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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 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Reaching a burning plasma and ignition using smaller capsules/ Hohlraums , higher radiation temperatures, and thicker ablator/ice on the national ignition facility

In indirect-drive implosions, the final core hot spot energy and pressure and, hence, neutron yield attainable in 1D increase with increasing laser peak power and, hence, radiation drive temperature at the fixed capsule and Hohlraum size. Here we present simple analytic scalings validated by 1D simulations that quantify the improvement in performance and use this to explain existing data and simulation trends. Extrapolating to the 500 TW National Ignition Facility peak power limit in a low gas-fill 5.4 mm diameter Hohlraum based on existing high adiabat implosion data at 400 TW, 1.3 MJ and 1 × 10 16 yield, we find that a 2–3 × 10 17 yield (0.5–0.7 MJ) is plausible using only 1.8 MJ of laser energy. Based on existing data varying deuterium–tritium (DT) fuel thickness and dopant areal density, further improvements should be possible by increasing DT fuel areal density, and hence confinement time and yield amplification.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Study of self-assembly behavior and ionic conductivity of conjugated liquid crystals with T-shaped facial-polyphilic structure

The unique self-assembly of liquid crystals (LCs), combined with their potential application as organic semiconductors, has become a focus of recent research. Here, a joint experimental and computational study of the self-assembly and ionic conduction was carried out on a series of T-shaped conjugated LCs consisting of three incompatible components. By extending the EOn side-chain length, several experimental evaluations confirmed a decrease of the order-disorder transition temperature, while coarse-grained simulations revealed a structural evolution from a smectic phase to a columnar phase. Ionic conductivity of these molecules was achieved by adding Li salt, leading to a maximum conductivity of 1.1 × 10 −3 siemens per centimeter observed at 120°C. All-atom simulations were performed to examine the Li-ion solvation environment and to evaluate the intrachain and interchain Li-ion hopping mechanisms. The molecule with a long EOn side chain was found to generate a densely distributed network of Li-ion solvation sites, which can facilitate effective interchain hopping to promote ion transport.

Liu, Ziwei [Cornell Univ., Ithaca, NY (United Stat↗
DOE OSTI2023

Hydrophobic Nanoconfinement Enhances CO 2 Conversion to H 2 CO 3

Understanding the formation of H 2 CO 3 in water from CO 2 is important in environmental and industrial processes. Although numerous investigations have studied this reaction, the conversion of CO 2 to H 2 CO 3 in nanopores, and how it differs from that in bulk water, has not been understood. We use ReaxFF metadynamics molecular simulations to demonstrate striking differences in the free energy of CO 2 conversion to H 2 CO 3 in bulk and nanoconfined aqueous environments. We find that nanoconfinement not only reduces the energy barrier but also reverses the reaction from endothermic in bulk water to exothermic in nanoconfined water. Also, charged intermediates are observed more often under nanoconfinement than in bulk water. Stronger solvation and more favorable proton transfer with increasing nanoconfinement enhance the thermodynamics and kinetics of the reaction. Here our results provide a detailed mechanistic understanding of an important step in the carbonation process, which depends intricately on confinement, surface chemistry, and CO 2 concentration.

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

Surface triggered stabilization of metastable charge-ordered phase in SrTiO 3

Charge ordering (CO), characterized by a periodic modulation of electron density and lattice distortion, has been a fundamental topic in condensed matter physics, serving as a potential platform for inducing novel functional properties. The charge-ordered phase is known to occur in a doped system with high d-electron occupancy, rather than low occupancy. Here, we report the realization of the charge-ordered phase in electron-doped (100) SrTiO 3 epitaxial thin films that have the lowest d-electron occupancy i.e., d 1 -d 0 . Theoretical calculation predicts the presence of a metastable CO state in the bulk state of electron-doped SrTiO 3 . Atomic scale analysis reveals that (100) surface distortion favors electron-lattice coupling for the charge-ordered state, and triggering the stabilization of the CO phase from a correlated metal state. This stabilization extends up to six unit cells from the top surface to the interior. Our approach offers an insight into the means of stabilizing a new phase of matter, extending CO phase to the lowest electron occupancy and encompassing a wide range of 3d transition metal oxides.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho10Ti6O27 by Materials Project

