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At least 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Exploring the potential and impact of single-crystal active materials on dry-processed electrodes for high-performance lithium-ion batteries

Roll-to-roll powder-to-film dry processing (DP) and single-crystal (SC) active materials (AMs) with many advantages are two hot topics of lithium-ion batteries (LIBs). However, DP of SC AMs for LIBs is rarely reported. Consequently, the impact of SC AMs on dry-processed LIBs is not well understood. Herein, for the first time, via a set of experimental and theoretical studies of the conventional polycrystalline-AM- and SC-AM-based DPed electrodes (DPEs), this work not only reports a high-performance dry SC-AM cathode for LIB manufacturing, but also establishes some fundamental understanding of SC-based dry-processed electrodes, including their morphology, structure, mechanical strength, electronic conductivity and LIB electrochemical behavior. Further, the results suggest that DP of SC AMs is promising, which can dramatically improve the electrochemical kinetics at electrode level and particle level. Specifically, for the rate capability and long-term cyclability in full cells, SC DPEs exhibit a discharge specific capacity of 152.1 mAh g -1 at 1C and a capacity retention rate of 79.9 % at C/3 over 500 cycles, which are superior to those of PC DPEs (135.6 mAh g -1 and 68.3 %) at the same conditions and are further confirmed by the simulation data from the theoretical modelling study. Therefore, this comprehensive work marks a significant milestone for DP strategy and SC AMs, enlightening future research and development of LIB manufacturing.

25 ENERGY STORAGE↗
DOE OSTI2024

Stabilization of N6 and N8 anionic units and 2D polynitrogen layers in high-pressure scandium polynitrides

Abstract Nitrogen catenation under high pressure leads to the formation of polynitrogen compounds with potentially unique properties. The exploration of the entire spectrum of poly- and oligo-nitrogen moieties is still in its earliest stages. Here, we report on four novel scandium nitrides, Sc 2 N 6 , Sc 2 N 8 , ScN 5, and Sc 4 N 3 , synthesized by direct reaction between yttrium and nitrogen at 78-125 GPa and 2500 K in laser-heated diamond anvil cells. High-pressure synchrotron single-crystal X-ray diffraction reveals that in the crystal structures of the nitrogen-rich Sc 2 N 6 , Sc 2 N 8, and ScN 5 phases nitrogen is catenated forming previously unknown N 6 6 − and N 8 6 − units and$${\!\,}_{\infty }{\!\,}^{2}({{{{{\rm{N}}}}}}_{5}^{3-})$$ ∞ 2 ( N 5 3 − ) anionic corrugated 2D-polynitrogen layers consisting of fused N 12 rings. Density functional theory calculations, confirming the dynamical stability of the synthesized compounds, show that Sc 2 N 6 and Sc 2 N 8 possess an anion-driven metallicity, while ScN 5 is an indirect semiconductor. Sc 2 N 6 , Sc 2 N 8 , and ScN 5 solids are promising high-energy-density materials with calculated volumetric energy density, detonation velocity, and detonation pressure higher than those of TNT.

Science & Technology - Other Topics↗
DOE OSTI2025

Impact of charge-density-wave pattern on the superconducting gap in Vanadium-based kagome superconductors

Kagome metals AV 3 Sb 5 (A = K, Rb, Cs) provide a compelling platform to explore the interplay between superconductivity (SC) and charge-density-wave (CDW) orders. While distinct CDW orders have been identified in K/RbV 3 Sb 5 versus CsV 3 Sb 5 , their influence on the SC order parameter remains unresolved. Here, we investigate low-energy quasiparticle excitations in AV 3 Sb 5 , uncovering a striking difference in SC gap anisotropy: K/RbV 3 Sb 5 exhibit fully gapped, nearly isotropic s-wave states, in contrast to the strongly anisotropic SC gap in CsV 3 Sb 5 . Impurity scattering introduced via electron irradiation in K/RbV 3 Sb 5 has a minimal impact on low-energy excitations, and it induces an increase in the SC transition temperature T c , consistent with more isotropic s-wave SC competing with CDW order. Our theoretical analysis attributes the observed SC gap anisotropy differences to distinct CDW modulation patterns: the star-of-David structure unique to CsV 3 Sb 5 preserves van Hove singularities near the Fermi level, promoting anisotropic s-wave SC with enhanced T c via bond-order fluctuations. These findings establish a systematic framework for understanding the interplay between SC and CDW orders in AV 3 Sb 5 , driven by electron correlations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

