoliths containing oxygen storage material (OSM)-promoted mixed Platinum group metals (PGM: Pt(95 %)/Pd(5 %)), to evaluate OSM promotion and to identify the best architecture. The studied OSMs include ceria-zirconia (Ce 0.3 Zr 0.7 O 2 ; CZO) and mixed metal oxide spinel (Mn 0.5 Fe 2.5 O 4 ; MFO). PGM supported directly on the OSM was found to be the best design for CZO, leading to a ~70 °C simultaneous decrease in the light-off temperature (T 80 ; feed temperature giving 80 % conversion) for NO, CO and C 3 H 6 conversion compared to the alumina-supported PGM. Close coupling between the PGM and CZO is responsible for the activity promotion. In contrast, a dual-layer architecture (top PGM layer, bottom MFO layer) outperformed the MFO-supported PGM catalyst. The dual-layer PGM-MFO catalyst decreased the T 80 by ~50 °C for NO, CO and C 3 H 6 conversion compared to the PGM-only catalyst. Enhancement obtained with the dual-layer PGM-MFO architecture relies on a direct catalytic contribution from the spinel. During lean/rich modulation the addition of CZO or spinel helps to mitigate the detrimental impact of modulation on NO, CO and C 3 H 6 conversion above 400 °C. The data suggest that both CZO and MFO can buffer lean/rich modulation but exhibit preference to different reductants; CZO-supported PGM and dual-layer PGM-MFO show no conversion decrease during modulation for CO or C 3 H 6 modulation, respectively. Dynamic oxygen storage capacity (DOSC) measurements show that the spinel exhibits ~10 times higher DOSC than CZO for both CO and C 3 H 6 reductants. Both CO and C 3 H 6 are equally effective reductants for the MFO but CO is better for CZO and PGM-deposited CZO. The study provides useful insight into benefits of OSM and provides guidance for optimization of the multi-component PGM + OSM catalyst composition and architecture.

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

Materials Data on Yb3Ge13Pt4 by Materials Project

Yb3Pt4Ge13 crystallizes in the tetragonal P4_2cm space group. The structure is three-dimensional. there are three inequivalent Yb sites. In the first Yb site, Yb is bonded in a 12-coordinate geometry to four equivalent Pt and twelve Ge atoms. All Yb–Pt bond lengths are 3.24 Å. There are a spread of Yb–Ge bond distances ranging from 3.25–3.30 Å. In the second Yb site, Yb is bonded in a 12-coordinate geometry to four equivalent Pt and twelve Ge atoms. All Yb–Pt bond lengths are 3.22 Å. There are a spread of Yb–Ge bond distances ranging from 3.01–3.45 Å. In the third Yb site, Yb is bonded in a 12-coordinate geometry to four Pt and twelve Ge atoms. There are a spread of Yb–Pt bond distances ranging from 3.16–3.26 Å. There are a spread of Yb–Ge bond distances ranging from 3.04–3.52 Å. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded in a 9-coordinate geometry to three Yb and six Ge atoms. There are a spread of Pt–Ge bond distances ranging from 2.55–2.58 Å. In the second Pt site, Pt is bonded in a 9-coordinate geometry to three Yb and six Ge atoms. There are a spread of Pt–Ge bond distances ranging from 2.50–2.61 Å. There are nine inequivalent Ge sites. In the first Ge site, Ge is bonded in a 2-coordinate geometry to three equivalent Yb, two Pt, and two Ge atoms. There are one shorter (2.62 Å) and one longer (2.67 Å) Ge–Ge bond lengths. In the second Ge site, Ge is bonded in a 2-coordinate geometry to three Yb, two equivalent Pt, and two equivalent Ge atoms. There are one shorter (2.81 Å) and one longer (2.87 Å) Ge–Ge bond lengths. In the third Ge site, Ge is bonded in a 2-coordinate geometry to three Yb, two equivalent Pt, and two Ge atoms. There are one shorter (2.69 Å) and one longer (2.80 Å) Ge–Ge bond lengths. In the fourth Ge site, Ge is bonded in a 6-coordinate geometry to six Ge atoms. There are a spread of Ge–Ge bond distances ranging from 2.53–2.82 Å. In the fifth Ge site, Ge is bonded in a 7-coordinate geometry to three equivalent Yb, two Pt, and two Ge atoms. The Ge–Ge bond length is 2.73 Å. In the sixth Ge site, Ge is bonded in a 7-coordinate geometry to three Yb, two equivalent Pt, and two Ge atoms. The Ge–Ge bond length is 2.68 Å. In the seventh Ge site, Ge is bonded in a 2-coordinate geometry to three Yb, two equivalent Pt, and two Ge atoms. In the eighth Ge site, Ge is bonded in a 2-coordinate geometry to three Yb, two equivalent Pt, and one Ge atom. In the ninth Ge site, Ge is bonded in a 2-coordinate geometry to three Yb, two equivalent Pt, and two Ge atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Quantifying the Site Heterogeneities of Non‐Uniform Catalysts Using QuantEXAFS

