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At least 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Self‐Assembled Monolayer Templating for Engineered Nanopinholes in Passivated Contact Solar Cells

We present a novel self-assembled monolayer (SAM)-based technique to make nanopinhole-enabled passivated contacts on silicon solar cells by tuning the SAM coverage area and etch selectivity. We deposit trimethyl-silyl Si(CH 3 ) 3 groups using hexamethyldisilazane (HMDS) as the precursor over passivating dielectric layers and their stacks (SiO 2 , SiN x , SiO 2 /SiN x ) and interrupt the HMDS attachment chemistry shortly before a full monolayer is formed on its surface. Subsequent etching in dilute HF produces pinholes through the dielectric layers due to the higher etch resistance of the SAM to HF etching. The pinhole areal density (10 4 –10 8 /cm 2 ) and size (10–1000 nm) can be tuned both by duration of HMDS attachment and HF etch time. Pinholes were characterized by atomic force microscopy, tetramethylammonium hydroxide (TMAH) selective etch, and Ag decoration by electroless plating. Polysilicon (poly-Si) passivated contacts enabled by pinholes were formed by subsequent deposition of doped amorphous silicon (a-Si:H) followed by thermal crystallization and dopant drive-in. At optimal areal pinhole density ≈10 7 /cm 2 , contacts exhibit both passivation and carrier transport via pinholes as evidenced by electron beam induced current, transmission line measurements, and carrier lifetime measurements. Solar cells based with these pinhole contacts show V oc = 723 mV and FF = 80.3%. The remaining SAM layer does not affect device performance.

14 SOLAR ENERGY↗
NASA NTRS2014

Carbon Dioxide Gas Sensors and Method of Manufacturing and Using Same

A gas sensor comprises a substrate layer; a pair of interdigitated metal electrodes, said electrodes include upper surfaces, the electrodes selected from the group consisting of Pt, Pd, Au, Ir, Ag, Ru, Rh, In, Os, and their alloys. A first layer of solid electrolyte staying in between electrode fingers and partially on said upper surfaces of said electrodes, said first layer selected from NASICON, LISICON, KSICON and.beta.''-Alumina. A second layer of metal carbonate(s) as an auxiliary electrolyte engaging said upper surfaces of the electrodes and the first solid electrolyte. The metal carbonates selected from the group consisting of the following ions Na.sup.+, K.sup.+, Li.sup.+, Ag.sup.+, H.sup.+, Pb.sup.2+, Sr.sup.2+, Ba.sup.2+, and any combination thereof. An extra layer of metal oxide selected from the group consisting of SnO.sub.2, In.sub.2O.sub.3, TiO.sub.2, WO.sub.3, ZnO, Fe.sub.2O.sub.3, ITO, CdO, U.sub.3O.sub.8, Ta.sub.2O.sub.5, BaO, MoO.sub.2, MoO.sub.3, V.sub.2O.sub.5, Nb.sub.2O.sub.5, CuO, Cr.sub.2O.sub.3, La.sub.2O.sub.3, RuO.sub.3, RuO.sub.2, ReO.sub.2, ReO.sub.3, Ag.sub.2O, CoO, Cu.sub.2O, SnO, NiO, Pr.sub.2O.sub.3, BaO, PdO.sub.2, HfO.sub.3, HfO.sub.3 or other metal oxide and their mixtures residing above and in engagement with the second electrolyte to improve sensor performance and/or to reduce sensor heating power consumption.

Hunter, Gary W.↗
DOE OSTI2025

XRISM/Resolve view of Abell 2319: Turbulence, sloshing, and ICM dynamics

Here, we present results from XRISM/Resolve observations of the core of the galaxy cluster Abell 2319, focusing on its kinematic properties. The intracluster medium (ICM) exhibits temperatures of approximately 8 keV across the core, with a prominent cold front and a high-temperature region (⁠~11 keV) in the north-west. The average gas velocity in the 3' x 4' region around the brightest cluster galaxy (BCG) covered by two Resolve pointings is consistent with that of the BCG to within 40 km s -1 ⁠ and we found modest average velocity dispersion of 230–250 km s -1 ⁠. On the other hand, spatially resolved spectroscopy reveals interesting variations. A blueshift of up to ~230 km s -1 ⁠ is observed around the east edge of the cold front, where the gas with the lowest specific entropy is found. The region further south inside the cold front shows only a small velocity difference from the BCG; however, its velocity dispersion is enhanced to ~400 km s -1 ⁠, implying the development of turbulence. These characteristics indicate that we are observing sloshing motion with some inclination angle following BCG and that gas phases with different specific entropy participate in sloshing with their own velocities, as expected from simulations. No significant evidence for a high-redshift ICM component associated with the subcluster Abell 2319B was found in the region covered by the current Resolve pointings. These results highlight the importance of sloshing and turbulence in shaping the internal structure of Abell 2319. Further deep observations are necessary to better understand the mixing and turbulent processes within the cluster.

