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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Acousto-optic modulators of high-power laser radiation on the basis of KGW and KYW crystals

Different modifications of acousto-optic modulators (AOMs) based on KG(WO{sub 4}){sub 2} (KGW) and KY(WO{sub 4}){sub 2} (KYW) crystals, designed for Q switching of high-power pulsed lasers, is developed and investigated. It is shown that AOMs based on these crystals are universal, can be combined with different lasers in the wavelength range of 1 – 3 μm, and have a high radiation resistance in the absence of antireflection coatings and light input at Brewster’s angle. The operation efficiency of KGW-based AOMs is experimentally demonstrated. Solid-state lasers based on Cr : Er : YSGG (λ = 2.78 μm), Cr : Yb : Ho : YSGG (λ = 2.87 μm), Cr : Tm : Ho : YSGG (λ = 2.09 μm), and Nd : YAG (λ = 1.064 μm) crystals with active acousto-optic Q switching, operating in the repetitively pulsed regime with a high beam quality and without surface destruction, are investigated. Lasing pulses (30 – 60)-ns long with energy up to 32 mJ at a repetition rate from 1 to 1000 Hz are obtained. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1997

HO(x) Measurements in SONEX with the Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS)

SONEX, which was delayed by aircraft inspection problems, began the second week of October and concluded in mid-November with 16 flights. These flights covered the Pacific Ocean off the western United States, transits across the United States, the western coast of Europe, and the North and Central Atlantic Ocean. Particular attention was paid to the North Atlantic Flight Corridor. ATHOS collected high-quality HO(x) data on 15 flights. Observations taken at 5 Hz were typically averaged into 20-second measurements. Each 20-second measurement has precision 1(sigma) of less than 0.01 pptv. OH measurements were generally made from the surface to flight altitudes. HO2 measurements, which require reagent NO flow, were made from flight altitudes to near the top of the planetary boundary layer. Measured OH and HO2 during SONEX was generally lower than the measured OH and HO2 during SUCCESS (April-May, 1996, central United States). Whereas during SUCCESS midday OH was 0.1-0.5 pptv and HO2 was 3-15 pptv, during SONEX midday OH was 0.02-0.2 pptv and HO2 was 0.5-8 pptv. Part of this difference results from the midday solar zenith angles, which were larger during SONEX than during SUCCESS due to both the season and the generally higher latitudes sampled during SONEX. However, some of the difference may be due to differences in HOx sources, since less air influenced by convection was sampled during SONEX. These possibilities await post-flight calibrations of ATHOS and analysis of observations of HO(x) and simultaneously measured meteorology and trace species.

Brune, William M.↗
DOE OSTI2023

Thermodynamic Understanding of Impurity Phase Segregation in a PdCrO 2 /CuCrO 2 Heterostructure

Abstract PdCrO 2 films are synthesized on CuCrO 2 buffer layers on Al 2 O 3 substrates. This synthesis is accompanied by impurity phase segregation, which hampers the synthesis of high quality PdCrO 2 films. Potential causes ofth impurity phase segregation are studied by using a combination of experiments and ab initio calculations. X‐ray diffraction and scanning transmission electron microscopy experiments reveal impurity phases of Cu x Pd 1 − x alloy and chromium oxides, Cr 2 O 3 and Cr 3 O 4 , in PdCrO 2 . Calculations determine that oxygen deficiency can cause the impurity phase segregation. Therefore, preventing oxygen release from delafossites can suppress the impurity phase segregation. The amounts of Cr 2 O 3 and Cr 3 O 4 depend on temperature and oxygen partial pressure. A reasonable theory‐based explanation for this experimental observation is provided.

2D metal↗
NASA NTRS1988

Global gravity survey by an orbiting gravity gradiometer

The scientific aims, design, and mission profile of the Superconducting Gravity Gradiometer Mission (SGGM), a NASA spacecraft mission proposed for the late 1990s, are discussed and illustrated with drawings and diagrams. SGGM would complement the two other planned gravimetry missions, GRM and Aristoteles, and would provide gravitational-field measurements with accuracy 2-3 mGal in 55 x 55-km blocks. The principal instruments are a (1) three-axis superconducting gravity gradiometer with intrinsic sensitivity 100 microeotvos/sq rt Hz, (2) a six-axis superconducting accelerometer with sensitivity 100 fg(E)/sq rt Hz linear and 10 prad/sec squared sq rt Hz angular, and (3) a six-axis shaker for active control of the platform. Consideration is given to the error budget and platform requirements, the orbit selection criteria, and the spacecraft design.

