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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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Phase composition of alloys of titanium aluminum chromium iron silicon system
Balanced filters evaluated for performance in X-ray fluorescence analysis of lunar and planetary surface materials
Subthreshold electron irradiation effects on surface recombination properties of n- and p-type germanium and silicon crystals
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Thermoelectric properties as function of time and temperature for phosphorous doped n-type silicon-germanium alloy
Thermal feedback theory for silicon junction FET operating at low temperatures
Elastic and inelastic scattering of proton beams from magnesium and silicon isotopes, using optical model
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Oxidation of nickel alloys determined by X ray diffraction, weight and thickness change measurements, and electron microprobe analysis
Infrared spectroscopic and photoconductivity determinations of electron irradiation effects in Li-doped floating zone and crucible grown silicon
Measurement of the Hall coefficient as a function of temperature between 15 and 300 K allows the separate determination of donor and acceptor concentrations in silicon samples which were irradiated at 240 K by 1-MeV electrons and then thermally annealed at 300 K. In both lithium- and phosphorus-doped silicon irradiation increased the acceptor concentration and decreased the donor concentration due to the formation of vacancy donor pairs. Annealing did not change either concentration in phosphorus-doped silicon and caused both concentrations to decrease in silicon doped with moderate amounts of lithium. In addition to this, in both lithium- and phosphorus-doped silicon the concentration and energy level of the A center were measured at each point in the sample's history. This experiment was limited to float-zoned silicon doped with less than 6 x 10 to the 14th power donors per cu cm.
Investigation of the effects of lithium on radiation-produced complexes having long-time stability by examining the localized energy levels in the forbidden gap which give rise to extrinsic photoconductivity. The levels are found to disappear and in some cases shift with annealing in the 100-450 C temperature range. Due to the complexity of the system and the present lack of adequate theory, no complete analysis of the data obtained could be made.
A position sensitive detector was made using the lithium diffused layer of a lithium-drifted-silicon detector as the uniform resistive layer. An expression is derived for estimating the resistance from the thickness of the lithium layer. Expressions for the noise and ballistic deficit for single differentiation-double integration pulse shaping are presented. Room temperature data for a 1 Mev proton beam on a 45 mm long detector shows that the linearity is better than .05% and that the position resolution is 1.06 + or - .05 mm.
The development of an alumina/silicate based composite material for space shuttle reusable surface insulation is reported. Physical property determinations, environmental testing, design analysis, and projected costs for a thermal protection system are outlined.
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The results are described of the final stage of the research involving the role of anions in the behavior of magnesium oxide, as well as the continued efforts of the fracture behavior of silicon nitride materials. These efforts, particularly the first, are further sub-divided in subsections describing individual types of behavior of materials.
A study of lunar rock samples from eight sites on the near side of the moon showed oxygen isotope abundance variations much smaller than those in meteorites and earth material. The grain-surface coatings of the lunar fines were found to be generally depleted in oxygen relative to silicon. The lunar soils, on the other hand, were somewhat richer in both O18 and Si30 than the lunar crystalline rock.