Astronomy and AstroPhysics↗
DOE OSTI2020

Electrochemical deposition of N-heterocyclic carbene monolayers on metal surfaces

N-heterocyclic carbenes (NHCs) have been widely utilized for the formation of self-assembled monolayers (SAMs) on various surfaces. The main methodologies for preparation of NHCs-based SAMs either requires inert atmosphere and strong base for deprotonation of imidazolium precursors or the use of specifically-synthesized precursors such as NHC(H)[HCO 3 ] salts or NHC–CO 2 adducts. Herein, we demonstrate an electrochemical approach for surface-anchoring of NHCs which overcomes the need for dry environment, addition of exogenous strong base or restricting synthetic steps. In the electrochemical deposition, water reduction reaction is used to generate high concentration of hydroxide ions in proximity to a metal electrode. Imidazolium cations were deprotonated by hydroxide ions, leading to carbenes formation that self-assembled on the electrode’s surface. SAMs of NO 2 -functionalized NHCs and dimethyl-benzimidazole were electrochemically deposited on Au films. SAMs of NHCs were also electrochemically deposited on Pt, Pd and Ag films, demonstrating the wide metal scope of this deposition technique.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRS1995

Creep Testing of High-Temperature Cu-8 Cr-4 Nb Alloy Completed

A Cu-8 at.% Cr-4 at.% Nb (Cu-8 Cr-4 Nb) alloy is under development for high-temperature, high heatflux applications, such as actively cooled, hypersonic vehicle heat exchangers and rocket engine combustion chambers. Cu-8 Cr-4 Nb offers a superior combination of strength and conductivity. It has also shown exceptional low-cycle fatigue properties. Following preliminary testing to determine the best processing route, a more detailed testing program was initiated to determine the creep lives and creep rates of Cu-8 Cr-4 Nb alloy specimens produced by extrusion. Testing was conducted at the NASA Lewis Research Center with constant-load vacuum creep units. Considering expected operating temperatures and mission lives, we developed a test matrix to accurately determine the creep properties of Cu-8 Cr-4 Nb between 500 and 800 C. Six bars of Cu-8 Cr-4 Nb were extruded. From these bars, 54 creep samples were machined and tested. The figure on the left shows the steady-state, or second-stage, creep rates for the samples. Comparison data for NARloy-Z (Cu-3 wt % Ag-0.5 wt % Zr), the alloy currently used in combustion chamber liners, were not unavailable. Therefore the steady-state creep rates for Cu at similar temperatures are presented. As expected, in comparison to pure Cu, the creep rates for Cu-8 Cr-4 Nb are much lower. The lives of the samples are presented in the figure on the right. As shown, Cu-8 Cr-4 Nb at 800 C is comparable to NARloy-Z at 648 C. At equivalent temperatures, Cu-8 Cr-4 Nb enjoys a 20 to 50 percent advantage in stress for a given life and 1 to 3 orders of magnitude greater life at a given stress. The improved properties allow for design tradeoffs and improvements in new and existing heat exchangers such as the next generation of combustion chamber liners. Average creep rates for Cu-8 Cr-4 Nb and pure Cu are shown. Average creep lives for Cu-8 Cr- 4 Nb and NARloy-Z are also shown. Currently, two companies are interested in the commercial usage of the Cu-8 Cr-4 Nb alloy. The Rocketdyne Division of Rockwell International is conducting independent testing to analyze the properties for their projected needs in advanced rocket engine applications. Metallamics, a company based in Traverse City, Michigan, is entering into a Space Act Agreement to evaluate and test Cu-Cr-Nb alloys as materials for welding electrodes that are used in robotic welding operations. Creep rate is one of the alloy properties that determines the degree to which a welding electrode will mushroom or expand at the tip. A material with a low creep rate will resist mushrooming and give the electrode a longer life, minimizing downtime. This application holds the potential for large-scale usage of the alloy in the automotive and other industries. Success here would dramatically decrease the cost of the alloy and increase availability for aerospace applications.

