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At least 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ba2Zn(HO)6 by Materials Project

Ba2Zn(HO)6 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one Ba2Zn(HO)6 sheet oriented in the (-1, 0, 2) direction. Ba2+ is bonded in a 6-coordinate geometry to two H1+ and four O2- atoms. There are one shorter (2.84 Å) and one longer (2.96 Å) Ba–H bond lengths. There are a spread of Ba–O bond distances ranging from 2.50–2.79 Å. Zn2+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (1.82 Å) and two longer (2.57 Å) Zn–O bond lengths. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a distorted water-like geometry to one Ba2+ and one H1+ atom. The H–H bond length is 0.76 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one H1+ atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Ba2+, one H1+, and one O2- atom. The O–O bond length is 1.50 Å. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+, one Zn2+, and one O2- atom. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to two equivalent Ba2+ and one Zn2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoB7Mo3 by Materials Project

HoMo3B7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ho3+ is bonded in a 12-coordinate geometry to thirteen B+1.29- atoms. There are a spread of Ho–B bond distances ranging from 2.68–3.34 Å. There are three inequivalent Mo2+ sites. In the first Mo2+ site, Mo2+ is bonded to twelve B+1.29- atoms to form face-sharing MoB12 cuboctahedra. There are a spread of Mo–B bond distances ranging from 2.37–2.49 Å. In the second Mo2+ site, Mo2+ is bonded in a 9-coordinate geometry to nine B+1.29- atoms. There are a spread of Mo–B bond distances ranging from 2.24–2.33 Å. In the third Mo2+ site, Mo2+ is bonded in a 9-coordinate geometry to nine B+1.29- atoms. There are a spread of Mo–B bond distances ranging from 2.24–2.35 Å. There are seven inequivalent B+1.29- sites. In the first B+1.29- site, B+1.29- is bonded in a 9-coordinate geometry to one Ho3+, five Mo2+, and three B+1.29- atoms. There is two shorter (1.81 Å) and one longer (1.85 Å) B–B bond length. In the second B+1.29- site, B+1.29- is bonded in a 2-coordinate geometry to two equivalent Ho3+, five Mo2+, and two equivalent B+1.29- atoms. Both B–B bond lengths are 1.80 Å. In the third B+1.29- site, B+1.29- is bonded in a 3-coordinate geometry to three equivalent Ho3+, three equivalent Mo2+, and three B+1.29- atoms. There is one shorter (1.76 Å) and two longer (1.82 Å) B–B bond length. In the fourth B+1.29- site, B+1.29- is bonded in a 3-coordinate geometry to one Ho3+, five Mo2+, and three B+1.29- atoms. Both B–B bond lengths are 1.79 Å. In the fifth B+1.29- site, B+1.29- is bonded in a 3-coordinate geometry to two equivalent Ho3+, four Mo2+, and three B+1.29- atoms. The B–B bond length is 1.77 Å. In the sixth B+1.29- site, B+1.29- is bonded in a 3-coordinate geometry to two equivalent Ho3+, four Mo2+, and three B+1.29- atoms. In the seventh B+1.29- site, B+1.29- is bonded in a 9-coordinate geometry to two equivalent Ho3+, four Mo2+, and three B+1.29- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(HO)2 by Materials Project

Ba(OH)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 2-coordinate geometry to five H1+ and seven O2- atoms. There are a spread of Ba–H bond distances ranging from 2.68–2.91 Å. There are a spread of Ba–O bond distances ranging from 2.72–3.04 Å. In the second Ba2+ site, Ba2+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Ba–O bond distances ranging from 2.64–2.71 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to two equivalent Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.97 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to two Ba2+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to two equivalent Ba2+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba3Ho2(PS4)4 by Materials Project

