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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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A shielded integrated complimentary MOS transistor structure is described which is used to prevent field inversion in the region not occupied by the gates and which permits the use of a thinner field oxide, reduces the chip area, and has provision for simplified multilayer connections. The structure is used in the design of a static shift register and results in a 20% reduction in area.
Use of an electron-beam phase-shift apparatus to obtain the radiative lifetimes for vibrational levels of the SiO E 1 Sigma (+) state. It is found that the radiative lifetimes for the vibrational transitions of the E-X band are independent of the vibrational upper state. The measured phase shifts yield cascade free lifetimes of 10.5 plus or minus 1.1 nsec for v' from 1 to 7. Spectroscopic data from Elander and Lagerqvist (1971) were used to calculate potential curves by the Klein-Dunham procedure, and Franck-Condon factors and r-centroids for the transition were computed.
One of three primary objectives of the reported study is related to the definition of the distribution of troilite and Fe and the evaluation of the role of FeS in subsolidus reduction assemblages. Another objective was concerned with the definition of the lower limit of stabilizing elements such as Mg, Al, and Cr in ulvospinel to determine the terminal compositions at which reduction is inhibited. The third objective involves a comparison of the mineral chemistries of decomposed olivine with unaltered olivine in an attempt to determine the temperature limits. The sample was selected because it is one of the most intensely reduced samples returned from the moon. The model invoked for reduction is a magmatic-deuteric process which requires an environment approximating that of a closed system in which the volatile constituents are contained and in which reduction proceeds continuously with crystallization.
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Reflection-absorption infrared and inelastic electron tunneling spectroscopies have been used to study adsorption of liquid phase mono-, di-, and trialkoxysilanes on evaporated Al and Cu substrates. Spectral evidence shows that substrate properties influence the chemical and physical nature of trialkoxysilane films and that silane functionality plays a role in molecular orientation. Results show that dialkoxysilane films contain structural gradients, with adsorption at the monomolecular level influenced by surface morphology, and with organofunctionality and dosing procedure affecting the formation of thicker films. Evidence is presented that monoalkoxysilanes react with alumina surfaces, and a broad, multipeaked band from 1600 to 1900/cm has been interpreted as characteristic of the silylated AlO(x)Pb interface.
Characterization of the performance of a silver-oxide-based absorbent in terms of its ability to remove both gaseous CO2 and water vapor in an astronaut portable life support systems (PLSS) is discussed. Attention is focused on regeneration of the absorbent from the carbonite state of the oxide state, preconditioning of the absorbent using a humidified gas stream, and absorption breakthrough testing. Based on the results of bench-scale experiments, a test plan is carried out to further characterize the silver-oxide-based absorbent on a larger scale; it calls for examination of the absorbent in both an adiabatic packed bed and a near-isothermal cooled bed configuration. It is demonstrated that the tested absorbent can be utilized in a way that removes substantial amounts of CO2 and water vapor during an 8-hour extravehicular activity mission, and that applying the absorbent to PLSS applications can simplify the ventilation loop.
We report the first fabrication of active semiconductor and high-temperature superconducting devices on the same substrate. Test structures of complementary MOS transistors were fabricated on the same sapphire substrate as test structures of Y1Ba2Cu3O(7-delta) flux-flow transistors, and separately, Y1Ba2Cu3O(7-delta) superconducting quantum interference devices utilizing both biepitaxial and step-edge Josephson junctions. Both semiconductor and superconductor devices were operated at 77 K. The cofabrication of devices using these disparate yet complementary electronic technologies on the same substrate opens the door for the fabrication of true semiconductive/superconductive hybrid integrated circuits capable of exploiting the best features of each of these technologies.
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The potential applications of rare-earth ion doped materials include fiber lasers which can be pumped conveniently by infrared semiconductor laser diodes. The host material systems most widely studied are fluoride crystals and glasses because fluorides have low nonradiative relaxation rates due to their lower phonon energies. However, the mechanical strength, chemical durability and temperature stability of the oxide glasses are generally much better than fluoride glasses. The objective of this research was to investigate the optical and spectroscopic properties of Er(3+)-doped lead-germanate and lead-tellurium-germanate glasses. The maximum vibrational energy of lead-tellurium-germanate glasses are in the range of 740-820/cm, intermediate between those of silicate (1150/cm) and fluoride (530/cm) glasses.