Abstract We present the Multi‐site (MS) QuantEXAFS approach, designed to model the EXAFS data from samples containing an element in different local bonding geometries. Building upon our QuantEXAFS method, which maps experimental extended X‐ray absorption fine structures (EXAFS) data to DFT‐optimized structures, MS‐QuantEXAFS introduces the key capability to probe fractional contributions of multiple sites that may be present in an experimental sample. Specifically, we demonstrate effectiveness of this technique by investigating mixed samples containing known fractions of site‐isolated subsurface Pt/MgO with Pt nanoparticles uniformly supported on MgO. The ‘site‐fractions’ obtained through MS‐QuantEXAFS closely match (i. e., ±6%) the known fractions of the physically mixed samples. This approach has been generalized to other oxides, and thus represents an important advance in quantifying the speciation of non‐uniform catalyst samples.

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

Materials Data on Ba5Co4PtClO13 by Materials Project

Ba5Co4PtO13Cl crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. there are five inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to nine O2- and one Cl1- atom. There are a spread of Ba–O bond distances ranging from 2.66–2.95 Å. The Ba–Cl bond length is 3.03 Å. In the second Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to nine O2- and one Cl1- atom. There are a spread of Ba–O bond distances ranging from 2.70–2.99 Å. The Ba–Cl bond length is 3.03 Å. In the third Ba2+ site, Ba2+ is bonded to nine O2- and three equivalent Cl1- atoms to form distorted BaCl3O9 cuboctahedra that share corners with three equivalent BaO12 cuboctahedra, edges with six equivalent BaCl3O9 cuboctahedra, edges with six CoO4 tetrahedra, a faceface with one CoO6 octahedra, and a faceface with one PtO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.96–3.37 Å. There are two shorter (3.35 Å) and one longer (3.36 Å) Ba–Cl bond lengths. In the fourth Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form distorted BaO12 cuboctahedra that share corners with nine BaCl3O9 cuboctahedra, corners with three equivalent PtO6 octahedra, faces with six CoO6 octahedra, and a faceface with one CoO4 tetrahedra. The corner-sharing octahedra tilt angles range from 9–13°. There are a spread of Ba–O bond distances ranging from 2.91–3.22 Å. In the fifth Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.82–2.95 Å. There are four inequivalent Co+2.75+ sites. In the first Co+2.75+ site, Co+2.75+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with three equivalent CoO6 octahedra, a cornercorner with one CoO4 tetrahedra, edges with three equivalent BaCl3O9 cuboctahedra, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 11–12°. There is two shorter (1.81 Å) and two longer (1.88 Å) Co–O bond length. In the second Co+2.75+ site, Co+2.75+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with three equivalent PtO6 octahedra, a cornercorner with one CoO4 tetrahedra, and edges with three equivalent BaCl3O9 cuboctahedra. The corner-sharing octahedral tilt angles are 19°. There is one shorter (1.84 Å) and three longer (1.85 Å) Co–O bond length. In the third Co+2.75+ site, Co+2.75+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three equivalent CoO4 tetrahedra, faces with four BaCl3O9 cuboctahedra, and a faceface with one CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.98–2.13 Å. In the fourth Co+2.75+ site, Co+2.75+ is bonded to six O2- atoms to form CoO6 octahedra that share faces with three equivalent BaO12 cuboctahedra, a faceface with one CoO6 octahedra, and a faceface with one PtO6 octahedra. There are a spread of Co–O bond distances ranging from 1.88–2.07 Å. Pt6+ is bonded to six O2- atoms to form PtO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, corners with three equivalent CoO4 tetrahedra, a faceface with one BaCl3O9 cuboctahedra, and a faceface with one CoO6 octahedra. There are a spread of Pt–O bond distances ranging from 2.03–2.05 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+ and two Co+2.75+ atoms. In the second O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+ and two Co+2.75+ atoms. In the third O2- site, O2- is bonded in a linear geometry to three equivalent Ba2+, two Co+2.75+, and three equivalent Cl1- atoms. There are one shorter (3.35 Å) and two longer (3.36 Å) O–Cl bond lengths. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two Co+2.75+ atoms. In the fifth O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two Co+2.75+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to three Ba2+, one Co+2.75+, and one Pt6+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to three Ba2+, one Co+2.75+, and one Pt6+ atom. In the eighth O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+, one Co+2.75+, and one Pt6+ atom. In the ninth O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+, one Co+2.75+, and one Pt6+ atom. Cl1- is bonded in a 8-coordinate geometry to five Ba2+ and three equivalent O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm3Pt4 by Materials Project