Ba3Ho2(PS4)4 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine S2- atoms. There are a spread of Ba–S bond distances ranging from 3.27–3.61 Å. In the second Ba2+ site, Ba2+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are a spread of Ba–S bond distances ranging from 3.31–3.44 Å. Ho3+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Ho–S bond distances ranging from 2.75–3.05 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a tetrahedral geometry to four S2- atoms. There are a spread of P–S bond distances ranging from 2.01–2.07 Å. In the second P5+ site, P5+ is bonded in a tetrahedral geometry to four S2- atoms. There are a spread of P–S bond distances ranging from 2.02–2.09 Å. There are eight inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, one Ho3+, and one P5+ atom. In the second S2- site, S2- is bonded in a 3-coordinate geometry to one Ba2+, one Ho3+, and one P5+ atom. In the third S2- site, S2- is bonded in a 1-coordinate geometry to three Ba2+ and one P5+ atom. In the fourth S2- site, S2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, one Ho3+, and one P5+ atom. In the fifth S2- site, S2- is bonded in a 1-coordinate geometry to two Ba2+ and one P5+ atom. In the sixth S2- site, S2- is bonded in a 3-coordinate geometry to one Ba2+, one Ho3+, and one P5+ atom. In the seventh S2- site, S2- is bonded in a 4-coordinate geometry to one Ba2+, two equivalent Ho3+, and one P5+ atom. In the eighth S2- site, S2- is bonded in a 4-coordinate geometry to one Ba2+, two equivalent Ho3+, and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba2Li3Ho3(WO4)8 by Materials Project

Li3Ba2Ho3(WO4)8 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.97–2.54 Å. In the second Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.98–2.50 Å. In the third Li1+ site, Li1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Li–O bond distances ranging from 2.29–2.64 Å. There are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.65–3.33 Å. In the second Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.63–3.26 Å. There are three inequivalent Ho3+ sites. In the first 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 2.25–2.51 Å. In the second 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 2.29–2.45 Å. In the third 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 2.28–2.50 Å. There are eight inequivalent W6+ sites. In the first W6+ site, W6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of W–O bond distances ranging from 1.82–1.84 Å. In the second W6+ site, W6+ is bonded to five O2- atoms to form distorted corner-sharing WO5 tetrahedra. There are a spread of W–O bond distances ranging from 1.79–2.40 Å. In the third W6+ site, W6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of W–O bond distances ranging from 1.82–1.85 Å. In the fourth W6+ site, W6+ is bonded in a distorted tetrahedral geometry to four O2- atoms. There are a spread of W–O bond distances ranging from 1.80–1.88 Å. In the fifth W6+ site, W6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of W–O bond distances ranging from 1.81–1.87 Å. In the sixth W6+ site, W6+ is bonded to four O2- atoms to form distorted corner-sharing WO4 tetrahedra. There are a spread of W–O bond distances ranging from 1.80–1.89 Å. In the seventh W6+ site, W6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of W–O bond distances ranging from 1.81–1.85 Å. In the eighth W6+ site, W6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of W–O bond distances ranging from 1.80–1.88 Å. There are thirty-two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Ho3+, and one W6+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one W6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ho3+, and one W6+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one W6+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Li1+, one Ba2+, and one W6+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Li1+, one Ba2+, and one W6+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Li1+, one Ba2+, and one W6+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Li1+, one Ba2+, and one W6+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ba2+, and one W6+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Li1+, one Ba2+, and one W6+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Li1+, one Ba2+, and one W6+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Li1+, one Ba2+, and one W6+ atom. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ba2+, and one W6+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ba2+, one Ho3+, and one W6+ atom. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to one Ba2+, one Ho3+, and one W6+ atom. In the sixteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, one Ho3+, and one W6+ atom. In the seventeenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Ho3+, and one W6+ atom. In the eighteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one W6+ atom. In the nineteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ho3+, and one W6+ atom. In the twentieth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one W6+ atom. In the twenty-first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Ho3+, and one W6+ atom. In the twenty-second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one W6+ atom. In the twenty-third O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ho3+, and one W6+ atom. In the twenty-fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one W6+ atom. In the twenty-fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ba2+, and one W6+ atom. In the twenty-sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ba2+, one Ho3+, and one W6+ atom. In the twenty-seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+, one Ho3+, and one W6+ atom. In the twenty-eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ba2+, one Ho3+, and one W6+ atom. In the twenty-ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ba2+, and one W6+ atom. In the thirtieth O2- site, O2- is bonded in a 1-coordinate geometry to one Li1+, one Ba2+, and two W6+ atoms. In the thirty-first O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Ba2+, and one W6+ atom. In the thirty-second O2- site, O2- is bonded in a 1-coordinate geometry to one Li1+, one Ba2+, and one W6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

