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At least 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ho5(ReO6)2 by Materials Project

Ho5(ReO6)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three 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 2.27–2.49 Å. In the second Ho3+ site, Ho3+ is bonded to six O2- atoms to form HoO6 octahedra that share corners with four equivalent ReO6 octahedra, corners with four equivalent HoO7 pentagonal bipyramids, and edges with two equivalent HoO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. There are two shorter (2.20 Å) and four longer (2.31 Å) Ho–O bond lengths. In the third Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 pentagonal bipyramids that share corners with two equivalent HoO6 octahedra, an edgeedge with one HoO6 octahedra, edges with two equivalent ReO6 octahedra, and edges with two equivalent HoO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 56°. There are a spread of Ho–O bond distances ranging from 2.27–2.42 Å. Re+4.50+ is bonded to six O2- atoms to form ReO6 octahedra that share corners with two equivalent HoO6 octahedra, edges with two equivalent ReO6 octahedra, and edges with two equivalent HoO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. There are a spread of Re–O bond distances ranging from 1.97–2.10 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ho3+ and two equivalent Re+4.50+ atoms to form distorted OHo2Re2 trigonal pyramids that share corners with eight OHo3Re tetrahedra, edges with four equivalent OHo3Re tetrahedra, and an edgeedge with one OHo2Re2 trigonal pyramid. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+ and two equivalent Re+4.50+ atoms. In the third O2- site, O2- is bonded to three Ho3+ and one Re+4.50+ atom to form distorted OHo3Re tetrahedra that share corners with ten OHo3Re tetrahedra, a cornercorner with one OHo2Re2 trigonal pyramid, edges with three OHo3Re tetrahedra, and edges with two equivalent OHo2Re2 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Ho3+ atoms to form OHo4 tetrahedra that share corners with ten OHo3Re tetrahedra, corners with three equivalent OHo2Re2 trigonal pyramids, and edges with four OHo3Re tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca2HoF7 by Materials Project

Ca2HoF7 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven F1- atoms. There are a spread of Ca–F bond distances ranging from 2.03–2.82 Å. In the second Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven F1- atoms. There are a spread of Ca–F bond distances ranging from 2.28–2.51 Å. In the third Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six F1- atoms. There are a spread of Ca–F bond distances ranging from 2.27–2.41 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six F1- atoms. There are a spread of Ca–F bond distances ranging from 2.27–2.42 Å. In the fifth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Ca–F bond distances ranging from 2.36–2.59 Å. In the sixth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Ca–F bond distances ranging from 2.28–2.60 Å. There are three inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 10-coordinate geometry to ten F1- atoms. There are a spread of Ho–F bond distances ranging from 2.15–2.80 Å. In the second Ho3+ site, Ho3+ is bonded in a 10-coordinate geometry to ten F1- atoms. There are a spread of Ho–F bond distances ranging from 2.15–2.78 Å. In the third Ho3+ site, Ho3+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of Ho–F bond distances ranging from 2.15–2.71 Å. There are twenty-one inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to four Ca2+ atoms. In the second F1- site, F1- is bonded in a distorted trigonal planar geometry to three Ca2+ atoms. In the third F1- site, F1- is bonded in a distorted trigonal planar geometry to three equivalent Ca2+ atoms. In the fourth F1- site, F1- is bonded in a distorted trigonal planar geometry to three Ca2+ atoms. In the fifth F1- site, F1- is bonded to three equivalent Ca2+ and one Ho3+ atom to form distorted corner-sharing FCa3Ho tetrahedra. In the sixth F1- site, F1- is bonded in a distorted trigonal planar geometry to three equivalent Ca2+ atoms. In the seventh F1- site, F1- is bonded in a distorted trigonal planar geometry to three Ca2+ atoms. In the eighth F1- site, F1- is bonded in a trigonal planar geometry to three Ho3+ atoms. In the ninth F1- site, F1- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca2+ and two equivalent Ho3+ atoms. In the tenth F1- site, F1- is bonded in a 4-coordinate geometry to one Ca2+ and three equivalent Ho3+ atoms. In the eleventh F1- site, F1- is bonded in a distorted trigonal planar geometry to three Ho3+ atoms. In the twelfth F1- site, F1- is bonded in a trigonal non-coplanar geometry to three Ho3+ atoms. In the thirteenth F1- site, F1- is bonded in a distorted trigonal planar geometry to one Ca2+ and two equivalent Ho3+ atoms. In the fourteenth F1- site, F1- is bonded in a distorted single-bond geometry to four Ho3+ atoms. In the fifteenth F1- site, F1- is bonded in a trigonal non-coplanar geometry to three Ho3+ atoms. In the sixteenth F1- site, F1- is bonded in a distorted single-bond geometry to four Ho3+ atoms. In the seventeenth F1- site, F1- is bonded in a 1-coordinate geometry to three Ca2+ atoms. In the eighteenth F1- site, F1- is bonded in a trigonal non-coplanar geometry to two equivalent Ca2+ and one Ho3+ atom. In the nineteenth F1- site, F1- is bonded in a 3-coordinate geometry to three equivalent Ca2+ atoms. In the twentieth F1- site, F1- is bonded to four Ca2+ atoms to form distorted corner-sharing FCa4 trigonal pyramids. In the twenty-first F1- site, F1- is bonded in a rectangular see-saw-like geometry to four Ca2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoAg(WO4)2 by Materials Project

