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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Optical Modem Enabling Broadband Datacom Links for Crewed Cis-Lunar Missions

We report on the design, development, and testing of our high-power broadband optical modem supporting NASA’s crewed Artemis-2 mission. The O2O modem will be mounted in the crewed Orion module and provide a broadband 505,000 km bi-directional optical link back to earth while en route to the moon. The full-duplex modem consists of a high-power optical transmitter and receiver optimized for serially-concatenated pulse-position modulation (SCPPM). The transmitter is a master-oscillator power-amplifier optical architecture using efficient cladding-pumped amplification in erbium-ytterbium co-doped fiber. The transmitter outputs up to 1 W at ≈1550 nm (limited for eye safety) and supports 6 different user-rates ranging from 20.39 Mb/s to 260.95 Mb/s using PPM16 and PPM32 modulation formats. The optical receiver supports two user-rates: 10.19 Mb/s and 20.39 Mb/s with both rates employing PPM32. The narrowband receiver filtering is optimized to simultaneously accept four separate wavelength channels to mitigate atmospherics through spatial diversity. A configurable interleaver provides additional protection against atmospherics-based signal fading and a powerful soft-decision error correction scheme enables highly sensitive detection. The measured sensitivities at the two bit-rates are -73.8 and -71.8dBm, respectively. The architecture was designed for reliable operation in space, featuring automatic hardware interlocks, pump sparing for the amplifiers, and autonomous operation of all internal hardware and software control loops. The protoflight unit (PFU) was put through rigorous environmental testing which included pyroshock, vibration, electromagnetic interference/compatibility, and thermal-vacuum testing. The modem successfully passed all the environmental screening and has been declared at Technology Readiness Level (TRL) 6.

space communications↗
DOE OSTI2020

Materials Data on Co(BW)3 by Materials Project

W3CoB3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent W+2.33+ sites. In the first W+2.33+ site, W+2.33+ is bonded in a 7-coordinate geometry to seven B3- atoms. There are a spread of W–B bond distances ranging from 2.36–2.49 Å. In the second W+2.33+ site, W+2.33+ is bonded in a 6-coordinate geometry to six B3- atoms. There are a spread of W–B bond distances ranging from 2.32–2.52 Å. Co2+ is bonded in a square co-planar geometry to four equivalent B3- atoms. All Co–B bond lengths are 2.07 Å. There are two inequivalent B3- sites. In the first B3- site, B3- is bonded in a 9-coordinate geometry to seven W+2.33+ and two equivalent B3- atoms. Both B–B bond lengths are 1.90 Å. In the second B3- site, B3- is bonded in a 9-coordinate geometry to six W+2.33+, two equivalent Co2+, and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Temperature-Dependent Mechanical Properties of Ni-Based Concentrated Alloys: Insights from First-Principles Calculations

The present work focuses on predicting temperature-dependent mechanical properties of Ni-based concentrated alloys Ni 18 Cr 10 Co 10 Fe 6 M 4 (abbreviated by X 44 M 4 , with M = Al, V, Mn, Fe, Nb, Mo, and W) using density functional theory (DFT). These predictions are based on shear (plastic) and elastic deformations, utilizing the special quasirandom structure (SQS), the phonon-based quasiharmonic approach (QHA), and the quasistatic approach. The resulting properties include coefficient of thermal expansion via QHA, ideal shear strength (τ IS ), and stable and unstable stacking fault energies (γ SF and γ US ) through pure alias shear deformation, and elastic constants (c ij ), bulk modulus (B 0 ), and shear modules (G 0 ) via elastic deformation. Notably, predicting accurate γ SF is challenging due to uncertainties that can exceed the γ SF values. τ IS and γ US exhibit a strong linear relationship, enabling the accurate prediction of γ US based on the precisely determined τ IS . All mechanical properties of X 44 M 4 decrease with increasing temperature, except for some γ SF cases such as X 44 M 4 with M = V, Mn, Fe, Mo, and W. Among the X 44 M 4 alloys, X 44 Nb 4 exhibits the lowest τ IS , γ US , and G 0 values, and the highest B 0 /G 0 ratio, while X 44 Mn 4 has the lowest B 0 and B 0 /G 0 ratio. We found that volume is a crucial descriptor for understanding and modeling mechanical properties (except B0 and maybe also γ SF ) affected by alloying elements and temperature. Ni-based dilute alloys (e.g., Ni 11 M 1 and Ni 31 M 1 ) and concentrated alloys (e.g., X 44 M 4 ) show similar trends in mechanical properties influenced by alloying elements and temperature, simplifying the analysis and design of Ni-based alloys.

