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Results for “SO(3) group”

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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Symmetry analysis of tensors in the honeycomb lattice of edge-sharing octahedra

In this work, we obtain the most general forms of rank-2 and rank-3 tensors allowed by the crystal symmetries of the honeycomb lattice of edge-sharing octahedra for crystals belonging to different crystallographic point groups, including the monoclinic point group 2/$\textit{m}$ and the trigonal (or rhombohedral) point group $\bar{3}$. Our results are relevant for two-dimensional materials, such as α-RuCl 3 , CrI 3 , and the honeycomb iridates. We focus on the magnetic-field-dependent thermal conductivity tensor $κ_{ij}$ (H), which describes a system’s longitudinal and thermal Hall responses, for the cases when the magnetic field is applied along high-symmetry directions, perpendicular to the plane and in the plane. We highlight some unexpected results, such as the equality of fully longitudinal components to partially transverse components in rank-3 tensors for

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Thermal transport properties of IrSbSe

Here we report a thermal transport study of IrSbSe, which crystallizes in a noncentrosymmetric cubic structure with the P2 1 3 space group and shows a narrow-gap semiconducting behavior. The large discrepancy between the activation energy for conductivity [E ρ = 128(2) meV] and for thermopower [E S = 17.7 (9) meV] from 200 to 300 K indicates a polaronic transport mechanism. The electrical resistivity varies as exp (T 0 /T) 1/4 and thermopower varies as T 1/2 at low temperatures, indicating that it evolves into Mott variable-range hopping dominant conduction with decreasing temperature. IrSbSe shows a relatively low value of thermal conductivity (~1.65 W/Km) and thermopower of about 0.24 mV/K around 100 K, yet poor electrical conductivity. On the other hand, a high vacancy defect concentration on both Ir and Sb atomic sites of up to 15% suggests a high defect tolerance and points to the possibility of a future improvement of carrier density by chemical substitution or defect optimization.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Evolution of noncollinear magnetism in magnetocaloric MnPtGa

MnPtGa crystallizes in the hexagonal Ni 2 In structure type in space group P6 3 /mmc and has been reported to display a ferromagnetic Curie temperature near 220K. Here we find a transition near T c = 236 K to a ferromagnetic state, albeit with a reduced moment from what is expected for collinear ordering. The peak magnetocaloric entropy change was determined to be ΔS M = –1.9 J kg –1 K –1 for an applied magnetic field of H = 5 T at the ferromagnetic ordering temperature. Magnetostructural coupling manifests as a change in the slope of the thermal expansion coefficients of the c lattice parameter near T c , with a negative spontaneous volume magnetostriction; ω = –300 ppm at 190K. In this work, neutron powder diffraction studies of the magnetic ground state reveal an evolution in complexity as temperature decreases: from a ferromagnet, to a canted antiferromagnet, to the eventual formation of a spin-density-wave state at low temperatures.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Spin disorder in a stacking polytype of a layered magnet

Strongly correlated ground states and exotic quasiparticle excitations in low-dimensional systems are central research topics in the solid-state research community. The present work develops a layered material and explores the physical properties. Single crystals of 3⁢R–Na 2 ⁢MnTe⁢O 6 were synthesized via a flux method. Single-crystal x-ray diffraction and transmission electron microscopy reveal a crystal structure with ABC-type stacking and an R–3 space group, which establishes this material as a stacking polytype to previously reported 2⁢H–Na 2 ⁢MnTe⁢O 6 . Magnetic- and heat-capacity measurements demonstrate dominant antiferromagnetic interactions, the absence of long-range magnetic order down to 0.5 K, and field-dependent short-range magnetic correlations. A structural transition at ~23 K observed in dielectric measurements may be related to displacements of the Na positions. In conclusion, our results demonstrate that 3⁢R–Na 2 ⁢MnTe⁢O 6 displays low-dimensional magnetism, disordered structure and spins, and the system displays a rich structure variety.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Differences in the resistive and thermodynamic properties of the single crystalline chiral superconductor candidate SrPtAs

The locally noncentrosymmetric superconductor SrPtAs is proposed to host a topological chiral d-wave state, but experimental reports have been limited to polycrystalline samples. Here we report the synthesis of single crystalline SrPtAs grown from Pb flux. SrPtAs crystallizes in the hexagonal space group P⁢6 3 /mmc with lattice parameters a=4.2445⁢(4) Å and c=8.9513⁢(18) Å. Additionally, magnetic susceptibility and electrical resistivity measurements reveal a superconducting transition at T c ~2.2 K, in agreement with previous reports on polycrystalline samples. Surprisingly, heat capacity data show only a small bulk transition at 0.7 K. We discuss the possible origins of the discrepancy between the various measurements.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Role of the third dimension in searching for Majorana fermions in α-RuCl 3 via phonons

