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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
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↗
DOE OSTI2023

Simultaneously improved J sc and V oc achieving 19.15% efficiency in ternary blend polymer solar cell containing a Y-type acceptor with thiophene based end groups

Simultaneously enhancing the short-circuit current density (J sc ) and open-circuit voltage (V oc ) of current state-of-the-art polymer solar cells (PSCs) containing wide bandgap polymers as donors and Y6 derivatives as acceptors is of great challenge but essential for further improvement of the photovoltaic performances. Here, in this work, two Y-type non-fullerene acceptors of BTP-T and BTP-TCl were designed and successfully synthesized with relatively weak electron-accepting thiophene based end groups, where blue-shifted absorption and upshifted LUMO energy levels were achieved to fill the well-known absorption gap at 700 nm of typical binary devices based Y-type molecules and rise the output voltage, respectively. Simultaneously increased J sc and V oc were achieved in ternary blend devices containing D18:BTP-eC9:BTP-TCl with a significantly improved PCE up to 19.15 %, which is over 7 % increase compared to the binary device. Our results illustrated the great potential of rational design of Y6 derivatives for constructing ternary PSCs to improve their performances.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A Landau–Devonshire analysis of strain effects on ferroelectric Al 1-x Sc x N

We present a thermodynamic analysis of the recently discovered nitride ferroelectric materials using the classic Landau–Devonshire approach. Electrostrictive and dielectric stiffness coefficients of Al 1-x Sc x N with a wurtzite structure (6 mm) are determined using a free energy density function assuming a hexagonal parent phase (6/mmm), with the first-order phase transition based on the dielectric stiffness relationships. The results of this analysis show that the strain sensitivity of the energy barrier is one order of magnitude larger than that of the spontaneous polarization in these wurtzite ferroelectrics, yet both are less sensitive to strain compared to classic perovskite ferroelectrics. These analysis results reported here explain experimentally reported sensitivity of the coercive field to elastic strain/stress in Al 1-x Sc x N films and would enable further thermodynamic analysis via phase field simulation and related methods.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Increased thermal conductivity and decreased electron–phonon coupling factor of the aluminum scandium intermetallic phase (Al 3 Sc) compared to solid solutions

Aluminum scandium alloys and their intermetallic phases have arisen as potential candidates for the next generation of electrical interconnects. Here, in this work, we measure the in-plane thermal conductivity and electron–phonon coupling factor of aluminum scandium alloy thin films deposited at different temperatures, where the temperature is used to control the grain size and volume fraction of the Al 3 Sc intermetallic phase. As the Al 3 Sc intermetallic formation increases with higher deposition temperature, we measure increasing in-plane thermal conductivity and a decrease in the electron–phonon coupling factor, which corresponds to an increase in grain size. Our findings demonstrate the role that chemical ordering from the formation of the intermetallic phase has on thermal transport.

Chemical elements↗
DOE OSTI2025

Relative Contributions of sc-DER, mel-DER, Color Rendition, Chromaticity, and Illuminance to Spatial Brightness Perception

An experiment was conducted to examine spectrally based factors that contribute to the visual perception of interior environments, with a focus on brightness perception. Thirty-two participants evaluated 60 different lighting scenes in a mock office. The lighting spectral power distributions varied systematically in illuminance, chromaticity (CCT and Duv), s cone opic daylight efficacy ratio (sc-DER), melanopic daylight efficacy ratio (mel-DER), and color rendition (R f , R g , and R cs,h1 ). At the operationalized levels of these variables, illuminance had the largest effect on brightness perception. Notably, the second largest effect was due to changes in red chroma (R cs,h1 ). The effect of sc-DER was also statistically significant but was a tertiary effect. The effects of mel-DER, CCT, and Duv were not statistically significant. This large effect of red chroma is consistent with the existing understanding that changes in color perception are often perceived when illuminance changes. In conclusion, with appropriate changes in color rendition and other factors held constant, spatial brightness perception was preserved through a decrease from 500 lux to 250 lux.

