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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Sc(SiNi)2 by Materials Project

Sc(NiSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sc3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Sc–Si bond lengths are 2.93 Å. Ni+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.27 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Sc3+, four equivalent Ni+2.50+, and one Si4- atom. The Si–Si bond length is 2.32 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(TiN)9 by Materials Project

Sc(TiN)9 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Sc3+ is bonded to six N3- atoms to form ScN6 octahedra that share corners with six TiN5 square pyramids, edges with six TiN6 octahedra, and edges with six TiN5 square pyramids. There are two shorter (2.18 Å) and four longer (2.19 Å) Sc–N bond lengths. There are five inequivalent Ti+2.67+ sites. In the first Ti+2.67+ site, Ti+2.67+ is bonded to five N3- atoms to form TiN5 square pyramids that share corners with two equivalent ScN6 octahedra, corners with seven TiN5 square pyramids, an edgeedge with one ScN6 octahedra, edges with five TiN6 octahedra, and edges with two TiN5 square pyramids. The corner-sharing octahedra tilt angles range from 2–3°. There are a spread of Ti–N bond distances ranging from 2.06–2.13 Å. In the second Ti+2.67+ site, Ti+2.67+ is bonded to six N3- atoms to form TiN6 octahedra that share corners with three TiN6 octahedra, corners with three equivalent TiN5 square pyramids, edges with two equivalent ScN6 octahedra, edges with two TiN6 octahedra, and edges with eight TiN5 square pyramids. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Ti–N bond distances ranging from 2.11–2.19 Å. In the third Ti+2.67+ site, Ti+2.67+ is bonded to five N3- atoms to form TiN5 square pyramids that share corners with four TiN6 octahedra, corners with five TiN5 square pyramids, an edgeedge with one ScN6 octahedra, edges with three TiN6 octahedra, and edges with four TiN5 square pyramids. The corner-sharing octahedra tilt angles range from 1–5°. There are a spread of Ti–N bond distances ranging from 2.06–2.16 Å. In the fourth Ti+2.67+ site, Ti+2.67+ is bonded to five N3- atoms to form TiN5 square pyramids that share a cornercorner with one ScN6 octahedra, corners with eight TiN5 square pyramids, an edgeedge with one ScN6 octahedra, edges with four TiN6 octahedra, and edges with three TiN5 square pyramids. The corner-sharing octahedral tilt angles are 2°. There are a spread of Ti–N bond distances ranging from 2.07–2.14 Å. In the fifth Ti+2.67+ site, Ti+2.67+ is bonded to six N3- atoms to form TiN6 octahedra that share corners with four equivalent TiN6 octahedra, corners with two equivalent TiN5 square pyramids, edges with two equivalent ScN6 octahedra, edges with two equivalent TiN6 octahedra, and edges with eight TiN5 square pyramids. The corner-sharing octahedra tilt angles range from 2–3°. There are four shorter (2.13 Å) and two longer (2.14 Å) Ti–N bond lengths. There are five inequivalent N3- sites. In the first N3- site, N3- is bonded to one Sc3+ and five Ti+2.67+ atoms to form a mixture of corner and edge-sharing NScTi5 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the second N3- site, N3- is bonded to one Sc3+ and five Ti+2.67+ atoms to form NScTi5 octahedra that share corners with six NTi6 octahedra and edges with eleven NScTi5 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the third N3- site, N3- is bonded to six Ti+2.67+ atoms to form a mixture of corner and edge-sharing NTi6 octahedra. The corner-sharing octahedra tilt angles range from 2–4°. In the fourth N3- site, N3- is bonded to one Sc3+ and five Ti+2.67+ atoms to form a mixture of corner and edge-sharing NScTi5 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the fifth N3- site, N3- is bonded to six Ti+2.67+ atoms to form NTi6 octahedra that share corners with six NTi6 octahedra and edges with ten NScTi5 octahedra. The corner-sharing octahedra tilt angles range from 0–5°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(CoSi)2 by Materials Project

Sc(CoSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sc3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Sc–Si bond lengths are 2.92 Å. Co+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing CoSi4 tetrahedra. All Co–Si bond lengths are 2.24 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Sc3+, four equivalent Co+2.50+, and one Si4- atom. The Si–Si bond length is 2.38 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(FeSi)2 by Materials Project

