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At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

2-Micron Diode-Pumped Pulsed Laser Transmitter for SPARCLE: A Coherent Wind Lidar Shuttle Mission

To enable a tropospheric vector wind velocity profiling from space with a pulsed Doppler lidar, a diode-pumped, room temperature Ho:Tm:YLF coherent pulsed transmitter has been developed at NASA Langley Research Center. This pulsed laser transmitter will be a part of coherent wind lidar shuttle mission SPARCLE. The acronym stands for SPAce Readiness Coherent Lidar Experiment and is primarily a technology demonstration mission and is expected to fly in 2001 as NASA's New Millennium Program (NMP) second Earth Orbiter (EO-2) mission. The laser transmitter for SPARCLE is a Ho:Tm:YLF power oscillator operating at eye-safe wavelength of 2.05 microns. The Q-switched output energy is 125 mJ at six Hz, and it has a near-transform limited beam with a pulse width of 170 ns. The high power and high beam quality of this laser makes it well suited as a coherent wind lidar transmitter on a space platform. When the output of this power oscillator is amplified by using four diode-pumped Ho:Tm:YLF amplifiers, an output energy of 600 mJ at 10 Hz is achieved. This is the highest energy ever produced at 10 Hz, and is at least an order of magnitude greater than previously achieved for a 2-micron diode-pumped laser at room temperature.

Singh, Upendra N.↗
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 OSTI2020

Materials Data on Ho2CoTe2(SO7)2 by Materials Project

Ho2CoTe2(SO7)2 crystallizes in the triclinic P-1 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 2.26–2.57 Å. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent SO4 tetrahedra. There are a spread of Co–O bond distances ranging from 2.05–2.13 Å. Te4+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Te–O bond distances ranging from 1.90–1.92 Å. S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share a cornercorner with one CoO6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are a spread of S–O bond distances ranging from 1.48–1.51 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one Ho3+ and one S6+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Co2+ and one S6+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ho3+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ho3+ and one S6+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ho3+ and one Te4+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ho3+, one Co2+, and one Te4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+, one Co2+, and one Te4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoMoBrO4 by Materials Project

HoMoO4Br crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to five O2- and three Br1- atoms. There are a spread of Ho–O bond distances ranging from 2.28–2.77 Å. There are one shorter (2.89 Å) and two longer (2.91 Å) Ho–Br bond lengths. In the second Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- and one Br1- atom. There are a spread of Ho–O bond distances ranging from 2.28–2.43 Å. The Ho–Br bond length is 2.99 Å. There are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 1.78–1.83 Å. In the second Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 1.77–1.85 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ho3+ and one Mo6+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to one Ho3+ and one Mo6+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two Ho3+ and one Mo6+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and one Mo6+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ho3+ and one Mo6+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ho3+ and one Mo6+ atom. In the seventh O2- site, O2- is bonded in a distorted linear geometry to one Ho3+ and one Mo6+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and one Mo6+ atom. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a distorted water-like geometry to two equivalent Ho3+ atoms. In the second Br1- site, Br1- is bonded in a 2-coordinate geometry to two Ho3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(HoS2)2 by Materials Project

Eu(HoS2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing HoS6 octahedra. The corner-sharing octahedra tilt angles range from 48–65°. There are a spread of Ho–S bond distances ranging from 2.69–2.75 Å. In the second Ho3+ site, Ho3+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing HoS6 octahedra. The corner-sharing octahedra tilt angles range from 48–65°. There are a spread of Ho–S bond distances ranging from 2.67–2.76 Å. Eu2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Eu–S bond distances ranging from 3.04–3.29 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to three Ho3+ and two equivalent Eu2+ atoms. In the second S2- site, S2- is bonded to three equivalent Ho3+ and two equivalent Eu2+ atoms to form a mixture of distorted corner and edge-sharing SEu2Ho3 square pyramids. In the third S2- site, S2- is bonded in a 5-coordinate geometry to three Ho3+ and two equivalent Eu2+ atoms. In the fourth S2- site, S2- is bonded to three equivalent Ho3+ and two equivalent Eu2+ atoms to form a mixture of distorted corner and edge-sharing SEu2Ho3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Controlling selective nucleation and growth of dysprosium islands on graphene by metal intercalation

