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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

The Effect of Environment on Galaxy Spiral Arms, Bars, Concentration, and Quenching

For a sample of 4378 nearby spiral and S0 galaxies, Yu & Ho used Fourier analysis of Sloan Digital Sky Survey images to show that the strengths of the spiral arms and the pitch angles of the arms are inversely correlated with central concentration. In the current study, we search for trends in the Yu & Ho spiral arm parameters with environment and specific star formation rate (sSFR). When comparing galaxies with similar concentrations, we do not find a significant difference in the arm strengths or pitch angles of spiral galaxies in clusters compared to field galaxies. When differences in concentration are taken into account, we also find no significant difference in the parameter f3 for cluster spirals compared to field spirals, where f3 is the normalized m = 3 Fourier amplitude. When concentration is held fixed, both arm strength and pitch angle are correlated with sSFR, but f3 is not. These relations support the suggestion by Davis et al. of a "fundamental plane" of spiral structure involving pitch angle, bulge stellar mass, and gas surface density. We discuss these results in terms of theories of spiral arm production and quenching in galaxies. To aid comparison with earlier studies based on Galaxy Zoo, we explore how the Yu & Ho parameters relate to similar parameters measured by Galaxy Zoo (i.e., f3 versus the number of arms, pitch angle versus winding parameter, and concentration versus bulge class).

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Materials Data on HoAl3(BO3)4 by Materials Project

HoAl3(BO3)4 is Calcite-derived structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are four shorter (2.33 Å) and two longer (2.34 Å) Ho–O bond lengths. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–1.95 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–1.95 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.37–1.39 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.38 Å) and two longer (1.39 Å) B–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+, one Al3+, and one B3+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one B3+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+, one Al3+, and one B3+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one B3+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+, one Al3+, and one B3+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one B3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Surface plasmon driven near- and midinfrared photoconductivity in ligand-free ITO nanocrystal films

Semiconductor nanocrystals (NCs) offer exciting opportunities to deploy infrared optoelectronic technology in a variety of applications that are off-limits to conventional single-crystalline materials. However, the performance and stability of state-of-the-art NC-based devices strongly depend on the details of the NC surface and its passivating ligands. Here, the authors use indium tin oxide NC films stripped of organic ligands and conformally coated with Al 2 O 3 to show that absorption enabled by infrared localized surface plasmon resonances permit infrared photoconduction. For Au electrodes, these metallic NC films exhibit stable photoconductive performance over months in ambient and under electrical stress.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al2FeP2(HO)18 by Materials Project

Fe(OH)2(AlPO4(H2O)2)2(H2O)4 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one iron dihydroxide molecule; four water molecules; and one AlPO4(H2O)2 sheet oriented in the (0, 0, 1) direction. In the AlPO4(H2O)2 sheet, there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra and corners with four equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Al–O bond distances ranging from 1.89–2.00 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Al–O bond distances ranging from 1.87–1.96 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three AlO6 octahedra. The corner-sharing octahedra tilt angles range from 41–51°. There are a spread of P–O bond distances ranging from 1.52–1.64 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.67 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Al3+ and two H1+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Al3+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Al3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a water-like geometry to one P5+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Al3+, one P5+, and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

High-volume and -adiabat capsule (“HVAC”) ignition: Lowered fuel compression requirements using advanced Hohlraums

Lower-than-expected deuterium–tritium fuel areal densities have been experimentally inferred across a variety of high-convergence, nominally low-adiabat implosion campaigns at the National Ignition Facility (NIF) using cylinder-shaped Hohlraums [Hurricane et al., Phys. Plasmas 26, 052704 (2019)]. A leading candidate explanation is the presence of atomic mix between the fuel and ablator from hydrodynamic instability growth [Clark et al., Phys. Plasmas 26, 050601 (2019)], leading to reduced fuel compressibility and an effectively higher (in-flight) fuel adiabat α. Tolerating a high-α implosion can be obtained with significantly higher capsule absorbed energy Ecap according to the one-dimensional (1-D) ignition-threshold-factor analytic scaling [S. Atzeni and J. Meyer-ter-Vehn, Nucl. Fusion 41, 465 (2001)], ITF∼Ecap·α−1.8. Recent experiments with large Al shells in rugby-shaped Hohlraums have established high laser-capsule coupling efficiencies of ≽ 30% [Ping et al., Nat. Phys. 15, 138 (2019)], enabling a path to Ecap≽ 0.5 MJ at the NIF and increased performance margin M ≡ ITF − 1. The ability to operate at high adiabat with large capsules using nonstandard Hohlraums leads to the predicted onset of a volume-ignition mode, defined as when both the entire fuel is the “hot spot” and inertial confinement is principally provided by the ablator compared with the compressed fuel. Such an ignition mode, normally reserved for high-Z targets, e.g., double shells [Amendt et al., Phys. Plasmas 14, 056312 (2007)], is predicted to lead to lower fuel convergence and less exposure to mix due to the intended high adiabat—but at the expense of ∼3–4 × reduced (1-D) yield compared with conventional central hot-spot ignition designs.