HoAg(WO4)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.32–2.56 Å. There are two inequivalent W6+ sites. In the first W6+ site, W6+ is bonded to six O2- atoms to form distorted edge-sharing WO6 octahedra. There are a spread of W–O bond distances ranging from 1.82–2.14 Å. In the second W6+ site, W6+ is bonded to six O2- atoms to form distorted edge-sharing WO6 octahedra. There are a spread of W–O bond distances ranging from 1.81–2.21 Å. Ag1+ is bonded in a 2-coordinate geometry to eight O2- atoms. There are a spread of Ag–O bond distances ranging from 2.34–2.98 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+, two W6+, and one Ag1+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+, one W6+, and one Ag1+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+, one W6+, and one Ag1+ atom. In the fourth O2- site, O2- is bonded to three W6+ and one Ag1+ atom to form distorted edge-sharing OAgW3 tetrahedra. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ho3+, one W6+, and one Ag1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Vertical Architecture Solution-Processed Quantum Dot Photodetectors with Amorphous Selenium Hole Transport Layer

Colloidal quantum dots (CQDs) provide wide spectral tunability and high absorption coefficients owing to quantum confinement and large oscillator strengths, which along with solution processability, allow a facile, low-cost, and room-temperature deposition technique for the fabrication of photonic devices. However, many solution-processed CQD photodetector devices demonstrate low specific-detectivity and slow temporal response. To achieve improved photodetector characteristics, limiting carrier recombination and enhancing photogenerated carrier separation are crucial. In this study, we develop and present an alternate vertical-stack photodetector wherein we use a solution-processed quantum dot photoconversion layer coupled to an amorphous selenium (a-Se) wide-bandgap charge transport layer that is capable of exhibiting single-carrier hole impact ionization and is compatible with active-matrix readout circuitry. This a-Se chalcogenide transport layer enables the fabrication of high-performance and reliable solution-processed quantum dot photodetectors, with enhanced charge extraction capabilities, high specific detectivity (D* ~ 0.5–5 × 10 12 Jones), fast 3 dB electrical bandwidth (3 dB BW ~ 22 MHz), low dark current density (J D ~ 5–10 pA/cm 2 ), low noise current (i n ~ 20–25 fW/Hz 1/2 ), and high linear dynamic range (LDR ~130–150 dB) across the measured visible electromagnetic spectrum (~405–656 nm).

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2020

Theoretical search for possible Li–Ni–B crystal structures using an adaptive genetic algorithm