Sc(FeSi)2 crystallizes in the orthorhombic Pbcm space group. The structure is three-dimensional. Sc3+ is bonded in a 6-coordinate geometry to eight Si4- atoms. There are a spread of Sc–Si bond distances ranging from 2.69–3.11 Å. There are two inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded in a 5-coordinate geometry to five Si4- atoms. There are a spread of Fe–Si bond distances ranging from 2.26–2.43 Å. In the second Fe+2.50+ site, Fe+2.50+ is bonded to five Si4- atoms to form a mixture of distorted corner and edge-sharing FeSi5 trigonal bipyramids. There are a spread of Fe–Si bond distances ranging from 2.40–2.48 Å. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Sc3+ and five Fe+2.50+ atoms. In the second Si4- site, Si4- is bonded in a 11-coordinate geometry to four equivalent Sc3+, five Fe+2.50+, and two equivalent Si4- atoms. Both Si–Si bond lengths are 2.49 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(PO3)3 by Materials Project

Sc(PO3)3 crystallizes in the cubic I-43d space group. The structure is three-dimensional. Sc3+ is bonded to six O2- atoms to form ScO6 octahedra that share corners with six equivalent PO4 tetrahedra. There are three shorter (2.09 Å) and three longer (2.10 Å) Sc–O bond lengths. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent ScO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 14–32°. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to one Sc3+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(VN)9 by Materials Project

Sc(VN)9 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Sc3+ is bonded to six N3- atoms to form ScN6 octahedra that share corners with six VN5 square pyramids, edges with six VN6 octahedra, and edges with six VN5 square pyramids. There are four shorter (2.14 Å) and two longer (2.15 Å) Sc–N bond lengths. There are five inequivalent V+2.67+ sites. In the first V+2.67+ site, V+2.67+ is bonded to five N3- atoms to form VN5 square pyramids that share corners with two equivalent ScN6 octahedra, corners with seven VN5 square pyramids, an edgeedge with one ScN6 octahedra, edges with five VN6 octahedra, and edges with two VN5 square pyramids. The corner-sharing octahedra tilt angles range from 5–6°. There are a spread of V–N bond distances ranging from 2.00–2.13 Å. In the second V+2.67+ site, V+2.67+ is bonded to six N3- atoms to form VN6 octahedra that share corners with three VN6 octahedra, corners with three equivalent VN5 square pyramids, edges with two equivalent ScN6 octahedra, edges with two VN6 octahedra, and edges with eight VN5 square pyramids. The corner-sharing octahedra tilt angles range from 0–7°. There are a spread of V–N bond distances ranging from 2.01–2.17 Å. In the third V+2.67+ site, V+2.67+ is bonded to five N3- atoms to form VN5 square pyramids that share a cornercorner with one ScN6 octahedra, corners with eight VN5 square pyramids, an edgeedge with one ScN6 octahedra, edges with four VN6 octahedra, and edges with three VN5 square pyramids. The corner-sharing octahedral tilt angles are 5°. There are a spread of V–N bond distances ranging from 1.96–2.16 Å. In the fourth V+2.67+ site, V+2.67+ is bonded to five N3- atoms to form VN5 square pyramids that share corners with four VN6 octahedra, corners with five VN5 square pyramids, an edgeedge with one ScN6 octahedra, edges with three VN6 octahedra, and edges with four VN5 square pyramids. The corner-sharing octahedra tilt angles range from 1–7°. There are a spread of V–N bond distances ranging from 2.02–2.19 Å. In the fifth V+2.67+ site, V+2.67+ is bonded to six N3- atoms to form VN6 octahedra that share corners with four equivalent VN6 octahedra, corners with two equivalent VN5 square pyramids, edges with two equivalent ScN6 octahedra, edges with two equivalent VN6 octahedra, and edges with eight VN5 square pyramids. The corner-sharing octahedra tilt angles range from 4–7°. There are a spread of V–N bond distances ranging from 2.04–2.12 Å. There are five inequivalent N3- sites. In the first N3- site, N3- is bonded to one Sc3+ and five V+2.67+ atoms to form a mixture of corner and edge-sharing NScV5 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the second N3- site, N3- is bonded to one Sc3+ and five V+2.67+ atoms to form a mixture of corner and edge-sharing NScV5 octahedra. The corner-sharing octahedra tilt angles range from 0–8°. In the third N3- site, N3- is bonded to six V+2.67+ atoms to form a mixture of corner and edge-sharing NV6 octahedra. The corner-sharing octahedra tilt angles range from 4–8°. In the fourth N3- site, N3- is bonded to one Sc3+ and five V+2.67+ atoms to form a mixture of corner and edge-sharing NScV5 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the fifth N3- site, N3- is bonded to six V+2.67+ atoms to form a mixture of corner and edge-sharing NV6 octahedra. The corner-sharing octahedra tilt angles range from 0–8°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(CuSi)2 by Materials Project