The use of guanidine salts of organic fatty acids (guanidine soaps) as vehicles and binders for coating substrate surfaces is disclosed. Being completely organic, the guanidine soaps can be burned off leaving no undesirable residue. Of special interest is the use of guanidine 2-ethyl hexanoate as the vehicle and binder for coating problematic surfaces such as in coating alumina fibers with platinum or zirconia. For this application the guanidine soap is used as a melt. For other applications the guanidine soap may be used in a solution with a variety of solvents, the solution containing chlorometalates or powdered metals, refractories or ceramics.
NASA Glenn Research Center (GRC) has been developing miniature chemical sensors for a variety of applications including fire detection, emissions monitoring, fuel leak detection, and environmental monitoring. Smart Lick and Stick sensor technology which integrates a sensor array, electronics, telemetry, and power into one microsystem are being developed. These microsystems require low power consumption for long-term aerospace applications. One approach to decreasing power consumption is the use of nanotechnology. Nanocrystalline tin oxide (SnO2) carbon monoxide (CO) sensors developed previously by this group have been successfully used for fire detection and emissions monitoring. This presentation will briefly review the overall NASA GRC chemical sensor program and discuss our further effort in nanotechnology applications. New carbon dioxide (CO2) sensing material using doped nanocrystalline SnO2 will be discussed. Nanocrystalline SnO2 coated solid electrolyte CO2 sensors and SnO2 nanorod and nanofiber hydrogen (H2) sensors operated at reduced or room temperatures will also be discussed.
MnO.sub.2-x thin films (12) exhibit irreversible memory switching (28) with an OFF/ON resistance ratio of at least about 10.sup.3 and the tailorability of ON state (20) resistance. Such films are potentially extremely useful as a connection element in a variety of microelectronic circuits and arrays (24). Such films provide a pre-tailored, finite, non-volatile resistive element at a desired place in an electric circuit, which can be electrically turned OFF (22) or disconnected as desired, by application of an electrical pulse. Microswitch structures (10) constitute the thin film element, contacted by a pair of separate electrodes (16a, 16b) and have a finite, pre-selected ON resistance which is ideally suited, for example, as a programmable binary synaptic connection for electronic implementation of neural network architectures. The MnO.sub.2-x microswitch is non-volatile, patternable, insensitive to ultraviolet light, and adherent to a variety of insulating substrates (14), such as glass and silicon dioxide-coated silicon substrates.
Single-event gate rupture (SEGR) continues to be a key failure mode in power MOSFETs. (1) SEGR is complex, making rate prediction difficult SEGR mechanism has two main components: (1) Oxide damage-- Reduces field required for rupture (2) Epilayer response -- Creates transient high field across the oxide.
No abstract available
The present invention is a nanoparticle mixture or suspension or nanofluid comprising nonmagnetically sensitive nanoparticles, magnetically sensitive nanoparticles, and surfactant(s). The present invention also relates to methods of preparing and using the same.
The present invention is a nanoparticle mixture or suspension or nanofluid comprising nonmagnetically sensitive nanoparticles, magnetically sensitive nanoparticles, and surfactant(s). The present invention also relates to methods of preparing and using the same.
Li-O2 batteries have traditionally used carbon based electrodes (graphite, buckypaper) as the cathode of choice due to its good electrical conductivity, stability against non-aqueous electrolytes like Dimethyl ether (DME) and ease of handling. But, the carbon cathode also leads to formation of carbonate by-products that increase overpotentials during charging leading to degradation of cathode and reduction of cyclability. In this work, we investigate some of the well-known oxides as cathodes with focus on the interface between the oxide surfaces and the discharge product: Li2O2, in the Li-O2 battery using first principles computations. Our results show that attention must be paid on choosing the appropriate surface of the oxides. We extend the analysis to suggest other possible oxide chemistries that should be investigated as cathodes in Li-O2 batteries.