Understanding phonons in α-RuCl 3 is critical to analyze the controversy around the observation of the half-integer thermal quantum Hall effect. While many studies have focused on the magnetic excitations in α-RuCl 3 , its vibrational excitation spectrum has remained relatively unexplored. We investigate the phonon structure of α-RuCl 3 via inelastic neutron-scattering experiments and density-functional-theory calculations. Our results show excellent agreement between experiment and first-principles calculations. After validating our theoretical model, we extrapolate the low-energy phonon properties. We find that the phonons in α-RuCl 3 that either propagate or vibrate in the out-of-plane direction have significantly reduced velocities and therefore have the potential to dominate the observability of the elusive half-integer plateaus in the thermal Hall conductance. In addition, we use low-energy interlayer phonons to resolve the low-temperature stacking structure of our large crystal of α-RuCl 3 , which we find to be consistent with that of the R$\bar{3}$ space group, in agreement with neutron diffraction.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Scalable Predictive And Risk Technologies

The research involves developing scalable technologies for risk-informed predictive analytics to achieve condition-based monitoring and maintenance strategies to reduce overall maintenance costs. The research utilizes data (real-time data, periodic data, and institutional knowledge) related to a particular plant asset from a specific nuclear plant site to develop technologies to scale risk-informed predictive analytic algorithms across different plant assets at the plant site and across the nuclear fleet. The developed algorithms and codes are used to optimize the maintenance strategy and estimate/forecast generation costs based on the state of health of the plant asset. Developed codes specifically include 1. Parameter estimation using plant operation data 2. Federated and Transfer learning model 3. Feature group based Multi-kernel SVM 4. Three state markov model

Manjunatha, KoushikAraseethota↗
DOE OSTI2023

Characterizing inhibitors of human AP endonuclease 1

AP endonuclease 1 (APE1) processes DNA lesions including apurinic/apyrimidinic sites and 3´-blocking groups, mediating base excision repair and single strand break repair. Much effort has focused on developing specific inhibitors of APE1, which could have important applications in basic research and potentially lead to clinical anticancer agents. We used structural, biophysical, and biochemical methods to characterize several reported inhibitors, including 7-nitroindole-2-carboxylic acid (CRT0044876), given its small size, reported potency, and widespread use for studying APE1. Intriguingly, NMR chemical shift perturbation (CSP) experiments show that CRT0044876 and three similar indole-2-carboxylic acids bind a pocket distal from the APE1 active site. A crystal structure confirms these findings and defines the pose for 5-nitroindole-2-carboxylic acid. However, dynamic light scattering experiments show the indole compounds form colloidal aggregates that could bind (sequester) APE1, causing nonspecific inhibition. Endonuclease assays show the compounds lack significant APE1 inhibition under conditions (detergent) that disrupt aggregation. Thus, binding of the indole-2-carboxylic acids at the remote pocket does not inhibit APE1 repair activity. Myricetin also forms aggregates and lacks APE1 inhibition under aggregate-disrupting conditions. Two other reported compounds (MLS000552981, MLS000419194) inhibit APE1 in vitro with low micromolar IC50 and do not appear to aggregate in this concentration range. However, NMR CSP experiments indicate the compounds do not bind specifically to apo- or Mg 2+ -bound APE1, pointing to a non-specific mode of inhibition, possibly DNA binding. Our results highlight methods for rigorous interrogation of putative APE1 inhibitors and should facilitate future efforts to discover compounds that specifically inhibit this important repair enzyme.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Materials Data on H16C3NF7 by Materials Project

C3H7NH3H6F7 crystallizes in the hexagonal P6_3 space group. The structure is zero-dimensional and consists of two ac1l3pq0 molecules and two trimethylazanium molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaSm3SiS7 by Materials Project

NaSm3SiS7 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. Na1+ is bonded to six equivalent S2- atoms to form face-sharing NaS6 octahedra. There are three shorter (2.73 Å) and three longer (2.74 Å) Na–S bond lengths. Sm3+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Sm–S bond distances ranging from 2.85–3.13 Å. Si4+ is bonded in a tetrahedral geometry to four S2- atoms. There are one shorter (2.12 Å) and three longer (2.15 Å) Si–S bond lengths. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to two equivalent Na1+ and four equivalent Sm3+ atoms. In the second S2- site, S2- is bonded in a 4-coordinate geometry to three equivalent Sm3+ and one Si4+ atom. In the third S2- site, S2- is bonded in a distorted tetrahedral geometry to three equivalent Sm3+ and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tl3AsO4 by Materials Project

Tl3AsO4 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. Tl1+ is bonded in a 4-coordinate geometry to three O2- atoms. There are a spread of Tl–O bond distances ranging from 2.56–2.62 Å. As5+ is bonded in a tetrahedral geometry to four O2- atoms. There is three shorter (1.73 Å) and one longer (1.75 Å) As–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Tl1+ and one As5+ atom. In the second O2- site, O2- is bonded in a tetrahedral geometry to three equivalent Tl1+ and one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La3AgSnSe7 by Materials Project