The structural diversity of rare-earth and transition metal borides indicates that alkali-transition metal borides (A-T-B) show tremendous promise in exhibiting a variety of crystal structures with different dimensionalities of T-B frameworks. On the other hand, the A-T-B ternary systems are severely underexplored because of the synthetic challenges associated with their preparation. Accurate and efficient computational predictions of low-energy stable and metastable phases can identify the optimal compositions of the hypothetical compounds in the A-T-B systems to guide the synthesis. As such, in this work, we have computationally discovered several new phases in the Li–Ni–B ternary system. The newly discovered LiNiB, Li 2 Ni 3 B, and Li 2 NiB phases expand the existing theoretical database, and the convex-hull surface of Li–Ni–B has been re-constructed. The lowest energy structure of the LiNiB compound has been found by an adaptive genetic algorithm with layered motif, which matches with the experimentally determined structure. According to our electrochemical calculations, LiNiB and another predicted layered Li 2 NiB compounds have great potential as anode materials for lithium batteries. The Li 2 Ni 3 B compound with the space group P4 3 32 was predicted to crystallize in a cubic structure composed of distorted octahedral units of BNi 6 , which is isostructural to two noncentrosymmetric superconductors Li 2 Pd 3 B and Li 2 Pt 3 B. While we were unable to experimentally confirm the Li 2 Ni 3 B compound utilizing the hydride synthetic route, attempts to synthesize this compound by alternate methods remain highly desirable, considering its potential superconducting properties.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Basic Research Needs for Transformative Manufacturing

This report is based on a Basic Research Needs workshop for Transformative Manufacturing, which was held March 9 - 11, 2020. The focus of the workshop was to identify the basic science research priorities that could accelerate innovation to transform manufacturing in the future. This was the first workshop of its kind to examine how basic energy science can drive manufacturing forward and innovate new ways to manufacture goods. Five Priority Research Directions were identified that address these science challenges: (1) innovative synthetic approaches to enable scalable assembly of matter, (2) computational methods and theoretical models to transform how manufacturing processes are controlled, (3) new characterization tools that can handle the necessary complexity, scales, and processing speeds to meet manufacturing needs, (4) new science to address opportunities relevant to sustainable and energy efficient manufacturing, and (5) foundational approaches to co-design of materials, process, and products.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Magnetic structure of magnetoelectric multiferroic HoFeWO 6

The polar magnetic oxide, HoFeWO6, is synthesized, and its crystal structure, magnetic structure, and thermodynamic properties are investigated. HoFeWO 6 forms the polar crystal structure (space group Pna2 1 (#33)) due to the cation ordering of W 6+ and Fe 3+ . An antiferromagnetic transition at T N = 17 K is accompanied by a significant change in magnetic entropy with a value of ≈ 5 J kg -1 K-1 in a 70 kOe applied field. Temperature dependent neutron diffraction and magnetization data indicate that the Fe sublattice orders in a strongly non-collinear and non-coplanar arrangement below T N . The Fe ordering initially leads to induced ordering of the Ho spins such that the Ho spins also show behavior of long-range ordering that is evident from the neutron diffraction measurements. Below T ≈ 4 K, the Ho spins order independently and pull the Fe spins toward the direction of Ho spins. A comparison with the magnetic structures and corresponding ferroelectric properties of other members of RMWO 6 (R = Y, Sm-Tm, M = Cr, Fe, V) family indicate that the spontaneous polarization is due to the magnetic structure specific to the Fe sublattice through magnetoelectric coupling whereas the polarization is independent of the Ho sublattice.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Adsorption of Rare Earth Elements onto DNA-Functionalized Mesoporous Carbon

The recovery and separation of rare earth elements (REEs) are of national importance owing to the specific usages, high demand, and low supply of these elements. In this research, we have investigated the adsorption of rare earth elements onto DNA-functionalized mesoporous carbons with a BET surface area of 605 m2/g and a median mesopore width of 48 Å. Additionally, three types of single-stranded DNA, one with 100 base units of thymine, another with 20 units of thymine, and the third, a 2000 unit long DNA from salmon milt were grafted on the carboxylated mesoporous carbon surface. All of the DNA-functionalized mesoporous carbons demonstrated higher adsorption of REEs compared to pristine mesoporous carbon and DNA grafted with 100 units of thymine demonstrated slightly higher adsorbed amounts compared to others. Pure neodymium (Nd(III)) adsorption in the aqueous phase demonstrated an adsorbed amount of 110.4 mg/g with respect to the initial concentration of 500 mg/g. A pH variation study with pure Nd(III) demonstrated that the adsorbed amount is higher at elevated pH compared to that at lower pH, thereby suggesting possible recovery at lower pH. Adsorption of a mixture of 16 REEs, including Sc, Lu, Tm, Yb, Er, Ho, Tb, Dy, Y, Eu, Gd, Sm, Ce, Nd, Pr, and La revealed that the adsorbed amount increased with an increase in the atomic weight and metallic radii of elements within the lanthanides. The calculation of the distribution coefficients for all of the equilibrium adsorption amounts suggested that adsorption is more effective in the lower concentration region. The Nd L3-edge X-ray absorption near edge structure (XANES) confirmed a 3+ oxidation state of Nd in the adsorbed phase. The extended X-ray absorption fine structure (EXAFS) confirmed the local atomic structure relaxation of Nd complexes in the adsorbed phase and shortening of the Nd–O bond distance by about 0.03–0.04 Å, which may be associated with their local complexation at the carbon surface.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Perturbation of Tropical Stratospheric Ozone Through Homogeneous and Heterogeneous Chemistry Due To Pinatubo

