Evaluation of true interlamellar spacing from microstructural observations

A method for evaluating true interlamellar spacing from micrographs is proposed for a multidomained lamellar structure. The microstructure of these materials is assumed to be composed of many domains with the lamellae aligned roughly parallel to each other within each domain and with the domains themselves randomly oriented relative to one another. An explicit expression for the distribution of apparent interlamellar spacing is derived assuming that the distribution of the true interlamellar spacing is Gaussian. The average interlamellar spacing is close to the peak interlamellar spacing observed in the distribution. The theoretical distributions are compared with experimental ones obtained by analyzing micrographs of PbTe–Sb2Te3 lamellar composites

Interplanetary mission design handbook. Volume 1, part 2: Earth to Mars ballistic mission opportunities, 1990-2005

Graphical data necessary for the preliminary design of ballistic missions to Mars are provided. Contours of launch energy requirements, as well as many other launch and Mars arrival parameters, are presented in launch date/arrival date space for all launch opportunities from 1990 through 2005. In addition, an extensive text is included which explains mission design methods, from launch window development to Mars probe and orbiter arrival design, utilizing the graphical data as well as numerous equations relating various parameters

Combination of large nanostructures and complex band structure for high performance thermoelectric lead telluride

The complexity of the valence band structure in p-type PbTe has been shown to enable a significant enhancement of the average thermoelectric figure of merit (zT) when heavily doped with Na. It has also been shown that when PbTe is nanostructured with large nanometer sized Ag_2Te precipitates there is an enhancement of zT due to phonon scattering at the interfaces. The enhancement in zT resulting from these two mechanisms is of similar magnitude but, in principle, decoupled from one another. This work experimentally demonstrates a successful combination of the complexity in the valence band structure with the addition of nanostructuring to create a high performance thermoelectric material. These effects lead to a high zT over a wide temperature range with peak zT > 1.5 at T > 650 K in Na-doped PbTe/Ag_2Te. This high average zT produces 30% higher efficiency (300–750 K) than pure Na-doped PbTe because of the nanostructures, while the complex valence band structure leads to twice the efficiency as the related n-type La-doped PbTe/Ag_2Te without such band structure complexity

Planetary geometry handbook: Venus positional data, 1988 - 2020, volume 2

Graphical data necessary for the analysis of planetary exploration missions to Venus are presented. Positional and geometric information spanning the time period from 1988 through 2020 is provided. The data and the usage are explained

Planetary geometry handbook: Mars positional data, 1990 - 2020, volume 3

Graphical data necessary for the analysis of planetary exploration missions to Mars are presented. Positional and geometric information spanning the time period from 1990 through 2020 is provided. The data and usage are explained

Planetary geometry handbook: Saturn positional data, 1985 - 2020, volume 5

Graphical data necessary for the analysis of planetary exploration missions to Saturn are presented. Positional and geometric information spanning the time period from 1985 through 2020 is provided. The data and their usage are explained

Planetary geometry handbook: Jupiter positional data, 1985 - 2020, volume 4

Graphical data necessary for the analysis of planetary exploration missions to Jupiter are presented. Positional and geometric information spanning the time period from 1985 through 2020 is provided. The data and their usage are explained

Hybrid carcinoma of the salivary gland: salivary duct adenocarcinoma adenoid cystic carcinoma

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73933/1/j.1365-2559.1999.00761.x.pd

High-Temperature Transport Properties of the Zintl Phases Yb_(11)GaSb_9 and Yb_(11)InSb_9

Two rare-earth Zintl phases, Yb_(11)GaSb_9 and Yb_(11)InSb_9, were synthesized in high-temperature self-fluxes of molten Ga and In, respectively. Structures were characterized by both single-crystal X-ray diffraction and powder X-ray diffraction and are consistent with the published orthorhombic structure, with the space group Iba2. High-temperature differential scanning calorimetry (DSC) and thermal gravimetry (TG) measurements reveal thermal stability to 1300 K. Seebeck coefficient and resistivity measurements to 1000 K are consistent with the hypothesis that Yb_(11)GaSb_9 and Yb_(11)InSb_9 are small band gap semiconductors or semimetals. Low doping levels lead to bipolar conduction at high temperature, preventing a detailed analysis of the transport properties. Thermal diffusivity measurements yield particularly low lattice thermal conductivity values, less than 0.6 W/m K for both compounds. The low lattice thermal conductivity suggests that Yb_(11)MSb_9 (M = Ga, In) has the potential for high thermoelectric efficiency at high temperature if charge-carrier doping can be controlled

Lattice thermal conductivity of self-assembled PbTe-Sb_2Te_3 composites with nanometer lamellae

In the system of PbTe and Sb_2Te_3, a metastable compound Pb_2Sb_6Te_(11) appears by solidification processing. It has been reported that this compound is decomposed into the two immiscible thermoelectric materials forming nanosized lamellar structure by heat treatments. The fraction transformed and the inter-lamellar spacing was systematically investigated. In this work, the thermal conductivities and the electrical resistivities have been measured as functions of annealing time through the transformation and the coarsening processes to clarify the effect of the fraction transformed and the inter-lamellar spacing. The thermal conductivity of Pb_2Sb_6Te_(11) is lower than that after the decomposition. The lattice part of the thermal conductivity of PbTe/Sb_2Te_3 lamellar samples decreases with decreasing inter-lamellar spacing. This is considered to be due to the coarsening of the microstructure