Paik, Ho Jung↗
DOE OSTI2020

Materials Data on HoAgTe2 by Materials Project

HoAgTe2 crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. Ho3+ is bonded to six Te2- atoms to form HoTe6 octahedra that share corners with six equivalent AgTe4 tetrahedra, edges with six equivalent HoTe6 octahedra, and edges with three equivalent AgTe4 tetrahedra. There are three shorter (3.06 Å) and three longer (3.16 Å) Ho–Te bond lengths. Ag1+ is bonded to four Te2- atoms to form AgTe4 tetrahedra that share corners with six equivalent HoTe6 octahedra, corners with six equivalent AgTe4 tetrahedra, and edges with three equivalent HoTe6 octahedra. The corner-sharing octahedra tilt angles range from 11–58°. There are one shorter (2.79 Å) and three longer (2.83 Å) Ag–Te bond lengths. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to three equivalent Ho3+ and one Ag1+ atom to form distorted TeHo3Ag trigonal pyramids that share corners with six equivalent TeHo3Ag3 octahedra, corners with six equivalent TeHo3Ag trigonal pyramids, and edges with three equivalent TeHo3Ag3 octahedra. The corner-sharing octahedra tilt angles range from 3–67°. In the second Te2- site, Te2- is bonded to three equivalent Ho3+ and three equivalent Ag1+ atoms to form TeHo3Ag3 octahedra that share corners with six equivalent TeHo3Ag trigonal pyramids, edges with six equivalent TeHo3Ag3 octahedra, and edges with three equivalent TeHo3Ag trigonal pyramids.

36 MATERIALS SCIENCE↗
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 Ho3Si11Pt23 by Materials Project

Ho3Pt23Si11 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ho3+ is bonded to eight equivalent Pt+1.26- atoms to form distorted corner-sharing HoPt8 cuboctahedra. All Ho–Pt bond lengths are 3.16 Å. There are four inequivalent Pt+1.26- sites. In the first Pt+1.26- site, Pt+1.26- is bonded in a distorted square co-planar geometry to four equivalent Si+1.82+ atoms. All Pt–Si bond lengths are 2.58 Å. In the second Pt+1.26- site, Pt+1.26- is bonded in a 3-coordinate geometry to two equivalent Ho3+ and three Si+1.82+ atoms. There are a spread of Pt–Si bond distances ranging from 2.43–2.46 Å. In the third Pt+1.26- site, Pt+1.26- is bonded to four Si+1.82+ atoms to form a mixture of edge and corner-sharing PtSi4 tetrahedra. There are one shorter (2.43 Å) and three longer (2.50 Å) Pt–Si bond lengths. In the fourth Pt+1.26- site, Pt+1.26- is bonded to four Si+1.82+ atoms to form a mixture of distorted edge and corner-sharing PtSi4 tetrahedra. All Pt–Si bond lengths are 2.51 Å. There are three inequivalent Si+1.82+ sites. In the first Si+1.82+ site, Si+1.82+ is bonded in a 7-coordinate geometry to seven Pt+1.26- atoms. In the second Si+1.82+ site, Si+1.82+ is bonded in a body-centered cubic geometry to eight Pt+1.26- atoms. In the third Si+1.82+ site, Si+1.82+ is bonded in a 7-coordinate geometry to seven Pt+1.26- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Origin of short- and medium-range order in supercooled liquid Ge 3 Sb 2 Te 6 from ab initio molecular dynamics simulations

