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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Electrochemical Synthesis and Investigation of Stoichiometric, Phase-Pure CoSb 2 O 6 and MnSb 2 O 6 Electrodes for the Oxygen Evolution Reaction in Acidic Media

The electrochemical oxidation of water to oxygen gas is the primary counter reaction to the formation of hydrogen gas via water splitting. In acidic media, the only well-established and active oxygen evolution catalysts are expensive noble metal oxides such as IrO x and RuO x , necessitating the development of practical oxygen evolution catalysts that are stable in acidic media. In this study, we prepared stoichiometric, phase-pure CoSb 2 O 6 and MnSb 2 O 6 electrodes using electrochemical synthesis and investigated their ability to oxidize water in 0.5 M H 2 SO 4 (pH 0.3). In addition, their stabilities during the oxygen evolution reaction (OER) were carefully examined by comparing their morphologies, crystallinities, compositions, and surface compositions before and after the OER. The chlorine evolution reaction on CoSb 2 O 6 and MnSb 2 O 6 in acidic media was also examined so that their performances can be compared with previously reported non-stoichiometric CoSb 2 O 6 and MnSb 2 O 6 electrodes. The electrochemical properties and stabilities of stoichiometric, phase-pure CoSb 2 O 6 and MnSb 2 O 6 reported in this study can provide useful insights into the development and understanding of acid-stable, non-noble metal oxide-based OER catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1994

CoSb(sub 3)-IrSb(sub 3)Solid Solutions: Preparations and Characterization

The binary antimonide compounds of the skutterudite family have a good potential for thermoelectric applications as recent results at JPL have shown. However, the room temperature thermal conductivity of these materials is about 10 Wm(sup -1)K(sup -1) with an 80 % contribution from the lattice. To achieve maximum ZT values, the lattice thermal conductivity needs to be lowered. Because the lattice thermal conductivity of solid solutions can substantially decrease due to the addition of point defect phonon scattering (all state-of-the-art thermoelectric materials are solid solutions), a study of the formation of solid solutions between the antimonide skutterudite compounds is of interest. The preparation and characterization of both p-type and n-type CoSb(sub 3)-IrSb(sub 3) solid solutions by several techniques is reviewed in this paper. Experimental results showed that solid solutions were successfully formed in a wide range of compositions. The changes in the thermoelectric properties indicated the influence of a strong point defect scattering, resulting in large decreases in Hall mobility and thermal conductivity. The potential for high ZT values in CoSb(sub 3)-IrSb(sub 3) solid solutions is discussed.

mobility↗
DOE OSTI2020

Materials Data on CoSb by Materials Project

CoSb is Tungsten Carbide-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Co2+ is bonded to six equivalent Sb2- atoms to form a mixture of corner, edge, and face-sharing CoSb6 octahedra. The corner-sharing octahedral tilt angles are 51°. All Co–Sb bond lengths are 2.59 Å. Sb2- is bonded in a 6-coordinate geometry to six equivalent Co2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoSbS by Materials Project

CoSbS is Hausmannite-derived structured and crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. Co3+ is bonded to three equivalent Sb1- and three equivalent S2- atoms to form CoSb3S3 octahedra that share corners with eight equivalent CoSb3S3 octahedra, corners with three equivalent SbCo3S tetrahedra, corners with three equivalent SCo3Sb tetrahedra, and edges with two equivalent CoSb3S3 octahedra. The corner-sharing octahedra tilt angles range from 56–59°. There are one shorter (2.49 Å) and two longer (2.50 Å) Co–Sb bond lengths. There are one shorter (2.28 Å) and two longer (2.35 Å) Co–S bond lengths. Sb1- is bonded to three equivalent Co3+ and one S2- atom to form SbCo3S tetrahedra that share corners with three equivalent CoSb3S3 octahedra, corners with six equivalent SbCo3S tetrahedra, corners with seven equivalent SCo3Sb tetrahedra, and an edgeedge with one SCo3Sb tetrahedra. The corner-sharing octahedra tilt angles range from 75–77°. The Sb–S bond length is 2.58 Å. S2- is bonded to three equivalent Co3+ and one Sb1- atom to form SCo3Sb tetrahedra that share corners with three equivalent CoSb3S3 octahedra, corners with six equivalent SCo3Sb tetrahedra, corners with seven equivalent SbCo3S tetrahedra, and an edgeedge with one SbCo3S tetrahedra. The corner-sharing octahedra tilt angles range from 72–82°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoSbS by Materials Project