High-Throughput Screening of Strong Electron–Phonon Couplings in Ternary Metal Diborides

Here, we perform a high-throughput screening on phonon-mediated superconductivity in a ternary metal diboride structure with alkali, alkaline earth, and transition metals. We find 17 ground states and 78 low-energy metastable phases. From fast calculations of zone-center electron–phonon coupling, 43 compounds are revealed to show electron–phonon coupling strength higher than that of MgB 2 . An anticorrelation between the energetic stability and electron–phonon coupling strength is identified. We suggest two phases, i.e., Li 3 ZrB 8 and Ca 3 YB 8 , to be synthesized, which show reasonable energetic stability and superconducting critical temperature.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Phonon modes and Raman signatures of MnBi 2n Te 3n+1 (n=1,2,3,4) magnetic topological heterostructures

An intrinsic antiferromagnetic topological insulator MnBi 2 Te 4 arises when intercalating a Mn-Te bilayer chain in a topological insulator, Bi 2 Te 3 . We present observations on the inter- and intralayer phonon modes of the generalized MnBi 2n Te 3n+1 (n=1,2,3,4) family using cryogenic low-frequency Raman spectroscopy with various polarization configurations. Two peaks at 66 and 112 cm –1 show abnormal perturbation in Raman linewidths below magnetic transition temperature due to spin-phonon coupling. In MnBi 4 Te 7 , B i2 Te 3 layers induce Davydov splitting of the A1g mode around 137 cm –1 at 5 K. The out-of-plane interlayer force constant estimated using the linear chain model was (3.98±0.14)×10 19 N/m 3 , three times weaker than that of Bi 2 Te 3 . Adding more Bi 2 Te 3 layers, such as MnBi 6 Te 10 and MnBi 8 Te 13 , makes Bi 2 Te 3 properties more dominant than magnetic properties. Our work experimentally and theoretically discovers the dynamics of phonon modes of MnBi 2n Te 3n+ 1 family, facilitating utilization of magnetic topological heterostructures.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2024

Study of Magnetic Field and Turbulence in the TeV Halo around the Monogem Pulsar

Magnetic fields are ubiquitous in the interstellar medium, including extended objects such as supernova remnants and diffuse halos around pulsars. Its turbulent characteristics govern the diffusion of cosmic rays and the multiwavelength emission from pulsar wind nebulae (PWNe). However, the geometry and turbulence nature of the magnetic fields in the ambient region of PWN is still unknown. Recent gamma-ray observations from HAWC and synchrotron observations suggest a highly suppressed diffusion coefficient compared to the mean interstellar value. In this study, we present the first direct observational evidence of the orientation of the mean magnetic field and turbulent characteristics by employing a recently developed statistical parameter "Y turb " in the extended halo around the Monogem pulsar. Our study points to two possible scenarios: nearly aligned toward the line of sight (LOS) with compressible modes dominance or high inclination angle toward the LOS and characterized by Alfvénic turbulence. The first scenario appears consistent with other observational signatures. Furthermore, we report that the magnetic field has an observed correlation length of approximately 3 ± 0.6 pc in the Monogem halo. Our study highlights the pivotal role of magnetic field and turbulence in unraveling the physical processes in TeV halos and cosmic-ray transport.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1994

Validation of Multitemperature Nozzle Flow Code

A computer code nozzle in n-temperatures (NOZNT), which calculates one-dimensional flows of partially dissociated and ionized air in an expanding nozzle, is tested against three existing sets of experimental data taken in arcjet wind tunnels. The code accounts for the differences among various temperatures, i.e., translational-rotational temperature, vibrational temperatures of individual molecular species, and electron-electronic temperature, and the effects of impurities. The experimental data considered are (1) the spectroscopic emission data; (2) electron beam data on vibrational temperature; and (3) mass-spectrometric species concentration data. It is shown that the impurities are inconsequential for the arcjet flows, and the NOZNT code is validated by numerically reproducing the experimental data.