Ho10Ti6O27 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are fifteen inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.12–2.58 Å. In the second Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 pentagonal bipyramids that share a cornercorner with one TiO6 octahedra, corners with two equivalent TiO5 square pyramids, a cornercorner with one TiO4 tetrahedra, and edges with two equivalent TiO5 square pyramids. The corner-sharing octahedral tilt angles are 57°. There are a spread of Ho–O bond distances ranging from 2.20–2.55 Å. In the third Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.19–2.40 Å. In the fourth Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.15–2.47 Å. In the fifth Ho3+ site, Ho3+ is bonded to six O2- atoms to form distorted HoO6 octahedra that share a cornercorner with one TiO4 tetrahedra. There are a spread of Ho–O bond distances ranging from 2.14–2.38 Å. In the sixth Ho3+ site, Ho3+ is bonded to six O2- atoms to form distorted HoO6 pentagonal pyramids that share an edgeedge with one HoO8 hexagonal bipyramid and edges with two equivalent TiO6 octahedra. There are a spread of Ho–O bond distances ranging from 2.13–2.44 Å. In the seventh Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.17–2.38 Å. In the eighth Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.20–2.37 Å. In the ninth Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.20–2.88 Å. In the tenth Ho3+ site, Ho3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.23–2.76 Å. In the eleventh Ho3+ site, Ho3+ is bonded to eight O2- atoms to form distorted HoO8 hexagonal bipyramids that share edges with four equivalent TiO6 octahedra, an edgeedge with one HoO6 pentagonal pyramid, and edges with two equivalent TiO5 trigonal bipyramids. There are a spread of Ho–O bond distances ranging from 2.10–2.59 Å. In the twelfth Ho3+ site, Ho3+ is bonded to eight O2- atoms to form distorted HoO8 hexagonal bipyramids that share edges with two equivalent TiO6 octahedra, edges with two equivalent TiO7 pentagonal bipyramids, and edges with two equivalent TiO5 square pyramids. There are a spread of Ho–O bond distances ranging from 2.14–2.60 Å. In the thirteenth Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 hexagonal pyramids that share a cornercorner with one TiO6 octahedra, corners with two equivalent TiO7 pentagonal bipyramids, and edges with three TiO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 63°. There are a spread of Ho–O bond distances ranging from 2.26–2.29 Å. In the fourteenth Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.19–2.50 Å. In the fifteenth Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to seven O2- atoms. There are a spread of Ho–O bond distances ranging from 2.31–2.37 Å. There are nine inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to five O2- atoms to form distorted TiO5 square pyramids that share a cornercorner with one TiO6 octahedra, a cornercorner with one HoO7 pentagonal bipyramid, corners with two equivalent TiO5 square pyramids, an edgeedge with one HoO8 hexagonal bipyramid, and an edgeedge with one HoO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 41°. There are a spread of Ti–O bond distances ranging from 1.81–2.16 Å. In the second Ti4+ site, Ti4+ is bonded in a trigonal pyramidal geometry to four O2- atoms. There are a spread of Ti–O bond distances ranging from 1.78–1.95 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with two equivalent TiO6 octahedra, a cornercorner with one TiO7 pentagonal bipyramid, corners with two equivalent TiO5 trigonal bipyramids, edges with two equivalent HoO8 hexagonal bipyramids, and an edgeedge with one HoO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 42–55°. There are a spread of Ti–O bond distances ranging from 1.80–2.22 Å. In the fourth Ti4+ site, Ti4+ is bonded to four O2- atoms to form distorted TiO4 tetrahedra that share a cornercorner with one HoO6 octahedra and a cornercorner with one HoO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 60°. There are a spread of Ti–O bond distances ranging from 1.79–2.03 Å. In the fifth Ti4+ site, Ti4+ is bonded to seven O2- atoms to form distorted TiO7 pentagonal bipyramids that share corners with two equivalent TiO6 octahedra, a cornercorner with one TiO5 trigonal bipyramid, an edgeedge with one HoO7 hexagonal pyramid, and edges with two equivalent TiO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. There are a spread of Ti–O bond distances ranging from 1.92–2.17 Å. In the sixth Ti4+ site, Ti4+ is bonded to five O2- atoms to form distorted TiO5 trigonal bipyramids that share corners with four equivalent TiO6 octahedra, a cornercorner with one TiO7 pentagonal bipyramid, and edges with two equivalent HoO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 37–59°. There are a spread of Ti–O bond distances ranging from 1.79–2.01 Å. In the seventh Ti4+ site, Ti4+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ti–O bond distances ranging from 1.87–1.94 Å. In the eighth Ti4+ site, Ti4+ is bonded to seven O2- atoms to form distorted TiO7 pentagonal bipyramids that share a cornercorner with one HoO7 hexagonal pyramid, a cornercorner with one TiO6 octahedra, a cornercorner with one TiO7 pentagonal bipyramid, an edgeedge with one HoO8 hexagonal bipyramid, an