Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Sc”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
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↗
NASA NTRS1981

SC 2059-247 - An unusual radio/X-ray source in a distant cluster of galaxies

The X-ray, optical and radio properties of a high redshift, Bautz-Morgan type I cluster of galaxies, namely SC 2059-247, are examined. This cluster is optically dominated by a cD galaxy with a powerful flat-spectrum radio source coincident with the possibly stellar nucleus. Two possible interpretations are suggested for the apparently soft X-ray spectrum of the extremely luminous cluster. Either the intracluster gas is much cooler in high-redshift clusters because they are less relaxed, or the X-ray and radio emissions from SC 2059-247 are the result of a nonthermal QSO/BL Lac type object in the nucleus of the cD. If the latter, it would be the first time that an X-ray source similar to a quasar or BL Lac object has been discovered in a previously identified galaxy.

White, R. A.↗
NASA NTRS1988

On the electron affinities of the Ca, Sc, Ti and Y atoms

For the Ca, Sc, Ti and Y atoms calculations are performed for the ground states of the neutrals and the ground and several low-lying excited states of the negative ions. Overall the computed electron affinities are in good accord with experiment. The calculations show the rapid stabilization of the 3d orbital relative to the 4p as the nuclear charge increases. The 3F(0) and 3D(0) terms are found to be close in energy in Sc(-) and in Y(-). This confirms earlier speculation that some of the peaks in the photodetachment spectra of Y(-) originate from the bound excited 3F(0) term of Y(-).

Bauschlicher, Charles W., Jr.↗
NASA NTRS1989

On the electron affinities of the Ca, Sc, Ti and Y atoms

For the Ca, Sc, Ti, and Y atoms calculations are performed for the ground states of the neutrals and the ground and several low-lying excited states of the negative ions. Overall, the computed electron affinities are in good accord with experiment. The calculations show the rapid stabilization of the 3d orbital relative to the 4p as the nuclear charge increases. The 3F0 and 3D0 terms are found to be close in energy in Sc(-) and in Y(-). This confirms earlier speculation that some of the peaks in the photodetachment spectra of Y(-) originate from the bound excited 3F0 term of Y(-).

Bauschlicher, Charles W., Jr.↗
NASA NTRS1993

Hot Deformation Of Si(3)N(4) Doped With Sc(2)O(3)

Report describes preparation, microstructural properties, and high-temperature deformation behavior of Si(3)N(4) doped with Sc(2)O(3). Powders of Si(3)N(4) with small additions of Sc(2)O(3) sintered under nitrogen overpressures to full density; expensive hot pressing or hot isostatic pressing not necessary to attain full density. Test of bars indicate high strengths at high temperatures and excellent time-dependent strength properties. Useful for fabrication of hot-section components of automotive gas-turbine engines.

Cheong, Deock-Soo↗
NASA NTRS1995

Unoccupied electronic resonances of Sc adsorbed on W(001) by k-resolved inverse photoemission

Scandium adsorbed on the (001) face of tungsten has been studied using Auger-electron spectroscopy, low-energy electron diffraction, k-resolved inverse photoelectron spectroscopy, work-function measurements, and relativistic-electronic-structure calculations. We find that the work function of W(001) does not decrease monotonically as a function of scandium adsorption but reaches a minimum value of Phi = 3.25 eV at 50% coverage. For a complete monolayer, an order 1 X 1 Sc overlayer is formed. Inverse photoemission in the isochromat mode was used to map the unoccupied energy levels of this overlayer along the bar-Gamma(bar-Mu) symmetry direction of the surface Brillouin zone. Local-density-functional calculations using the muffin-tin orbital method were performed for a 1 X 1 Sc overlayer on W and are compared with the experimental two-dimensional band structure.

Lamouri, A.↗
NASA NTRS1988

Consistency Between SC#21REF Solar XUV Energy Input and the 1973 Pioneer 10 Observations of the Jovian Photoelectron Excited H2 Airglow

It has been suggested in the literature that the F74113 solar spectrum for the solar minimum condition needs to be modified to explain the production of photoelectrons in the Earth's atmosphere. We have studied here the effect of another solar minimum spectrum, SC#21REF, on the Jovian upper atmosphere emissions and we have compared the predicted photoelectron excited H2 airglow with the 1973 Pioneer 10 observations, analyzed according to the methodology of Shemansky and Judge (1988). In this model calculation we find that in 1973, the Jovian H2 band emissions can be accounted for almost entirely by photoelectron excitation, if the preflight calibration of the Pioneer 10 ultraviolet photometer is adopted. If the SC#21REF flux shortward of 250 A is multiplied by 2 as proposed by Richards and Torr (1988) then the Pioneer 10 calibration and/or the airglow model used must be modified in order to have a self consistent set of observations.

Gangopadhyay, P.↗
NASA NTRS2014

ACES Study of DAA-Mitigated UAS Operations SC-228 Requirements Sub Group

Realization of the expected proliferation of Unmanned Aircraft System (UAS) operations in the National Airspace System (NAS) depends on the development and validation of performance standards for UAS Detect and Avoid (DAA) Systems. The RTCA Special Committee 228 is charged with leading the development of draft Minimum Operational Performance Standards (MOPS) for UAS DAA Systems. NASA, as a participating member of RTCA SC-228 is committed to supporting the development and validation of draft requirements as well as the safety substantiation and end-to-end assessment of DAA system performance. A recent study conducted using NASA's ACES (Airspace Concept Evaluation System) simulation capability begins to address questions surrounding the development of draft MOPS for DAA systems by assessing DAA performance in a NAS-wide context. ACES analyses were conducted to determine the impact of varying elements of UAS pilot performance and uncertainty mitigations on DAA system performance. Simulations were conducted with recorded cooperative and non-cooperative VFR (Visual Flight Rules) traffic to accurately model UAS encounters with other NAS traffic (ATC (Air Traffic Control) being responsible for separation with other IFR (Instrument Flight Rules) aircraft) and with roughly 25, 000 simulated UAS operations The number of Loss of Well Clear (LoWC) events were recorded across the range of independent variables: pilot response time, horizontal LoWC prediction buffer and horizontal LoWC resolution buffer. The number of LoWC events was compared to the unmitigated case (without the benefit of a DAA system) to determine the resultant risk-ratio for each of 8 simulation conditions. The parameter trades presented by the resultant DAA system performance (risk ratio) will be used by SC 228 to inform decisions about future requirements development and validation efforts.

Detect-and-Avoid↗
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↗