Elastic properties↗
NASA NTRS1995

Structure of V(H2)n(+) Clusters for n = 1-6

Geometries, vibrational frequencies, spin states, H2 binding energies, and Delta(S) values have been determined for V(H2)n(+), for n = 1-6, using the B3LYP hybrid functional. The binding energies and Delta(S) values are in good agreement with experiment, thus showing that the B3LYP functional offers a reliable approach for optimizing the geometry and determining the H2 binding energies for this system. The calculations show that the increase in the binding energy and entropy associated with the addition of the sixth H2 to V(+) is due to a change in spin state from quintet for the smaller clusters to triplet for V(H2)6(+). The results for V(H2)n(+) are compared with those for CO(H2)n(+).

Maitre, Philippe↗
NASA NTRS2012

Siderophile Element Constraints on the Conditions of Core Formation in Mars

Siderophile element concentrations in planetary basalts and mantle samples have been used to estimate conditions of core formation for many years and have included applications to Earth, Moon, Mars and asteroid 4 Vesta [1]. For Earth, we have samples of mantle and a diverse collection of mantle melts which have provided a mature understanding of the how to reconstruct the concentration of siderophile elements in mantle materials, from only concentrations in surficial basalt (e.g., [2]). This approach has led to the consensus views that Earth underwent an early magma ocean stage to pressures of 40-50 GPa (e.g., [3,4]), Moon melted extensively and formed a small (approx. 2 mass %) metallic core [5], and 4 Vesta contains a metallic core that is approximately 18 mass % [6,7]. Based on new data from newly found meteorites, robotic spacecraft, and experimental partitioning studies, [8] showed that eight siderophile elements (Ni, Co, Mo, W, Ga, P, V and Cr) are consistent with equilibration of a 20 mass% S-rich metallic core with the mantle at pressures of 14 +/- 3 GPa. We aim to test this rather simple scenario with additional analyses of meteorites for a wide range of siderophile elements, and application of new experimental data for the volatile siderophile and highly siderophile elements.

Righter, K.↗
NASA NTRS2016

Microstructural and Creep Properties of Boron- and Zirconium-Containing Cobalt-Based Superalloys

The effects of micro-additions of boron and zirconium on grain-boundary (GB) structure and strength inpolycrystalline γ(f.c.c.) plus γ’(L12) strengthened Co-9.5Al-7.5W-X at. % alloys (X=0-Ternary, 0.05B, 0.01B,0.05Zr, and 0.005B-0.05Zr at. %) are studied. Creep tests performed at 850 °C demonstrate that GB strength and cohesion limit the creep resistance and ductility of the ternary B- and Zr-free alloy due to intergranular fracture. Alloys with 0.05B and 0.005B-0.05Zr both exhibit improved creep strength due to enhanced GB cohesion,compared to the baseline ternary Co-9.5Al-7.5W alloy, but alloys containing 0.01B or 0.05Zr additions displayed no benefit. Atom-probe tomography (APT) is utilized to measure GB segregation, where B and Zr are demonstrated to segregate at GBs. A Gibbsian interfacial excess of 5.57 ± 1.04 atoms nm(exp) -2 was found for B at aGB in the 0.01B alloy and 2.88 ± 0.81 and 2.40 ± 0.84 atoms nm2 for B and Zr, respectively, for the 0.005B-0.05Zr alloy. The GBs in the highest B-containing (0.05B) alloy exhibit micrometer-sized boride precipitates with adjacent precipitate denuded-zones (PDZs), whereas secondary precipitation at the GBs is absent in theother four alloys. The 0.05B alloy has the smallest room temperature yield strength, by 6%, which is attributedto the PDZs, but it exhibits the largest increase in creep strength (with an ~2.5 order of magnitude decrease inthe minimum strain rate for a given stress at 850 °C) over the baseline Co-9.5Al-7.5W alloy.