42 ENGINEERING↗
DOE OSTI2021

Magnetic structure and multiferroicity of Sc-substituted hexagonal YbFeO 3

The hexagonal rare-earth ferrite RFeO 3 family represents a unique class of multiferroics exhibiting weak ferromagnetism, and a strong coupling between magnetism and structural trimerization is predicted. However, the hexagonal structure for RFeO 3 remains metastable in conventional conditions. We have succeeded in stabilizing the hexagonal structure of polycrystalline YbFeO 3 by partial Sc substitution of Yb. Using bulk magnetometry and neutron diffraction, we find that Yb 0.42 Sc 0.58 FeO 3 orders into a canted antiferromagnetic state with the Néel temperature T N ~ 165K, below which the Fe 3+ moments form the triangular configuration in the ab plane and their in-plane projections are parallel to the [100] axis, consistent with magnetic space group P6 3 c'm'. It is determined that the spin canting is aligned along the c axis, giving rise to the weak ferromagnetism. Furthermore, the Fe 3+ moments reorient toward a new direction below reorientation temperature T R ~ 40K, satisfying magnetic subgroup P6 3 , while the Yb 3+ moments order independently and ferrimagnetically along the c axis at the characteristic temperature T Yb ~ 15K. Interestingly, reproducible modulation of electric polarization induced by magnetic field at low temperature is achieved, suggesting that the delicate structural distortion associated with two-up/one-down buckling of the Yb/Sc planes and tilting of the FeO 5 bipyramids may mediate the coupling between ferroelectric and magnetic orders under magnetic field. Furthermore, the present work represents substantial progress to search for high-temperature multiferroics in hexagonal ferrites and related materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Neutron scattering study of the kagome metal Sc 3 Mn 3 Al 7 Si 5

Sc 3 Mn 3 Al 7 Si 5 is a rare example of a correlated metal in which the Mn moments form a kagome lattice. The absence of magnetic ordering to the lowest temperatures suggests that geometrical frustration of magnetic interactions may lead to strong magnetic fluctuations. We have performed inelastic neutron scattering measurements on Sc 3 Mn 3 Al 7 Si 5 , finding that phonon scattering dominates for energies from ~20–50 meV. These results are in good agreement with ab initio calculations of the phonon dispersions and densities of states, and as well reproduce the measured specific heat. A weak magnetic signal was detected at energies less than ~10 meV, present only at the lowest temperatures. The magnetic signal is broad and quasielastic, as expected for metallic paramagnets.

36 MATERIALS SCIENCE↗
DOE OSTI2020

LDA + $U_{sc}$ calculations of phase relations in FeO

Using the LDA + $U_{sc}$ method, we present calculation phase relations of iron monoxides involving five polytypes in multiple spin-state configurations. In this work, the Hubbard parameter $\textit{U}$ is determined self-consistently simultaneously with the occupation matrix and structures at arbitrary pressures. The Hubbard parameter strongly depends on pressure, structure, and spin state. Comparison with experimental structural data indicates the LDA + $U_{sc}$ can predict structure, compression curves, phase relations, and transition pressures very well for the insulating $\textit{B}$1 and $\textit{iB}$8 states. However, it requires additional calculations using the Mermin functional that includes the electronic entropic contribution to the free energy to obtain an $\textit{nB}$8 metallic state and a consistent $\textit{iB}$8 to $\textit{nB}$8 insulator to metal transition pressure.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(BC)2 by Materials Project

ScB2C2 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Sc2+ is bonded in a 6-coordinate geometry to six C4- atoms. There are a spread of Sc–C bond distances ranging from 2.43–2.53 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three C4- atoms. There are a spread of B–C bond distances ranging from 1.55–1.64 Å. In the second B3+ site, B3+ is bonded in a water-like geometry to two C4- atoms. There is one shorter (1.55 Å) and one longer (1.62 Å) B–C bond length. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded in a 3-coordinate geometry to four equivalent Sc2+ and three B3+ atoms. In the second C4- site, C4- is bonded in a 2-coordinate geometry to two equivalent Sc2+, two B3+, and one C4- atom. The C–C bond length is 1.45 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(AlC)3 by Materials Project