Phase-change materials such as Ge–Sb–Te compounds have attracted much attention due to their potential value in electrical data storage. In contrast to the amorphous and crystalline phases, supercooled liquids are far from being deeply understood despite their inevitable role in both amorphization and crystallization processes. To this end, we have studied the dynamics properties and structural characteristics of liquid and supercooled liquid Ge 3 Sb 2 Te 6 during the fast cooling process. As the temperature decreases, chemical bonds become more homogeneous, but coordination numbers of Ge, Sb and Te atoms change very little. Meanwhile, the structural order of short-range configuration is obviously enhanced. Further studies suggest that Ge-centered, Sb-centered and Te-centered configurations change to the more ordered defective octahedrons mainly by adjusting the bond-angle relationship and bond length, rather than just by changing the coordination environment. It is the more ordered octahedrons that promote the formation of medium-range order. Our findings provide a deep insight into the origin of local structural order in supercooled liquid Ge 3 Sb 2 Te 6 , which is of great importance for the comprehensive understanding of amorphization and crystallization processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Study of an Integration Platform Based on an Adiabatic Active-Layer Waveguide Connection for InP Photonic Device Integration Mirroring That of Heterogeneous Integration on Silicon

In this work, a photonic device integration platform capable of integration of active-passive InP-based photonic devices without the use of material regrowth is introduced. The platform makes use of an adiabatic active-layer waveguide connection (ALWC) to move an optical beam between active and passive devices. The performance of this platform is analyzed using an example made up of four main sections: (1) a fiber coupling section for enabling vertical beam coupling from optical fiber into the photonic chip using a mode-matched surface grating with apodized duty cycles; (2) a transparent waveguide section for realizing passive photonic devices; (3) an adiabatic mode connection structure for moving the optical beam between passive and active device sections; and (4) an active device section for realizing active photonic devices. It is shown that the coupled surface grating, when added with a bottom gold reflector, can achieve a high chip-to-fiber coupling efficiency (CE) of 88.3% at 1550 nm. The adiabatic active-layer mode connection structure has an optical loss of lower than 1% (CE > 99%). The active device section can achieve an optical gain of 20 dB/mm with the use of only 3 quantum wells. The optimized structural parameters of the entire waveguide module are analyzed and discussed.

42 ENGINEERING↗
DOE OSTI2020

Materials Data on Na2HoPWO8 by Materials Project

Na2HoWPO8 is Esseneite-derived structured and crystallizes in the orthorhombic Ibca space group. The structure is three-dimensional. Na1+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.95 Å. Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.28–2.45 Å. W6+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.81 Å) and two longer (1.83 Å) W–O bond length. P5+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Na1+ and one W6+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Na1+, one Ho3+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, two equivalent Ho3+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Ho3+, and one W6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoCuPbSe3 by Materials Project

HoCuPbSe3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ho3+ is bonded to six Se2- atoms to form HoSe6 octahedra that share corners with two equivalent HoSe6 octahedra, corners with six equivalent PbSe7 pentagonal bipyramids, edges with two equivalent HoSe6 octahedra, edges with four equivalent PbSe7 pentagonal bipyramids, and edges with four equivalent CuSe4 tetrahedra. The corner-sharing octahedral tilt angles are 45°. There are a spread of Ho–Se bond distances ranging from 2.84–2.88 Å. Cu1+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with three equivalent PbSe7 pentagonal bipyramids, corners with two equivalent CuSe4 tetrahedra, edges with four equivalent HoSe6 octahedra, and edges with three equivalent PbSe7 pentagonal bipyramids. There are a spread of Cu–Se bond distances ranging from 2.44–2.52 Å. Pb2+ is bonded to seven Se2- atoms to form distorted PbSe7 pentagonal bipyramids that share corners with six equivalent HoSe6 octahedra, corners with three equivalent CuSe4 tetrahedra, edges with four equivalent HoSe6 octahedra, edges with two equivalent PbSe7 pentagonal bipyramids, edges with three equivalent CuSe4 tetrahedra, and faces with two equivalent PbSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 24–66°. There are a spread of Pb–Se bond distances ranging from 3.15–3.29 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to two equivalent Ho3+, one Cu1+, and three equivalent Pb2+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to two equivalent Ho3+, one Cu1+, and two equivalent Pb2+ atoms. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to two equivalent Ho3+, two equivalent Cu1+, and two equivalent Pb2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbHoP2O7 by Materials Project