Sc(CuSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sc3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Sc–Si bond lengths are 2.93 Å. Cu+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing CuSi4 tetrahedra. All Cu–Si bond lengths are 2.36 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Sc3+, four equivalent Cu+2.50+, and one Si4- atom. The Si–Si bond length is 2.28 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(CuO2)2 by Materials Project

Sc(CuO2)2 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Sc3+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All Sc–O bond lengths are 2.02 Å. Cu+2.50+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Cu–O bond lengths are 1.90 Å. O2- is bonded in a distorted trigonal planar geometry to one Sc3+ and two equivalent Cu+2.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(CuO2)2 by Materials Project

Sc(CuO2)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Sc3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sc–O bond distances ranging from 2.23–2.31 Å. There are two inequivalent Cu+2.50+ sites. In the first Cu+2.50+ site, Cu+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.89 Å) and two longer (1.92 Å) Cu–O bond length. In the second Cu+2.50+ site, Cu+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.89 Å) and two longer (1.91 Å) Cu–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Sc3+ and two Cu+2.50+ atoms to form a mixture of distorted edge and corner-sharing OSc2Cu2 tetrahedra. In the second O2- site, O2- is bonded to two equivalent Sc3+ and two Cu+2.50+ atoms to form a mixture of distorted edge and corner-sharing OSc2Cu2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(VSi)5 by Materials Project

Sc(VSi)5 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Sc2+ is bonded to seven Si+2.40- atoms to form ScSi7 pentagonal bipyramids that share corners with two equivalent ScSi7 pentagonal bipyramids, corners with eight VSi7 pentagonal bipyramids, edges with three equivalent ScSi7 pentagonal bipyramids, and faces with six VSi7 pentagonal bipyramids. There are a spread of Sc–Si bond distances ranging from 2.64–2.79 Å. There are four inequivalent V2+ sites. In the first V2+ site, V2+ is bonded in a 8-coordinate geometry to two equivalent V2+ and six Si+2.40- atoms. There are one shorter (2.45 Å) and one longer (2.48 Å) V–V bond lengths. There are a spread of V–Si bond distances ranging from 2.45–2.62 Å. In the second V2+ site, V2+ is bonded to seven Si+2.40- atoms to form distorted VSi7 pentagonal bipyramids that share corners with three equivalent ScSi7 pentagonal bipyramids, corners with five VSi7 pentagonal bipyramids, edges with four VSi7 pentagonal bipyramids, faces with two equivalent ScSi7 pentagonal bipyramids, and faces with four VSi7 pentagonal bipyramids. There are a spread of V–Si bond distances ranging from 2.38–2.75 Å. In the third V2+ site, V2+ is bonded to seven Si+2.40- atoms to form distorted VSi7 pentagonal bipyramids that share a cornercorner with one ScSi7 pentagonal bipyramid, corners with seven VSi7 pentagonal bipyramids, edges with four VSi7 pentagonal bipyramids, faces with two equivalent ScSi7 pentagonal bipyramids, and faces with four VSi7 pentagonal bipyramids. There are a spread of V–Si bond distances ranging from 2.41–2.74 Å. In the fourth V2+ site, V2+ is bonded to seven Si+2.40- atoms to form VSi7 pentagonal bipyramids that share corners with four equivalent ScSi7 pentagonal bipyramids, corners with six VSi7 pentagonal bipyramids, edges with three equivalent VSi7 pentagonal bipyramids, faces with two equivalent ScSi7 pentagonal bipyramids, and faces with four VSi7 pentagonal bipyramids. There are a spread of V–Si bond distances ranging from 2.57–2.82 Å. There are five inequivalent Si+2.40- sites. In the first Si+2.40- site, Si+2.40- is bonded in a 10-coordinate geometry to seven V2+ and three Si+2.40- atoms. There are one shorter (2.49 Å) and two longer (2.79 Å) Si–Si bond lengths. In the second Si+2.40- site, Si+2.40- is bonded in a 9-coordinate geometry to three equivalent Sc2+ and six V2+ atoms. In the third Si+2.40- site, Si+2.40- is bonded in a 11-coordinate geometry to one Sc2+ and eight V2+ atoms. In the fourth Si+2.40- site, Si+2.40- is bonded in a 10-coordinate geometry to two equivalent Sc2+, six V2+, and two equivalent Si+2.40- atoms. There are one shorter (2.43 Å) and one longer (2.50 Å) Si–Si bond lengths. In the fifth Si+2.40- site, Si+2.40- is bonded in a 10-coordinate geometry to one Sc2+, six V2+, and three Si+2.40- atoms. The Si–Si bond length is 2.40 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(CuN)3 by Materials Project