edgeedge with one HoO7 hexagonal pyramid, and edges with two TiO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 44°. There are a spread of Ti–O bond distances ranging from 1.97–2.15 Å. In the ninth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one HoO7 hexagonal pyramid, a cornercorner with one HoO7 pentagonal bipyramid, corners with two equivalent TiO7 pentagonal bipyramids, corners with two equivalent TiO5 square pyramids, and edges with two equivalent HoO8 hexagonal bipyramids. There are a spread of Ti–O bond distances ranging from 1.89–2.11 Å. There are thirty-eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Ho3+ and one Ti4+ atom. In the second O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form a mixture of distorted edge and corner-sharing OHo3Ti tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Ho3+ and two Ti4+ atoms. In the fourth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form distorted OHo3Ti tetrahedra that share corners with four OHo4 tetrahedra and edges with three OHo3Ti tetrahedra. In the fifth O2- site, O2- is bonded to four Ho3+ atoms to form a mixture of edge and corner-sharing OHo4 tetrahedra. In the sixth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form OHo3Ti tetrahedra that share corners with eight OHo3Ti tetrahedra and edges with two equivalent OHo4 tetrahedra. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+ and one Ti4+ atom. In the eighth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form a mixture of distorted edge and corner-sharing OHo3Ti tetrahedra. In the ninth O2- site, O2- is bonded to four Ho3+ atoms to form distorted OHo4 tetrahedra that share corners with seven OHo4 tetrahedra and edges with four OHo3Ti tetrahedra. In the tenth O2- site, O2- is bonded to two Ho3+ and two Ti4+ atoms to form OHo2Ti2 tetrahedra that share corners with eight OHo4 tetrahedra and edges with three OHoTi3 tetrahedra. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and two equivalent Ti4+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Ho3+ and two Ti4+ atoms. In the thirteenth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form a mixture of distorted edge and corner-sharing OHo3Ti tetrahedra. In the fourteenth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form OHo3Ti tetrahedra that share corners with six OHo4 tetrahedra and edges with three OHo3Ti tetrahedra. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ho3+ and one Ti4+ atom. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Ho3+ atoms. In the seventeenth O2- site, O2- is bonded to four Ho3+ atoms to form OHo4 tetrahedra that share corners with three OHo4 tetrahedra and an edgeedge with one OHo3Ti tetrahedra. In the eighteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Ho3+ and two Ti4+ atoms. In the nineteenth O2- site, O2- is bonded to four Ho3+ atoms to form OHo4 tetrahedra that share corners with six OHo4 tetrahedra and edges with three OHo2Ti2 tetrahedra. In the twentieth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ho3+ and two Ti4+ atoms. In the twenty-first O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form distorted OHo3Ti tetrahedra that share corners with nine OHo3Ti tetrahedra and edges with five OHo4 tetrahedra. In the twenty-second O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+ and two Ti4+ atoms. In the twenty-third O2- site, O2- is bonded to two Ho3+ and two equivalent Ti4+ atoms to form distorted OHo2Ti2 tetrahedra that share corners with eight OHo4 tetrahedra and edges with four OHoTi3 tetrahedra. In the twenty-fourth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form OHo3Ti tetrahedra that share corners with eight OHo4 tetrahedra and edges with four OHoTi3 tetrahedra. In the twenty-fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Ho3+ and two equivalent Ti4+ atoms. In the twenty-sixth O2- site, O2- is bonded in a 1-coordinate geometry to two Ho3+ and two Ti4+ atoms. In the twenty-seventh O2- site, O2- is bonded to four Ho3+ atoms to form a mixture of edge and corner-sharing OHo4 tetrahedra. In the twenty-eighth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form a mixture of edge and corner-sharing OHo3Ti tetrahedra. In the twenty-ninth O2- site, O2- is bonded to four Ho3+ atoms to form OHo4 tetrahedra that share corners with six OHo4 tetrahedra and edges with four OHo3Ti tetrahedra. In the thirtieth O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and one Ti4+ atom. In the thirty-first O2- site, O2- is bonded in a 4-coordinate geometry to three Ho3+ and one Ti4+ atom. In the thirty-second O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form distorted OHo3Ti tetrahedra that share corners with seven OHo3Ti tetrahedra and an edgeedge with one OHo4 tetrahedra. In the thirty-third O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+ and two equivalent Ti4+ atoms. In the thirty-fourth O2- site, O2- is bonded to four Ho3+ atoms to form corner-sharing OHo4 tetrahedra. In the thirty-fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Ho3+ and two Ti4+ atoms. In the thirty-sixth O2- site, O2- is bonded to one Ho3+ and three Ti4+ atoms to form a mixture of edge and corner-sharing OHoTi3 tetrahedra. In the thirty-seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Ho3+ and two equivalent Ti4+