Amendt, Peter (ORCID:0000000174021777)↗
DOE OSTI2023

PotLib 2023: New version of a potential energy surface library for chemical systems

POTLIB is a library of global and semiglobal potential energy surface subprograms. The library currently features 410 entries, including both single-state entries and multi-state entries. When one calls the routine of a single-state entry, it returns the ground-electronic-state adiabatic potential energy surface at the input geometry. In addition, some entries also return the gradient of the surface. Further, when one calls a multi-state entry, it returns a diabatic potential energy matrix (DPEM). If the entry also has the gradient of the DPEM, one can compute adiabatic surfaces, their gradients, and the nonadiabatic coupling vectors (NACs) from the DPEM and its gradient by diagonalization. Some but not all the routines conform to one of a set of standard interfaces. The goal is to facilitate chemical dynamics research by collecting and disseminating a comprehensive collection of state-of-the-art potential energy routines (developed by a wide, international group of researchers) with systematic and well-defined interfaces for use with chemical dynamics programs. Systems in the library include CHArO 2 , CHN 2 O + , CH 2 O, CH 2 O 2 , CH 3 N 2 , CH 3 O, CH 4 , CH 4 Br, CH 4 Cl, CH 4 F, CH 4 O, CH 4 OCl, CH 4 OF, CH 4 OH, CH 5 , CH$^{+}_{5}$, CH 5 N, CH 5 O 2 , CH 8 O 2 , C 2 H 2 N 2 O, C 2 H 2 O, C 2 H 4 N, C 2 H 4 O 4 , C 2 H 6 Cl, C 2 H 6 F, C 2 H 6 H, C 2 H 6 O, C 2 H 6 OH, C 2 H 7 , C 2 O 2 , C 3 H 4 O 2 , C 3 H 7 NO, C 6 H 6 O, C 6 H 6 S, C 7 H8S, HBrCl, HCl 2 , HF 2 , HI 2 , HLiF, HNaF, HO 2 , HO 3 , HOBr, HSiO, H 2 Br, H 2 ClO, H 2 F, H 2 F 2 , H 2 FO, H 2 Na, H 2 O, H 2 O 2 , H 2 OBr, H 3 , H 3 Cl, H 3 ClN, H 3 ClO, H 3 N, H 3 O, H 3 O 2 , H$^{+}_{3}$, H 3 S, H 4 ClSi, H 4 N, H 4 NO, H 4 O 2 , H 5 GeO, H 5 Si, H$^{+}_{7}$, Al m H n , Al n , Ar N O, K 2 Rb 2 , NO 2 , N 2 O, N 2 O 2 , N 3 , N 4 , O 3 , and O 4 .

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

Materials Data on Mg4Al2H12CO18 by Materials Project

(Mg2Al(HO)6)4(CO3)2(O2)3 crystallizes in the trigonal P31m space group. The structure is two-dimensional and consists of one carbonic acid molecule; three water molecules; and two Mg2Al(HO)6 sheets oriented in the (0, 0, 1) direction. In each Mg2Al(HO)6 sheet, Mg is bonded to six O atoms to form MgO6 octahedra that share edges with three equivalent MgO6 octahedra and edges with three equivalent AlO6 octahedra. There are three shorter (2.09 Å) and three longer (2.10 Å) Mg–O bond lengths. Al is bonded to six O atoms to form AlO6 octahedra that share edges with six equivalent MgO6 octahedra. All Al–O bond lengths are 1.93 Å. There are two inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. There are two inequivalent O sites. In the first O site, O is bonded in a 1-coordinate geometry to two equivalent Mg, one Al, and one H atom. In the second O site, O is bonded in a 1-coordinate geometry to two equivalent Mg, one Al, and one H atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiMn3Al2(HO2)6 by Materials Project

