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NASA NTRS2016

Filled Nd(z)Fe(x)Co(4-x)Sb(12-y)Ge(y) Skutterudites: Processing and Thermoelectric Properties

Skutterudites have proven to be a useful thermoelectric system as a result of their enhanced figure of merit (ZT1), cheap material cost, favorable mechanical properties, and good thermal stability. The majority of skutterudite interest in recent years has been focused on binary skutterudites like CoSb3. Binary skutterudites are often double and triple filled, with a range of elements from the lanthanide series, in order to reduce the lattice component of thermal conductivity. Ternary and quaternary skutterudites, such as Co4Ge6Se6 or Ni4Sb8Sn4, provide additional paths to tune the electronic structure. The thermal conductivity can further be improved in these complex skutterudites by the introduction of fillers. The Nd(z)Fe(x)Co(4-x)Sb(12-y)Ge(y) system has been investigated as a p-type thermoelectric material, and is stable up to 600 C. The influence of Fe and Ge content, along with filler Nd, was investigated on thermoelectric transport properties. In addition to the chemical influence on properties, some processing details of the system will also be addressed.

Thermoelectric↗

NASA NTRS1999

Modified Stranski-Krastanow Mode for Ge Island Growth on (001) Si at High Temperature

Transmission electron microscopy is used to study the morphology and the composition profile of pure Ge islands grown at high temperature on (001) Si by molecular beam epitaxy.

transmission electron microscopy growth modes Ge i↗

NASA NTRS2018

Optical Characterization of Fuel Injection in a Flame Tube Combustor Using a GE TAPS Injector Configuration

This paper presents results in which we compare fuel staging and its effect on fuel spray pattern, velocity and speciation during combustion for several inlet conditions using a GE TAPS injector configuration. Planar laser-induced fluorescence (PLIF), particle image velocimetry (PIV) and phase Doppler interferometry (PDI) were used to investigate spray patterns and velocity. The 2D PIV provides slices in the flow of axial-vertical or axial horizontal velocity components. With 3D PDI, we obtained 3 components of velocity, and fuel drop sizes. Chemiluminescence imaging and spontaneous Raman scattering (SRS) were used to investigate flame structure, species location and relative species concentration. Phase Doppler and PIV data were acquired using scatter from fuel droplets; therefore, those data were obtained only at the pilot-only test points. Raman measurements were acquired only at 10/90 split points to avoid droplets.

optical diagnostics↗

NASA NTRS1967

Concentrations of Ni, Ga, and Ge in a series of Canyon Diablo and Odessa meteorite specimens.

Concentration of Ni, Ga and Ge in series of Odessa and Canyon Diablo meteorite specimens

NICKEL↗

NASA NTRS1968

Gunn-type oscillations in Ge, GaAs, and other materials.

Gunn type oscillations in Ge, GaAs and other materials related to sample parameters, including DC electric field and drift velocity

Holmstrom, R.↗

NASA NTRS1968

Piezo-electroreflectance in Ge, GaAs, and Si.

Piezoelectroreflectance in Ge, Si and GaAs studied for uniaxial stress effects on electronic energy bands

Cardona, M.↗

NASA NTRS1968

On the efficiency of segmented Si-Ge-PbTe thermocouples.

Si-Ge/cold/-Pb-Te/hot/ segmented thermocouples joined by bonding to tungsten intermediate, determining efficiency by measuring heat flux from cold side

Bates, H. E.↗

NASA NTRS1969

Ge-diode detector combined with crystal-diffraction spectrometer permits high-resolution gamma ray spectroscopy

Crystal-diffraction spectrometer, combined with a lithium-drifted Ge-diode detector, performs high-resolution gamma ray spectroscopy on the complicated neutron-capture gamma ray spectra. The system is most useful in the 1-3 MeV energy range and improves the signal to background ratio.

Namenson, A. I.↗

NASA NTRS1968

Study of semiconductor heterojunctions of ZnSe, GaAs and Ge Semiannual progress report, period ending 30 Sep. 1968

Gain, frequency and temperature dependence in heterojunction transistors of GaAs, ZnSe, and Ge

Feucht, D. L.↗

NASA NTRS1969

Shock histories of hexahedrites and Ga-Ge group III octahedrites.

Shock histories of hexahedrites and Ga-Ge group III octahedrites based on metallographic and X ray diffraction analysis, noting meteorites shocked preterrestrially

Jain, A. V.↗

NASA NTRS1970

Study of semiconductor heterojunctions of ZnSe, GaAs and Ge, 1 May - 31 July 1970

Fabrication problems and device characteristics of ZnSe-GaAs and Ge-GaAs heterojunctions

Feucht, D. L.↗

NASA NTRS1970

Autodoping effects at the interface of GaAs-Ge heterojunctions

Epitaxial surface morphology layer electrical properties and autodoping at GaAs-Ge heterojunctions as function of substrate temperature, orientation and HCl concentration

Feucht, D. L.↗

NASA NTRS1970

One-electron and phonon-assisted tunneling in n-Ge Schottky barriers

Metal-Ge n-type semiconductor tunnel junctions, discussing Sb and As doped units and conductance and barrier heights air cleavage effects

Davis, L. C.↗

NASA NTRS1970

Ga, Ge, In, Ir and Au in lunar, terrestrial and meteoritic basalts

Apollo 11 lunar, terrestrial and meteoritic basalts relationships, examining Ga, Ge, In, Ir and Au concentrations by neutron activation analyses

Baedecker, P. A.↗

NASA NTRS1970

Ni, Ga, Ge and Ir in the metal of iron- meteorites-with-silicate-inclusions

Neutron activation determined concentrations of Ni, Ga, Ge and Ir in iron meteorites with silicate inclusions

Wasson, J. T.↗

NASA NTRS1971

Thermodynamic properties of Mg-Ge alloys

Mg-Ge alloys liquid and two phase mixtures thermodynamic properties at 660-1130 C, using galvanic cell with magnesium chloride electrolyte

Belton, G. R.↗

NASA NTRS1972

Ge(Li) data reduction using small computers

The advantages and limitations of using a small computer to analyze Ge(Li) radiation spectra are studied. The computer has to: (1) find the spectrum peaks, (2) determine the count rate in the photopeaks, and (3) relate the count rate to known gamma transitions to find the amount of each radionuclide present. Results show that tasks one and two may be done by the computer but task three must be done by an experimenter or a larger computer.

Mcdermott, W. E.↗

NASA NTRS1972

Some gamma-ray shielding measurements made at altitudes greater than 115000 feet using large Ge(Li) detectors

A series of balloon-flight experiments at altitudes greater than 115,000 feet were conducted to gain information relative to the use of composite shields (passive and/or active) for shielding large-volume, lithium-drifted, germanium (Ge(Li)) detectors used in gamma-ray spectrometers. Data showing the pulse-height spectra of the environmental gamma radiation as measured at 5.3 and 3.8 gms sq cm residual atmosphere with an unshielded diode detector are also presented.

Chapman, G. T.↗