Source record↗
DOE OSTI2020

Sputtered indium tin oxide as a recombination layer formed on the tunnel oxide/poly-Si passivating contact enabling the potential of efficient monolithic perovskite/Si tandem solar cells

We focus on utilizing sputtered indium tin oxide (ITO) as a recombination layer, having low junction damage to an n-type silicon solar cell with a front-side tunnel oxide passivating electron contact, thereby enabling the development of a high efficiency monolithic perovskite/Si tandem device. High transparency and low resistivity ITO films are deposited via low power DC magnetron sputtering at room temperature onto a front-side thin SiO x /n + poly-Si contact in a complete Cz n-Si cell with a back-side Al 2 O 3 /SiN x passivating boron-diffused p + -emitter on a random pyramid textured surface. We report the cell characteristics before and after ITO sputtering, and we find a cure at 250 °C in air is highly effective at mitigating any sputtering induced damage. Our ITO coated sample resulted in an implied open-circuit voltage (iV oc ) of 684.7 ± 11.3 mV with the total saturation current density of 49.2 ± 14.8 fA/cm 2 , an implied fill factor (iFF) of 81.9 ± 0.8%, and a contact resistivity in the range of 60 mΩ-cm 2 to 90 mΩ-cm 2 . After formation of a local Ag contact to the rear emitter and sputtered ITO film as the front-side contact without grid fingers, the pseudo-efficiency of 20.2 ± 0.5% was obtained with the V oc of 670.4 ± 7 mV and pseudo FF of 77.3 ± 1.3% under simulated one sun with the calculated short-circuit current density of 30.9 mA/cm 2 from the measured external quantum efficiency. Furthermore, our modelling result shows that efficiency exceeding 25% under one sun is practically achievable in perovskite/Si tandem configuration using the ITO recombination layer connecting a perovskite top cell and a poly-Si bottom cell.

14 SOLAR ENERGY↗
DOE OSTI2024

“Green” Fabrication of High-performance Transparent Conducting Electrodes by Blade Coating and Photonic Curing on PET for Perovskite Solar Cells

This study presents an innovative material processing approach to fabricate transparent conducting electrodes (TCEs) on polyethylene terephthalate (PET) substrates using blade coating and photonic curing. The hybrid TCEs consist of a multiscale Ag network, combining silver metal bus lines and nanowires, overcoated by an indium zinc oxide layer, and then photonically cured. Blade coating ensures film uniformity and thickness control over large areas. Photonic curing, a non-thermal processing method with significantly lower carbon emissions, enhances the conductivity and transparency of the coated layers. Our hybrid TCEs achieve an average transmittance of (81 ± 0.4)% referenced to air ((90 ± 0.4)% referenced to the PET substrate) in the visible range, an average sheet resistance of (11 ± 0.5) Ω sq−1, and an average surface roughness of (4.3 ± 0.4) nm. We benchmark these values against commercial PET/TCE substrates. Mechanical durability tests demonstrate <3% change in resistance after 2000 bending cycles at a 1 in radius. The scalable potential of the hybrid TCE fabrication method is demonstrated by high uniformity and excellent properties in 7 in × 8 in large-area samples and by performing the photonic curing process at 11 m min−1. Furthermore, halide perovskite solar cells fabricated on these hybrid TCEs achieve average and champion power conversion efficiencies of (10.5 ± 1.0) % and 12.2%, respectively, and significantly outperform devices made on commercial PET/TCEs. This work showcases our approach as a viable pathway for high-speed “green” manufacturing of high-performance TCEs on PET substrates for flexible optoelectronic devices.

Bonner, Justin C↗
DOE OSTI2020

Materials Data on BeAgPO4 by Materials Project

AgBePO4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Be2+ sites. In the first Be2+ site, Be2+ is bonded to four O2- atoms to form BeO4 tetrahedra that share corners with four PO4 tetrahedra. There are a spread of Be–O bond distances ranging from 1.63–1.66 Å. In the second Be2+ site, Be2+ is bonded to four O2- atoms to form BeO4 tetrahedra that share corners with four PO4 tetrahedra. There are a spread of Be–O bond distances ranging from 1.63–1.65 Å. In the third Be2+ site, Be2+ is bonded to four O2- atoms to form BeO4 tetrahedra that share corners with four PO4 tetrahedra. There are a spread of Be–O bond distances ranging from 1.62–1.66 Å. There are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.37–2.58 Å. In the second Ag1+ site, Ag1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ag–O bond distances ranging from 2.40–2.85 Å. In the third Ag1+ site, Ag1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Ag–O bond distances ranging from 2.62–3.20 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four BeO4 tetrahedra. There is three shorter (1.55 Å) and one longer (1.56 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four BeO4 tetrahedra. All P–O bond lengths are 1.55 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four BeO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.54–1.56 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Be2+, two Ag1+, and one P5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Be2+, two Ag1+, and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Be2+, two Ag1+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Be2+, one Ag1+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Be2+, two Ag1+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Be2+, two Ag1+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Be2+, two Ag1+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Be2+, two equivalent Ag1+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one Be2+, two equivalent Ag1+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to one Be2+, two equivalent Ag1+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Be2+, one Ag1+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to one Be2+, two Ag1+, and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Constraining gas motion and non-thermal pressure beyond the core of the Abell 2029 galaxy cluster with XRISM