CoSbS is Hausmannite-derived structured and crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Co3+ is bonded to three equivalent Sb1- and three equivalent S2- atoms to form distorted CoSb3S3 octahedra that share corners with ten equivalent CoSb3S3 octahedra, corners with three equivalent SbCo3S tetrahedra, corners with three equivalent SCo3Sb tetrahedra, and an edgeedge with one CoSb3S3 octahedra. The corner-sharing octahedra tilt angles range from 54–65°. There are a spread of Co–Sb bond distances ranging from 2.53–2.57 Å. There are a spread of Co–S bond distances ranging from 2.28–2.31 Å. Sb1- is bonded to three equivalent Co3+ and one S2- atom to form distorted SbCo3S tetrahedra that share corners with three equivalent CoSb3S3 octahedra, corners with six equivalent SbCo3S tetrahedra, and corners with nine equivalent SCo3Sb tetrahedra. The corner-sharing octahedra tilt angles range from 73–82°. The Sb–S bond length is 2.55 Å. S2- is bonded to three equivalent Co3+ and one Sb1- atom to form distorted SCo3Sb tetrahedra that share corners with three equivalent CoSb3S3 octahedra, corners with four equivalent SCo3Sb tetrahedra, corners with nine equivalent SbCo3S tetrahedra, and an edgeedge with one SCo3Sb tetrahedra. The corner-sharing octahedra tilt angles range from 77–79°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoSb(PO4)2 by Materials Project

CoSb(PO4)2 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Co3+ is bonded to six O2- atoms to form distorted CoO6 pentagonal pyramids that share corners with four equivalent SbO6 octahedra, corners with four PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–50°. There are a spread of Co–O bond distances ranging from 1.99–2.26 Å. Sb3+ is bonded to six O2- atoms to form SbO6 octahedra that share corners with four equivalent CoO6 pentagonal pyramids, corners with four PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. There are a spread of Sb–O bond distances ranging from 2.12–2.21 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 a cornercorner with one SbO6 octahedra, corners with three equivalent CoO6 pentagonal pyramids, and an edgeedge with one SbO6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are a spread of P–O bond distances ranging from 1.51–1.60 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent SbO6 octahedra, a cornercorner with one CoO6 pentagonal pyramid, and an edgeedge with one CoO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of P–O bond distances ranging from 1.51–1.59 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Co3+ and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Sb3+ and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Co3+, one Sb3+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Co3+, one Sb3+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Co3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Sb3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Evolution of magnetic field induced ordering in the layered quantum Heisenberg triangular-lattice antiferromagnet Ba 3 CoSb 2 O 9

Quantum fluctuations in the effective spin-12 layered triangular-lattice quantum Heisenberg antiferromagnet Ba 3 CoSb 2 O 9 lift the classical degeneracy of the antiferromagnetic ground state in magnetic field, producing a series of novel spin structures for magnetic fields applied within the crystallographic ab plane, including a celebrated collinear “up-up-down” spin ordering with magnetization equal to 1/3 of the saturation magnetization over an extended field range. Theoretically unresolved, however, are the effects of interlayer antiferromagnetic coupling and transverse magnetic fields on the ground states of this system. Additional magnetic field induced phase transitions are theoretically expected and in some cases have been experimentally observed, but details regarding their number, location, and physical character appear inconsistent with the predictions of existing models. Conversely, an absence of experimental measurements as a function of magnetic-field orientation has left other key predictions of these models untested. To address these issues, in this study we have used specific heat, neutron diffraction, thermal conductivity, and magnetic torque measurements to map out the phase diagram as a function of magnetic field intensity and orientation relative to the crystallographic ab plane. For H||ab, we have discovered an additional magnetic field induced phase transition at low temperature and an unexpected tetracritical point in the high-field phase diagram, which coupled with the apparent second-order nature of the phase transitions eliminates several theoretically proposed spin structures for the high-field phases. Our calorimetric measurements as a function of magnetic field orientation are in general agreement with theory for field-orientation angles close to plane parallel (H||a) but diverge at angles near plane perpendicular; a predicted convergence of two phase boundaries at finite angle and a corresponding change in the order of the field induced phase transition are not observed experimentally. Our results emphasize the role of interlayer coupling in selecting and stabilizing field induced phases, provide guidance on the nature of the magnetic order in each phase, and reveal the need for new physics to account for the nature of magnetic ordering in this archetypal two-dimensional spin-12 triangular-lattice quantum Heisenberg antiferromagnet.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Ingredients for enhanced thermoelectric power at cryotemperatures in the correlated semiconductor CoSbS revealed by its optical response

The semiconducting CoSbS is well-known for its thermoelectric performance at high-temperatures but it is also of interest because of its colossal low-temperature thermopower. Here, we address the temperature dependence of its optical response over a broad spectral range, from which we reveal several ingredients determining the thermoelectric properties at cryo-temperatures. Furthermore, we discover co- herent phonon modes and with the additional support of scanning transmission electron microscopy investigations we provide evidences for in-gap impurity states driving the formation of correlated electrons in the valence band. Their implications, with respect to the high thermoelectric power at low temperatures, are discussed within the framework of the phonon-drag transport of low-mobility heavy quasiparticles.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1996

Properties of Single Crystalline Semiconducting CoSb(sub 3)

A study of the properties of the skutterudite compound CoSb(sub 3) was caried out on single crystals grown by the Bridgman gradient freze technique....Our results show that the dominant carrier scattering mechanism around room temperature is acoustic phonon scattering.

skutterudites↗
DOE OSTI2020

Materials Data on CoSb(PO4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoSb(PO4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoSb(PO4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoSb(PO4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoSb(PO4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoSb(PO4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