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Results for “magnetism in solids”

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

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Chlorination of Hydrogenated Silicon Nanosheets Revealed by Solid-State Nuclear Magnetic Resonance Spectroscopy

We report two-dimensional silicon nanosheets (Si-NS) synthesized by topotactic deintercalation of CaSi 2 are hypothesized to consist of buckled layers of sp 3 -hybridized silicon atoms that are bonded to three other framework Si atoms and a terminal atom or functional group such as H, Cl, or OH. Here, we apply 1 H{ 35 Cl} and 29 Si{ 35 Cl} Resonance-Echo Saturation-Pulse DOuble-Resonance (RESPDOR) solid-state NMR experiments to directly confirm the presence of chlorinated Si atoms within Si-NS. Plotting the 1 H{ 35 Cl} RESPDOR dephasing as a function of the 35 Cl saturation pulse offset reveals that the 35 Cl quadrupolar coupling constant (C Q ) is 38 MHz, consistent with Cl atoms that are covalently bonded to silicon. Modeling the 1 H{ 35 Cl} RESPDOR dephasing curve shows that the Si–Si interlayer spacing is approximately 6 Å. Plane-wave density functional theory (DFT) calculations show that the direct band gap transition of the Si-NS decreases with increasing chlorination and hydroxylation, suggesting that the band gap of Si-NS can be tuned by modifying the terminal atoms or functional groups.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Observing the Surface Termination of LaScO 3 Perovskite Using Solid-State Nuclear Magnetic Resonance

Materials with well-defined surfaces are drawing increased attention for the design of bespoke catalysts and nanomaterials. Gaining a detailed understanding of the surfaces of these materials is an important challenge, which is often complicated by surface polymorphism and dynamic restructuring. We introduce the use of surface-enhanced NMR spectroscopy for the observation of such surfaces, focusing on LaScO 3 as an example. Here, we show that double-resonance NMR experiments correlating surface oxygen and probe molecules to the 139 La and 45 Sc nuclei at the surface reveal the material to be terminated by a ScO x monolayer. Surface-selective 17 O and 45 Sc NMR experiments further showed the material to be hydroxyl terminated and that the surface may be prone to dynamic restructuring as a result of moisture exposure. Perhaps most interestingly, surface-selective 139 La NMR experiments revealed the existence of previously undetected surface lanthanum defects, suggesting that surface-enhanced NMR may be useful as a guide in the synthesis of defect-free surfaces in the design of various nanomaterials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1983

NMR (Nuclear Magnetic Resonance) of solid biopolymers

It has been possible through the study of proton relaxation in solid proteins and related molecules to identify and characterize the following molecular motions which contribute to relaxation: (1) methyl group reorientation; (2) segmental motion; (3) side chain motion; (4) proline ring puckering; and (5) water molecule reorientation.

Andrew, E. R.↗
DOE OSTI2021

Magnetic and structural properties of the solid solution CuAl 2(1–x) Ga 2x O 4

CuAl 2 O 4 is a ternary oxide spinel with Cu 2+ ions (s = 1/2) primarily populating the A-site diamond sublattice. The compound is reported to display evidence of spin glass behavior but possess a non-frozen magnetic ground state below the transition temperature. On the other hand, the spinel CuGa 2 O 4 displays spin glass behavior at ~ 2.5 K with Cu 2+ ions more readily tending to the B-site pyrochlore sublattice. Therefore, we investigate the magnetic and structural properties of the solid solution CuAl 2(1-x) Ga 2x O 4 examining the evolution of the magnetic behavior as Al 3+ is replaced with a much larger Ga 3+ ion. Our results show that the Cu 2+ ions tend to migrate from tetrahedral to octahedral sites as the Ga 3+ ion concentration increases, resulting in a concomitant change in the glassy magnetic properties of the solution. Results indicate glassy behavior for much of the solution with a general trend towards decreasing magnetic frustration as the Cu 2+ ion shifts to the B-site. However, the x = 0.1 and 0.2 members of the system do not show glassy behavior down to our measurement limit (1.9 K) suggesting a delayed spin glass transition. We suggest that these two members are additional candidates for investigation to access highly frustrated exotic quantum states.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Structure of Self-Generated Magnetic Fields in Laser-Solid Interaction from Proton Tomography

Self-generated magnetic fields in laser-solid interactions are experimentally characterized to reveal the 3D location and local field strength, rather than path-integrated quantities, using multi-view proton radiography and tomographic inversion. We infer magnetic fields that extend several millimeters off the target into the hot, rarefied corona, sufficient to strongly magnetize the plasma (Ω e τ e ≫ 1). The data are compared to MHD simulations incorporating recent improvements in modeling magnetic field generation and transport; the volume-averaged coronal field strength and magnetic flux agree to within 25% using a model with magnetic re-localization of transport, although the near-target morphology is not reproduced. This work demonstrates tomographic proton radiography as a valuable tool for investigating magnetic fields in laser-produced plasmas.

High-energy-density plasmas↗
DOE OSTI2024

Crafting Multifunctional Materials with Tailored Mechanical and Magnetic Properties by Solid-State Non-equilibrium Processing

Aluminum matrix composites hold promise for creating lightweight structural components with multifunctional properties. Nonetheless, achieving desired magnetic or electrical characteristics without compromising their fundamental mechanical properties presents a significant challenge. Here, in this study, we explore mechanical stir-based extrusion as a solid-state metalworking technique to develop fine-grained microstructures and highly refined metallic composites. Our study focuses on creating a SmCo 5 -reinforced aluminum matrix composite using solid stir extrusion (SSE) and assessing its microstructure, mechanical, and magnetic properties through a comprehensive suite of characterization tools, including x-ray diffraction, electron microscopy, and magnetometry. Our findings reveal that incorporating a small amount (3.76 wt.%) of SmCo 5 phase in a non-heat-treatable, non-magnetic aluminum alloy via SSE yields a composite that exhibits good hard magnetic characteristics with a large coercivity (H ci = 13.5 kOe) and improved mechanical properties. This study underscores non-equilibrium processing via solid-state high-speed stirring as a compelling method for crafting multifunctional materials with tailored mechanical and magnetic properties.