We report on a detailed spectroscopic study of the gas dynamics and hydrostatic mass bias of the galaxy cluster Abell 2029, utilizing high-resolution observations from XRISM Resolve. Abell 2029, known for its cool core and relaxed X-ray morphology, provides an excellent opportunity to investigate the influence of gas motions beyond the central region. Expanding upon prior studies that revealed low turbulence and bulk motions within the core, our analysis covers regions out to the scale radius $R_{2500}$ (670 kpc) based on three radial pointings extending from the cluster center toward the northern side. We obtain accurate measurements of bulk and turbulent velocities along the line of sight. The results indicate that non-thermal pressure accounts for no more than 2% of the total pressure at all radii, with a gradual decrease outward. The observed radial trend differs from many numerical simulations, which often predict an increase in non-thermal pressure fraction at larger radii. These findings suggest that deviations from hydrostatic equilibrium are small, leading to a hydrostatic mass bias of around 2% across the observed area.

X-rays: galaxies: clusters↗
DOE OSTI2020

Materials Data on K3AgC4(SN)4 by Materials Project

K3AgC4(NS)4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 2-coordinate geometry to two equivalent N3- and four S2- atoms. There are one shorter (2.78 Å) and one longer (2.82 Å) K–N bond lengths. There are a spread of K–S bond distances ranging from 3.43–3.60 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to three N3- and four S2- atoms. There are a spread of K–N bond distances ranging from 2.82–2.98 Å. There are a spread of K–S bond distances ranging from 3.36–3.68 Å. In the third K1+ site, K1+ is bonded in a 7-coordinate geometry to five N3- and two equivalent S2- atoms. There are a spread of K–N bond distances ranging from 2.92–3.04 Å. There are one shorter (3.42 Å) and one longer (3.59 Å) K–S bond lengths. Ag1+ is bonded in a tetrahedral geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.59–2.63 Å. There are four inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.65 Å. In the second C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.19 Å. The C–S bond length is 1.65 Å. In the third C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.65 Å. In the fourth C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.19 Å. The C–S bond length is 1.64 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted single-bond geometry to three K1+ and one C4+ atom. In the second N3- site, N3- is bonded in a 3-coordinate geometry to two equivalent K1+ and one C4+ atom. In the third N3- site, N3- is bonded in a 1-coordinate geometry to two K1+, one C4+, and one S2- atom. The N–S bond length is 3.38 Å. In the fourth N3- site, N3- is bonded in a distorted single-bond geometry to three K1+ and one C4+ atom. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 2-coordinate geometry to three K1+, one Ag1+, one C4+, and one N3- atom. In the second S2- site, S2- is bonded in a 5-coordinate geometry to three K1+, one Ag1+, and one C4+ atom. In the third S2- site, S2- is bonded in a 5-coordinate geometry to three K1+, one Ag1+, and one C4+ atom. In the fourth S2- site, S2- is bonded in a 2-coordinate geometry to one K1+, one Ag1+, and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba4Mn2Ag2As4O17 by Materials Project

Ba4Mn2Ag2As4O17 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Ba2+ sites. In the first 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 2.72–3.17 Å. In the second 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 2.72–3.21 Å. In the third Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ba–O bond distances ranging from 2.68–2.95 Å. In the fourth Ba2+ site, Ba2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ba–O bond distances ranging from 2.65–2.86 Å. There are two inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with three AsO4 tetrahedra and edges with two equivalent MnO6 octahedra. There are a spread of Mn–O bond distances ranging from 1.90–2.17 Å. In the second Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with three AsO4 tetrahedra and edges with two equivalent MnO6 octahedra. There are a spread of Mn–O bond distances ranging from 1.91–2.19 Å. There are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.12–2.88 Å. In the second Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.14–2.84 Å. There are four inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with two MnO6 octahedra. The corner-sharing octahedra tilt angles range from 60–61°. There are a spread of As–O bond distances ranging from 1.71–1.75 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with two MnO6 octahedra. The corner-sharing octahedra tilt angles range from 58–60°. There is two shorter (1.72 Å) and two longer (1.74 Å) As–O bond length. In the third As5+ site, As5+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of As–O bond distances ranging from 1.77–1.83 Å. In the fourth As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with two MnO6 octahedra. The corner-sharing octahedra tilt angles range from 45–46°. There are a spread of As–O bond distances ranging from 1.71–1.76 Å. There are seventeen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Ba2+, one Mn2+, and one As5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two Ba2+, one Mn2+, and one As5+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two Ba2+, one Mn2+, and one As5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Ba2+, one Mn2+, and one As5+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to one Ba2+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+ and one As5+ atom. In the seventh O2- site, O2- is bonded to one Ba2+, two Mn2+, and one Ag1+ atom to form distorted corner-sharing OBaMn2Ag tetrahedra. In the eighth O2- site, O2- is bonded to one Ba2+, two Mn2+, and one Ag1+ atom to form distorted corner-sharing OBaMn2Ag tetrahedra. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+ and one As5+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+ and one As5+ atom. In the eleventh O2- site, O2- is bonded in a distorted T-shaped geometry to two Mn2+ and one As5+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to two Mn2+ and one As5+ atom. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, two Ag1+, and one As5+ atom. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, two Ag1+, and one As5+ atom. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+ and one As5+ atom. In the sixteenth O2- site, O2- is bonded in a distorted single-bond geometry to three Ba2+ and one As5+ atom. In the seventeenth O2- site, O2- is bonded in a distorted single-bond geometry to three Ba2+ and one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Hollow-structured Ni-N-C catalysts for highly selective CO 2 electroreduction