36 MATERIALS SCIENCE↗
DOE OSTI2023

Interactions among soil texture, pore structure, and labile carbon influence soil carbon gains

Perennial vegetation with high plant diversity, e.g., restored prairie, is known for stimulation of soil carbon (C) gains, due in part to enhanced formation of pore structure beneficial for long-term C storage. However, the prevalence of this phenomenon across soils of different types remains poorly understood. The aim of the study was to assess the associations between pore structure, soil C, and their differences in monoculture switchgrass and polyculture restored prairie vegetation across a wide range of soils dominating the Upper Midwest of the USA. Six experimental sites were sampled, representing three soil types with texture ranging from sandy to silt loams. The two vegetation systems studied at each site were (i) monoculture switchgrass (Panicum virgatum L.), and (ii) polyculture restored prairie, also containing switchgrass as one of its species. X-ray computed micro-tomography (µCT) was employed to analyze soil pore structure. Structural equation modeling and multiple path analyses were used to assess direct and indirect effects of soil texture and pore characteristics on microbial biomass C (MBC), particulate organic matter (POM), dissolved organic C (DOC), short-term respiration (CO 2 ), and, ultimately, soil organic C (SOC). Across studied sites, prairie increased fractions of medium (50–150 µm Ø) pores by 11–45 %, SOC by 3–69 %, and MBC by 18–59 % (except for one site). The greater were the prairie-induced increases in the medium pore volumes, the greater were the prairie-induced SOC gains. Greater C losses via CO 2 and DOC contributed to slower C accumulation in the prairie soil. We surmise that the interactive feedback loop relating medium pores and soil C acts across a wide range of soil textures and is an important mechanism through which perennial vegetation with high plant diversity, such as restored prairie, promotes rapid SOC gains.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Aberrant electronic and structural alterations in pressure tuned perovskite NaOsO 3

The perovskite NaOsO 3 has a metal–insulator transition at temperature 410 K, which is delicate, intriguing, and provokes a lot of debate on its nature. Our combined electrical resistance, Raman, and synchrotron x-ray diffraction experiments show that the insulating ground state in this osmate endures under high pressure up to at least 35 GPa. In this pressure range, compression reveals hidden hysteretic resistance properties with a transient metallic state near 200 K, manifested three electronic character anomalies (at 1.7, 9.0, and 25.5 GPa), and a structural transition to the singular polar phase (at ~18 GPa). We distinguish NaOsO 3 from the regular crystallographic behavior of perovskites, though the electrical specificities resemble iridates and nickelates. The theoretical first-principle band structure and lattice dynamics calculations demonstrate that the magnetically itinerant Lifshitz-type mechanism with spin–orbit and spin–phonon interactions is responsible for these pressure-induced changes. Our findings provide another new playground for the emergence of new states in 5d materials by using high-pressure methods.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho5Cu(WO4)8 by Materials Project

