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Results for “Os-W”

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3 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Theoretical study of cathode surfaces and high-temperature superconductors

Calculations are presented for the work functions of BaO on W, Os, Pt, and alloys of Re-W, Os-W, and Ir-W that are in excellent agreement with experiment. The observed emission enhancement for alloy relative to tungsten dispenser cathodes is attributed to properties of the substrate crystal structure and explained by the smaller depolarization of the surface dipole on hexagonal as compared to cubic substrates. For Ba and BaO on W(100), the geometry of the adsorbates has been determined by a comparison of inverse photoemission spectra with calculated densities of unoccupied states based on the fully relativistic embedded cluster approach. Results are also discussed for models of scandate cathodes and the electronic structure of oxygen on W(100) at room and elevated temperatures. A detailed comparison is made for the surface electronic structure of the high-temperature superconductor YBa2Cu3O7 as obtained with non-, quasi-, and fully relativistic cluster calculations.

Mueller, Wolfgang↗
DOE OSTI2020

Materials Data on Os3W by Materials Project

WOs3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. W6+ is bonded to twelve equivalent Os2- atoms to form WOs12 cuboctahedra that share corners with six equivalent WOs12 cuboctahedra, corners with twelve equivalent OsOs8W4 cuboctahedra, edges with eighteen equivalent OsOs8W4 cuboctahedra, faces with eight equivalent WOs12 cuboctahedra, and faces with twelve equivalent OsOs8W4 cuboctahedra. There are six shorter (2.73 Å) and six longer (2.78 Å) W–Os bond lengths. Os2- is bonded to four equivalent W6+ and eight equivalent Os2- atoms to form OsOs8W4 cuboctahedra that share corners with four equivalent WOs12 cuboctahedra, corners with fourteen equivalent OsOs8W4 cuboctahedra, edges with six equivalent WOs12 cuboctahedra, edges with twelve equivalent OsOs8W4 cuboctahedra, faces with four equivalent WOs12 cuboctahedra, and faces with sixteen equivalent OsOs8W4 cuboctahedra. There are a spread of Os–Os bond distances ranging from 2.73–2.79 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Materials Data on OsW2 by Materials Project

W2Os is beta Uranium-derived structured and crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. there are three inequivalent W sites. In the first W site, W is bonded in a 9-coordinate geometry to nine W and six Os atoms. There are a spread of W–W bond distances ranging from 2.66–3.22 Å. There are two shorter (2.88 Å) and four longer (2.97 Å) W–Os bond lengths. In the second W site, W is bonded in a 6-coordinate geometry to two W and four equivalent Os atoms. The W–W bond length is 2.65 Å. There are three shorter (2.72 Å) and one longer (2.74 Å) W–Os bond lengths. In the third W site, W is bonded in a 7-coordinate geometry to five W and five Os atoms. Both W–W bond lengths are 2.50 Å. There are a spread of W–Os bond distances ranging from 2.78–2.84 Å. There are two inequivalent Os sites. In the first Os site, Os is bonded to eight W and four equivalent Os atoms to form OsOs4W8 cuboctahedra that share corners with sixteen equivalent OsOs2W10 cuboctahedra, edges with two equivalent OsOs4W8 cuboctahedra, and faces with four equivalent OsOs2W10 cuboctahedra. All Os–Os bond lengths are 2.65 Å. In the second Os site, Os is bonded to ten W and two Os atoms to form OsOs2W10 cuboctahedra that share corners with eleven OsOs4W8 cuboctahedra, edges with three equivalent OsOs2W10 cuboctahedra, and faces with seven OsOs4W8 cuboctahedra. The Os–Os bond length is 2.68 Å.

36 MATERIALS SCIENCE↗