McMillan electron lens in a system with space charge

Space charge (SC) forces of a circulating beam in a ring have both linear (defocusing) and nonlinear components, due to a nonuniform beam distribution. The linear component of SC forces produces a betatron tune shift, which is the largest for a zero-amplitude particle, while the nonlinear component produces an amplitude-dependent betatron tune spread. These SC effects are responsible for several undesirable phenomena in accelerators: emittance growth, particle losses, beam halo, etc. In this paper, we investigate the possibility to mitigate the distributed SC forces by a thin McMillan lens, providing an axially-symmetric kick, which is qualitatively opposite to the accumulated effect of beam's own SC. Experimentally, the proposed concept can be tested in Fermilab's IOTA ring. A thin McMillan lens can be implemented by a short (70) insertion of an electron beam with a specifically chosen density distribution in transverse directions. In this article, to test if McMillan lenses can reduce the tune spread induced by SC, we make several simulations with a 6-D particle tracking code, Synergia. We choose such beam and lattice parameters that the SC tune spread is roughly 0.5 and the emittance growth due to the half-integer resonance is clearly observed without the SC compensation. Then, we focus on reducing the emittance growth by adjusting the bare betatron tunes using the ring quadrupoles, and reducing the tune spread by the McMillan lenses. The results of reducing a large tune spread (≈ 0.5), reported here, are not perfect, but substantial. There is still room for further investigation. The simulations performed so far in this work indicate that McMillan lenses can cope with an SC tune spread of ≈ 0.1 per lens.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Analysis of diagonal G and subspace W approximations within fully self-consistent GW calculations for bulk semiconducting systems

Fully self-consistent GW (sc-GW) methods are now available to evaluate quasiparticle and spectral properties of various molecular and bulk systems. However, such techniques based on the full matrix of G and W are computationally demanding. Additionally, the routinely used single-shot GW approximation (G 0 W 0 ) has an undesirable dependency on the choice of initial exchange-correlation functional. In the literature, many so-called self-consistent GW methods are based on diagonal approximation of G and low-ranking approximation of W. It is thus worth checking how good such approximations are in comparison with the full matrix method. In this work, we consider AlAs, AlP, GaP, and ZnS as the prototype systems to perform sc-GW calculations by expressing the full G matrix using a plane-wave basis set. We compared our sc-GW results with the diagonal G and subspace W approximated sc-GW results (sc-GW-diagG and sc-GW-subW methods). In the sc-GW-diagG method, interacting G is expanded in the eigenvectors of noninteracting G such that only diagonal elements are retained, whereas the number of eigenmodes is truncated in sc-GW-subW calculations. A systematic analysis of the results obtained from the above techniques is presented. The differences in the quasiparticle band gap between the approximated and the full matrix sc-GW approaches are mostly less than 1.7%, which validates such widely adopted approximations, and also shows how such low-ranking approximation can be used to include higher-order terms such as the vertex correction.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Comparison and Discussion on Shortcircuit Protections for Silicon-Carbide MOSFET Modules: Desaturation Versus Rogowski Switch-Current Sensor

Survivability of silicon-carbide (SiC) mosfet modules during short circuit (SC) is essential for modern power electronics systems due to large economic implications. SiC mosfet modules exhibit narrow SC withstand times and generally much lower SC robustness than silicon (Si) insulated-gate bipolar transistors (IGBTs). This puts a critical concern on their utilization, further stressing the importance of reliable protection. This article presents a comprehensive analysis and discussion on the SiC mosfet module SC protection and performance comparison between conventional desaturation detection, previously used for Si IGBT protection, and Rogowski switch-current sensor (RSCS) detection. In addition, this article presents the experimental design for soft turn-off as a reaction to the SC detection to avoid excessive overshoots during the abrupt turn-off of the SC current. To perform different types of SC with various fault inductances on different temperatures, and for the sake of fair comparison under the same conditions, a gate-driver unit for 1.2 kV SiC mosfet half-bridge modules is developed containing both detection methods. The results demonstrate that both methods are successful in protecting the module in all SC types, with superiority of the RSCS detection and concerns for desaturation detection in high-inductance and high dc-bus voltage SC events.