Atomically dispersed single-atom catalysts have emerged as promising non-precious catalyst alternatives to expensive Ag and Au catalysts for electrochemical CO 2 reduction reaction (CO 2 RR). In particular, nickel-nitrogen-carbon (Ni-N-C) catalysts have demonstrated a high faradaic efficiency (FE) toward CO formation at low overpotentials. Nonetheless, the exact nature of Ni active sites under CO 2 RR remains elusive and conventional Ni-N-C catalysts are limited by microporosity and low density of Ni single atoms, hindering performance in CO 2 electrolyzers. Here, we report the synthesis of hollow-structured Ni-N-C ( hs -Ni-N-C) catalysts via a post-synthesis modification (PSM) strategy using partial ligand exchange of 2-methylimidazole with 3-amino-1,2,4-triazole. This approach enables the formation of a hollow structure, resulting in more than a twofold increase in Ni atom density compared to regular Ni-N-C (r-Ni-N-C). In a zero-gap CO 2 electrolyzer, the optimized hs -Ni-N-C allows for achieving an FE CO of 97% at a current density of > 100 mA cm⁻ 2 , while maintaining high CO selectivity with stable performance over 100 h at 2.5 V. hs-Ni-N-C shows a more than sevenfold increase in the CO partial current density relative to r-Ni-N-C resulting from the combined effects of a higher density of Ni single-atom sites, improved kinetics, and lower transport resistance under the operating conditions, as indicated by electrochemical impedance spectra and distribution of relaxation times analysis. Operando high energy-resolution X-ray absorption spectroscopy (XAS) reveals that atop-bonded CO on Ni single sites induces dynamic transformations of the Ni–N coordination environment, leading to a symmetric coordination structure of hs -Ni-N-C. Under CO 2 RR, the catalysts undergo a more pronounced structural change and form a minor fraction of Ni nanoparticles. Density functional theory calculations are consistent with the XAS results and provide molecular insights showing that the interplay between protonation and CO adsorption leads to adsorbate-induced restructuring of the Ni single atom. This work demonstrates the synergistic role of hollow structure and high-density Ni atoms in governing CO 2 RR selectivity and provides mechanistic insights into the structural dynamics of single-atom catalysts under operating conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZnAg2P2O9 by Materials Project