RbHoP2O7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Rb1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Rb–O bond distances ranging from 3.03–3.57 Å. Ho3+ is bonded to six O2- atoms to form HoO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Ho–O bond distances ranging from 2.20–2.28 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent HoO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 16–49°. There is three shorter (1.53 Å) and one longer (1.64 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent HoO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 14–46°. There are a spread of P–O bond distances ranging from 1.52–1.63 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to one Rb1+, one Ho3+, and one P5+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Rb1+ and two P5+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Rb1+, one Ho3+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Rb1+, one Ho3+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Rb1+, one Ho3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Rb1+, one Ho3+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted linear geometry to one Rb1+, one Ho3+, and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho2TeO6 by Materials Project

Ho2TeO6 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 2.23–2.60 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 TeO6 octahedra, edges with two equivalent HoO7 hexagonal pyramids, and edges with two equivalent TeO6 octahedra. The corner-sharing octahedra tilt angles range from 39–46°. There are a spread of Ho–O bond distances ranging from 2.27–2.47 Å. Te6+ is bonded to six O2- atoms to form TeO6 octahedra that share corners with three equivalent HoO7 hexagonal pyramids and edges with two equivalent HoO7 hexagonal pyramids. There are a spread of Te–O bond distances ranging from 1.93–1.98 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 Te6+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ho3+ and one Te6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and one Te6+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and one Te6+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Ho3+ and one Te6+ atom. In the sixth O2- site, O2- is bonded to three Ho3+ and one Te6+ atom to form distorted corner-sharing OHo3Te tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaHo2(GeO3)4 by Materials Project

Ho2CaGe4O12 crystallizes in the orthorhombic Cmme space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with eight equivalent GeO4 tetrahedra. There are four shorter (2.29 Å) and two longer (2.57 Å) Ca–O bond lengths. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to six O2- atoms to form HoO6 octahedra that share corners with eight equivalent GeO4 tetrahedra. There are four shorter (2.21 Å) and two longer (2.45 Å) Ho–O bond lengths. In the second Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.34 Å) and four longer (2.42 Å) Ho–O bond lengths. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent CaO6 octahedra, corners with two equivalent HoO6 octahedra, and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–71°. There are a spread of Ge–O bond distances ranging from 1.73–1.85 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Ho3+, and one Ge4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and one Ge4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ca2+ and two equivalent Ge4+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ho3+ and two equivalent Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Experimental Evidence of Dioxole Unimolecular Decay Pathway for Isoprene-Derived Criegee Intermediates

Ozonolysis of isoprene, one of the most abundant volatile organic compounds emitted into the Earth’s atmosphere, generates two four-carbon unsaturated Criegee intermediates, methyl vinyl ketone oxide (MVK-oxide) and methacrolein oxide (MACR-oxide). The extended conjugation between the vinyl substituent and carbonyl oxide groups of these Criegee intermediates facilitates rapid electrocyclic ring closures that form 5-membered cyclic peroxides, known as dioxoles. This research discusses the first experimental evidence of this novel decay pathway, which is predicted to be the dominant atmospheric sink for specific conformational forms of MVK-oxide (anti) and MACR-oxide (syn) with the vinyl substituent adjacent to the terminal O atom. The resulting dioxoles are predicted to undergo rapid unimolecular decay to oxygenated hydrocarbon radical products, including acetyl, vinoxy, formyl, and 2-methyl-vinoxy radicals. In the presence of O 2 , these radicals rapidly react to form peroxy radicals (ROO), which quickly decay via carbon-centered radical intermediates (QOOH) to stable carbonyl products that are identified in this work. The carbonyl products are detected under thermal conditions (298 K, 10 torr He) using multiplexed photoionization mass spectrometry (MPIMS). The main products (and associated relative abundances) originating from unimolecular decay of anti-MVK-oxide and subsequent reaction with O 2 are formaldehyde (88 ± 5%), ketene (9 ± 1%) and glyoxal (3 ± 1%). Those identified from the unimolecular decay of syn-MACR-oxide and subsequent reaction of O 2 are acetaldehyde (37 ± 7%), vinyl alcohol (9 ± 1%), methylketene (2 ± 1%), and acrolein (52 ± 5%). In addition to the stable carbonyl products, the secondary peroxy chemistry also generates OH or HO 2 radical co-products.