We report metal intercalation is an effective method to modify the physical and chemical properties of low-dimensional systems such as epitaxial graphene. Here, we show that the nucleation and growth of metal nanostructures on epitaxial graphene on SiC(0001) can be dramatically changed by metal intercalation. Using scanning tunneling microscopy experiments, we demonstrate that dysprosium (Dy) metal islands are selectively nucleated on the area with Dy intercalation under both graphene and carbon buffer layers, while the adjacent area with only buffer layer intercalated remains relatively bare. Using first-principles calculations based on density functional theory, we show that adsorption of Dy adatom on the preferred nucleation area is energetically more favorable than on other areas. Moreover, changes in the electronic structure and the interlayer spacing upon Dy intercalation obtained from our calculations are also consistent with experimental observations. Our results indicate that metal intercalation is a promising way to manipulate the interaction between graphene and deposited adatoms.

2-dimensional systems↗
NASA NTRS2000

Tunable Single-Frequency Near IR Lasers for DIAL Applications

Tunable single-frequency sources in the 2-4 micron wavelength region are useful for remote DIAL measurements of chemicals and pollutants. We are developing tunable single-frequency transmitters and receivers for both direct and coherent detection lidar measurement applications. We have demonstrated a direct-diode-pumped PPLN-based OPO that operates single frequency, produces greater than 10 mW cw and is tunable over the 2.5 - 3.9 micron wavelength region. This laser has been used to injection seed a pulsed PPLN OPO, pumped by a 1.064 micron Nd:YAG laser, producing 50-100 microJoule single-frequency pulses at 100 Hz PRF near 3.6 micron wavelength. In addition, we have demonstrated a cw Cr:ZnSe laser that is tunable over the 2.1 - 2.8 micron wavelength region. This laser is pumped by a cw diode-pumped Tm:YALO laser and has produced over 1.8 W cw. Tm- and Tm, Ho-doped single-frequency solid-state lasers that produce over 50 mW cw and are tunable over approximately 10 nm in the 2 -2.1 micron band with fast PZT tuning have also been demonstrated. A fast PZT-tunable Tm, Ho:YLF laser was used for a direct-detection column content DIAL measurement of atmospheric CO2. Modeling shows that that all these cw and pulsed sources are useful for column-content coherent DIAL measurements at several km range using topographic targets.

Henderson, Sammy W.↗
DOE OSTI2020

Materials Data on CsHo(WO4)2 by Materials Project

CsHo(WO4)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Cs1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Cs–O bond distances ranging from 2.97–3.49 Å. Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.28–2.35 Å. W6+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing WO6 octahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of W–O bond distances ranging from 1.85–2.18 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Cs1+ and two equivalent W6+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Cs1+, one Ho3+, and one W6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Cs1+, one Ho3+, and two equivalent W6+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Cs1+, one Ho3+, and one W6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho2Cu(GeO4)2 by Materials Project

Ho2Cu(GeO4)2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are two 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 2.24–2.81 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 2.26–2.73 Å. Cu2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Cu–O bond distances ranging from 1.91–2.66 Å. There are three inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded in a tetrahedral geometry to four O2- atoms. All Ge–O bond lengths are 1.79 Å. In the second Ge4+ site, Ge4+ is bonded to five O2- atoms to form corner-sharing GeO5 trigonal bipyramids. There are a spread of Ge–O bond distances ranging from 1.78–1.96 Å. In the third Ge4+ site, Ge4+ is bonded to four O2- atoms to form corner-sharing GeO4 tetrahedra. There is two shorter (1.77 Å) and two longer (1.80 Å) Ge–O bond length. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ho3+ and one Ge4+ atom. In the second O2- site, O2- is bonded to two Ho3+, one Cu2+, and one Ge4+ atom to form a mixture of distorted corner and edge-sharing OHo2CuGe trigonal pyramids. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two Ho3+, two equivalent Cu2+, and one Ge4+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two Ho3+, one Cu2+, and one Ge4+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ho3+ and one Ge4+ atom. In the sixth O2- site, O2- is bonded to two Ho3+, one Cu2+, and one Ge4+ atom to form a mixture of distorted corner and edge-sharing OHo2CuGe trigonal pyramids. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two Ho3+ and two Ge4+ atoms. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ho3+ and one Ge4+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ho3+ and one Ge4+ atom. In the tenth O2- site, O2- is bonded to two Ho3+, one Cu2+, and one Ge4+ atom to form a mixture of distorted corner and edge-sharing OHo2CuGe trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Performance Evaluation of a Prototype Moving Packed-Bed Particle/sCO 2 Heat Exchanger