Ag2ZnP2O9 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are four inequivalent Ag3+ sites. In the first Ag3+ site, Ag3+ is bonded to six O2- atoms to form distorted AgO6 octahedra that share corners with two equivalent AgO6 octahedra, corners with four ZnO6 octahedra, corners with three equivalent PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–63°. There are a spread of Ag–O bond distances ranging from 2.05–2.24 Å. In the second Ag3+ site, Ag3+ is bonded to six O2- atoms to form distorted AgO6 octahedra that share corners with two equivalent AgO6 octahedra, corners with four ZnO6 octahedra, corners with three equivalent PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–62°. There are a spread of Ag–O bond distances ranging from 2.05–2.27 Å. In the third Ag3+ site, Ag3+ is bonded to six O2- atoms to form distorted AgO6 octahedra that share corners with two equivalent AgO6 octahedra, corners with two equivalent ZnO6 octahedra, corners with four PO4 tetrahedra, and edges with two equivalent AgO6 octahedra. The corner-sharing octahedra tilt angles range from 55–70°. There are a spread of Ag–O bond distances ranging from 2.03–2.61 Å. In the fourth Ag3+ site, Ag3+ is bonded to six O2- atoms to form distorted AgO6 octahedra that share corners with two equivalent AgO6 octahedra, corners with two equivalent ZnO6 octahedra, corners with four PO4 tetrahedra, and edges with two equivalent AgO6 octahedra. The corner-sharing octahedra tilt angles range from 55–70°. There are a spread of Ag–O bond distances ranging from 2.03–2.62 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to six O2- atoms to form distorted ZnO6 octahedra that share corners with six AgO6 octahedra, corners with four PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–70°. There are a spread of Zn–O bond distances ranging from 2.11–2.56 Å. In the second Zn2+ site, Zn2+ is bonded to six O2- atoms to form distorted ZnO6 octahedra that share corners with six AgO6 octahedra, corners with four PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–70°. There are a spread of Zn–O bond distances ranging from 2.09–2.57 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with five AgO6 octahedra and an edgeedge with one ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 36–54°. There are a spread of P–O bond distances ranging from 1.51–1.57 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with five AgO6 octahedra and an edgeedge with one ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 36–54°. There are a spread of P–O bond distances ranging from 1.50–1.57 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent AgO6 octahedra, corners with four ZnO6 octahedra, and an edgeedge with one AgO6 octahedra. The corner-sharing octahedra tilt angles range from 29–60°. There are a spread of P–O bond distances ranging from 1.55–1.59 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent AgO6 octahedra, corners with four ZnO6 octahedra, and an edgeedge with one AgO6 octahedra. The corner-sharing octahedra tilt angles range from 28–60°. There are a spread of P–O bond distances ranging from 1.55–1.59 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ag3+, one Zn2+, and one P5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ag3+, one Zn2+, and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ag3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ag3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to three Ag3+ atoms. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to three Ag3+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ag3+, one Zn2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Ag3+, one Zn2+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Ag3+, one Zn2+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ag3+, one Zn2+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ag3+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to one Ag3+, one Zn2+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a 1-coordinate geometry to one Ag3+, one Zn2+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ag3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbAgS2 by Materials Project

TbAgS2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are four inequivalent Tb3+ sites. In the first Tb3+ site, Tb3+ is bonded to six S2- atoms to form TbS6 octahedra that share corners with four equivalent TbS6 octahedra, corners with two AgS5 trigonal bipyramids, edges with four TbS6 octahedra, and edges with five AgS5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 17–22°. There are a spread of Tb–S bond distances ranging from 2.74–2.79 Å. In the second Tb3+ site, Tb3+ is bonded to six S2- atoms to form TbS6 octahedra that share corners with four equivalent TbS6 octahedra, corners with two equivalent AgS5 trigonal bipyramids, edges with four TbS6 octahedra, and edges with six AgS5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 17–22°. There are a spread of Tb–S bond distances ranging from 2.74–2.79 Å. In the third Tb3+ site, Tb3+ is bonded to six S2- atoms to form TbS6 octahedra that share corners with four equivalent TbS6 octahedra, corners with two AgS5 trigonal bipyramids, edges with four TbS6 octahedra, and edges with five AgS5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 17–22°. There are a spread of Tb–S bond distances ranging from 2.74–2.79 Å. In the fourth Tb3+ site, Tb3+ is bonded to six S2- atoms to form TbS6 octahedra that share corners with four equivalent TbS6 octahedra, corners with three AgS5 trigonal bipyramids, edges with four TbS6 octahedra, and edges with two equivalent AgS5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 17–22°. There are a spread of Tb–S bond distances ranging from 2.75–2.78 Å. There are four inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded to five S2- atoms to form distorted AgS5 trigonal bipyramids that share corners with three TbS6 octahedra, corners with five AgS5 trigonal bipyramids, edges with six TbS6 octahedra, and an edgeedge with one AgS5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 9–79°. There are a spread of Ag–S bond distances ranging from 2.48–3.15 Å. In the second Ag1+ site, Ag1+ is bonded to five S2- atoms to form distorted AgS5 trigonal bipyramids that share corners with three TbS6 octahedra, corners with six AgS5 trigonal bipyramids, edges with six TbS6 octahedra, and an edgeedge with one AgS5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 9–81°. There are a spread of Ag–S bond distances ranging from 2.48–3.29 Å. In the third Ag1+ site, Ag1+ is bonded to five S2- atoms to form distorted AgS5 trigonal bipyramids that share corners with three TbS6 octahedra, corners with five AgS5 trigonal bipyramids, and edges with six TbS6 octahedra. The corner-sharing octahedra tilt angles range from 11–76°. There are a spread of Ag–S bond distances ranging from 2.48–3.14 Å. In the fourth Ag1+ site, Ag1+ is bonded in a 5-coordinate geometry to five S2- atoms. There are a spread of Ag–S bond distances ranging from 2.46–3.32 Å. There are eight inequivalent S2- sites. In the first S2- site, S2- is bonded to three Tb3+ and two Ag1+ atoms to form distorted STb3Ag2 square pyramids that share corners with two equivalent STb3Ag3 octahedra, corners with two STb3Ag2 square pyramids, edges with two equivalent STb3Ag3 octahedra, and edges with three STb3Ag2 square pyramids. The corner-sharing octahedral tilt angles are 79°. In the second S2- site, S2- is bonded to three Tb3+ and three Ag1+ atoms to form distorted STb3Ag3 octahedra that share corners with seven STb3Ag2 square pyramids, edges with two equivalent STb3Ag3 octahedra, and edges with four STb3Ag2 square pyramids. In the third S2- site, S2- is bonded to three Tb3+ and three Ag1+ atoms to form distorted STb3Ag3 octahedra that share corners with seven STb3Ag2 square pyramids, edges with two equivalent STb3Ag3 octahedra, and edges with four STb3Ag2 square pyramids. In the fourth S2- site, S2- is bonded in a 6-coordinate geometry to three Tb3+ and three Ag1+ atoms. In the fifth S2- site, S2- is bonded to three Tb3+ and two equivalent Ag1+ atoms to form distorted STb3Ag2 square pyramids that share corners with five STb3Ag3 octahedra, corners with two STb3Ag2 square pyramids, edges with two equivalent STb3Ag3 octahedra, and edges with three STb3Ag2 square pyramids. The corner-sharing octahedra tilt angles range from 3–27°. In the sixth S2- site, S2- is bonded to three Tb3+ and two Ag1+ atoms to form distorted STb3Ag2 square pyramids that share corners with two equivalent STb3Ag3 octahedra, corners with two STb3Ag2 square pyramids, edges with two equivalent STb3Ag3 octahedra, and edges with three STb3Ag2 square pyramids. The corner-sharing octahedra tilt angles range from 77–78°. In the seventh S2- site, S2- is bonded to three Tb3+ and two equivalent Ag1+ atoms to form distorted STb3Ag2 square pyramids that share corners with five STb3Ag3 octahedra, corners with two STb3Ag2 square pyramids, edges with two equivalent STb3Ag3 octahedra, and edges with three STb3Ag2 square pyramids. The corner-sharing octahedra tilt angles range from 5–26°. In the eighth S2- site, S2- is bonded in a 6-coordinate geometry to three Tb3+ and three Ag1+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS2011