Sm3Pt4 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Sm+2.67+ is bonded in a 9-coordinate geometry to nine Pt2- atoms. There are a spread of Sm–Pt bond distances ranging from 2.92–3.34 Å. There are three inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in a 6-coordinate geometry to six equivalent Sm+2.67+ atoms. In the second Pt2- site, Pt2- is bonded in a distorted octahedral geometry to six equivalent Sm+2.67+ atoms. In the third Pt2- site, Pt2- is bonded in a 10-coordinate geometry to seven equivalent Sm+2.67+ and three equivalent Pt2- atoms. There are one shorter (2.92 Å) and two longer (3.03 Å) Pt–Pt bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La3Pt4 by Materials Project

La3Pt4 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. La+2.67+ is bonded in a 9-coordinate geometry to nine Pt2- atoms. There are a spread of La–Pt bond distances ranging from 2.96–3.44 Å. There are three inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in a 6-coordinate geometry to six equivalent La+2.67+ atoms. In the second Pt2- site, Pt2- is bonded in a distorted octahedral geometry to six equivalent La+2.67+ atoms. In the third Pt2- site, Pt2- is bonded in a 10-coordinate geometry to seven equivalent La+2.67+ and three equivalent Pt2- atoms. There are one shorter (2.98 Å) and two longer (3.08 Å) Pt–Pt bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Atomic Layer Deposition Overcoating Improves Catalyst Selectivity and Longevity in Propane Dehydrogenation

Propylene, a precursor for commodity chemicals and plastics, is produced by propane dehydrogenation (PDH). An increase in PDH yield via added catalyst activity, lifetime, or selectivity represents significant energy and economic savings. Using Pt dispersed on Al2O3 extrudate supports as a commercially relevant model system, we demonstrate that atomic layer deposition (ALD) metal oxide overcoats, used to tailor metal-active sites, can increase PDH yield and selectivity. We investigate the interplay of Pt loading, ALD overcoat thickness, and Al 2 O 3 support surface area on PDH activity, selectivity, and catalyst stability to show that applying a 6-8 A thick layer of Al 2 O 3 on low-surface area Al 2 O 3 supports of similar to 90 m 2 /g surface area yields the optimal combination of stability and activity, while increasing propylene selectivity from 91 to 96%. Increased stability upon steaming deactivation occurs because the Al 2 O 3 overcoat prevents the Pt nanoparticles from sintering. We speculate that the ALD overcoat selectively binds to the undercoordinated sites on the Pt nanoparticles, while leaving the more selective terrace sites available for dehydrogenation.

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

Andrieslombaardite, RhSbS, a new platinum-group mineral from the platiniferous Onverwacht Pipe, Republic of South Africa