42 ENGINEERING↗
DOE OSTI2025

Dynamic molecular architecture of the synaptonemal complex

During meiosis, pairing between homologous chromosomes is stabilized by the assembly of the synaptonemal complex (SC). The SC ensures the formation of crossovers between homologous chromosomes and regulates their distribution. However, how the SC regulates crossover formation remains elusive. We isolated an unusual mutation in Caenorhabditis elegans that disrupts crossover interference but not SC assembly. This mutation alters the unique C terminal domain of an essential SC protein, SYP-4, a likely ortholog of the vertebrate SC protein SIX6OS1. We use three-dimensional stochastic optical reconstruction microscopy (3D-STORM) to interrogate the molecular architecture of the SC from wild-type and mutant C. elegans animals. Using a probabilistic mapping approach to analyze super-resolution image data, we detect changes in the organization of the synaptonemal complex in wild-type animals that coincide with crossover designation. We also found that our syp-4 mutant perturbs SC architecture. Our findings add to growing evidence that the SC is an active material whose molecular organization contributes to chromosome-wide crossover regulation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Production of Radioisotopes of Scandium for Imaging and Therapy (Final Report)

The theranostic approach is a powerful technique that enables scientists and physicians to diagnose and treat diseases using the same targeting moiety labeled with radionuclides for imaging and therapy. A challenge behind synthesizing and evaluating these theranostic radiopharmaceuticals lies in the production of suitable radionuclides. This study aimed to investigate the production of high radionuclidic purity 43 Sc from enriched [ 46 Ti]TiO 2 for Positron Emission Tomography (PET) and 47 Sc from enriched [ 50 Ti]TiO 2 for targeted radiotherapy, as well as establish a target recycling technique for continued production of these radionuclides. Methods: Targets were prepared with 100 mg of either enriched [ 46 Ti]TiO 2 or [ 50 Ti]TiO 2 , pressed into pellets, and placed into Ta target holders with a 0.127 mm natTi cover foil. The 46 Ti targets were bombarded with 18 MeV protons at 20 µA for 1.5 h, while 50Ti targets were bombarded with 24 MeV protons at 20 µA for 4 or 8 h. The radioscandium nuclides were purified using branched N, N, N’, N’ -tetra-2-ethylhexyldiglycolamide (DGA) resin. The titanium targets were recycled by precipitating the dissolved Ti collected from the column effluent and wash streams, pH adjustment, vacuum filtration, and then drying the solid at 250 °C prior to reforming the target for the subsequent bombardment. The apparent molar activity of the isolated radioscandiums was analyzed by titration with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). The relative imaging performance of 18 F, 43 Sc, and 68 Ga were analyzed with PET images acquired with 30-min static scans. Results: The average radioscandium recovery for 43Sc was 91.7 ± 7.4 %, with a radionuclidic purity of 98.8 %. The average recovery of 47Sc was 89.9 ± 3.9 %, with a radionuclidic purity of 90.8%. The average recovery of enriched TiO2 was 96 ± 4.0 %. The highest apparent molar activity for [43Sc]Sc-DOTA was 23.2 GBq/µmol and 3.39 GBq/µmol for [ 47 Sc]Sc-DOTA. The order of PET resolution from highest to lowest was 18 F > 43 Sc > 68 Ga. Conclusions: This work demonstrates the feasibility of using enriched recycled [ 46 Ti]TiO 2 and [ 50 Ti]TiO 2 targets for the production of the 43 Sc and 47 Sc theranostic isotope pair in high purity.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
NASA NTRS2022

Effect of the Heliospheric State on CME Evolution

The culmination of solar cycle 24 by the end of 2019 has created the opportunity to compare the differing properties of coronal mass ejections (CMEs) between two whole solar cycles: solar cycle 23 (SC 23) and solar cycle 24 (SC 24). We report on the width evolution of limb CMEs in SCs 23 and 24 in order to test the suggestion by Gopalswamy et al. that CME flux ropes attain pressure balance at larger heliocentric distances in SC 24. We measure CME width as a function of heliocentric distance for a significantly large number of limb CMEs (∼1000) and determine the distances where the CMEs reach constant width in each cycle. We introduced a new parameter, the transition height (hc) of a CME, defined as the critical heliocentric distance beyond which the CME width stabilizes to a quasi-constant value. Cycle and phase-to-phase comparisons are based on this new parameter. We find that the average value of hc in SC 24 is 62% higher than that in SC 23. SC 24 CMEs attain their peak width at larger distances from the Sun than SC 23 CMEs do. The enhanced transition height in SC 24 is new observational ratification of the anomalous expansion. The anomalous expansion of SC 24 CMEs, which is caused by the weak state of the heliosphere, accounts for the larger heliocentric distance where the pressure balance between CME flux rope and the ambient medium is attained.