Park, Chul↗
DOE OSTI2021

Multipacting Analysis of Warm Linac RF Vacuum Windows

Multipacting in accelerating structures is a complex phenomenon with which there is much to be understood. While multipacting research efforts have primarily been focused on superconducting radio frequency (SRF) systems, normal conducting accelerating structures that have a higher thermal capacity and a greater vacuum pressure tolerance could benefit from additional investigation. This research details multipacting simulation methods and the results of 3-D electromagnetic simulations of RF vacuum windows used on normal conducting linac (NCL) cavities. Possible techniques for reducing and eliminating multipacting activities in these structures are discussed.

Toby, George↗
DOE OSTI2020

Materials Data on Ho2WO6 by Materials Project

Ho2WO6 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. 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 2.23–2.58 Å. In the second Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 hexagonal pyramids that share corners with three equivalent WO6 octahedra, edges with two equivalent HoO7 hexagonal pyramids, and edges with two equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 39–46°. There are a spread of Ho–O bond distances ranging from 2.29–2.40 Å. W6+ is bonded to six O2- atoms to form WO6 octahedra that share corners with three equivalent HoO7 hexagonal pyramids and edges with two equivalent HoO7 hexagonal pyramids. There are a spread of W–O bond distances ranging from 1.89–2.03 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to two equivalent Ho3+ and one W6+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one W6+ atom. 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 two Ho3+ and one W6+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Ho3+ and one W6+ atom. In the sixth O2- site, O2- is bonded to three Ho3+ and one W6+ atom to form distorted corner-sharing OHo3W tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al2FeP2(HO)18 by Materials Project

Fe(OH)2(AlPO4(H2O)2)2(H2O)4 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one iron dihydroxide molecule; four water molecules; and one AlPO4(H2O)2 sheet oriented in the (0, 0, 1) direction. In the AlPO4(H2O)2 sheet, there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra and corners with four equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Al–O bond distances ranging from 1.89–2.00 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Al–O bond distances ranging from 1.87–1.96 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three AlO6 octahedra. The corner-sharing octahedra tilt angles range from 41–51°. There are a spread of P–O bond distances ranging from 1.52–1.64 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.67 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Al3+ and two H1+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Al3+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Al3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a water-like geometry to one P5+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Al3+, one P5+, and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Machine learning guided discovery of ternary compounds involving La and immiscible Co and Pb elements

Abstract Ternary compounds with an immiscible pair of elements are relatively unexplored but promising for novel quantum materials discovery. Exploring what third element and its ratio that can be added to make stable ternary compounds out of an immiscible pair of elements remains a great challenge. In this work, we combine a machine learning (ML) method with ab initio calculations to efficiently search for the energetically favorable ternary La-Co-Pb compounds containing immiscible elements Co and Pb. Three previously reported structures are correctly captured by our approach. Moreover, we predict a ground state La 3 CoPb compound and 57 low-energy La-Co-Pb ternary compounds. Attempts to synthesize La 3 CoPb via multiple techniques produce mixed or multi-phases samples with, at best, ambiguous signals of the predicted lowest-energy La 3 CoPb and the second lowest-energy La 18 Co 28 Pb 3 phases. The calculated results of Gibbs free energy are consistent with experiments, and will provide very useful guidance for further experimental synthesis.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Fate of multiparticle resonances: From Q-balls to 3 He droplets

We study a system of N nonrelativistic particles which form a near-threshold resonance. Assuming no subset of these particles can form a bound state, the resonance can only decay through an “explosion” into N particles. We find that the decay width of the resonance scales as E Δ –5/2 in the limit when the energy E of the resonance goes to zero, where Δ is the ground-state energy of a system of N particles in a spherical harmonic trap with unit frequency. Here, the formula remains valid when some pairs of final particles have zero-energy s-wave resonance, but the Efimov effect is not present. In the limit of large N, we show that the final particles follow a Maxwell-Boltzmann distribution if they are bosons and a semicirclelike law if they are fermions. We expect our general result to be applicable to various systems that exist in nature. In particular, we argue that metastable 3 He droplets exist with the lifetime varying over many orders of magnitude ranging from a fraction of a nanosecond to values greatly exceeding the age of the Universe.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2020