Ho5Cu(WO4)8 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are three inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 pentagonal bipyramids that share corners with seven WO6 octahedra, an edgeedge with one HoO6 octahedra, an edgeedge with one WO6 octahedra, and an edgeedge with one HoO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 28–54°. There are a spread of Ho–O bond distances ranging from 2.25–2.43 Å. In the second Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 pentagonal bipyramids that share corners with seven WO6 octahedra, an edgeedge with one WO6 octahedra, an edgeedge with one HoO7 pentagonal bipyramid, and an edgeedge with one CuO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 35–54°. There are a spread of Ho–O bond distances ranging from 2.26–2.42 Å. In the third Ho3+ site, Ho3+ is bonded to six O2- atoms to form distorted HoO6 octahedra that share corners with eight WO6 octahedra and edges with two equivalent HoO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 47–61°. There are a spread of Ho–O bond distances ranging from 2.21–2.34 Å. There are four inequivalent W6+ sites. In the first W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share a cornercorner with one HoO6 octahedra, corners with two equivalent WO6 octahedra, corners with three HoO7 pentagonal bipyramids, an edgeedge with one WO6 octahedra, and an edgeedge with one HoO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 13–60°. There are a spread of W–O bond distances ranging from 1.83–2.17 Å. In the second W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with two equivalent WO6 octahedra, corners with three HoO7 pentagonal bipyramids, a cornercorner with one CuO6 pentagonal pyramid, an edgeedge with one WO6 octahedra, and an edgeedge with one HoO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 15°. There are a spread of W–O bond distances ranging from 1.82–2.19 Å. In the third W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with two equivalent HoO6 octahedra, corners with four HoO7 pentagonal bipyramids, a cornercorner with one CuO6 pentagonal pyramid, and edges with two WO6 octahedra. The corner-sharing octahedra tilt angles range from 50–61°. There are a spread of W–O bond distances ranging from 1.79–2.14 Å. In the fourth W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share a cornercorner with one HoO6 octahedra, corners with four HoO7 pentagonal bipyramids, corners with two equivalent CuO6 pentagonal pyramids, and edges with two WO6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are a spread of W–O bond distances ranging from 1.80–2.17 Å. Cu1+ is bonded to six O2- atoms to form distorted CuO6 pentagonal pyramids that share corners with eight WO6 octahedra and edges with two equivalent HoO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 44–63°. There are two shorter (2.10 Å) and four longer (2.43 Å) Cu–O bond lengths. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to one Ho3+ and two W6+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ho3+ and two W6+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one W6+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+, one W6+, and one Cu1+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one W6+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one W6+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Ho3+ and one W6+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Ho3+ and one W6+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one W6+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+, one W6+, and one Cu1+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ho3+ and two W6+ atoms. In the twelfth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ho3+ and two W6+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted linear geometry to two equivalent W6+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted linear geometry to two equivalent W6+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two W6+ and one Cu1+ atom. In the sixteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ho3+ and two W6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Electrochemical stability, physical, and electronic properties of thermally pre-formed oxide compared to artificially sputtered oxide on Fe thin films in aqueous chloride

Here the electrochemical stability and corrosion behavior of the thermally pre-oxidized and sputter deposited variant of an oxide single-crystalline Fe thin film were compared. Thermal oxides formed Fe 2 O 3 over an inner layer of Fe 3 O 4 while the sputtered oxides were found to have grown Fe 3 O 4 instead of the target stoichiometry of Fe 2 O 3 . Oxide films of both types were stable in pH=9.3 borate buffer solution, however, were altered in pH=9.3, 0.1 M NaCl solution in the case of thermally pre-oxidized Fe thin film. The stability of the oxide differed in pH=4, 0.1 M NaCl where sputtered Fe films were more stable against acidic chemical dissolution than the thermally formed Fe oxide film. These differences were traced by AC/DC electrochemical analysis including electronic defect densities, and molecular identity characterized by ex-situ X-ray photoelectron spectroscopy.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Improving the accuracy of freight mode choice models: A case study using the 2017 CFS PUF data set and ensemble learning techniques