Creep↗
DOE OSTI2020

Materials Data on ZnW5O7 by Materials Project

W5ZnO7 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are three inequivalent W+2.40+ sites. In the first W+2.40+ site, W+2.40+ is bonded to six O2- atoms to form edge-sharing WO6 octahedra. There are a spread of W–O bond distances ranging from 2.12–2.45 Å. In the second W+2.40+ site, W+2.40+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of W–O bond distances ranging from 2.11–2.67 Å. In the third W+2.40+ site, W+2.40+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All W–O bond lengths are 2.53 Å. Zn2+ is bonded in a see-saw-like geometry to four O2- atoms. There are two shorter (2.04 Å) and two longer (2.18 Å) Zn–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to four W+2.40+ and one Zn2+ atom to form distorted OZnW4 trigonal bipyramids that share a cornercorner with one OZnW4 trigonal bipyramid, edges with two equivalent OZn2W2 tetrahedra, and edges with two equivalent OZnW4 trigonal bipyramids. In the second O2- site, O2- is bonded to two equivalent W+2.40+ and two equivalent Zn2+ atoms to form OZn2W2 tetrahedra that share corners with two equivalent OZn2W2 tetrahedra and edges with four equivalent OZnW4 trigonal bipyramids. In the third O2- site, O2- is bonded in a 6-coordinate geometry to six W+2.40+ atoms. In the fourth O2- site, O2- is bonded in a trigonal non-coplanar geometry to three W+2.40+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1980

Spectrophotometric observations of P/Schwassmann-Wachmann 1 during outburst

Spectra of Comet Schwassmann-Wachmann 1 were obtained on November 26-27, 1978 and February 15, 1979 using the Cassegrain Digicon spectrograph, and on February 21-23, 1979 using the IDS spectrograph of McDonald Observatory. All spectra were obtained while the comet was in an extended series of outburst (12th-13th mag). The spectra were predominantly reflected solar light, indicating the outburst was very rich in dust. Weak emission between 4000 and 4050 A, and between 4240 and 4290 A was detected in November 1978 and is probably due to CO(+). These outbursts, and the detection of CO(+), indicate that comets are not inactive at distances as great as 6 AU.

Cochran, A. L.↗
DOE OSTI2023

Boosting the performance of reversible solid oxide electrochemical cells with a novel hybrid oxygen electrode, Pr 1.39 Ba 0.14 Sr 0.53 Co 1.48 Fe 0.76 O 6- δ -Ba 0.66 Sr 0.34 CoO 3- δ

Solid oxide electrochemical cells (SOECs) stand out as a highly promising clean energy technology that offers several benefits, showing significant potential to play a pivotal role in the transition towards a sustainable and low-carbon energy future. SOECs can efficiently convert the chemical energy stored in fuels to electricity in fuel cell mode, and produce various chemicals from abundant feedstocks (e.g., CO 2 , H 2 O) and intermittent solar/wind-based renewable electricity. Despite extensive efforts that have been devoted to designing novel materials and optimizing SOEC manufacturing processes, aiming to achieve enhanced energy efficiency, the current SOECs still suffer from poor performance, which is mainly due to the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics. To address this challenge, in this work, we have successfully designed an in situ formed hybrid oxygen electrode material (Pr 1.39 Ba 0.14 Sr 0.53 Co 1.48 Fe 0.76 O 6- δ -Ba 0.66 Sr 0.34 CoO 3- δ ), which significantly improves the surface oxygen exchange coefficient and bulk oxygen-ion diffusion coefficient, enhancing the OER and ORR electrocatalytic activities. Further, the SOECs equipped with this newly developed oxygen electrode achieved exceptional performance for power generation using both hydrogen and propane as the fuels. At 750 °C, a peak power density of 2.4 W cm -2 was obtained with H 2 as the fuel. Additionally, the SOECs attain unprecedented performance in steam electrolysis mode. A current density of 4.4 A cm -2 was achieved at 1.3 V and 750 °C, which represents the highest performance among all yttria-stabilized zirconia (YSZ) electrolyte-based SOECs. The SOECs also deliver remarkable stability during the accelerated stability testing, highlighting the great potential of Pr 1.39 Ba 0.14 Sr 0.53 Co 1.48 Fe 0.76 O 6- δ -Ba 0.66 Sr 0.34 CoO 3- δ as a high-performance oxygen electrode for next generation SOECs.

