Nanostructuring and its Influence on the Thermoelectric Properties of the AgSbTe2-SnTe Quaternary System

2005 ◽  
Vol 886 ◽  
Author(s):  
Ioannis Androulakis ◽  
R. Pcionek ◽  
E. Quarez ◽  
O. Palchik ◽  
H. Kong ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Quaternary System ◽  
Rest Mass ◽  
Heterogeneous Systems ◽  
High Resolution Electron Microscopy ◽  
Tetragonal Symmetry ◽  
X Ray Diffraction ◽  
Microscopy Imaging ◽  
Resolution Electron ◽  
Power Response

ABSTRACTThe structural and thermoelectric properties of the AgSbTe2-SnTe quaternary system were studied. Powder averaged x-ray diffraction of Ag0.85SnSb1.15Te3 indicates a cubic NaCl-type structure in contrast with the single crystal refinements, which point towards tetragonal symmetry. Furthermore, high-resolution electron microscopy imaging revealed the system to be a nano-composite formed by thermodynamically driven compositional fluctuations rather than a solid solution as it was viewed in the past. The lattice thermal conductivity attains very low values, which is in accord with recent theories on thermal transport in heterogeneous systems. The charge transport properties of the system exhibit a rich physical behavior highlighted in the coexistence of an almost metallic carrier concentration (∼5×1021 cm−3) with a large thermoelectric power response of ∼160 μV/K at 650 K. This is attributed to a heavy hole effective mass that is almost six times that of the electron rest mass.

Transmission electron microscopy observation in a liquid-phase-sintered SiC with oxynitride glass

2001 ◽  
Vol 16 (8) ◽  
pp. 2189-2191 ◽  
Author(s):  
Guo-Dong Zhan ◽  
Mamoru Mitomo ◽  
Young-Wook Kim ◽  
Rong-Jun Xie ◽  
Amiya K Mukherjee
Keyword(s):  
Electron Microscopy ◽  
Liquid Phase ◽  
High Resolution Electron Microscopy ◽  
Nitrogen Atmosphere ◽  
X Ray Diffraction ◽  
Sintering Additive ◽  
Transmission Electron ◽  
High Annealing ◽  
Resolution Electron ◽  
Oxynitride Glass

Using a pure α–SiC starting powder and an oxynitride glass composition from the Y–Mg–Si–Al–O–N system as a sintering additive, a powder mixture was hot-pressed at 1850 °C for 1 h under a pressure of 20 MPa and further annealed at 2000 °C for 4 h in a nitrogen atmosphere of 0.1 MPa. High-resolution electron microscopy and x-ray diffraction studies confirmed that a small amount of β–SiC was observed in the liquid-phase-sintered α–SiC with this oxynitride glass, indicating stability of β–SiC even at high annealing temperature, due to the nitrogen-containing liquid phase.

HIGH RESOLUTION ELECTRON MICROSCOPY OF THE HIGH Tc SUPERCONDUCTOR Bi2Sr2CaCu2O8+δ

1988 ◽  
Vol 02 (06) ◽  
pp. 835-839 ◽  
Author(s):  
M. HERVIEU ◽  
B. DOMENGES ◽  
C. MICHEL ◽  
B. RAVEAU
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction Study ◽  
High Resolution Electron Microscopy ◽  
Basic Structure ◽  
Tetragonal Symmetry ◽  
High Tc ◽  
Resolution Electron ◽  
High Resolution Images ◽  
New Superconductor

The new superconductor Bi 2 Sr 2 CaCu 2 O 8+δ with T c ranging from 80 to 105K, was studied by electron microscopy. The electron diffraction study shows a pseudo-tetragonal symmetry with a≈b≈5.4 Å and c≈30.7 Å and satellites along a, which settle in an incommensurate way. The high resolution images agree with the proposed basic structure. The stacking of the ( BiO y)2 and [ Sr 2 CaCu 2 O 6] layers is quite regular, with only some defects corresponding to c≈24 Å. The lamellar character of the oxide results in splitting and bending of the crystals.

Crystal Structure of and Defects in the Pentacene Thin Film Phase

2002 ◽  
Vol 734 ◽  
Author(s):  
Lawrence F. Drummy ◽  
Paul K. Miska ◽  
David C. Martin
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Low Voltage ◽  
Field Effect Transistors ◽  
High Resolution Electron Microscopy ◽  
Orthorhombic Symmetry ◽  
Extended Defects ◽  
X Ray Diffraction ◽  
Voltage Electron ◽  
Resolution Electron

The aromatic hydrocarbon pentacene is currently under investigation for use as the active layer in electronic devices such as thin film field effect transistors. We have used X-Ray Diffraction (XRD), Electron Diffraction (ED), Low Voltage Electron Microscopy (LVEM), High Resolution Electron Microscopy (HREM) and molecular modeling to investigate the thin film phase of pentacene. We will report the orthorhombic symmetry and lattice parameters of the thin film phase measured experimentally from these techniques. The structure of extended defects such as dislocations and grain boundaries will influence the electrical and mechanical characteristics of the films. Here we show a direct image of an edge dislocation in the thin film phase and discuss the way in which the lattice accommodates the defect.