Here, the US Census Bureau has collected two rounds of experimental data from the Commodity Flow Survey, providing shipment-level characteristics of nationwide commodity movements, published in 2012 (i.e., Public Use Microdata) and in 2017 (i.e., Public Use File). With this information, data-driven methods have become increasingly valuable for understanding detailed patterns in freight logistics. In this study, we used the 2017 Commodity Flow Survey Public Use File data set to explore building a high-performance freight mode choice model, considering three main improvements: (1) constructing local models for each separate commodity/industry category; (2) extracting useful geographical features, particularly the derived distance of each freight mode between origin/destination zones; and (3) applying additional ensemble learning methods such as stacking or voting to combine results from local and unified models for improved performance. The proposed method achieved over 92% accuracy without incorporating external information, an over 19% increase compared to directly fitting Random Forests models over 10,000 samples. Furthermore, SHAP (Shapely Additive Explanations) values were computed to explain the outputs and major patterns obtained from the proposed model. The model framework could enhance the performance and interpretability of existing freight mode choice models.

42 ENGINEERING↗
DOE OSTI2021

The Pre-He White Dwarfs in Eclipsing Binaries. II. WASP 0843–11

We present the Transiting Exoplanet Survey Satellite (TESS) photometry and our high-resolution spectra of the EL CVn–type star 1SWASP J084356.46–113327.5 (WASP 0843–11), which consists of an F-type main-sequence (MS) star and a hotter low-mass helium white dwarf precursor (pre-He WD). In a spectral analysis, double-lined radial velocities (RVs) were obtained for the first time. From a simultaneous analysis of the TESS light and RV curves, the masses, radii, and temperatures of each component were determined to be M {sub 1} = 1.733 ± 0.031 M {sub ⊙}, M {sub 2} = 0.220 ± 0.008 M {sub ⊙}, R {sub 1} = 2.094 ± 0.013 R {sub ⊙}, R {sub 2} = 0.331 ± 0.003 R {sub ⊙}, T {sub 1} = 6960 ± 120 K, and T {sub 2} =9870 ± 310 K, respectively. According to their physical properties, the primary and secondary stars are located on the instability strips of δ Sct/γ Dor hybrids and extremely low-mass WDs, respectively. We applied multiple frequency analyses to the residual light curve after subtracting the binarity effects and detected a total of four independent frequencies. A frequency of f {sub 3} = 1.6356 day{sup −1} in the low-frequency region was reminiscent of γ Dor stars, while the other three frequencies of f {sub 2}, f {sub 15}, and f {sub 18} in the high-frequency region (150–196 day{sup −1}) are probably related to pre-He WD components. Our results demonstrate that the more massive MS primary star of WASP 0843–11 is a γ Dor pulsator, whereas the hotter secondary component is a pre-He WD with high-frequency pulsations.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Origin of spin-driven ferroelectricity and effect of external pressure on the complex magnetism of the 6⁢ H perovskite Ba 3 ⁢Ho⁢Ru 2⁢ O 9

The compound Ba 3 HoRu 2 O 9 magnetically orders at 50 K (T N1 ), followed by another complex magnetic ordering at 10.2 K (T N2 ). The second magnetic phase transition was characterized by the coexistence of two competing magnetic ground states associated with two different magnetic wave vectors (K 1 = 0.5 0 0 and K 2 = 0.25 0.25 0). The multiferroicity and magnetoelectric coupling were predicted below T N2 in these 4d-based materials. Here, in this work, we have discussed the origin of spin-driven ferroelectricity, which is not known yet, and the nature of magnetoelectric domains. We have investigated the compound through time-of-flight neutron diffraction, synchrotron x-ray diffraction (XRD), ac susceptibility, frequency-dependent complex dielectric spectroscopy, and dc magnetization under external pressure. We have demonstrated that the noncollinear structure involving two different magnetic ions, Ru (4d) and Ho (4f), breaks the spatial inversion symmetry via inverse Dzyaloshinskii-Moriya (DM) interaction through strong 4d-4f magnetic correlation, which shifts the oxygen atoms and results in nonzero polarization. Such an observation of inverse DM interaction from two different magnetic ions which cause ferroelectricity is rarely observed. The stronger spin-orbit coupling of 4d orbital might play a major role in creating DM interaction of noncollinear spins. We have systematically studied the spin and dipolar dynamics, which exhibit intriguing behavior with shorter coherence lengths of second magnetic phase associated with the k 2 wave vector. The results manifest the development of finite-size magnetoelectric domains instead of true long-range ordering, which justifies the experimentally obtained low value of ferroelectric polarization. The lattice parameters and volume show a sharp anomaly at T N2 obtained by analyzing the temperature-dependence XRD, which is consistent with the ferroelectric transition, predicting a noncentrosymmetric space group, $P\bar{6}2c$, for this compound. Furthermore, we have investigated the effect of external pressure on this complex magnetism. The result reveals an enhancement of ordering temperature by the application of external pressure (~1.6 K/GPa). The external pressure might favor stabilizing the magnetic ground state associated with second magnetic phase. Our study shows an unconventional mechanism of spin-driven ferroelectricity involving inverse DM interaction between Ru (4d) and Ho (4f) magnetic ions due to strong 4d-4f cross coupling.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Strong spin-dephasing in a topological insulator-paramagnet heterostructure