08 HYDROGEN↗
DOE OSTI2020

Materials Data on Ni(BW)2 by Materials Project

Ni(WB)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. W2+ is bonded in a 6-coordinate geometry to six equivalent B3- atoms. There are four shorter (2.33 Å) and two longer (2.54 Å) W–B bond lengths. Ni2+ is bonded in a square co-planar geometry to four equivalent B3- atoms. All Ni–B bond lengths are 2.10 Å. B3- is bonded in a 9-coordinate geometry to six equivalent W2+, two equivalent Ni2+, and one B3- atom. The B–B bond length is 1.86 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe(BW)2 by Materials Project

Fe(WB)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. W2+ is bonded in a 6-coordinate geometry to six equivalent B3- atoms. There are four shorter (2.35 Å) and two longer (2.52 Å) W–B bond lengths. Fe2+ is bonded in a square co-planar geometry to four equivalent B3- atoms. All Fe–B bond lengths are 2.08 Å. B3- is bonded in a 9-coordinate geometry to six equivalent W2+, two equivalent Fe2+, and one B3- atom. The B–B bond length is 1.88 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Lowering the operating temperature of protonic ceramic electrochemical cells to <450 °C

Protonic ceramic electrochemical cells (PCECs) can be employed for power generation and sustainable hydrogen production. Lowering the PCEC operating temperature can facilitate its scale-up and commercialization. However, achieving high energy efficiency and long-term durability at low operating temperatures is a long-standing challenge. Here, in this work, we report a simple and scalable approach for fabricating ultrathin, chemically homogeneous, and robust proton-conducting electrolytes and demonstrate an in situ formed composite positive electrode, Ba 0.62 Sr 0.38 CoO 3–δ –Pr 1.44 Ba 0.11 Sr 0.45 Co 1.32 Fe 0.68 O 6–δ , which significantly reduces ohmic resistance, positive electrode–electrolyte contact resistance and electrode polarization resistance. The PCECs attain high power densities in fuel-cell mode (~0.75 W cm –2 at 450 °C and ~0.10 W cm –2 at 275 °C) and exceptional current densities in steam electrolysis mode (–1.28 A cm –2 at 1.4 V and 450 °C). At 600 °C, the PCECs achieve a power density of ~2 W cm –2 . Additionally, we demonstrate the direct utilization of methane and ammonia for power generation at <450 °C. Our PCECs are also stable for power generation and hydrogen production at 400 °C.