LiAl2(HO)6(MnO2)3 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one LiAl2(HO)6 sheet oriented in the (0, 0, 1) direction and one MnO2 sheet oriented in the (0, 0, 1) direction. In the LiAl2(HO)6 sheet, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share edges with six equivalent AlO6 octahedra. There are four shorter (2.10 Å) and two longer (2.14 Å) Li–O bond lengths. Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share edges with three equivalent LiO6 octahedra and edges with three equivalent AlO6 octahedra. There is four shorter (1.91 Å) and two longer (1.93 Å) Al–O bond length. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Li1+, two equivalent Al3+, and one H1+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Li1+, two equivalent Al3+, and one H1+ atom. In the MnO2 sheet, there are two inequivalent Mn+3.67+ sites. In the first Mn+3.67+ site, Mn+3.67+ is bonded to six O2- atoms to form edge-sharing MnO6 octahedra. There are a spread of Mn–O bond distances ranging from 1.92–1.97 Å. In the second Mn+3.67+ site, Mn+3.67+ is bonded to six O2- atoms to form edge-sharing MnO6 octahedra. There are four shorter (1.98 Å) and two longer (2.15 Å) Mn–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Mn+3.67+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three Mn+3.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Interfacial stabilization for epitaxial CuCrO 2 delafossites

AB O 2 delafossites are fascinating materials that exhibit a wide range of physical properties, including giant Rashba spin splitting and anomalous Hall effects, because of their characteristic layered structures composed of noble metal A and strongly correlated B O 2 sublayers. However, thin film synthesis is known to be extremely challenging owing to their low symmetry rhombohedral structures, which limit the selection of substrates for thin film epitaxy. Hexagonal lattices, such as those provided by Al 2 O 3 (0001) and (111) oriented cubic perovskites, are promising candidates for epitaxy of delafossites. However, the formation of twin domains and impurity phases is hard to suppress, and the nucleation and growth mechanisms thereon have not been studied for the growth of epitaxial delafossites. In this study, we report the epitaxial stabilization of a new interfacial phase formed during pulsed-laser epitaxy of (0001)-oriented CuCrO 2 epitaxial thin films on Al 2 O 3 substrates. Through a combined study using scanning transmission electron microscopy/electron-energy loss spectroscopy and density functional theory calculations, we report that the nucleation of a thermodynamically stable, atomically thick CuCr 1-x Al x O 2 interfacial layer is the critical element for the epitaxy of CuCrO 2 delafossites on Al 2 O 3 substrates. This finding provides key insights into the thermodynamic mechanism for the nucleation of intermixing-induced buffer layers that can be used for the growth of other noble-metal-based delafossites, which are known to be challenging due to the difficulty in initial nucleation.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba2Ho2Al3Si5N11O3 by Materials Project

Ba2Ho2Al3Si5N11O3 crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to three equivalent N3- and three equivalent O2- atoms to form BaN3O3 octahedra that share corners with three equivalent AlN4 tetrahedra and corners with nine SiN4 tetrahedra. All Ba–N bond lengths are 2.50 Å. All Ba–O bond lengths are 2.69 Å. In the second Ba2+ site, Ba2+ is bonded to six N3- atoms to form BaN6 octahedra that share corners with six equivalent AlN4 tetrahedra and corners with six SiN2O2 tetrahedra. There are three shorter (2.52 Å) and three longer (2.64 Å) Ba–N bond lengths. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 3-coordinate geometry to three equivalent N3- atoms. All Ho–N bond lengths are 2.26 Å. In the second Ho3+ site, Ho3+ is bonded in a distorted T-shaped geometry to three equivalent N3- atoms. All Ho–N bond lengths are 2.47 Å. Al3+ is bonded to four N3- atoms to form AlN4 tetrahedra that share corners with three BaN3O3 octahedra, corners with two SiN4 tetrahedra, and corners with four equivalent AlN4 tetrahedra. The corner-sharing octahedral tilt angles are 61°. There are a spread of Al–N bond distances ranging from 1.80–2.07 Å. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with three equivalent BaN6 octahedra, corners with three equivalent AlN4 tetrahedra, and corners with three equivalent SiN2O2 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There is three shorter (1.72 Å) and one longer (1.88 Å) Si–N bond length. In the second Si4+ site, Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with three equivalent BaN3O3 octahedra, corners with three equivalent AlN4 tetrahedra, and corners with three equivalent SiN2O2 tetrahedra. The corner-sharing octahedral tilt angles are 52°. There is three shorter (1.68 Å) and one longer (1.99 Å) Si–N bond length. In the third Si4+ site, Si4+ is bonded to two N3- and two equivalent O2- atoms to form SiN2O2 tetrahedra that share corners with three BaN3O3 octahedra and corners with six SiN4 tetrahedra. The corner-sharing octahedra tilt angles range from 64–68°. There is one shorter (1.64 Å) and one longer (2.10 Å) Si–N bond length. Both Si–O bond lengths are 1.72 Å. There are five inequivalent N3- sites. In the first N3- site, N3- is bonded in a trigonal planar geometry to one Ba2+, one Al3+, and one Si4+ atom. In the second N3- site, N3- is bonded to three equivalent Al3+ and one Si4+ atom to form distorted corner-sharing NAl3Si trigonal pyramids. In the third N3- site, N3- is bonded in a tetrahedral geometry to four Si4+ atoms. In the fourth N3- site, N3- is bonded in a distorted trigonal planar geometry to one Ba2+ and two Si4+ atoms. In the fifth N3- site, N3- is bonded to one Ba2+, two Ho3+, and two equivalent Al3+ atoms to form distorted NBaHo2Al2 trigonal bipyramids that share corners with two equivalent NAl3Si trigonal pyramids and edges with four equivalent NBaHo2Al2 trigonal bipyramids. O2- is bonded in a distorted trigonal planar geometry to one Ba2+ and two equivalent Si4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaMn6Al3H42(SO19)2 by Materials Project