A swelling hematite/layer-silicate complex in weathered granite

Clay Minerals ◽  
1981 ◽  
Vol 16 (3) ◽  
pp. 261-278 ◽  
Author(s):  
M. J. Wilson ◽  
J. D. Russell ◽  
J. M. Tait ◽  
D. R. Clark ◽  
A. R. Fraser ◽  
...  
Keyword(s):  
High Resolution Electron Microscopy ◽  
Basal Spacing ◽  
Layer Silicate ◽  
X Ray Diffraction ◽  
Geological Time ◽  
Weathered Granite ◽  
North East ◽  
Selected Area Electron Diffraction ◽  
Resolution Electron ◽  
Silicate Complex

AbstractA naturally occurring hematitic iron oxide/layer-silicate complex has been found in red mottled patches of a deeply weathered granite in north-east Scotland. X-ray diffraction shows a basal spacing of 36 Å—also observable by high resolution electron microscopy—which expands to 40 Å with glycerol and contracts to 33·5 Å on heating. Selected area electron diffraction reveals a composite hematite/layer-silicate pattern with the a-axis of hematite parallel to the b-axis of the silicate. The IR spectrum of the complex clearly shows the contribution made by each of the components. The silicate, with bands due to OH stretching at 3602 cm−1, OH deformation at 855 cm−1, and Si-O stretching at 1085, 1035, 540 and 471 cm−1 resembles ferruginous pyrophyllite, while the hematite, with a perpendicular band at 647 cm−1, in-plane bands at 519, 438, 400, 302 and 227 cm−1 and a characteristic pattern of relative band intensities, is similar to a platy form of soil hematite. Electron microprobe analysis of individual particles gives the complex an (Fe + Al): Si ratio of 6:1, which is consistent with a structure made up of twelve octahedral sheets terminated on both sides by a silicate sheet. It seems likely that the complex developed from a siliceous ferrihydrite which became progressively more organized with geological time.

Kinetic Study on the Formation of the Aragonite-Like Phase Ba(CuOx)1-Y(CO3)y

1995 ◽  
Vol 398 ◽  
Author(s):  
A. Tomasi ◽  
E. Galvanetto ◽  
F.C. Matacotta ◽  
P. Nozar ◽  
P. Scardi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
High Resolution Electron Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Analysis Techniques ◽  
Formation Kinetics ◽  
Resolution Electron ◽  
Thermal Analysis Techniques ◽  
Kinetics Of

ABSTRACTA systematic study on phase formation and stabilisation in the Ba-Cu-C-O system in the temperature range 20-500°C, under various atmospheres, by traditional thermal analysis techniques, high temperature X-ray diffraction and high resolution electron microscopy, has permitted to identify and characterise the formation kinetics of a new copper containing phase isomorphic to γ-BaCO3.

Epitaxial Growth and Structure of Cubic and Pseudocubic Perovskite Films on Perovskite Substrates

1995 ◽  
Vol 401 ◽  
Author(s):  
P. A. Langjahr ◽  
T. Wagner ◽  
M. RÜhle ◽  
F. F. Lange
Keyword(s):  
Electron Microscopy ◽  
Epitaxial Growth ◽  
Lattice Mismatch ◽  
High Resolution Electron Microscopy ◽  
Lattice Parameter ◽  
Ternary Oxide ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Resolution Electron

AbstractCubic and pseudocubic perovskite films on perovskite substrates are used to study the influence of the lattice mismatch on the epitaxial growth of thin films on substrates of the same structure. For the growth of the films, a metalorganic decomposition route (MOD) using 2-ethylhexanoates and neodecanoates as precursors, was developed. The decomposition of the precursors was investigated with thermogravimetric analysis (TGA) and x-ray diffraction (XRD). The films were spin-coated on (001)-oriented SrTiO3- and LaAlO3-substrates, pyrolyzed and afterwards annealed between 600°C and 1200°C. XRD-nvestigations and conventional transmission electron microscopy (CTEM) show, that epitaxial films with the orientation relationship [100](001) film ║ [100](001) substrate can be grown. With XRD, it could be shown, that not only ternary oxide films (SrZrO3, BaZrO3 and BaCeO3), but also perovskite solid solution films (SrTi0.5Zr0.5O3and BaCe0.5Zr0.5O3) can be prepared. Strong interdiffusion, detected by a shift of the film lattice parameter towards the substrate lattice parameter was found in SrZrO3- and BaZrO3-films on SrTiO3, annealed at temperatures above 1050°C. High resolution electron microscopy (HREM) studies of SrZrO3 on SrTiO3 show that a crystalline semicoherent interface with a periodical array of misfit dislocations is present.

A structural model for charoite

2009 ◽  
Vol 73 (5) ◽  
pp. 883-890 ◽  
Author(s):  
I. V. Rozhdestvenskaya ◽  
T. Kogure ◽  
E. Abe ◽  
V. A. Drits
Keyword(s):  
Structural Model ◽  
High Resolution Electron Microscopy ◽  
Tubular Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Resolution Electron ◽  
Xrd Patterns ◽  
Silicon Oxygen ◽  
Monoclinic Cell

AbstractThe crystal structure of charoite was investigated mainly by using selected-area electron diffraction (SAED), X-ray diffraction (XRD) and high-resolution electron microscopy (HREM). SAED and XRD patterns indicate that the structure has a monoclinic cell: a = 32.296, b = 19.651, c = 7.16 Å, β = 96.3° and V = 4517 Å3. The space group inferred from systematic absences and HREM images is P21/m. A model of the charoite structure is proposed that is based on the features of related Ca-alkaline silicate structures and HREM images. The structure of charoite consists of three different silicon-oxygen radicals (polymerized SiO4 tetrahedra) which are located between Ca polyhedra. Two of these radicals form continuous tubular structures comprising pectolite-like tetrahedral chains. Calcium polyhedra are joined to form blocks, each of which consists of four columns sharing edges and apices. Potassium and H2O molecules are probably located inside the tubular silicate radicals. From these results, a general formula is derived: K6-7(Ca,Na)18[(Si6O17)(Si12O30)(Si18O45)](OH,F)2.nH2O with two formula units in the unit cell (Z = 2).

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