Nanocrystalline Solid Solutions of Cu/Co and Other Novel Nanomaterials

1996 ◽  
Vol 457 ◽  
Author(s):  
A. S. Edelstein ◽  
V. G. Harris ◽  
D. Rolison ◽  
J. H. Perepezko ◽  
D. Smith
Keyword(s):  
Heat Treatment ◽  
Lattice Constant ◽  
Solid Solutions ◽  
Nearest Neighbor ◽  
Neighbor Distance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vegard’S Law ◽  
Minimum Heat ◽  
Special Case

ABSTRACTA brief review will be given of the preparation, synthesis and properties of the Cu/Co system. The special case of the synthesis of nanocrystalline Cu.80Co.20 by precipitation and reduction of hydroxides is discussed in more detail. It was found that the lattice constant of nanocrystalline Cu.80Co.20. determined from x-ray diffraction measurements, approximately fits Vegard's Law and the average nearest neighbor distance from both the Cu and Co atoms, determined from EXAFS measurements, ir shifted from their bulk values. Samples given the minimum heat treatment needed to reduce the hydroxides contained Co-rich regions. Heat treatments cause the Co to segregate preferentially onto the surface of the Cu crystals. The presence of the Co delays the oxidation of the Cu surfaces.

EFFECT OF HEAT TREATMENT ON MICROSTRUCTURE AND MAGNETOSTRICTIVE PROPERTY OF MELT-SPUN Fe85Ga15 RIBBONS

2013 ◽  
Vol 27 (30) ◽  
pp. 1350174 ◽  
Author(s):  
HAO LIU ◽  
HAIOU WANG ◽  
MENGXIONG CAO ◽  
WEISHI TAN ◽  
YANGGUANG SHI ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fine Structure ◽  
High Resolution ◽  
Nearest Neighbor ◽  
Annealed Sample ◽  
X Ray Diffraction ◽  
X Ray ◽  
Absorption Fine ◽  
Melt Spun ◽  
X Ray Absorption

In order to study the microstructure of Fe – Ga alloy, Fe 85 Ga 15 ribbons prepared with different wheel velocity were studied by high resolution X-ray diffraction (HRXRD) and extend X-ray absorption fine structure (EXAFS). HRXRD patterns showed that only disordered A 2 phase was observed in as-cast Fe 85 Ga 15 alloy. A modified- DO 3 phase was detected in all of the melt spun samples. The HRXRD associated with EXAFS results indicated that Ga atoms were located as second-nearest neighbor along [100] orientation. A little DO 3 phase was found in ribbons annealed at 1000°C under 0.06 MPa Ar atmosphere. The result of magnetostriction measurement revealed that in the ribbon prepared with higher wheel velocity, more modified- DO 3 phase will enhance the magnetostriction. DO 3 phase in the annealed sample will deteriorate the magnetostrictive properties of Fe – Ga ribbons.

scholarly journals X-ray Diffraction Analysis of NdCl3 Melt

1990 ◽  
Vol 45 (5) ◽  
pp. 623-626 ◽  
Author(s):  
Kazuo Igarashi ◽  
Mineo Kosaka ◽  
Masahiro Ikeda ◽  
Junichi Mochinaga
Keyword(s):  
Coordination Number ◽  
Short Range ◽  
Nearest Neighbor ◽  
Correlation Method ◽  
Neighbor Distance ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Nearest Neighbor Distance ◽  
Short Range Structure

Abstract The structure of molten NdClj at 800 CC has been investigated by X-ray scattering and the correlation method. The nearest neighbor distance and coordination number of Nd-Cl are 2.77 Ä and 5.5 A, respectively. The Nd-Nd and CI-CI distances are 5.08 and 4.04 Ä, respectively. The average nearest neighbor distance and coordination number decrease markedly on melting, and the resulting short range structure of the melt is approximately octahedral

Observations of coexistence of FCC and HCP phases in C60 by HREM

1992 ◽  
Vol 50 (1) ◽  
pp. 110-111
Author(s):  
Z.G. Li ◽  
Paul J. Fagan
Keyword(s):  
Carbon Atom ◽  
Crystalline Structure ◽  
Diffraction Data ◽  
Large Scale ◽  
Nearest Neighbor ◽  
Neighbor Distance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hexagonal Close Packed ◽  
Correct Structure

Since the discovery of a large scale synthesis of fullerenes there has been intense interest in the structure of these materials. The first diffraction data suggested that crystalline C60 had a hexagonal close-packed (hep) structure with a nearest neighbor distance of 10.04 Å. The possibility of a disordered stacking of C60 molecules was first noted in this study. Since then, there has been some confusion regarding the exact crystalline structure of C60 as determined by electron and X-ray diffraction. In particular, a diffraction feature corresponding to a spacing of 8.7 Å has been noted in several studies. Recendy there had been a growing consensus that fcc is the correct structure for sublimed C60. Although the internal carbon atom arrangement of the C60 molecules cannot be determined, the actual packing and defects in C60 crystals over small and relatively large regions are readily seen by HRTEM. We have found by direct imaging a relatively large region of defect-free hep packing of C60 spheres sublimed onto a relatively cool microscopy grid.