36 MATERIALS SCIENCE↗
NASA NTRS2002

Solid state 31phosphorus nuclear magnetic resonance of iron-, manganese-, and copper-containing synthetic hydroxyapatites

The incorporation of micronutrients into synthetic hydroxyapatite (SHA) is proposed for slow release of these nutrients to crops in the National Aeronautics and Space Administration's (NASA's) Advanced Life Support (ALS) program for Lunar or Martian outposts. Solid state 31P nuclear magnetic resonance (NMR) was utilized to examine the paramagnetic effects of Fe3+, Mn2+, and Cu2+ to determine if they were incorporated into the SHA structure. Separate Fe3+, Mn2+, and Cu2+ containing SHA materials along with a transition metal free SHA (pure-SHA) were synthesized using a precipitation method. The proximity (<1 nm) of the transition metals to the 31P nuclei of SHA were apparent when comparing the integrated 31P signal intensities of the pure-SHA (87 arbitrary units g-1) with the Fe-, Mn-, and Cu-SHA materials (37-71 arbitrary units g-1). The lower integrated 31P signal intensities of the Fe-, Mn-, and Cu-SHA materials relative to the pure-SHA suggested that Fe3+, Mn2+, and Cu2+ were incorporated in the SHA structure. Further support for Fe3+, Mn2+, and Cu2+ incorporation was demonstrated by the reduced spin-lattice relaxation constants of the Fe-, Mn-, and Cu-SHA materials (T'=0.075-0.434s) relative to pure-SHA (T1=58.4s). Inversion recovery spectra indicated that Fe3+, Mn2+, and Cu2+ were not homogeneously distributed about the 31P nuclei in the SHA structure. Extraction with diethylene-triamine-penta-acetic acid (DTPA) suggested that between 50 and 80% of the total starting metal concentrations were incorporated in the SHA structure. Iron-, Mn-, and Cu-containing SHA are potential slow release sources of Fe, Mn, and Cu in the ALS cropping system.

NASA Discipline Life Support Systems↗
DOE OSTI2025

Magnetism in EuAlSi and the Eu 1−𝑥 ⁢Sr 𝑥 ⁢ AlSi solid solution solid solution

The magnetic properties of EuAlSi, a compound comprising a honeycomb lattice of Al/Si atoms and a triangular lattice of Eu atoms, are presented. By means of single-crystal x-ray diffraction, we find that EuAlSi crystallizes in an AlB 2 -type structure with space group 𝑃⁢6/mmm and unit cell parameters 𝑎 = 4.2229⁢ (10) ⁢Å and 𝑐 = 4.5268 ⁢(12)⁢ Å. Our magnetic measurements indicate that EuAlSi is a soft ferromagnetic material with 𝑇 Curie = 25.8 K. The susceptibility follows the Curie-Weiss law at high temperatures, which allowed us to determine the paramagnetic Curie temperature 𝜃 𝑃 = 36.2 ⁢(1) ⁢K and an effective magnetic moment 𝜇 eff = 8.07 ⁢(1)⁢ µ 𝐵 /Eu. This value is in agreement with the theoretical value of 7.9 µ 𝐵 for Eu 2+ free ion. Moreover, we have prepared the Eu 1−𝑥 ⁢Sr 𝑥 ⁢ AlSi solid solution, where the atoms in the triangular lattice were systematically exchanged, in order to study the evolution of the collective quantum properties from the ferromagnetic EuAlSi toward the superconducting SrAlSi. Across the Eu 1−𝑥 ⁢Sr 𝑥 AlSi solid solution, the unit cell parameters change linearly, following Vegard’s law, and making the system reliable for studying composition dependence of the interplay between the crystal structure and physical properties. As the Sr content increases, i.e., 𝑥 increases, we note a consistent reduction of 𝜇 eff and 𝑇 Curie . Long-range magnetic order in Eu 1−𝑥 ⁢Sr 𝑥 ⁢ AlSi persists up to 𝑥 = 0.95, whereas superconductivity is only observed for samples with 𝑥 > 0.97.

Walicka, Dorota I. [University of Geneva (Switzerl↗
DOE OSTI2020

Solid state grain alignment of permanent magnets in near-final shape

Magnet microstructure manipulation in the solid state by controlled application of a sufficient stress in a direction during high temperature annealing in a single-phase region of heat-treatable magnet alloys, e.g., alnico-type magnets is followed by magnetic annealing and draw annealing to improve coercivity and saturation magnetization properties. The solid-state process can be termed highly controlled abnormal grain growth (hereafter AGG) and will make aligned sintered anisotropic magnets that meet or exceed the magnetic properties of cast versions of the same alloy types.

Anderson, Iver E.↗
DOE OSTI2022

Solid state grain alignment of permanent magnets in near-final shape

Magnet microstructure manipulation in the solid state by controlled application of a sufficient stress in a direction during high temperature annealing in a single-phase region of heat-treatable magnet alloys, e.g., alnico-type magnets is followed by magnetic annealing and draw annealing to improve coercivity and saturation magnetization properties. The solid-state process can be termed highly controlled abnormal grain growth (hereafter AGG) and will make aligned sintered anisotropic magnets that meet or exceed the magnetic properties of cast versions of the same alloy types.

Anderson, Iver E.↗