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Results for “Ir-W”

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4 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 IrW by Materials Project

WIr is beta-prime cadmium gold structured and crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. W is bonded to four equivalent W and eight equivalent Ir atoms to form WIr8W4 cuboctahedra that share corners with eight equivalent IrIr4W8 cuboctahedra, corners with ten equivalent WIr8W4 cuboctahedra, edges with six equivalent WIr8W4 cuboctahedra, edges with twelve equivalent IrIr4W8 cuboctahedra, faces with eight equivalent IrIr4W8 cuboctahedra, and faces with twelve equivalent WIr8W4 cuboctahedra. There are two shorter (2.78 Å) and two longer (2.80 Å) W–W bond lengths. There are a spread of W–Ir bond distances ranging from 2.75–2.82 Å. Ir is bonded to eight equivalent W and four equivalent Ir atoms to form IrIr4W8 cuboctahedra that share corners with eight equivalent WIr8W4 cuboctahedra, corners with ten equivalent IrIr4W8 cuboctahedra, edges with six equivalent IrIr4W8 cuboctahedra, edges with twelve equivalent WIr8W4 cuboctahedra, faces with eight equivalent WIr8W4 cuboctahedra, and faces with twelve equivalent IrIr4W8 cuboctahedra. There are two shorter (2.78 Å) and two longer (2.82 Å) Ir–Ir bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ir3W by Materials Project

WIr3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. W is bonded to twelve equivalent Ir atoms to form WIr12 cuboctahedra that share corners with six equivalent WIr12 cuboctahedra, corners with twelve equivalent IrIr8W4 cuboctahedra, edges with eighteen equivalent IrIr8W4 cuboctahedra, faces with eight equivalent WIr12 cuboctahedra, and faces with twelve equivalent IrIr8W4 cuboctahedra. There are six shorter (2.74 Å) and six longer (2.78 Å) W–Ir bond lengths. Ir is bonded to four equivalent W and eight equivalent Ir atoms to form IrIr8W4 cuboctahedra that share corners with four equivalent WIr12 cuboctahedra, corners with fourteen equivalent IrIr8W4 cuboctahedra, edges with six equivalent WIr12 cuboctahedra, edges with twelve equivalent IrIr8W4 cuboctahedra, faces with four equivalent WIr12 cuboctahedra, and faces with sixteen equivalent IrIr8W4 cuboctahedra. There are a spread of Ir–Ir bond distances ranging from 2.74–2.78 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on IrW by Materials Project

WIr crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. W is bonded to six equivalent W and six equivalent Ir atoms to form WIr6W6 cuboctahedra that share corners with eighteen equivalent WIr6W6 cuboctahedra, edges with six equivalent WIr6W6 cuboctahedra, edges with twelve equivalent IrIr6W6 cuboctahedra, faces with eight equivalent WIr6W6 cuboctahedra, and faces with twelve equivalent IrIr6W6 cuboctahedra. All W–W bond lengths are 2.81 Å. All W–Ir bond lengths are 2.77 Å. Ir is bonded to six equivalent W and six equivalent Ir atoms to form IrIr6W6 cuboctahedra that share corners with eighteen equivalent IrIr6W6 cuboctahedra, edges with six equivalent IrIr6W6 cuboctahedra, edges with twelve equivalent WIr6W6 cuboctahedra, faces with eight equivalent IrIr6W6 cuboctahedra, and faces with twelve equivalent WIr6W6 cuboctahedra. All Ir–Ir bond lengths are 2.81 Å.

36 MATERIALS SCIENCE↗