Solar coronal mass ejections↗
DOE OSTI2020

Biaxial steel plated concrete constitutive models for composite structures: Implementation and validation

The Steel-plated Concrete (SC) technique is an alternative construction technique with faster onsite construction speed, reduced construction time, and increased structural performance. Aiming to predict the force transfer mechanism of SC elements, an innovative constitutive model package is proposed by implementing experimental-based biaxial steel plate concrete models into the nonlinear finite element (FE) model “Membrane Model of SC (MM-CS).” First, the formulation and implementation of the MM-SC is illustrated in detail, including the equilibrium and compatibility equations and the implementation of constitutive models. Next, various experimental data of SC members are selected and simulated using the proposed MM-SC model. In this research, two types of structures, SC panels and framed SC shear walls, and three types of loading conditions, including uniaxial compression, pure shear, and combined axial-flexural-shear tests, are analyzed respectively. Good agreements were obtained between the reported results and the FE simulation results in terms of yield capacity and ultimate capacity, proving the reliability of the implemented analytical constitutive material models and the biaxial membrane model formulations.

42 ENGINEERING↗
DOE OSTI2020

Materials Data on Sc2Al3Ru by Materials Project

Sc2RuAl3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Sc is bonded in a 12-coordinate geometry to four equivalent Sc, three equivalent Ru, and nine equivalent Al atoms. There are three shorter (3.20 Å) and one longer (3.33 Å) Sc–Sc bond lengths. All Sc–Ru bond lengths are 3.10 Å. There are three shorter (3.03 Å) and six longer (3.13 Å) Sc–Al bond lengths. Ru is bonded to six equivalent Sc and six equivalent Al atoms to form RuSc6Al6 cuboctahedra that share corners with twelve equivalent AlSc6Al4Ru2 cuboctahedra, edges with six equivalent RuSc6Al6 cuboctahedra, faces with two equivalent RuSc6Al6 cuboctahedra, and faces with eighteen equivalent AlSc6Al4Ru2 cuboctahedra. All Ru–Al bond lengths are 2.62 Å. Al is bonded to six equivalent Sc, two equivalent Ru, and four equivalent Al atoms to form distorted AlSc6Al4Ru2 cuboctahedra that share corners with four equivalent RuSc6Al6 cuboctahedra, corners with fourteen equivalent AlSc6Al4Ru2 cuboctahedra, edges with six equivalent AlSc6Al4Ru2 cuboctahedra, faces with six equivalent RuSc6Al6 cuboctahedra, and faces with twelve equivalent AlSc6Al4Ru2 cuboctahedra. There are two shorter (2.63 Å) and two longer (2.68 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc2Pt by Materials Project

Sc2Pt is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Sc sites. In the first Sc site, Sc is bonded in a 3-coordinate geometry to three equivalent Pt atoms. There are one shorter (2.70 Å) and two longer (2.89 Å) Sc–Pt bond lengths. In the second Sc site, Sc is bonded to four equivalent Pt atoms to form a mixture of edge and corner-sharing ScPt4 tetrahedra. There are a spread of Sc–Pt bond distances ranging from 2.70–2.78 Å. Pt is bonded in a 7-coordinate geometry to seven Sc atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc5Ge3 by Materials Project

Sc5Ge3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Sc sites. In the first Sc site, Sc is bonded in a 6-coordinate geometry to six equivalent Ge atoms. All Sc–Ge bond lengths are 2.86 Å. In the second Sc site, Sc is bonded in a 5-coordinate geometry to five equivalent Ge atoms. There are a spread of Sc–Ge bond distances ranging from 2.74–3.20 Å. Ge is bonded in a 9-coordinate geometry to nine Sc atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc5Ga3 by Materials Project

Sc5Ga3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Sc sites. In the first Sc site, Sc is bonded in a 6-coordinate geometry to six equivalent Ga atoms. All Sc–Ga bond lengths are 2.89 Å. In the second Sc site, Sc is bonded in a 5-coordinate geometry to five equivalent Ga atoms. There are a spread of Sc–Ga bond distances ranging from 2.83–3.24 Å. Ga is bonded in a 9-coordinate geometry to nine Sc atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc5Sn3 by Materials Project

Sc5Sn3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Sc sites. In the first Sc site, Sc is bonded in a 6-coordinate geometry to six equivalent Sn atoms. All Sc–Sn bond lengths are 3.01 Å. In the second Sc site, Sc is bonded in a 5-coordinate geometry to five equivalent Sn atoms. There are a spread of Sc–Sn bond distances ranging from 2.91–3.33 Å. Sn is bonded in a 9-coordinate geometry to nine Sc atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc2Co3Si by Materials Project