Sc(CuN)3 crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Sc3+ is bonded to six equivalent N3- atoms to form corner-sharing ScN6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Sc–N bond lengths are 2.13 Å. Cu2+ is bonded in a square co-planar geometry to four equivalent N3- atoms. All Cu–N bond lengths are 2.13 Å. N3- is bonded to two equivalent Sc3+ and four equivalent Cu2+ atoms to form a mixture of corner and edge-sharing NSc2Cu4 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(CuS)3 by Materials Project

Sc(CuS)3 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Sc3+ is bonded to six equivalent S2- atoms to form ScS6 octahedra that share corners with twelve equivalent CuS4 tetrahedra, edges with three equivalent ScS6 octahedra, and edges with six equivalent CuS4 tetrahedra. There are three shorter (2.62 Å) and three longer (2.63 Å) Sc–S bond lengths. Cu1+ is bonded to four equivalent S2- atoms to form CuS4 tetrahedra that share corners with four equivalent ScS6 octahedra, corners with six equivalent CuS4 tetrahedra, edges with two equivalent ScS6 octahedra, and edges with three equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 14–56°. There are a spread of Cu–S bond distances ranging from 2.30–2.42 Å. S2- is bonded in a 6-coordinate geometry to two equivalent Sc3+ and four equivalent Cu1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(Ni2As)2 by Materials Project

Sc(Ni2As)2 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Sc2+ is bonded to six equivalent As3- atoms to form a mixture of edge and corner-sharing ScAs6 octahedra. The corner-sharing octahedral tilt angles are 41°. There are two shorter (2.84 Å) and four longer (2.87 Å) Sc–As bond lengths. Ni1+ is bonded in a trigonal non-coplanar geometry to three equivalent As3- atoms. There are one shorter (2.35 Å) and two longer (2.36 Å) Ni–As bond lengths. As3- is bonded in a 9-coordinate geometry to three equivalent Sc2+ and six equivalent Ni1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(SeO3)3 by Materials Project

Sc(SeO3)3 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Sc2+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Sc–O bond distances ranging from 2.10–2.12 Å. There are three inequivalent Se+5.33+ sites. In the first Se+5.33+ site, Se+5.33+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of Se–O bond distances ranging from 1.66–1.71 Å. In the second Se+5.33+ site, Se+5.33+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.66 Å) and two longer (1.70 Å) Se–O bond length. In the third Se+5.33+ site, Se+5.33+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.68 Å) and two longer (1.70 Å) Se–O bond length. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Se+5.33+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc2+ and one Se+5.33+ atom. In the third O2- site, O2- is bonded in a linear geometry to one Sc2+ and one Se+5.33+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Se+5.33+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sc2+ and one Se+5.33+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc2+ and one Se+5.33+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one Se+5.33+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc2+ and one Se+5.33+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to one Sc2+ and one Se+5.33+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(CuSe)3 by Materials Project