Na(H2O)6(Mn2Al(HO)6)3(H2O)6(SO4)2 crystallizes in the trigonal R-3 space group. The structure is two-dimensional and consists of three sodium;hexahydrate molecules; six sulfuric acid molecules; eighteen water molecules; and three Mn2Al(HO)6 sheets oriented in the (0, 0, 1) direction. In each Mn2Al(HO)6 sheet, Mn is bonded to six O atoms to form distorted MnO6 octahedra that share edges with three equivalent MnO6 octahedra and edges with three AlO6 octahedra. There are a spread of Mn–O bond distances ranging from 2.19–2.26 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to six O atoms to form AlO6 octahedra that share edges with six equivalent MnO6 octahedra. There is three shorter (1.92 Å) and three longer (1.94 Å) Al–O bond length. In the second Al site, Al is bonded to six equivalent O atoms to form AlO6 octahedra that share edges with six equivalent MnO6 octahedra. All Al–O bond lengths are 1.93 Å. There are three inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. There are three inequivalent O sites. In the first O site, O is bonded in a 1-coordinate geometry to two equivalent Mn, one Al, and one H atom. In the second O site, O is bonded in a 1-coordinate geometry to two equivalent Mn, one Al, and one H atom. In the third O site, O is bonded in a 1-coordinate geometry to two equivalent Mn, one Al, and one H atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Novel Transformational Membranes and Process for CO 2 Capture from Flue Gas (FE0031731)

The objectives of this project are to develop a cost-effective design and fabrication process for a novel transformational membrane and its membrane modules that capture CO 2 from flue gas. Optimization of the novel transformational membrane, scale-up of the membrane to a prototype size of about 20" wide in continuous roll-to-roll fabrication, and construction and testing of a skid for the integrated membrane process will be performed. For the design of this membrane, we use a cost-effective polymer support and coat a thin top layer of the membrane. The simplicity of this membrane design offers a low cost for the membrane element in commercial spiral-wound (SW) configuration (<$2.00/ft 2 or $21.5/m 2 ). The prototype membrane will be used to fabricate 6 pilot-size membrane modules (each about 20" length, 3 modules each at the commercial-size diameter of 8 inches with 35 m 2 membrane area for Stage 1 and 3 modules each at 5-inch diameter with 12 m 2 membrane area for Stage 2) for testing with simulated flue gas at OSU and with actual flue gas at the National Carbon Capture Center, Wilsonville, AL using the skid to capture the CO 2 (at 60 – 90%) with at least 95% CO 2 purity. The prototype membrane modules will be in commercial SW configuration with a minimal pressure drop (<0.103 bar/meter (1.5 psi/meter)). These objectives have been achieved successfully.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2020

