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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Imaging performance of a normal incidence soft X-ray telescope

Measurements are presented of the imaging performance of a normal incidence spherical soft X-ray mirror at BK-alpha (67.6 A). The reflector was a 124-layer coating consisting of alternating Re-W alloy and C layers with a protective C overcoat 34 A thick deposited on a Zerodur substrate. Measurements made at an angle of 1.5 deg off axis with the prototype of the Einstein Observatory high resolution imager reveal the resolution of the mirror to be about 1 arcsec FWHM, with 50% of the reflected power within the detector field of 512 arcsec contained within a diameter of 5 arcsec. The data demonstrate the practicality and potential good performance of normal-incidence soft X-ray optics, and show that the scattering performances of such devices may be as good or better than the best grazing incidence devices.

Henry, J. P.↗
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 Re3W by Materials Project

Re3W is Uranium Silicide-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. W is bonded to twelve equivalent Re atoms to form WRe12 cuboctahedra that share corners with six equivalent WRe12 cuboctahedra, corners with twelve equivalent ReRe8W4 cuboctahedra, edges with eighteen equivalent ReRe8W4 cuboctahedra, faces with eight equivalent WRe12 cuboctahedra, and faces with twelve equivalent ReRe8W4 cuboctahedra. There are six shorter (2.79 Å) and six longer (2.80 Å) W–Re bond lengths. Re is bonded to four equivalent W and eight equivalent Re atoms to form distorted ReRe8W4 cuboctahedra that share corners with four equivalent WRe12 cuboctahedra, corners with fourteen equivalent ReRe8W4 cuboctahedra, edges with six equivalent WRe12 cuboctahedra, edges with twelve equivalent ReRe8W4 cuboctahedra, faces with four equivalent WRe12 cuboctahedra, and faces with sixteen equivalent ReRe8W4 cuboctahedra. There are six shorter (2.79 Å) and two longer (2.80 Å) Re–Re bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Re3W by Materials Project

Re3W is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. W is bonded to twelve Re atoms to form WRe12 cuboctahedra that share corners with four equivalent WRe12 cuboctahedra, corners with eight equivalent ReRe8W4 cuboctahedra, edges with eight equivalent WRe12 cuboctahedra, edges with sixteen equivalent ReRe8W4 cuboctahedra, faces with four equivalent WRe12 cuboctahedra, and faces with fourteen ReRe8W4 cuboctahedra. There are eight shorter (2.79 Å) and four longer (2.80 Å) W–Re bond lengths. There are two inequivalent Re sites. In the first Re site, Re is bonded to four equivalent W and eight Re atoms to form distorted ReRe8W4 cuboctahedra that share corners with twelve equivalent ReRe8W4 cuboctahedra, edges with eight equivalent WRe12 cuboctahedra, edges with sixteen ReRe8W4 cuboctahedra, faces with four equivalent WRe12 cuboctahedra, and faces with fourteen ReRe8W4 cuboctahedra. There are four shorter (2.79 Å) and four longer (2.80 Å) Re–Re bond lengths. In the second Re site, Re is bonded to four equivalent W and eight equivalent Re atoms to form distorted ReRe8W4 cuboctahedra that share corners with four equivalent ReRe8W4 cuboctahedra, corners with eight equivalent WRe12 cuboctahedra, edges with twenty-four ReRe8W4 cuboctahedra, faces with six equivalent WRe12 cuboctahedra, and faces with twelve ReRe8W4 cuboctahedra.

36 MATERIALS SCIENCE↗