The interface between magnetic materials and topological insulators can drive the formation of exotic phases of matter and enable functionality through the manipulation of the strong spin polarized transport. Here, we report that the transport processes that rely on strong spin-momentum locking in the topological insulator Bi 2 Se 3 are completely suppressed by scattering at a heterointerface with the kagome-lattice paramagnet, Co 7 Se 8 . Bi 2 Se 3 –Co 7 Se 8 –Bi 2 Se 3 trilayer heterostructures were grown using molecular beam epitaxy, where magnetotransport measurements revealed a substantial suppression of the weak antilocalization effect for Co 7 Se 8 at thicknesses as thin as a monolayer, indicating a strong dephasing mechanism. Bi 2- x Co x Se 3 films, in which Co is in a non-magnetic 3 + state, show weak antilocalization that survives to higher than x = 0.4, which, in comparison with the heterostructures, suggests that the unordered moments of Co 2+ act as a far stronger dephasing element. This work highlights several important points regarding coherent transport processes involving spin-momentum locking in topological insulator interfaces and how magnetic materials can be integrated with topological materials to realize both exotic phases and novel device functionality.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A new approach to zip–lignin: 3,4–dihydroxybenzoate is compatible with lignification

Renewed interests in the development of bioenergy, biochemicals, and biomaterials have elicited new strategies for engineering the lignin of biomass feedstock plants. Furthermore, this study shows, for the first time, that 3,4-dihydroxybenzoate (DHB) is compatible with the radical coupling reactions that assemble polymeric lignin in plants. We introduced a bacterial 3-dehydroshikimate dehydratase into hybrid poplar (Populus alba × grandidentata) to divert carbon flux away from the shikimate pathway, which lies upstream of lignin biosynthesis. Transgenic poplar wood had up to 33% less lignin with p-hydroxyphenyl units comprising as much as 10% of the lignin. Mild alkaline hydrolysis of transgenic wood released fewer ester-linked p-hydroxybenzoate groups than control trees, and revealed the novel incorporation of cell-wall-bound DHB, as well as glycosides of 3,4-dihydroxybenzoic acid (DHBA). Two-dimensional nuclear magnetic resonance (2D-NMR) analysis uncovered DHBA-derived benzodioxane structures suggesting that DHB moieties were integrated into the lignin polymer backbone. In addition, up to 40% more glucose was released from transgenic wood following ionic liquid pretreatment and enzymatic hydrolysis. This work highlights the potential of diverting carbon flux from the shikimate pathway for lignin engineering and describes a new type of ‘zip-lignin’ derived from the incorporation of DHB into poplar lignin.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Materials Data on Na3Ho(PO4)2 by Materials Project

Na3Ho(PO4)2 crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. there are six inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.35–2.92 Å. In the second Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.91 Å. In the third Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.31–2.57 Å. In the fourth Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.87 Å. In the fifth Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.35–2.95 Å. In the sixth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.31–2.60 Å. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ho–O bond distances ranging from 2.25–2.53 Å. In the second Ho3+ site, Ho3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ho–O bond distances ranging from 2.26–2.53 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the second P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the third P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.54–1.56 Å. In the fourth P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to four Na1+, one Ho3+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+, one Ho3+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to four Na1+, one Ho3+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Ho3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Ho3+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Ho3+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Ho3+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Ho3+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Energy characteristics of multi-chiller load distribution algorithms in a large office building