A hundred years after the discovery of the Merensky Reef in 1924, it is appropriate to present the new mineral andrieslombaardite in honour of Andries Frederik Lombaard who was instrumental in its discovery. Andrieslombaardite, RhSbS, was first described as an unknown mineral from placer deposits associated with the Tulameen Alaskan-Uralian type complex, British Colombia, Canada (Raicevic and Cabri, 1976) but has since been reported from several other deposits including the platiniferous Driekop, Mooihoek, and Onverwacht pipes in the eastern Bushveld Complex, South Africa. The mineral and the name were approved by the Commission on New Minerals Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA no. 2022-076) based on data in the co-type samples from Onverwacht and a co-type sample from the Yubdo stream, Birbir River, Ethiopia. Andrieslombaardite in the Onverwacht sample is a single 8 x 20 μm grain attached to laurite in a matrix of altered silicate and Fe-oxyhydroxide minerals. In the Yubdo samples, there are many grains of pale brownish gray andrieslombaardite up to 25 x 55 μm in size, included in Pt-Fe alloys, some associated with erlichmanite, and others attached to bornite and chalcopyrite. The reflectance values (R%) measured in air and in oil at the COM wavelengths are 48.3 and 33.0 (470 nm), 49.3 and 34.0 (546 nm), 51.0 and 35.9 (589 nm), and 51.8 and 36.7 (650 nm). The colour values x, y, Y, λd, and Pe in air are 0.317, 0.322, 50.3, 580, and 3.2, and in oil are 0.319, 0.324, 35.6, 579, and 4.5. The composition of andrieslombaardite is ideally RhSbS, but it contains variable amounts of Fe, Pt, Pd, and Ir that may substitute for Rh. The mineral is cubic with unit-cell dimensions of a = 6.0278(4) Å, V = 219.01(6) Å 3 and Z = 4. It was synthesised at 400 and 550°C using stoichiometric elemental amounts. It is a member of the cobaltite group. The mineralisation of the intrusive dunite pipes was probably introduced at high temperatures, under magmatic conditions. The primary assemblages were to a certain degree overprinted and redistributed by low-temperature hydrothermal fluids. The Pt-Fe alloys from Yubdo containing PGM inclusions such as andrieslombaardite in the Yubdo-Alaskan-type complex were formed at some post-magmatic stage owing to PGE remobilisation during hydrothermal or metamorphic episodes.

58 GEOSCIENCES↗
DOE OSTI2024

In situ electric-field control of ferromagnetic resonance in the low-loss organic-based ferrimagnet V[TCNE] x ∼2

We demonstrate indirect electric-field control of ferromagnetic resonance (FMR) in devices that integrate the low-loss, molecule-based, room-temperature ferrimagnet vanadium tetracyanoethylene (V[TCNE]x∼2) mechanically coupled to PMN-PT piezoelectric transducers. Upon straining the V[TCNE]x films, the FMR frequency is tuned by more than 6 times the resonant linewidth with no change in Gilbert damping for samples with α = 6.5 × 10−5. We show this tuning effect is due to a strain-dependent magnetic anisotropy in the films and find the magnetoelastic coefficient |λs| ∼ (1–4.4) ppm, backed by theoretical predictions from density-functional theory calculations and magnetoelastic theory. Noting the rapidly expanding application space for strain-tuned FMR, we define a new metric for magnetostrictive materials, magnetostrictive agility, given by the ratio of the magnetoelastic coefficient to the FMR linewidth. This agility allows for a direct comparison between magnetostrictive materials in terms of their comparative efficacy for magnetoelectric applications requiring ultra-low loss magnetic resonance modulated by strain. With this metric, we show V[TCNE]x is competitive with other magnetostrictive materials, including YIG and Terfenol-D. This combination of ultra-narrow linewidth and magnetostriction, in a system that can be directly integrated into functional devices without requiring heterogeneous integration in a thin film geometry, promises unprecedented functionality for electric-field tuned microwave devices ranging from low-power, compact filters and circulators to emerging applications in quantum information science and technology.

Materials Science↗
DOE OSTI2020

Materials Data on Sc3Si3Pt by Materials Project

Sc3PtSi3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Sc2+ sites. In the first Sc2+ site, Sc2+ is bonded in a 10-coordinate geometry to three equivalent Pt2- and seven Si+1.33- atoms. There are one shorter (3.04 Å) and two longer (3.10 Å) Sc–Pt bond lengths. There are a spread of Sc–Si bond distances ranging from 2.72–2.93 Å. In the second Sc2+ site, Sc2+ is bonded in a 6-coordinate geometry to six Si+1.33- atoms. There are a spread of Sc–Si bond distances ranging from 2.77–2.85 Å. In the third Sc2+ site, Sc2+ is bonded in a 9-coordinate geometry to three equivalent Pt2- and six Si+1.33- atoms. There are two shorter (3.11 Å) and one longer (3.14 Å) Sc–Pt bond lengths. There are a spread of Sc–Si bond distances ranging from 2.75–2.90 Å. Pt2- is bonded in a 4-coordinate geometry to six Sc2+ and four Si+1.33- atoms. There are three shorter (2.42 Å) and one longer (2.58 Å) Pt–Si bond lengths. There are three inequivalent Si+1.33- sites. In the first Si+1.33- site, Si+1.33- is bonded in a 9-coordinate geometry to six Sc2+, two equivalent Pt2-, and one Si+1.33- atom. The Si–Si bond length is 2.38 Å. In the second Si+1.33- site, Si+1.33- is bonded in a 9-coordinate geometry to six Sc2+, one Pt2-, and two Si+1.33- atoms. The Si–Si bond length is 2.43 Å. In the third Si+1.33- site, Si+1.33- is bonded in a 9-coordinate geometry to seven Sc2+, one Pt2-, and one Si+1.33- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Optimizing the lean hydrocarbon NO x trap: Sequential and dual-layer configurations

