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

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Th3(SbAs)2 by Materials Project

Th3(SbAs)2 crystallizes in the cubic I2_13 space group. The structure is three-dimensional. Th4+ is bonded to four equivalent Sb3- and four equivalent As3- atoms to form a mixture of distorted edge, face, and corner-sharing ThSb4As4 hexagonal bipyramids. There are two shorter (3.18 Å) and two longer (3.28 Å) Th–Sb bond lengths. There are two shorter (3.12 Å) and two longer (3.14 Å) Th–As bond lengths. Sb3- is bonded in a 6-coordinate geometry to six equivalent Th4+ atoms. As3- is bonded to six equivalent Th4+ atoms to form a mixture of face and corner-sharing AsTh6 octahedra. The corner-sharing octahedra tilt angles range from 22–46°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SbAs by Materials Project

AsSb is Halite, Rock Salt structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three AsSb sheets oriented in the (0, 0, 1) direction. Sb3+ is bonded in a 6-coordinate geometry to three equivalent As3- atoms. All Sb–As bond lengths are 2.76 Å. As3- is bonded in a 6-coordinate geometry to three equivalent Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Weyl semimetal phases and intrinsic spin-Hall conductivity in SbAs ordered alloys

Here, using density functional theory calculations, we investigated possible Weyl semimetal (WSM) phases in antimony arsenide ordered alloys Sb 1-x ⁢As x (x=0, 1/6, 1/3, 1/2, 2/3, 5/6, 1). We find WSM phases for all As compositions of Sb 1-x ⁢As x with broken inversion symmetry, in contrast to Bi 1-x⁢ Sb x where only compositions x=1/2 and 5/6 were predicted to exhibit WSM phases. The WSM phases in Sb 1-x ⁢As x are characterized by the presence of 12 Weyl points, located within 55 meV from the Fermi level in the case of x = 1/2. The robust spin-orbit coupling strength and Berry curvature in these alloys produce large spin-Hall conductivity in the range of 176–602 ($\hslash$/e)(S/cm), comparable to that in the BiSb alloys. Finally, Sb 0.5 ⁢As 0.5 is predicted to be almost lattice matched to GaAs(111), with the Fermi level within the gap of the semiconductor, facilitating growth and characterization, and thus, offering promising integration with conventional semiconductors.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Impact of Site Identity, Location, and Accessibility on Polyethylene Conversion Rates and Product Selectivities over Metal-Free MFI Zeolites

Brønsted (BAS), Lewis (LAS), and surface Brønsted (SBAS) acid sites have been investigated for polyethylene (PE) upcycling by zeolite catalysts, but there is no clear consensus regarding their catalytic roles, partly due to the complexity of the catalysts used and varying reaction conditions across studies. This work systematically determined how these sites impact PE conversion rates and product distributions by utilizing a suite of microporous MFI catalysts with varying Si/Al ratios, acid site densities, and inherent mesoporosities. PE conversion rates did not trend with total BAS or LAS densities due to a combination of internal mass transfer limitation and the apparent inability of LAS alone to cleave C–C bonds, but a strong, statistically significant correlation was present with respect to SBAS density and mesopore surface area, jointly, owing to accelerated polymer activation on external surfaces to smaller diffusion-limited chains. However, ingress of these SBAS-derived fragments ultimately remained rate limiting, as demonstrated by solid conversion rates that increased with mesopore surface area at similar SBAS density and likewise increased with SBAS density at similar mesopore surface area. In batch PE cracking reactions, light gaseous product selectivities were most sensitive to total BAS, with higher densities generally exhibiting higher selectivity to C 3 and linear C 4 –C 7 products and higher alkane/alkene product ratios, consistent with increased β-scission turnovers. Insights from this work help systematically clarify the roles of BAS, LAS, SBAS, and mesopores in PE cracking reactions and inform the development of tailored zeolite catalysts for efficient polyolefin upcycling.

accessibility↗
DOE OSTI2020

Materials Data on SbAsN(O2F)2 by Materials Project

N2(SbAs(O2F)2)2 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of four ammonia molecules and one SbAs(O2F)2 sheet oriented in the (1, 0, 0) direction. In the SbAs(O2F)2 sheet, Sb3+ is bonded to three O2- and two F1- atoms to form SbO3F2 trigonal bipyramids that share corners with three equivalent AsO4 tetrahedra. There is one shorter (1.95 Å) and two longer (1.97 Å) Sb–O bond length. Both Sb–F bond lengths are 1.89 Å. As2+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with three equivalent SbO3F2 trigonal bipyramids. There are a spread of As–O bond distances ranging from 1.63–1.80 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Sb3+ and one As2+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one As2+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Sb3+ and one As2+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Sb3+ and one As2+ atom. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Sb3+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Sb3+ atom.

36 MATERIALS SCIENCE↗