La3AgSnSe7 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. La3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of La–Se bond distances ranging from 3.06–3.42 Å. Ag1+ is bonded in a trigonal planar geometry to three equivalent Se2- atoms. All Ag–Se bond lengths are 2.59 Å. Sn4+ is bonded in a tetrahedral geometry to four Se2- atoms. There are one shorter (2.52 Å) and three longer (2.58 Å) Sn–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a tetrahedral geometry to three equivalent La3+ and one Sn4+ atom. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to four equivalent La3+ and one Ag1+ atom. In the third Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent La3+ and one Sn4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr3CuSnSe7 by Materials Project

Pr3CuSnSe7 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. Pr3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Pr–Se bond distances ranging from 2.96–3.51 Å. Cu1+ is bonded in a trigonal planar geometry to three equivalent Se2- atoms. All Cu–Se bond lengths are 2.40 Å. Sn4+ is bonded in a tetrahedral geometry to four Se2- atoms. There are one shorter (2.52 Å) and three longer (2.57 Å) Sn–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Pr3+ and one Sn4+ atom. In the second Se2- site, Se2- is bonded in a tetrahedral geometry to three equivalent Pr3+ and one Sn4+ atom. In the third Se2- site, Se2- is bonded in a 5-coordinate geometry to four equivalent Pr3+ and one Cu1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr3SiAgSe7 by Materials Project

Pr3AgSiSe7 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. Pr3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Pr–Se bond distances ranging from 3.03–3.25 Å. Ag1+ is bonded in a trigonal planar geometry to three equivalent Se2- atoms. All Ag–Se bond lengths are 2.58 Å. Si4+ is bonded in a tetrahedral geometry to four Se2- atoms. There are one shorter (2.27 Å) and three longer (2.31 Å) Si–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 4-coordinate geometry to three equivalent Pr3+ and one Si4+ atom. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to four equivalent Pr3+ and one Ag1+ atom. In the third Se2- site, Se2- is bonded in a distorted tetrahedral geometry to three equivalent Pr3+ and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho3CuSiS7 by Materials Project

Ho3CuSiS7 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. Ho3+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Ho–S bond distances ranging from 2.75–3.15 Å. Cu1+ is bonded in a trigonal planar geometry to three equivalent S2- atoms. All Cu–S bond lengths are 2.24 Å. Si4+ is bonded in a tetrahedral geometry to four S2- atoms. There are one shorter (2.11 Å) and three longer (2.15 Å) Si–S bond lengths. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to three equivalent Ho3+ and one Si4+ atom. In the second S2- site, S2- is bonded in a 5-coordinate geometry to four equivalent Ho3+ and one Cu1+ atom. In the third S2- site, S2- is bonded in a distorted tetrahedral geometry to three equivalent Ho3+ and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La3SiAgS7 by Materials Project

La3AgSiS7 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. La3+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of La–S bond distances ranging from 2.93–3.15 Å. Ag1+ is bonded in a trigonal planar geometry to three equivalent S2- atoms. All Ag–S bond lengths are 2.46 Å. Si4+ is bonded in a tetrahedral geometry to four S2- atoms. There are one shorter (2.12 Å) and three longer (2.15 Å) Si–S bond lengths. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted tetrahedral geometry to three equivalent La3+ and one Si4+ atom. In the second S2- site, S2- is bonded in a 4-coordinate geometry to three equivalent La3+ and one Si4+ atom. In the third S2- site, S2- is bonded in a 5-coordinate geometry to four equivalent La3+ and one Ag1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y3CuSnS7 by Materials Project

Y3CuSnS7 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. Y3+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of Y–S bond distances ranging from 2.73–3.15 Å. Cu1+ is bonded in a trigonal planar geometry to three equivalent S2- atoms. All Cu–S bond lengths are 2.23 Å. Sn4+ is bonded in a tetrahedral geometry to four S2- atoms. There are one shorter (2.41 Å) and three longer (2.42 Å) Sn–S bond lengths. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a tetrahedral geometry to three equivalent Y3+ and one Sn4+ atom. In the second S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Y3+ and one Sn4+ atom. In the third S2- site, S2- is bonded in a 4-coordinate geometry to three equivalent Y3+ and one Cu1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd3SiAgSe7 by Materials Project

Nd3AgSiSe7 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. Nd3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Nd–Se bond distances ranging from 3.01–3.25 Å. Ag1+ is bonded in a trigonal planar geometry to three equivalent Se2- atoms. All Ag–Se bond lengths are 2.57 Å. Si4+ is bonded in a tetrahedral geometry to four Se2- atoms. There are one shorter (2.27 Å) and three longer (2.31 Å) Si–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 4-coordinate geometry to three equivalent Nd3+ and one Si4+ atom. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to four equivalent Nd3+ and one Ag1+ atom. In the third Se2- site, Se2- is bonded in a distorted tetrahedral geometry to three equivalent Nd3+ and one Si4+ atom.

36 MATERIALS SCIENCE↗