Particle heat exchangers are a critical enabling technology for next generation concentrating solar power (CSP) plants that use supercritical carbon dioxide (sCO 2 ) as a working fluid. This report covers the design, manufacturing and testing of a prototype particle-to-sCO 2 heat exchanger targeting thermal performance levels required to meet commercial scale cost targets. In addition, the the design and assembly of integrated particle and sCO 2 flow loops for heat exchanger performance testing are detailed. The prototype heat exchanger was tested to particle inlet temperatures of 500 °C at 17 MPa which resulted in overall heat transfer coefficients of approximately 300 W/m 2 -K at the design point and cases using high approach temperature with peak values as high as 400 W/m 2 -K

14 SOLAR ENERGY↗
NASA NTRS1985

High-Speed Computer-Controlled Switch-Matrix System

High-speed computer-controlled switch-matrix system developed for communication satellites. Satellite system controlled by onboard computer and all message-routing functions between uplink and downlink beams handled by newly developed switch-matrix system. Message requires only 2-microsecond interconnect period, repeated every millisecond.

Spisz, E.↗
DOE OSTI2020

Materials Data on KHo2Cl7 by Materials Project

KHo2Cl7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. K1+ is bonded in a 2-coordinate geometry to eight Cl1- atoms. There are a spread of K–Cl bond distances ranging from 3.16–3.78 Å. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to seven Cl1- atoms to form a mixture of distorted face and edge-sharing HoCl7 pentagonal bipyramids. There are a spread of Ho–Cl bond distances ranging from 2.69–2.78 Å. In the second Ho3+ site, Ho3+ is bonded to seven Cl1- atoms to form a mixture of distorted face and edge-sharing HoCl7 pentagonal bipyramids. There are a spread of Ho–Cl bond distances ranging from 2.68–2.73 Å. There are seven inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 2-coordinate geometry to one K1+ and two Ho3+ atoms. In the second Cl1- site, Cl1- is bonded in a distorted trigonal non-coplanar geometry to one K1+ and two Ho3+ atoms. In the third Cl1- site, Cl1- is bonded in a 3-coordinate geometry to one K1+ and two Ho3+ atoms. In the fourth Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent K1+ and two Ho3+ atoms. In the fifth Cl1- site, Cl1- is bonded in a distorted L-shaped geometry to one K1+ and two Ho3+ atoms. In the sixth Cl1- site, Cl1- is bonded in a distorted water-like geometry to one K1+ and two Ho3+ atoms. In the seventh Cl1- site, Cl1- is bonded in a distorted trigonal non-coplanar geometry to one K1+ and two Ho3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsHo(MoO4)2 by Materials Project

CsHo(MoO4)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Cs1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Cs–O bond distances ranging from 2.90–3.41 Å. Ho3+ is bonded in a 6-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.30–2.74 Å. Mo6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.78–2.39 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Cs1+ and two equivalent Mo6+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Cs1+, two equivalent Ho3+, and one Mo6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Cs1+, one Ho3+, and two equivalent Mo6+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Cs1+, one Ho3+, and one Mo6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbHo(WO4)2 by Materials Project