Abstract The Pinatubo eruption in 1991 injected 10–20 Tg SO 2 into the stratosphere, which formed sulfate aerosols through oxidation. Our modeling results show that volcanic heating significantly perturbs the heterogeneous and homogeneous chemistry including NO x and HO x catalytic cycles in the tropical stratosphere. The simulated tropical chemical ozone tendency is positive at 20 mb while negative at 10 mb in the tropics. The simulated ozone chemical tendency is of the same magnitude as the dynamical ozone tendency caused by the accelerated tropical upwelling, but with the opposite sign. Our study finds that the tropical ozone chemical tendency due to homogeneous chemistry becomes more important than heterogeneous chemistry 3 months after eruption. Sensitivity simulations further suggest that the tropical ozone tendency through heterogeneous chemistry is saturated when the injected amount exceeds 2 Tg.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1984

Collision strengths for 1199 and 1729 of S III

Collision strengths are calculated for the S III ground state from electron impact excitation in the Io torus. The study is based on data taken at 119.9 nm and 172.9 nm by the IUE spacecraft and with the rocket-borne Faint Object Telescope. The collision strengths of the 3p(2)3P3s3p(3)(5)S(4) and (3)P-3s3p(3)(3)D(0) UV lines are derived from a three-state close coupling aproximation. A Gailitis averaging scheme accounts for resonance effects in the forbidden transition. The calculated intensities of the two transitions at an electron temperature of 80,000 K are in agreement with observed intensities.

Ho, Y. K.↗
NASA NTRS1996

Pasma Wave Characteristics of the Jovian Magnetopause Boundary Layer: Can Wave-Particle Interactions Cause the Jovian Aurora?

The full Jovian magnetopause boundary layer (BL) plasma wave spectra from 10(sup -3) to 10(sup 3) Hz, have been measured for the first time...The B'/E' ration does not have a f(sup -1) dependency, so it was suggested that the waves are a mixture of whistler mode electromagnetic emissions and electrostatic waves.

jovian magnetosphere Jupiter Jovian magnetopause E↗
DOE OSTI2020

Materials Data on HoV2O6 by Materials Project

HoV2O6 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.26–2.55 Å. There are two inequivalent V+4.50+ sites. In the first V+4.50+ site, V+4.50+ is bonded to six O2- atoms to form distorted corner-sharing VO6 octahedra. The corner-sharing octahedra tilt angles range from 15–45°. There are a spread of V–O bond distances ranging from 1.78–2.25 Å. In the second V+4.50+ site, V+4.50+ is bonded to six O2- atoms to form distorted corner-sharing VO6 octahedra. The corner-sharing octahedra tilt angles range from 15–45°. There are a spread of V–O bond distances ranging from 1.77–2.31 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted T-shaped geometry to one Ho3+ and two V+4.50+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ho3+ and two V+4.50+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+ and two V+4.50+ atoms. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ho3+ and two V+4.50+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ho3+ and two V+4.50+ atoms. In the sixth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ho3+ and two V+4.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho2Cu(BO2)8 by Materials Project

Ho2Cu(BO2)8 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.28–2.47 Å. Cu2+ is bonded in an octahedral geometry to six O2- atoms. There are four shorter (1.99 Å) and two longer (2.44 Å) Cu–O bond lengths. There are three inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.35–1.40 Å. In the second B3+ site, B3+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.47 Å) and two longer (1.48 Å) B–O bond length. In the third B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.35 Å) and two longer (1.40 Å) B–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ho3+ and one B3+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+, one Cu2+, and one B3+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+ and two B3+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+ and two B3+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cu2+ and two equivalent B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho6Ni20P13 by Materials Project