Sc(CuSe)3 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Sc3+ is bonded to six equivalent Se2- atoms to form ScSe6 octahedra that share corners with twelve equivalent CuSe4 tetrahedra, edges with three equivalent ScSe6 octahedra, and edges with six equivalent CuSe4 tetrahedra. All Sc–Se bond lengths are 2.73 Å. Cu1+ is bonded to four equivalent Se2- atoms to form CuSe4 tetrahedra that share corners with four equivalent ScSe6 octahedra, corners with six equivalent CuSe4 tetrahedra, edges with two equivalent ScSe6 octahedra, and edges with three equivalent CuSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–60°. There are a spread of Cu–Se bond distances ranging from 2.40–2.50 Å. Se2- is bonded to two equivalent Sc3+ and four equivalent Cu1+ atoms to form a mixture of distorted edge and corner-sharing SeSc2Cu4 octahedra. The corner-sharing octahedra tilt angles range from 2–95°.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Jamming Detection for Low-Resolution SC-FDE Systems: A Machine Learning Approach

Jammers interfere with communication between base stations (BSs) and legitimate users, leading to degradation of wireless system performance. Our study focuses on jamming detection for wideband single-carrier frequency domain equalization (SC-FDE) systems with low-resolution analog-to digital converters (ADCs). In such systems, jamming detection is challenging because traditional analytical approaches cannot be directly applied due to the delay dispersion in wideband channels and the non-linearity induced by low-resolution ADCs. We propose a machine learning (ML)-based jamming detection method that directly uses the quantized receive signals. Significantly, our ML-based detector can be integrated into existing standard frameworks, such as unique word (UW)-based SC-FDE systems, as it uses existing pilots without requiring additional pilots for jamming detection. Through numerical simulations, we show that two or more bits provide satisfactory performance compared to unquantized scenarios. Additionally, we demonstrate that using more and well-separated pilot symbols improves performance.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2020

Additively manufactured novel Al-Cu-Sc-Zr alloy: Microstructure and mechanical properties

An in-depth understanding of microstructure and resultant properties is paramount in the design of a novel alloy system, especially for additive manufacturing (AM). The present investigation aims to characterize a prototypical AM Al alloy with great potential for structural applications. An Al-1.5Cu-0.8Sc-0.4Zr alloy designed using integrated computational material engineering was printed using the laser powder bed fusion AM process. This novel alloy shows promising combination of strength and ductility in as-built and peak-aged conditions. This improvement in the tensile properties is attributed to the presence of both coherent L1 2 Al 3 Sc/Al 3 (Sc,Zr) precipitates and Cu-rich regions. The microstructures were studied via extensive microscopy at different length scales using X-ray microscopy, scanning electron microscopy, and transmission electron microscopy. Fractography revealed that the columnar grain boundaries in as-built condition allow easy slip transfer as compared to the equiaxed grains, with the apex of the melt pool acting as the crack nucleation site. Furthermore, the peak aged condition resulted in improved strength while marginally sacrificing ductility due to precipitates decorating dislocations, grain boundaries and melt pool boundaries thus acting as obstacles to slip transfer.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Selective carboxylation of alkenes with CO 2 to form unsaturated carboxylic acid on Sc-exchanged MFI zeolite

Utilization of CO 2 in chemical synthesis as C1 carbon feedstock to introduce a carboxylic group into alkene is valuable for producing unsaturated carboxylic acids. Selective carboxylation of alkenes at targeted positions can be used to regulate the production of such specific unsaturated carboxylic acids or functionalize hydrocarbon plastics that possess residual C=C double bonds. In this study, we investigated the carboxylation of 1-butene and 2-butene (as representative alkene) with CO 2 on Sc-exchanged MFI zeolites using density functional theory calculations. Here, we find that similar to ethylene, the carboxylation of butene is also rate-limited by the β–H transfer. We examined carboxylation at the C1 and C2 positions of 1-butene and cis and trans isomers for 2-butene. Based on activation barriers of the β–H transfer, our results demonstrate that Sc-MFI zeolite preferably carboxylates at the terminal position of butene. In the case of 2-butene, carboxylation of the trans isomer is more favorable than the cis isomer. Furthermore, We show that the energy of degenerate orbitals of C, O and H atoms (involved in the β–H transfer) in the metallalactone ring regulates the activation energy of the β–H transfer.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