ScAl3C3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Sc3+ is bonded to six equivalent C4- atoms to form ScC6 octahedra that share corners with six equivalent AlC4 tetrahedra, edges with six equivalent ScC6 octahedra, and edges with six equivalent AlC4 tetrahedra. All Sc–C bond lengths are 2.42 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent ScC6 octahedra, corners with seven equivalent AlC4 tetrahedra, and edges with three equivalent ScC6 octahedra. The corner-sharing octahedral tilt angles are 17°. There are one shorter (2.03 Å) and three longer (2.07 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. All Al–C bond lengths are 1.94 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to three equivalent Sc3+ and three equivalent Al3+ atoms to form distorted CSc3Al3 octahedra that share corners with three equivalent CSc3Al3 octahedra, corners with three equivalent CAl5 trigonal bipyramids, and edges with nine equivalent CSc3Al3 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with six equivalent CSc3Al3 octahedra and corners with six equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 70°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(ReO3)2 by Materials Project

ScRe2O6 is beta Vanadium nitride-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Sc3+ is bonded to six O2- atoms to form ScO6 octahedra that share corners with four equivalent ScO6 octahedra, corners with four equivalent ReO6 octahedra, and edges with two equivalent ReO6 octahedra. The corner-sharing octahedra tilt angles range from 45–56°. There are four shorter (2.12 Å) and two longer (2.18 Å) Sc–O bond lengths. Re+4.50+ is bonded to six O2- atoms to form ReO6 octahedra that share corners with two equivalent ScO6 octahedra, corners with six equivalent ReO6 octahedra, an edgeedge with one ScO6 octahedra, and an edgeedge with one ReO6 octahedra. The corner-sharing octahedra tilt angles range from 36–54°. There are a spread of Re–O bond distances ranging from 1.96–2.03 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Sc3+ and one Re+4.50+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three equivalent Re+4.50+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Sc3+ and two equivalent Re+4.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(AlC)3 by Materials Project

ScAl3C3 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Sc3+ is bonded to six C4- atoms to form ScC6 octahedra that share corners with six AlC4 tetrahedra, edges with six equivalent ScC6 octahedra, and edges with six AlC4 tetrahedra. There are three shorter (2.39 Å) and three longer (2.47 Å) Sc–C bond lengths. There are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent ScC6 octahedra, corners with seven AlC4 tetrahedra, and edges with three equivalent ScC6 octahedra. The corner-sharing octahedral tilt angles are 20°. There are one shorter (2.04 Å) and three longer (2.05 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent ScC6 octahedra, corners with seven AlC4 tetrahedra, and edges with three equivalent ScC6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are one shorter (2.02 Å) and three longer (2.09 Å) Al–C bond lengths. In the third Al3+ site, Al3+ is bonded in a distorted trigonal planar geometry to four C4- atoms. There are three shorter (1.95 Å) and one longer (2.58 Å) Al–C bond lengths. There are three inequivalent C4- sites. In the first C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with three equivalent CSc3Al3 octahedra and corners with six equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 68°. In the second C4- site, C4- is bonded in a 3-coordinate geometry to three equivalent Sc3+ and four Al3+ atoms. In the third C4- site, C4- is bonded to three equivalent Sc3+ and three equivalent Al3+ atoms to form CSc3Al3 octahedra that share corners with three equivalent CAl5 trigonal bipyramids and edges with six equivalent CSc3Al3 octahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(NF2)3 by Materials Project

ScNF6N2 is High-temperature superconductor-derived structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of eight ammonia molecules and one ScNF6 framework. In the ScNF6 framework, Sc3+ is bonded to six equivalent F1- atoms to form ScF6 octahedra that share corners with six equivalent NF6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Sc–F bond lengths are 2.07 Å. N1+ is bonded to six equivalent F1- atoms to form NF6 octahedra that share corners with six equivalent ScF6 octahedra. The corner-sharing octahedral tilt angles are 0°. All N–F bond lengths are 1.84 Å. F1- is bonded in a linear geometry to one Sc3+ and one N1+ atom.

36 MATERIALS SCIENCE↗