Ho6Ni20P13 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. there are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to six P3- atoms to form distorted HoP6 pentagonal pyramids that share corners with four equivalent HoP6 pentagonal pyramids, corners with twelve NiP4 tetrahedra, edges with two equivalent HoP6 pentagonal pyramids, edges with eight NiP4 tetrahedra, and faces with two equivalent HoP6 pentagonal pyramids. There are a spread of Ho–P bond distances ranging from 2.85–2.91 Å. In the second Ho3+ site, Ho3+ is bonded to six P3- atoms to form distorted HoP6 pentagonal pyramids that share corners with four equivalent HoP6 pentagonal pyramids, corners with twelve NiP4 tetrahedra, edges with two equivalent HoP6 pentagonal pyramids, edges with seven NiP4 tetrahedra, and faces with two equivalent HoP6 pentagonal pyramids. There are a spread of Ho–P bond distances ranging from 2.82–2.90 Å. There are eight inequivalent Ni+1.05+ sites. In the first Ni+1.05+ site, Ni+1.05+ is bonded to four P3- atoms to form NiP4 tetrahedra that share corners with four HoP6 pentagonal pyramids, corners with ten NiP4 tetrahedra, an edgeedge with one HoP6 pentagonal pyramid, and edges with three NiP4 tetrahedra. There are a spread of Ni–P bond distances ranging from 2.14–2.35 Å. In the second Ni+1.05+ site, Ni+1.05+ is bonded in a trigonal planar geometry to three equivalent P3- atoms. All Ni–P bond lengths are 2.21 Å. In the third Ni+1.05+ site, Ni+1.05+ is bonded in a 5-coordinate geometry to five P3- atoms. There are a spread of Ni–P bond distances ranging from 2.27–2.58 Å. In the fourth Ni+1.05+ site, Ni+1.05+ is bonded in a trigonal planar geometry to three equivalent P3- atoms. All Ni–P bond lengths are 2.21 Å. In the fifth Ni+1.05+ site, Ni+1.05+ is bonded to four P3- atoms to form NiP4 tetrahedra that share corners with six HoP6 pentagonal pyramids, corners with five NiP4 tetrahedra, edges with four HoP6 pentagonal pyramids, and edges with four NiP4 tetrahedra. There are a spread of Ni–P bond distances ranging from 2.27–2.29 Å. In the sixth Ni+1.05+ site, Ni+1.05+ is bonded to four P3- atoms to form NiP4 tetrahedra that share corners with four HoP6 pentagonal pyramids, corners with eight NiP4 tetrahedra, edges with three HoP6 pentagonal pyramids, and edges with four NiP4 tetrahedra. There are a spread of Ni–P bond distances ranging from 2.29–2.32 Å. In the seventh Ni+1.05+ site, Ni+1.05+ is bonded to four P3- atoms to form NiP4 tetrahedra that share corners with six HoP6 pentagonal pyramids, corners with six NiP4 tetrahedra, edges with four HoP6 pentagonal pyramids, and edges with four NiP4 tetrahedra. There are a spread of Ni–P bond distances ranging from 2.24–2.30 Å. In the eighth Ni+1.05+ site, Ni+1.05+ is bonded to four P3- atoms to form NiP4 tetrahedra that share corners with four HoP6 pentagonal pyramids, corners with eleven NiP4 tetrahedra, edges with three HoP6 pentagonal pyramids, and edges with three NiP4 tetrahedra. There are a spread of Ni–P bond distances ranging from 2.24–2.35 Å. There are five inequivalent P3- sites. In the first P3- site, P3- is bonded in a 9-coordinate geometry to four equivalent Ho3+ and five Ni+1.05+ atoms. In the second P3- site, P3- is bonded in a 9-coordinate geometry to two equivalent Ho3+ and seven Ni+1.05+ atoms. In the third P3- site, P3- is bonded in a 3-coordinate geometry to nine Ni+1.05+ atoms. In the fourth P3- site, P3- is bonded in a 9-coordinate geometry to four equivalent Ho3+ and five Ni+1.05+ atoms. In the fifth P3- site, P3- is bonded in a 9-coordinate geometry to two equivalent Ho3+ and seven Ni+1.05+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Colloidal InAs Quantum Dot-Based Infrared Optoelectronics Enabled by Universal Dual-Ligand Passivation