Materials Data on Ho11Cd45 by Materials Project

Ho11Cd45 is Bergman Structure: Mg32(Al,Zn)49 Bergman-derived structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. there are five inequivalent Ho sites. In the first Ho site, Ho is bonded in a 8-coordinate geometry to fourteen Cd atoms. There are a spread of Ho–Cd bond distances ranging from 3.13–3.39 Å. In the second Ho site, Ho is bonded in a 12-coordinate geometry to fourteen Cd atoms. There are a spread of Ho–Cd bond distances ranging from 3.16–3.80 Å. In the third Ho site, Ho is bonded in a 4-coordinate geometry to sixteen Cd atoms. There are four shorter (3.25 Å) and twelve longer (3.36 Å) Ho–Cd bond lengths. In the fourth Ho site, Ho is bonded in a 3-coordinate geometry to sixteen Cd atoms. There are a spread of Ho–Cd bond distances ranging from 3.25–3.52 Å. In the fifth Ho site, Ho is bonded in a 10-coordinate geometry to sixteen Cd atoms. There are a spread of Ho–Cd bond distances ranging from 3.13–3.66 Å. There are fourteen inequivalent Cd sites. In the first Cd site, Cd is bonded in a 9-coordinate geometry to five Ho and eight Cd atoms. There are a spread of Cd–Cd bond distances ranging from 3.01–3.11 Å. In the second Cd site, Cd is bonded in a 4-coordinate geometry to four equivalent Ho and twelve equivalent Cd atoms. All Cd–Cd bond lengths are 3.35 Å. In the third Cd site, Cd is bonded to three Ho and nine Cd atoms to form a mixture of distorted corner, edge, and face-sharing CdHo3Cd9 cuboctahedra. There are a spread of Cd–Cd bond distances ranging from 2.79–3.16 Å. In the fourth Cd site, Cd is bonded in a 8-coordinate geometry to four Ho and four Cd atoms. There are two shorter (2.89 Å) and two longer (3.02 Å) Cd–Cd bond lengths. In the fifth Cd site, Cd is bonded to four Ho and eight Cd atoms to form a mixture of distorted corner, edge, and face-sharing CdHo4Cd8 cuboctahedra. There are a spread of Cd–Cd bond distances ranging from 2.81–3.32 Å. In the sixth Cd site, Cd is bonded in a 3-coordinate geometry to three Ho and eight Cd atoms. There are a spread of Cd–Cd bond distances ranging from 3.00–3.27 Å. In the seventh Cd site, Cd is bonded in a 12-coordinate geometry to four Ho and eight Cd atoms. Both Cd–Cd bond lengths are 3.21 Å. In the eighth Cd site, Cd is bonded in a 11-coordinate geometry to three equivalent Ho and eight Cd atoms. There are one shorter (3.01 Å) and one longer (3.13 Å) Cd–Cd bond lengths. In the ninth Cd site, Cd is bonded in a 11-coordinate geometry to four Ho and seven Cd atoms. The Cd–Cd bond length is 3.02 Å. In the tenth Cd site, Cd is bonded in a 12-coordinate geometry to three Ho and nine Cd atoms. In the eleventh Cd site, Cd is bonded in a distorted body-centered cubic geometry to four Ho and four Cd atoms. In the twelfth Cd site, Cd is bonded in a distorted body-centered cubic geometry to four equivalent Ho and four equivalent Cd atoms. In the thirteenth Cd site, Cd is bonded in a 11-coordinate geometry to four Ho and seven Cd atoms. In the fourteenth Cd site, Cd is bonded in a 11-coordinate geometry to four Ho and seven Cd atoms. There are one shorter (3.26 Å) and three longer (3.45 Å) Cd–Ho bond lengths. There are a spread of Cd–Cd bond distances ranging from 3.06–3.24 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Thermodynamic Understanding of Impurity Phase Segregation in a PdCrO 2 /CuCrO 2 Heterostructure

Abstract PdCrO 2 films are synthesized on CuCrO 2 buffer layers on Al 2 O 3 substrates. This synthesis is accompanied by impurity phase segregation, which hampers the synthesis of high quality PdCrO 2 films. Potential causes ofth impurity phase segregation are studied by using a combination of experiments and ab initio calculations. X‐ray diffraction and scanning transmission electron microscopy experiments reveal impurity phases of Cu x Pd 1 − x alloy and chromium oxides, Cr 2 O 3 and Cr 3 O 4 , in PdCrO 2 . Calculations determine that oxygen deficiency can cause the impurity phase segregation. Therefore, preventing oxygen release from delafossites can suppress the impurity phase segregation. The amounts of Cr 2 O 3 and Cr 3 O 4 depend on temperature and oxygen partial pressure. A reasonable theory‐based explanation for this experimental observation is provided.