Sc2Co3Si crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Sc is bonded in a 12-coordinate geometry to four equivalent Sc, nine equivalent Co, and three equivalent Si atoms. There are one shorter (2.82 Å) and three longer (3.04 Å) Sc–Sc bond lengths. There are three shorter (2.72 Å) and six longer (2.88 Å) Sc–Co bond lengths. All Sc–Si bond lengths are 2.94 Å. Co is bonded to six equivalent Sc, four equivalent Co, and two equivalent Si atoms to form CoSc6Co4Si2 cuboctahedra that share corners with four equivalent SiSc6Co6 cuboctahedra, corners with fourteen equivalent CoSc6Co4Si2 cuboctahedra, edges with six equivalent CoSc6Co4Si2 cuboctahedra, faces with six equivalent SiSc6Co6 cuboctahedra, and faces with twelve equivalent CoSc6Co4Si2 cuboctahedra. There are two shorter (2.45 Å) and two longer (2.58 Å) Co–Co bond lengths. Both Co–Si bond lengths are 2.39 Å. Si is bonded to six equivalent Sc and six equivalent Co atoms to form SiSc6Co6 cuboctahedra that share corners with twelve equivalent CoSc6Co4Si2 cuboctahedra, edges with six equivalent SiSc6Co6 cuboctahedra, faces with two equivalent SiSc6Co6 cuboctahedra, and faces with eighteen equivalent CoSc6Co4Si2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc3Si4Ni11 by Materials Project

Sc3Ni11Si4 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Sc is bonded in a 5-coordinate geometry to ten Ni and five Si atoms. There are a spread of Sc–Ni bond distances ranging from 2.73–2.92 Å. There are one shorter (2.72 Å) and four longer (2.96 Å) Sc–Si bond lengths. There are three inequivalent Ni sites. In the first Ni site, Ni is bonded in a 12-coordinate geometry to three equivalent Sc, six Ni, and three Si atoms. There are a spread of Ni–Ni bond distances ranging from 2.53–2.62 Å. There are one shorter (2.47 Å) and two longer (2.52 Å) Ni–Si bond lengths. In the second Ni site, Ni is bonded in a 12-coordinate geometry to two equivalent Sc, eight Ni, and two equivalent Si atoms. There are two shorter (2.51 Å) and two longer (2.56 Å) Ni–Ni bond lengths. Both Ni–Si bond lengths are 2.24 Å. In the third Ni site, Ni is bonded in a 12-coordinate geometry to three equivalent Sc, six Ni, and three equivalent Si atoms. All Ni–Si bond lengths are 2.29 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to three equivalent Sc and six equivalent Ni atoms. In the second Si site, Si is bonded to four equivalent Sc and eight Ni atoms to form a mixture of corner and face-sharing SiSc4Ni8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ScUS2 by Materials Project

UScS2 is Caswellsilverite-like structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. U is bonded to six S atoms to form US6 octahedra that share corners with two equivalent ScS6 octahedra, corners with four equivalent US6 octahedra, edges with four equivalent US6 octahedra, and edges with eight equivalent ScS6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are four shorter (2.67 Å) and two longer (2.72 Å) U–S bond lengths. Sc is bonded to six S atoms to form ScS6 octahedra that share corners with two equivalent US6 octahedra, corners with four equivalent ScS6 octahedra, edges with four equivalent ScS6 octahedra, and edges with eight equivalent US6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (2.61 Å) and four longer (2.67 Å) Sc–S bond lengths. There are four inequivalent S sites. In the first S site, S is bonded to three equivalent U and three equivalent Sc atoms to form a mixture of edge and corner-sharing SSc3U3 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the second S site, S is bonded to three equivalent U and three equivalent Sc atoms to form a mixture of edge and corner-sharing SSc3U3 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are one shorter (2.61 Å) and two longer (2.67 Å) S–Sc bond lengths. In the third S site, S is bonded to three equivalent U and three equivalent Sc atoms to form a mixture of edge and corner-sharing SSc3U3 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are one shorter (2.61 Å) and two longer (2.67 Å) S–Sc bond lengths. In the fourth S site, S is bonded to three equivalent U and three equivalent Sc atoms to form a mixture of edge and corner-sharing SSc3U3 octahedra. The corner-sharing octahedra tilt angles range from 0–2°.

36 MATERIALS SCIENCE↗