Kinematics and Kinetics of Squat and Deadlift Exercises with Varying Stance Widths

The primary motion of squat and deadlift exercise involves flexion and extension of the hips, knees, and ankles, but each exercise can be performed with variations in stance width. These variations may result in differing kinematics and ground reaction forces (GRF), which may in turn affect joint loading. PURPOSE: The purpose of this investigation was to compare ankle, knee, and hip kinematics and kinetics of normal squat (NS), wide-stance squat (WS), normal deadlift (ND), and sumo deadlift (SD). We hypothesized that hip joint kinematics and work at each joint would differ between exercise variations. METHODS: Six subjects (3 m/3 f; 70.0 plus or minus 13.7 kg; 168 plus or minus 9.9 cm) performed each lift in normal gravity on the ground-based version of the Advanced Resistive Exercise Device (ARED) used on the International Space Station. The ARED provided resistance with a combination vacuum tube/flywheel mechanism designed to replicate the gravitational and inertial forces of free weights. Subjects completed each lift with their 10-repetition maximum load. Kinematic data were collected at 250 Hz by a 12-camera motion-capture system (Smart-D, BTS Bioengineering, Milan, Italy), and GRF data were collected at 1000 Hz with independent force platforms for each leg (Model 9261, Kistler Instruments AG, Winterhur, Switzerland). All data were captured simultaneously on a single workstation. The right leg of a single lift for each motion was analyzed. Modeling software (OpenSim 2.2.0, Simbios, Palo Alto, CA) determined joint kinematics and net positive and negative work at each lower extremity joint. Total work was found as the sum of work across all joints and was normalized by system mass. Effect sizes and their 95% confidence intervals were computed between conditions. RESULTS: Peak GRF were similar for each lift. There were no differences between conditions in hip flexion range of motion (ROM). For hip adduction ROM, there were no differences between the NS, WS, and SD. However, hip adduction ROM was greater during the NS and SD than during the ND. Hip rotation ROM was greater during the WS than during the NS and SD, and was greater during the SD than during the ND. For knee and ankle flexion ROM, the ND, WS, and SD were not different, but ROM was greater during the NS than the ND and greater during the WS than the SD. Total eccentric work was greater during the WS than the SD. Otherwise, there were no differences in eccentric or concentric work between conditions. CONCLUSIONS: Although squat and deadlift exercises consist of similar motions, there are kinematic differences between them that depend on stance width. Total eccentric and concentric work are similar for different lifts, but differing kinematics may require activation of different musculature for each variation. With respect to each condition, in the ND the ROM of each joint tended to be less, and the WS tended to trade knee motion for hip motion. PRACTICAL APPLICATIONS: Knowledge of differences in kinematics and kinetics between different squat and deadlift variations is important for coaches and rehabilitation personnel to understand when prescribing exercise. Our results suggest that each variation of the squat and deadlift should be considered a separate exercise that may induce different long-term training effects.