RbHo(WO4)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Rb1+ is bonded in a 12-coordinate geometry to ten O2- atoms. There are a spread of Rb–O bond distances ranging from 2.91–3.10 Å. Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.27–2.32 Å. W6+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing WO6 octahedra. The corner-sharing octahedral tilt angles are 42°. There are a spread of W–O bond distances ranging from 1.84–2.14 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Rb1+ and two equivalent W6+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Rb1+, one Ho3+, and one W6+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Rb1+, one Ho3+, and two equivalent W6+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Rb1+, one Ho3+, and one W6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Influence of hydrostatic pressure on hidden order, the Kondo lattice, and magnetism in URu 2 Si 2-x P x

Within the chemical substitution series URu 2 Si 2-x P x , there is an evolution in the ground-state behavior from hidden ordered (HO) for x ≲ 0.03, to Kondo lattice behavior with no ordering (NO) for 0.03 ≲ x ≲ 0.26, to antiferromagnetism (AFM-2) for 0.26 ≲ x ≲ 0.5 [A. Gallagher et al., Nat. Commun. 7, 10712 (2016); A. Gallagher et al., J. Phys.: Condens. Matter 29, 024004 (2016)]. To better understand what factors control this behavior, temperature-dependent electrical resistivity measurements are performed for this series under applied pressures P up to 20.5 kbar. Specimens in the HO x region show similarities to the parent compound, where HO transforms into antiferromagnetism (AFM-1) at a critical pressure (P c ). P c decreases with increasing x and collapses towards P = 0 near x ≈ 0.03, suggesting that AFM-1 occurs at ambient pressure for this concentration. No pressure-induced phase transitions are observed in the NO x region and the AFM-2 state is only weakly suppressed by P. Measurements further reveal that AFM-1 and AFM-2 are distinct from each other. Calculations of the wave functions using the tight-binding Hartree-Fock approximation are performed and show (i) that the radial probability distributions for the phosphorus ions are more tightly bound than those for the silicon and (ii) that the energy difference between the orbitals decreases with increasing x. The cumulative effect of these two factors is that Si → P substitution decreases the hybridization strength, which correlates with the weakening of HO. At large x, additional effects such as electrical charge tuning also play an important role in determining the ground-state

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on Ho2Re2Si2C by Materials Project

Ho2Re2Si2C crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ho3+ is bonded in a 2-coordinate geometry to five equivalent Si4- and two equivalent C4- atoms. There are a spread of Ho–Si bond distances ranging from 3.01–3.14 Å. Both Ho–C bond lengths are 2.62 Å. Re3+ is bonded in a single-bond geometry to three equivalent Si4- and one C4- atom. There are two shorter (2.45 Å) and one longer (2.48 Å) Re–Si bond lengths. The Re–C bond length is 1.94 Å. Si4- is bonded in a 9-coordinate geometry to five equivalent Ho3+, three equivalent Re3+, and one Si4- atom. The Si–Si bond length is 2.53 Å. C4- is bonded to four equivalent Ho3+ and two equivalent Re3+ atoms to form edge-sharing CHo4Re2 octahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho2Fe2Si2C by Materials Project

Ho2Fe2Si2C crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ho3+ is bonded in a 2-coordinate geometry to five equivalent Si4- and two equivalent C4- atoms. There are a spread of Ho–Si bond distances ranging from 2.98–3.02 Å. Both Ho–C bond lengths are 2.55 Å. Fe3+ is bonded in a distorted single-bond geometry to three equivalent Si4- and one C4- atom. There are two shorter (2.28 Å) and one longer (2.31 Å) Fe–Si bond lengths. The Fe–C bond length is 1.78 Å. Si4- is bonded in a 9-coordinate geometry to five equivalent Ho3+, three equivalent Fe3+, and one Si4- atom. The Si–Si bond length is 2.70 Å. C4- is bonded to four equivalent Ho3+ and two equivalent Fe3+ atoms to form distorted edge-sharing CHo4Fe2 octahedra.

36 MATERIALS SCIENCE↗