Materials Data on Ho3ReO8 by Materials Project

Ho3ReO8 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Ho3+ sites. In the first 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 2.19–2.56 Å. In the second 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 2.31–2.57 Å. In the third 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 2.22–2.61 Å. Re7+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Re–O bond distances ranging from 1.82–1.99 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two Ho3+ and one Re7+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and one Re7+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Ho3+ and one Re7+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to three Ho3+ and one Re7+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Ho3+ and one Re7+ atom. In the sixth O2- site, O2- is bonded to four Ho3+ atoms to form a mixture of distorted edge and corner-sharing OHo4 tetrahedra. In the seventh O2- site, O2- is bonded to four Ho3+ atoms to form a mixture of distorted edge and corner-sharing OHo4 trigonal pyramids. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to three Ho3+ and one Re7+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoReB4 by Materials Project

HoReB4 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Ho3+ is bonded in a 4-coordinate geometry to fourteen B+1.50- atoms. There are a spread of Ho–B bond distances ranging from 2.66–2.82 Å. Re3+ is bonded in a 10-coordinate geometry to ten B+1.50- atoms. There are a spread of Re–B bond distances ranging from 2.33–2.39 Å. There are four inequivalent B+1.50- sites. In the first B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Ho3+, two equivalent Re3+, and three B+1.50- atoms. There are a spread of B–B bond distances ranging from 1.76–1.85 Å. In the second B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to two equivalent Ho3+, four equivalent Re3+, and three B+1.50- atoms. Both B–B bond lengths are 1.75 Å. In the third B+1.50- site, B+1.50- is bonded in a 3-coordinate geometry to four equivalent Ho3+, two equivalent Re3+, and three B+1.50- atoms. There is one shorter (1.78 Å) and one longer (1.82 Å) B–B bond length. In the fourth B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Ho3+, two equivalent Re3+, and three B+1.50- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

High pressure ammonia/methanol oxidation up to 100 atm

Here, high pressure ammonia/methanol oxidation and NOx formations were investigated using a recently developed supercritical pressure jet-stirred reactor (SP-JSR) at 20 and 100 atm with temperatures between 550 and 950 K and equivalence ratios of 0.138 and 1.15. The experimental results show that NH 3 oxidation at high pressure is significantly accelerated by the active OH radicals produced from CH 3 OH oxidation. Furthermore, the kinetic interactions between NH 3 and CH 3 OH are governed mainly by the reactions CH 3 OH + NH 2 = CH 2 OH + NH 3 , CH 3 OH + NH 2 = CH 3 O + NH 3 , and CH 2 O + NH 2 = HCO + NH 3 . A HP-Mech model for high-pressure NH 3 /CH 3 OH oxidation was developed in this study. It consists of the most recent NH 3 and CH 3 OH models including some new reactions and updated rate constants from the literature as well as NH 3 -CH 3 OH interactions where rate constants of CH 3 OH + NH 2 = CH 2 OH + NH 3 , CH 3 OH + NH 2 = CH 3 O + NH 3 , NH 2 + CH 2 O = NH 3 + HCO, and NH 2 + CH 2 O = NH 2 CHO + H were theoretically calculated in this study. Our model with these updates improves the prediction for the measured N 2 O/NO x temperature dependence at 100 atm. In addition, the reaction pathway and sensitivity analysis show that N 2 O/NO x /HONO interactions with HO 2 are very important, especially for a fuel-lean mixture at 100 atm. The HONO mole fraction for the fuel-lean mixture at 100 atm was then measured by off-axis integrated cavity output spectroscopy (ICOS) at wavenumber of 6638.26 cm -1 . The experimental data show a significant HONO formation at intermediate temperature that is strongly underpredicted by numerical simulation at 100 atm. Therefore, the HONO related reactions with notable uncertainty at high pressure such as NO + OH (+M) = HONO (+M) and H 2 NO + NO 2 = HONO + HNO need deeper exploration in the future.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