25 ENERGY STORAGE↗
DOE OSTI2020

Materials Data on Na9(WO3)13 by Materials Project

Na9(WO3)13 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are five inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to twelve O2- atoms to form NaO12 cuboctahedra that share corners with eleven NaO12 cuboctahedra, faces with two equivalent NaO12 cuboctahedra, and faces with eight WO6 octahedra. There are a spread of Na–O bond distances ranging from 2.77–2.80 Å. In the second Na1+ site, Na1+ is bonded to twelve O2- atoms to form NaO12 cuboctahedra that share corners with seven NaO12 cuboctahedra, faces with four NaO12 cuboctahedra, and faces with eight WO6 octahedra. There are a spread of Na–O bond distances ranging from 2.76–2.81 Å. In the third Na1+ site, Na1+ is bonded to twelve O2- atoms to form NaO12 cuboctahedra that share corners with ten NaO12 cuboctahedra, faces with four equivalent NaO12 cuboctahedra, and faces with eight WO6 octahedra. There are ten shorter (2.78 Å) and two longer (2.79 Å) Na–O bond lengths. In the fourth Na1+ site, Na1+ is bonded to twelve O2- atoms to form NaO12 cuboctahedra that share corners with nine NaO12 cuboctahedra, faces with three NaO12 cuboctahedra, and faces with eight WO6 octahedra. There are a spread of Na–O bond distances ranging from 2.78–2.81 Å. In the fifth Na1+ site, Na1+ is bonded to twelve O2- atoms to form NaO12 cuboctahedra that share corners with eight NaO12 cuboctahedra, faces with four NaO12 cuboctahedra, and faces with eight WO6 octahedra. There are a spread of Na–O bond distances ranging from 2.73–2.82 Å. There are seven inequivalent W+5.31+ sites. In the first W+5.31+ site, W+5.31+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and faces with five NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of W–O bond distances ranging from 1.85–2.00 Å. In the second W+5.31+ site, W+5.31+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and faces with six NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–5°. There are a spread of W–O bond distances ranging from 1.89–1.97 Å. In the third W+5.31+ site, W+5.31+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and faces with five NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–2°. There are a spread of W–O bond distances ranging from 2.01–2.07 Å. In the fourth W+5.31+ site, W+5.31+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and faces with six NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–2°. There are four shorter (2.02 Å) and two longer (2.06 Å) W–O bond lengths. In the fifth W+5.31+ site, W+5.31+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and faces with five NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of W–O bond distances ranging from 1.91–2.04 Å. In the sixth W+5.31+ site, W+5.31+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and faces with six NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–6°. There are a spread of W–O bond distances ranging from 1.88–2.01 Å. In the seventh W+5.31+ site, W+5.31+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and faces with six NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–6°. There are a spread of W–O bond distances ranging from 1.91–2.02 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted square co-planar geometry to two equivalent Na1+ and two equivalent W+5.31+ atoms. In the second O2- site, O2- is bonded to three Na1+ and two W+5.31+ atoms to form distorted ONa3W2 square pyramids that share a cornercorner with one ONa4W2 octahedra, corners with twelve ONa3W2 square pyramids, edges with four ONa3W2 square pyramids, and faces with four ONa3W2 square pyramids. The corner-sharing octahedral tilt angles are 61°. In the third O2- site, O2- is bonded to three Na1+ and two W+5.31+ atoms to form a mixture of distorted edge, face, and corner-sharing ONa3W2 square pyramids. In the fourth O2- site, O2- is bonded to three Na1+ and two W+5.31+ atoms to form distorted ONa3W2 square pyramids that share a cornercorner with one ONa4W2 octahedra, corners with twelve ONa3W2 square pyramids, edges with four ONa3W2 square pyramids, and faces with four ONa3W2 square pyramids. The corner-sharing octahedral tilt angles are 61°. In the fifth O2- site, O2- is bonded to three Na1+ and two W+5.31+ atoms to form a mixture of distorted edge, face, and corner-sharing ONa3W2 square pyramids. In the sixth O2- site, O2- is bonded to three Na1+ and two W+5.31+ atoms to form a mixture of distorted edge, face, and corner-sharing ONa3W2 square pyramids. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+ and two W+5.31+ atoms. In the eighth O2- site, O2- is bonded to three Na1+ and two W+5.31+ atoms to form distorted ONa3W2 square pyramids that share a cornercorner with one ONa4W2 octahedra, corners with fifteen ONa3W2 square pyramids, edges with five ONa3W2 square pyramids, a faceface with one ONa4W2 octahedra, and faces with three ONa3W2 square pyramids. The corner-sharing octahedral tilt angles are 60°. In the ninth O2- site, O2- is bonded to three Na1+ and two W+5.31+ atoms to form distorted ONa3W2 square pyramids that share corners with seventeen ONa3W2 square pyramids, edges with two equivalent ONa4W2 octahedra, edges with four ONa3W2 square pyramids, and faces with four ONa3W2 square pyramids. In the tenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+ and two W+5.31+ atoms. In the eleventh O2- site, O2- is bonded to three equivalent Na1+ and two W+5.31+ atoms to form a mixture of distorted edge, face, and corner-sharing ONa3W2 square pyramids. In the twelfth O2- site, O2- is bonded to three Na1+ and two W+5.31+ atoms to form distorted ONa3W2 square pyramids that share a cornercorner with one ONa4W2 octahedra, corners with seventeen ONa3W2 square pyramids, edges with five ONa3W2 square pyramids, a faceface with one ONa4W2 octahedra, and faces with three ONa3W2 square pyramids. The corner-sharing octahedral tilt angles are 60°. In the thirteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+ and two W+5.31+ atoms. In the fourteenth O2- site, O2- is bonded to four Na1+ and two equivalent W+5.31+ atoms to form distorted ONa4W2 octahedra that share corners with two equivalent ONa4W2 octahedra, corners with sixteen ONa3W2 square pyramids, edges with four equivalent ONa3W2 square pyramids, and faces with eight ONa3W2 square pyramids. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoSiW by Materials Project