Solution-processed low-bandgap semiconductors are crucial to next-generation infrared (IR) detection for various applications, such as autonomous driving, virtual reality, recognitions, and quantum communications. In particular, III–V group colloidal quantum dots (CQDs) are interesting as nontoxic bandgap-tunable materials and suitable for IR absorbers; however, the device performance is still lower than that of Pb-based devices. Herein, a universal surface-passivation method of InAs CQDs enabled by intermediate phase transfer (IPT), a preliminary process that exchanges native ligands with aromatic ligands on the CQD surface is presented. IPT yields highly stable CQD ink. In particular, desirable surface ligands with various reactivities can be obtained by dispersing them in green solvents. Furthermore, CQD near-infrared (NIR) photodetectors are demonstrated using solution processes. Careful surface ligand control via IPT is revealed that enables the modulation of surface-mediated photomultiplication, resulting in a notable gain control up to ≈10 with a fast rise/fall response time (≈12/36 ns). Considering the figure of merit (FOM), EQE versus response time (or –3 dB bandwidth), the optimal CQD photodiode yields one of the highest FOMs among all previously reported solution-processed nontoxic semiconductors comprising organics, perovskites, and CQDs in the NIR wavelength range.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2012

Design and Evaluation of Nextgen Aircraft Separation Assurance Concepts

To support the development and evaluation of future function allocation concepts for separation assurance systems for the Next Generation Air Transportation System, this paper presents the design and human-in-the-loop evaluation of three feasible function allocation concepts that allocate primary aircraft separation assurance responsibilities and workload to: 1) pilots; 2) air traffic controllers (ATC); and 3) automation. The design of these concepts also included rules of the road, separation assurance burdens for aircraft of different equipage levels, and utilization of advanced weather displays paired with advanced conflict detection and resolution automation. Results of the human-in-the-loop simulation show that: a) all the concepts are robust with respect to weather perturbation; b) concept 1 (pilots) had highest throughput, closest to assigned spacing, and fewest violations of speed and altitude restrictions; c) the energy of the aircraft during the descent phase was better managed in concepts 1 and 2 (pilots and ATC) than in concept 3 (automation), in which the situation awareness of pilots and controllers was lowest, and workload of pilots was highest. The paper also discusses further development of these concepts and their augmentation and integration with future air traffic management tools and systems that are being considered for NextGen.

Johnson, Walter↗
DOE OSTI2020

Materials Data on HoCo(BO2)5 by Materials Project

HoCo(BO2)5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ho3+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ho–O bond distances ranging from 2.25–2.92 Å. Co2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Co–O bond distances ranging from 2.06–2.43 Å. There are five inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.37 Å) and two longer (1.38 Å) B–O bond length. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.35–1.40 Å. In the third B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.47–1.51 Å. In the fourth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.47–1.50 Å. In the fifth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.47–1.50 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Ho3+, two equivalent Co2+, and one B3+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+, one Co2+, and two B3+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Ho3+ and two B3+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+ and two B3+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ho3+ and two B3+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Co2+ and two B3+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+, one Co2+, and two B3+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Co2+ and two B3+ atoms. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+ and two B3+ atoms. In the tenth O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ho3+ and one B3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Magnetic anisotropy in ferromagnetic CrI 3

We use neutron scattering to show that ferromagnetic (FM) phase transition in the two-dimensional (2D) honeycomb lattice CrI 3 is a weakly first order transition and controlled by spin-orbit coupling (SOC) induced magnetic anisotropy, instead of magnetic exchange coupling as in a conventional ferromagnet. With increasing temperature, the magnitude of magnetic anisotropy, seen as a spin gap at the Brillouin zone center, decreases in a power law fashion and vanishes at T C , while the in-plane and c-axis spin-wave stiffnesses associated with magnetic exchange couplings remain robust at T C . We also compare parameter regimes where spin waves in CrI 3 can be described by a Heisenberg Hamiltonian with Dzyaloshinskii-Moriya interaction or a Heisenberg-Kitaev Hamiltonian. These results suggest that the SOC induced magnetic anisotropy plays a dominant role in stabilizing the FM order in single layer 2D van der Waals ferromagnets.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