DeWitt, John K.↗
NASA NTRS2002

M-FISH Analysis of Chromosome Aberrations in Human Fibroblast Cells After In Vitro Exposure to Low- and High-LET Radiation

The recently commercialized multiplex fluorescence in situ hybridization (m-FISH) technique, which allows human chromosomes to be painted in 24 different colors, was used to analyze chromosome aberrations in diploid human fibroblast cells after in vitro radiation exposure. Confluent flasks of a normal primary fibroblast cell line (AG 1522) were irradiated at high dose rates with either gamma rays or 200 MeV/nucleon Fe ions (LET = 440 keV/micron), incubated at 37 C for 24 hours after exposure, and subsequently subcultured. A chemically induced premature chromosome condensation technique was used to collect chromosome samples 32 hours after subculture. Results showed that the fraction of exchanges which were identified as complex, i.e. involving misrejoining of three or more DSB, were higher in the Fe-irradiated samples compared with the gamma-irradiated samples, as has been shown previously using FISH with one or two painted chromosomes . The ratios of complex/simple type exchanges were similar for samples irradiated with 0.7 Gy and 3 Gy of Fe ions, although exchanges involving five or more breaks were found only in 3 Gy irradiated samples. The fraction of incomplete exchanges was also higher in Fe- than gamma-irradiated samples. Data on the distribution of individual chromosome involvement in interchromosomal exchanges will be presented.

Wu, Honglu↗
DOE OSTI2020

Materials Data on Ag3B5O9 by Materials Project

Ag3B5O9 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. there are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to two O2- atoms. Both Ag–O bond lengths are 2.21 Å. In the second Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.30–2.58 Å. In the third Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.39–2.54 Å. There are five inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.47–1.49 Å. In the second B3+ site, B3+ is bonded in a distorted trigonal planar geometry to three O2- atoms. There is two shorter (1.38 Å) and one longer (1.42 Å) B–O bond length. In the third B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.52 Å. In the fourth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.47–1.50 Å. In the fifth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.38 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ag1+ and two B3+ atoms. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Ag1+ and two B3+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ag1+ and two B3+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ag1+ and two B3+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ag1+ and two B3+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ag1+ and two B3+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ag1+ and two B3+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ag1+ and two B3+ atoms. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NdAgH10C20(N3O4)2 by Materials Project

Nd(CO2)4AgH4(CN)6(C)4(CH)6 crystallizes in the monoclinic C2/c space group. The structure is one-dimensional and consists of sixteen methane molecules; twenty-four methane molecules; four AgH4(CN)6 clusters; and two Nd(CO2)4 ribbons oriented in the (0, 0, 1) direction. In each AgH4(CN)6 cluster, Ag1+ is bonded in a distorted linear geometry to two equivalent N3- atoms. Both Ag–N bond lengths are 2.11 Å. There are three inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a trigonal planar geometry to two N3- and one H1+ atom. There is one shorter (1.32 Å) and one longer (1.36 Å) C–N bond length. The C–H bond length is 1.08 Å. In the second C1+ site, C1+ is bonded in a trigonal planar geometry to two N3- and one H1+ atom. There is one shorter (1.31 Å) and one longer (1.37 Å) C–N bond length. The C–H bond length is 1.08 Å. In the third C1+ site, C1+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.43 Å. There are three inequivalent N3- sites. In the first N3- site, N3- is bonded in a trigonal planar geometry to three C1+ atoms. In the second N3- site, N3- is bonded in a 3-coordinate geometry to one Ag1+, one C1+, and one N3- atom. The N–N bond length is 1.38 Å. In the third N3- site, N3- is bonded in a distorted single-bond geometry to one C1+ and one N3- atom. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C1+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C1+ atom. In each Nd(CO2)4 ribbon, Nd3+ is bonded in a distorted hexagonal bipyramidal geometry to eight O2- atoms. There are a spread of Nd–O bond distances ranging from 2.39–2.57 Å. There are two inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.28 Å. In the second C1+ site, C1+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.27 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Nd3+ and one C1+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to one Nd3+ and one C1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Nd3+ and one C1+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Nd3+ and one C1+ atom.

36 MATERIALS SCIENCE↗