2D metal↗
DOE OSTI2023

Effect of nitrogen doping and pressure on the stability of $\mathrm{LuH_3}$

A report on the near-ambient superconductivity in a nitrogen-doped lutetium hydride has stimulated great interest in this material [Dasenbrock-Gammon et al. , Nature (London) 615, 244 (2023)]. While its superconductivity is still a subject of debate, the structure of the claimed cubic phase remains uncertain. In this work, we study the effect of nitrogen doping and pressure on the energetic and dynamic stability of cubic $\mathrm{LuH_3}$. Our findings indicate that both pressure and nitrogen doping can enhance the stability of the cubic $\mathrm{LuH_3}$ phase. Here, we propose a $\mathrm{Lu_8}$$\mathrm{H_{21}}$$\mathrm{Lu}$ structure that exhibits a stable phonon, reasonable thermodynamic stability at 1 GPa, and an x-ray diffraction pattern similar to the experimental data. However, we do not observe electron-phonon coupling in the zone-center phonon modes of these crystal structures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Reversing the Irreversible: Thermodynamic Stabilization of LiAlH 4 Nanoconfined Within a Nitrogen-Doped Carbon Host

A general problem when designing functional nanomaterials for energy storage is the lack of control over the stability and reactivity of metastable phases. Using the high-capacity hydrogen storage candidate LiAlH4 as an exemplar, we demonstrate an alternative approach to the thermodynamic stabilization of metastable metal hydrides by coordination to nitrogen binding sites within the nanopores of N-doped CMK-3 carbon (NCMK-3). The resulting LiAlH 4 @NCMK-3 material releases H 2 at temperatures as low as 126 °C with full decomposition below 240 °C, bypassing the usual Li 3 AlH 6 intermediate observed in bulk. Moreover, >80% of LiAlH 4 can be regenerated under 100 MPa H 2 , a feat previously thought to be impossible. Nitrogen sites are critical to these improvements, as no reversibility is observed with undoped CMK-3. Density functional theory predicts a drastically reduced Al–H bond dissociation energy and supports the observed change in the reaction pathway. Finally, the calculations also provide a rationale for the solid-state reversibility, which derives from the combined effects of nanoconfinement, Li adatom formation, and charge redistribution between the metal hydride and the host.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

A Sobering Examination of the Feasibility of Aqueous Aluminum Batteries

Recent reports on aqueous aluminum (Al) batteries boast encouraging metrics including high energy density, nonflammability, and low raw material cost. However, the poorly understood solvation environment around the trivalent aluminum ions (Al3+) raises uncertainty regarding their feasibility. Furthermore, the corrosiveness of the acidic solutions and degree of hydration of aluminum trifluoromethanesulfonate (Al(OTf)3) salt is routinely mischaracterized. This study provides a rigorous examination of aqueous Al electrolytes, with the first compelling evidence for a dynamic octahedral solvation structure around Al3+ dominated by labile water and OH-, without Al-OTf contact ion pairs, at high concentrations. This solvation behavior and the concomitant electrostatic hydrolysis differs greatly from previously reported water-in-salt electrolytes, and occurs due to the high charge density of the Lewis acidic Al3+. Nuclear magnetic resonance spectroscopy and other physicochemical measurements quantitatively reveal how species activity evolves with concentration. The high proton activity observed in transport and electrochemical measurements constitutes a prohibitive barrier to the feasibility of rechargeable aluminum batteries with aqueous electrolyte.

Pastel, Glenn R.↗
DOE OSTI2020

Remote heteroepitaxy of GaN microrod heterostructures for deformable light-emitting diodes and wafer recycle

There have been rapidly increasing demands for flexible lighting apparatus, and micrometer-scale light-emitting diodes (LEDs) are regarded as one of the promising lighting sources for deformable device applications. Herein, we demonstrate a method of creating a deformable LED, based on remote heteroepitaxy of GaN microrod (MR) p - n junction arrays on c -Al 2 O 3 wafer across graphene. The use of graphene allows the transfer of MR LED arrays onto a copper plate, and spatially separate MR arrays offer ideal device geometry suitable for deformable LED in various shapes without serious device performance degradation. Moreover, remote heteroepitaxy also allows the wafer to be reused, allowing reproducible production of MR LEDs using a single substrate without noticeable device degradation. The remote heteroepitaxial relation is determined by high-resolution scanning transmission electron microscopy, and the density functional theory simulations clarify how the remote heteroepitaxy is made possible through graphene.

36 MATERIALS SCIENCE↗