CoWSi crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent W2+ sites. In the first W2+ site, W2+ is bonded in a 7-coordinate geometry to seven Si4- atoms. There are a spread of W–Si bond distances ranging from 2.69–2.84 Å. In the second W2+ site, W2+ is bonded in a 5-coordinate geometry to five Si4- atoms. There are a spread of W–Si bond distances ranging from 2.70–2.81 Å. There are three inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded in a 6-coordinate geometry to four equivalent Co2+ and two equivalent Si4- atoms. There are two shorter (2.28 Å) and two longer (2.44 Å) Co–Co bond lengths. Both Co–Si bond lengths are 2.27 Å. In the second Co2+ site, Co2+ is bonded in a 6-coordinate geometry to three Co2+ and two equivalent Si4- atoms. The Co–Co bond length is 2.32 Å. Both Co–Si bond lengths are 2.26 Å. In the third Co2+ site, Co2+ is bonded in a distorted hexagonal planar geometry to six Si4- atoms. There are a spread of Co–Si bond distances ranging from 2.32–2.38 Å. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded to six W2+, two equivalent Co2+, and four Si4- atoms to form a mixture of edge, corner, and face-sharing SiCo2Si4W6 cuboctahedra. There are a spread of Si–Si bond distances ranging from 2.34–2.54 Å. In the second Si4- site, Si4- is bonded to six W2+, four Co2+, and two equivalent Si4- atoms to form distorted SiCo4Si2W6 cuboctahedra that share corners with four equivalent SiCo2Si4W6 cuboctahedra, edges with six equivalent SiCo4Si2W6 cuboctahedra, and faces with eight SiCo2Si4W6 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr2CoWO6 by Materials Project

Sr2CoWO6 is Orthorhombic Perovskite-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Sr2+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Sr–O bond distances ranging from 2.54–3.18 Å. W6+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six equivalent CoO6 octahedra. The corner-sharing octahedra tilt angles range from 15–20°. There is four shorter (1.95 Å) and two longer (1.96 Å) W–O bond length. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 15–20°. There are two shorter (2.08 Å) and four longer (2.11 Å) Co–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to four equivalent Sr2+, one W6+, and one Co2+ atom. In the second O2- site, O2- is bonded in a 6-coordinate geometry to four equivalent Sr2+, one W6+, and one Co2+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to four equivalent Sr2+, one W6+, and one Co2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Understanding of A-site deficiency in layered perovskites: promotion of dual reaction kinetics for water oxidation and oxygen reduction in protonic ceramic electrochemical cells

Protonic ceramic electrochemical cells (PCECs) are promising solid-state energy conversion devices which enable the conversion of energy between electricity and hydrogen at intermediate temperatures. Rapid conversion between chemical and electrical energy via PCEC technology will assist in overcoming grand challenges in energy storage. To achieve highly efficient reversible operation between hydrogen production and electricity generation, boosting water-oxidation and oxygen reduction activities of the oxygen electrode while maintaining the durable operation is one of the early-stage technical opportunities. In this study, an A-site deficient layered perovskite (PrBa 0.8 Ca 0.2 ) 0.95 Co 2 O 6–δ has been developed as an oxygen electrode for a PCEC which presents superior electrochemical performances. The electrolysis current density reached as high as –0.72 A cm –2 at 1.3 V, and a peak power density of 0.540 W cm –2 was obtained at 600 °C in electrolysis and fuel cell mode, respectively. The PCEC with the new electrode shows good durability under practical operating conditions for 160 hours in both operating modes with no observable degradation. Here, the reversibility between the electrolysis and fuel cell mode is also successfully demonstrated.

30 DIRECT ENERGY CONVERSION↗