Here, this study evaluates the energy efficiency of multi-chiller systems in large office buildings, focusing on their optimization across various climate zones as defined by ASHRAE. Using EnergyPlus for simulations, the research examines five different load distribution algorithms in multi-chiller systems that range from one to ten chillers, aiming to understand their effectiveness in 15 distinct climate zones. The primary objectives of the study include identifying the energy efficiency of multi-chiller systems in each climate zone, determining the appropriate number of chillers for each zone, and evaluating the performance of the load distribution algorithms. Based on the U.S. Department of Energy’s commercial building model, the results suggest that multi-chiller systems can significantly reduce cooling energy consumption in various climates. Among the algorithms evaluated, the Sequential Uniform Part Load Ratio (SUPLR) algorithm demonstrates notable efficiency, especially in the 4A climate zone (Baltimore), where it achieves substantial energy savings. Applying the SUPLR algorithm in a multi-chiller setup with four chillers in this zone leads to an estimated 24.5 % reduction in energy usage, equivalent to 183 MW annually. The research indicates that a range of 3 to 5 chillers is typically optimal for most climate zones. In-depth analysis in the 4A climate zone highlights the importance of minimizing operation hours at low Part Load Ratios (PLR) to ensure that chillers operate at a high Coefficient of Performance (COP). This strategy underscores the potential of well-designed multi-chiller systems to reduce cooling energy demand, particularly in climates with transitional seasons. This study provides an overview of the energy-saving potential of multi-chiller systems, applicable across a variety of climatic scenarios.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

Additive roles of antiferromagnetically coupled elements in the magnetic proximity effect in the GdFeCo/Pt system

Abstract Interfacial magnetic interactions between different elements are the origin of various spin-transport phenomena in multi-elemental magnetic systems. We investigate the coupling between the magnetic moments of the rare-earth, transition-metal, and heavy-metal elements across the interface in a GdFeCo/Pt thin film, an archetype system to investigate ferrimagnetic spintronics. The Pt magnetic moments induced by the antiferromagnetically aligned FeCo and Gd moments are measured using element-resolved x-ray measurements. It is revealed that the proximity-induced Pt magnetic moments are always aligned parallel to the FeCo magnetic moments, even below the ferrimagnetic compensation temperature where FeCo has a smaller moment than Gd. This is understood by a theoretical model showing distinct effects of the rare-earth Gd 4 f and transition-metal FeCo 3 d magnetic moments on the Pt electronic states. In particular, the Gd and FeCo work in-phase to align the Pt moment in the same direction, despite their antiferromagnetic configuration. The unexpected additive roles of the two antiferromagnetically coupled elements exemplify the importance of detailed interactions among the constituent elements in understanding magnetic and spintronic properties of thin film systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Highly Efficient Room‐Temperature Spin‐Orbit‐Torque Switching in a Van der Waals Heterostructure of Topological Insulator and Ferromagnet

Abstract All‐Van der Waals (vdW)‐material‐based heterostructures with atomically sharp interfaces offer a versatile platform for high‐performing spintronic functionalities at room temperature. One of the key components is vdW topological insulators (TIs), which can produce a strong spin‐orbit‐torque (SOT) through the spin‐momentum locking of their topological surface state (TSS). However, the relatively low conductance of the TSS introduces a current leakage problem through the bulk states of the TI or the adjacent ferromagnetic metal layers, reducing the interfacial charge‐to‐spin conversion efficiency ( q ICS ). Here, a vdW heterostructure is used consisting of atomically‐thin layers of a bulk‐insulating TI Sn‐doped Bi 1.1 Sb 0.9 Te 2 S 1 and a room‐temperature ferromagnet Fe 3 GaTe 2, to enhance the relative current ratio on the TSS up to ≈20%. The resulting q ICS reaches ≈1.65 nm −1 and the critical current density J c ≈0.9 × 10 6 Acm −2 at 300 K, surpassing the performance of TI‐based and heavy‐metal‐based SOT devices. These findings demonstrate that an all‐vdW heterostructure with thickness optimization offers a promising platform for efficient current‐controlled magnetization switching at room temperature.

2D ferromagnet↗