09 BIOMASS FUELS↗
NASA NTRS2000

A High Energy 2-microns Laser for Multiple Lidar Applications

Solid-state 2-microns laser has been receiving considerable interest because of its eye-safe property and efficient diode pump operation, It has potential for multiple lidar applications to detect water vapor. carbon dioxide and winds. In this paper, we describe a 2-microns double pulsed Ho:Tm:YLF laser and end-pumped amplifier system. A comprehensive theoretical model has been developed to aid the design and optimization of the laser performance. In a single Q-switched pulse operation the residual energy stored in the Tm atoms will be wasted. However, in a double pulses operation mode, the residual energy stored in the Tm atoms will repopulate the Ho atoms that were depleted by the extraction of the first Q-switched pulse. Thus. the Tin sensitized Ho:YLF laser provides a unique advantage in applications that require double pulse operation, such as Differential Absorption Lidar (DIAL). A total output energy of 146 mJ per pulse pair under Q-switch operation is achieved with as high as 4.8% optical to optical efficiency. Compared to a single pulse laser, 70% higher laser efficiency is realized. To obtain high energy while maintaining the high beam quality, a master-oscillator-power-amplifier 2-microns system is designed. We developed an end-pumped Ho:Tm:YLF disk amplifier. This amplifier uses two diode arrays as pump source. A non-imaging lens duct is used to couple the radiation from the laser diode arrays to the laser disk. Preliminary result shows that the efficiency of this laser can be as high as 3%, a factor of three increases over side-pump configuration. This high energy, highly efficient and high beam quality laser is a promising candidate for use in an efficient, multiple lidar applications.

Yu, Jirong↗
DOE OSTI2020

Materials Data on HoZr6(PO4)9 by Materials Project

HoZr6(PO4)9 crystallizes in the trigonal P-3c1 space group. The structure is three-dimensional. Ho3+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All Ho–O bond lengths are 2.34 Å. There are three inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded to six O2- atoms to form ZrO6 octahedra that share corners with six equivalent PO4 tetrahedra. There are three shorter (2.08 Å) and three longer (2.11 Å) Zr–O bond lengths. In the second Zr4+ site, Zr4+ is bonded to six O2- atoms to form ZrO6 octahedra that share corners with six PO4 tetrahedra. There are three shorter (2.02 Å) and three longer (2.25 Å) Zr–O bond lengths. In the third Zr4+ site, Zr4+ is bonded to six O2- atoms to form ZrO6 octahedra that share corners with six PO4 tetrahedra. There are three shorter (2.07 Å) and three longer (2.12 Å) Zr–O bond lengths. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four ZrO6 octahedra. The corner-sharing octahedra tilt angles range from 25–49°. There are a spread of P–O bond distances ranging from 1.53–1.59 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four ZrO6 octahedra. The corner-sharing octahedra tilt angles range from 26–27°. There is two shorter (1.52 Å) and two longer (1.56 Å) P–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Zr4+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Zr4+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Zr4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Zr4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+, one Zr4+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Zr4+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaHo2F7 by Materials Project

NaHo2F7 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Na1+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are a spread of Na–F bond distances ranging from 2.40–2.85 Å. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 7-coordinate geometry to seven F1- atoms. There are a spread of Ho–F bond distances ranging from 2.13–2.41 Å. In the second Ho3+ site, Ho3+ is bonded in a 7-coordinate geometry to seven F1- atoms. There are a spread of Ho–F bond distances ranging from 2.08–2.44 Å. There are seven inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to three equivalent Na1+ and one Ho3+ atom. In the second F1- site, F1- is bonded in a distorted trigonal planar geometry to three Ho3+ atoms. In the third F1- site, F1- is bonded in a distorted trigonal planar geometry to three Ho3+ atoms. In the fourth F1- site, F1- is bonded in a 3-coordinate geometry to one Na1+ and two equivalent Ho3+ atoms. In the fifth F1- site, F1- is bonded in a distorted trigonal non-coplanar geometry to one Na1+ and two equivalent Ho3+ atoms. In the sixth F1- site, F1- is bonded in a distorted bent 120 degrees geometry to two equivalent Ho3+ atoms. In the seventh F1- site, F1- is bonded to three equivalent Na1+ and one Ho3+ atom to form distorted corner-sharing FNa3Ho tetrahedra.

36 MATERIALS SCIENCE↗