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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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9 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Fabrication and analysis of Mo-Si multilayers

Mo-Si multilayers have been fabricated in our laboratory for reflecting various soft X-ray wavelengths. Several normal incidence mirrors have been produced for a solar sounding rocket flight. Using properly shaped masks on 3-inch diameter dc magnetrons, we can produce multilayers of a similar size having a uniformity of better than +/- 3 percent over their entire surface area. Peak reflectance of the multilayers are as high as 42 percent at 171 A. Efforts are underway to deposit several layers of different period on top of the multilayers in order to attenuate the reflection of 304 A, a very bright line of He II in the solar spectrum. In the interim, we have made a Mo-Si mirror that reflects at 304 A. In addition to obtaining information on the solar corona at this wavelength, this will greatly reduce the effects of the He II line when its image is appropriately subtracted from others.

Shing, L.↗
NASA NTRS1981

Molybdenum-tin as a solar cell metallization system

The operations of solar cell manufacture are briefly examined. The formation of reliable, ohmic, low-loss, and low-cost metal contacts on solar cells is a critical process step in cell manufacturing. In a commonly used process, low-cost metallization is achieved by screen printing a metal powder-glass frit ink on the surface of the Si surface and the conductive metal powder. A technique utilizing a molybdenum-tin alloy for the metal contacts appears to lower the cost of materials and to reduce process complexity. The ink used in this system is formulated from MoO3 with Sn powder and a trace amount of titanium resonate. Resistive losses of the resulting contacts are low because the ink contains no frit. The MoO3 is finally melted and reduced in forming gas (N2+H2) to Mo metal. The resulting Mo is highly reactive which facilitates the Mo-Si bonding.

Boyd, D. W.↗
NASA NTRS1981

Amorphous metallizations for high-temperature semiconductor device applications

The initial results of work on a class of semiconductor metallizations which appear to hold promise as primary metallizations and diffusion barriers for high temperature device applications are presented. These metallizations consist of sputter-deposited films of high T sub g amorphous-metal alloys which (primarily because of the absence of grain boundaries) exhibit exceptionally good corrosion-resistance and low diffusion coefficients. Amorphous films of the alloys Ni-Nb, Ni-Mo, W-Si, and Mo-Si were deposited on Si, GaAs, GaP, and various insulating substrates. The films adhere extremely well to the substrates and remain amorphous during thermal cycling to at least 500 C. Rutherford backscattering and Auger electron spectroscopy measurements indicate atomic diffussivities in the 10 to the -19th power sq cm/S range at 450 C.

Wiley, J. D.↗
DOE OSTI2020

Materials Data on SiMo3 by Materials Project

Mo3Si crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. Mo is bonded in a 6-coordinate geometry to two equivalent Mo and four equivalent Si atoms. Both Mo–Mo bond lengths are 2.46 Å. All Mo–Si bond lengths are 2.75 Å. Si is bonded to twelve equivalent Mo atoms to form a mixture of edge and face-sharing SiMo12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si3Mo5 by Materials Project

Mo5Si3 crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. there are two inequivalent Mo+2.40+ sites. In the first Mo+2.40+ site, Mo+2.40+ is bonded to four equivalent Si4- atoms to form MoSi4 tetrahedra that share corners with sixteen equivalent MoSi6 pentagonal pyramids, edges with eight equivalent MoSi6 pentagonal pyramids, and edges with two equivalent MoSi4 tetrahedra. All Mo–Si bond lengths are 2.60 Å. In the second Mo+2.40+ site, Mo+2.40+ is bonded to six Si4- atoms to form distorted MoSi6 pentagonal pyramids that share corners with fifteen equivalent MoSi6 pentagonal pyramids, corners with four equivalent MoSi4 tetrahedra, edges with three equivalent MoSi6 pentagonal pyramids, edges with two equivalent MoSi4 tetrahedra, and faces with seven equivalent MoSi6 pentagonal pyramids. There are a spread of Mo–Si bond distances ranging from 2.54–2.82 Å. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 10-coordinate geometry to ten Mo+2.40+ atoms. In the second Si4- site, Si4- is bonded in a 10-coordinate geometry to eight equivalent Mo+2.40+ and two equivalent Si4- atoms. Both Si–Si bond lengths are 2.47 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si2Mo by Materials Project

MoSi2 is Titanium Disilicide-like structured and crystallizes in the hexagonal P6_222 space group. The structure is three-dimensional. Mo is bonded in a distorted q6 geometry to ten equivalent Si atoms. There are a spread of Mo–Si bond distances ranging from 2.58–2.69 Å. Si is bonded in a 10-coordinate geometry to five equivalent Mo and five equivalent Si atoms. There are a spread of Si–Si bond distances ranging from 2.57–2.69 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SiMo by Materials Project

MoSi is Tungsten Carbide structured and crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Mo4+ is bonded to six equivalent Si4- atoms to form a mixture of distorted corner, edge, and face-sharing MoSi6 pentagonal pyramids. All Mo–Si bond lengths are 2.52 Å. Si4- is bonded to six equivalent Mo4+ atoms to form a mixture of distorted corner, edge, and face-sharing SiMo6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si3Mo by Materials Project

MoSi3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mo4+ is bonded to twelve equivalent Si+1.33- atoms to form a mixture of corner and face-sharing MoSi12 cuboctahedra. There are six shorter (2.61 Å) and six longer (2.81 Å) Mo–Si bond lengths. Si+1.33- is bonded in a 12-coordinate geometry to four equivalent Mo4+ and eight equivalent Si+1.33- atoms. There are a spread of Si–Si bond distances ranging from 2.48–2.89 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si2Mo3 by Materials Project

Mo3Si2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are two inequivalent Mo+2.67+ sites. In the first Mo+2.67+ site, Mo+2.67+ is bonded in a square co-planar geometry to four equivalent Si4- atoms. All Mo–Si bond lengths are 2.58 Å. In the second Mo+2.67+ site, Mo+2.67+ is bonded to six equivalent Si4- atoms to form a mixture of distorted corner, edge, and face-sharing MoSi6 pentagonal pyramids. There are two shorter (2.53 Å) and four longer (2.57 Å) Mo–Si bond lengths. Si4- is bonded in a 9-coordinate geometry to eight Mo+2.67+ and one Si4- atom. The Si–Si bond length is 2.52 Å.

36 MATERIALS SCIENCE↗