Vehicular emission control catalysts are ineffective in eliminating CO, hydrocarbons, and NO x during engine cold-start when exhaust temperatures are below 200 °C. In this study the performance of coupled low temperature NO x , n-C 12 H 26 (C 12 ), and C 3 H 6 trapping, release and conversion for a series of model Lean Hydrocarbon NO x Trap (LHCNT) catalysts are examined. Pd and Pt supported on small-pore (SSZ-13) and large-pore (BEA) zeolites are selected based on the performance during transient NO and C 12 uptake, release and conversion experiments. These catalysts are combined into sequential (Pt + Pd/BEA → Pd/SSZ-13; Pd/SSZ-13 → Pt + Pd/BEA) and dual-layer (Pt + Pd/BEA top, Pd/SSZ-13 bottom) configurations in an attempt to improve the trapping and conversion performance. While all three configurations trap between 75 and 100 μmolNO x /g-cat, the Pd/SSZ-13 → Pt + Pd/BEA sequential configuration is most effective in simultaneously trapping C 12 and NO in the presence of H 2 O, resulting in excellent NO and C 12 storage below 100 °C with release and/or conversion at or above 200 °C. For each configuration, C 12 oxidation lights-off below 300 °C and NO oxidation achieves ~35 % conversion in the absence of C 12 . Neither the presence of C 12 nor the order of the sequential configuration has a significant impact on NO uptake. C 12 significantly delays NO and NO 2 desorption to temperatures exceeding 300 °C. The more compact dual-layer catalyst is most effective in forming NO 2 as the release temperature lines up with the maximum NO conversion temperature but traps less C 12 than the sequential configurations. The addition of C 3 H 6 in the feed on the dual-layer catalyst leads to further delay in the NO x desorption as well as increased NO and C 12 conversion at high temperatures. Here, the overall findings provide guidance in the optimizing LHCNT configuration for realistic feeds.

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

Materials Data on Ba6Ru2Pt(ClO6)2 by Materials Project

Ba6Ru2Pt(O6Cl)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are three inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to nine O2- and one Cl1- atom. There are three shorter (2.69 Å) and six longer (2.99 Å) Ba–O bond lengths. The Ba–Cl bond length is 3.18 Å. In the second Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with six equivalent BaO12 cuboctahedra, corners with three equivalent RuO6 octahedra, faces with three equivalent BaO12 cuboctahedra, faces with three equivalent RuO6 octahedra, and faces with three equivalent PtO6 octahedra. The corner-sharing octahedral tilt angles are 11°. There are a spread of Ba–O bond distances ranging from 2.96–3.17 Å. In the third Ba2+ site, Ba2+ is bonded in a 7-coordinate geometry to three equivalent O2- and four equivalent Cl1- atoms. All Ba–O bond lengths are 2.56 Å. There are one shorter (3.24 Å) and three longer (3.52 Å) Ba–Cl bond lengths. Ru5+ is bonded to six O2- atoms to form RuO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, faces with three equivalent BaO12 cuboctahedra, and a faceface with one PtO6 octahedra. There are three shorter (1.89 Å) and three longer (2.13 Å) Ru–O bond lengths. Pt4+ is bonded to six equivalent O2- atoms to form PtO6 octahedra that share faces with six equivalent BaO12 cuboctahedra and faces with two equivalent RuO6 octahedra. All Pt–O bond lengths are 2.04 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+, one Ru5+, and one Pt4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+ and one Ru5+ atom. Cl1- is bonded to five Ba2+ atoms to form a mixture of distorted edge and corner-sharing ClBa5 trigonal bipyramids.

36 MATERIALS SCIENCE↗