Thermoelectric properties of Tl9BiTe6 / Tl9BiSe6 solid solutions

2000 ◽  
Vol 626 ◽  
Author(s):  
Bernd Wölfing ◽  
Christian Kloc ◽  
Ernst Bucher
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
State Of The Art ◽  
High Resistivity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Vegard’S Law

ABSTRACTThe compounds Tl9BiTe6 (TBT) and Tl9BiSe6 (TBS) crystallize in the tetragonal space group I4/mcm. Tl9BiTe6 has a thermopower of 185 μV/K and an electrical resistivity of 5.5 mΩcm at 300K, resulting in a power factor of S2/ρ = 0.6 mW/mK2. Compared to Bi2Te3 which is the state of the art material at this temperature this is about a factor of 7 lower. At 300 K TBS has a thermopower of 750 μV/K but a high resistivity of 130 Ωcm. To optimize the thermoelectric properties of TBT solid solutions have been formed with TBS. The resistivities and have been measured on Tl9BiTe1-xSex with x = 0.05, 0.08, 0.2 and 0.5. In addition to the electrical properties the lattice constants have been measured by X-ray diffraction. The dependence of the lattice constants on the Te/Se ratio clearly deviates from Vegard's law. Different affinities of Te and Se towards the two chalcogenide sites in the crystal can explain this behavior.

X-Ray Diffraction Analysis of Titanium Carbonitride 30/70 and 70/30 Solid Solutions

1992 ◽  
Vol 7 (1) ◽  
pp. 34-35 ◽  
Author(s):  
J.M. Guilemany ◽  
I. Sanchiz ◽  
X. Alcobé
Keyword(s):  
Diffraction Analysis ◽  
Solid Solutions ◽  
Titanium Carbonitride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Vegard’S Law

AbstractX-ray powder data and refined cell parameters for two titanium carbonitride solid solutions are presented. Some deviations from Vegard's law were observed.

Density and Packing in Uranium Based Metallic Glasses

1985 ◽  
Vol 57 ◽  
Author(s):  
A. J. Drehman
Keyword(s):  
Metallic Glasses ◽  
Excess Volume ◽  
Nearest Neighbor ◽  
Glass Composition ◽  
Neighbor Distance ◽  
Compositional Dependence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Compositional Range ◽  
Nearest Neighbor Distance

AbstractDensity and x-ray diffraction measurements were performed over a wide compositional range of U-Fe and U-Co metallic glass ribbons. The compositional dependence of both the density and the average nearest neighbor distance exhibits a change in slope at approximately 28 at.% transition metal. This suggests an “ideal” glass composition possessing a minimum excess volume. A qualitative model of atomic packing is proposed, which is based on the compositional dependence of the atomic volume and nearest neighbor distance.

Composition Dependent Band Gaps of Single Crystal Cu2ZnSn(SxSe1-x)4 Solid Solutions

2012 ◽  
Vol 194 ◽  
pp. 139-143 ◽  
Author(s):  
Yi Ping Wang ◽  
Sergiu Levcenco ◽  
Dumitru O. Dumcenco ◽  
Ying Sheng Huang ◽  
Ching Hwa Ho ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Chemical Vapor ◽  
Vapor Transport ◽  
Band Gaps ◽  
Chemical Vapor Transport ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vegard’S Law ◽  
Diffraction Patterns ◽  
Transport Technique

Single crystals of Cu2ZnSn(SxSe1-x)4(CZTSSe) solid solutions have deen grown by chemical vapor transport technique using ICl3as a transport agent. Analyzing the X-ray diffraction patterns reveal that the as-grown CZTSSe solid solutions are crystallized in kesterite structure and the lattice parameters are determined. The S contents of the obtained crystals are estimated by Vegard’s law. The composition dependent band gaps of CZTSSe solid solutions are studied by electrolyte electroreflectance (EER) techniques. The band gaps of CZTSSe are evaluated by a lineshape fit of the EER spectra and are found to increase almost linearly with the increase of S content.

Cation distribution and crystal chemistry of Y3Al5−x Ga x O12 (0 ≤ x ≤ 5) garnet solid solutions

1999 ◽  
Vol 55 (3) ◽  
pp. 266-272 ◽  
Author(s):  
Akihiko Nakatsuka ◽  
Akira Yoshiasa ◽  
Takamitsu Yamanaka
Keyword(s):  
Solid Solutions ◽  
Large Deviation ◽  
Repulsive Force ◽  
Compositional Dependence ◽  
X Ray Diffraction ◽  
Flux Method ◽  
X Ray ◽  
Lattice Constants ◽  
Vegard’S Law ◽  
Cation Distributions

Five single crystals of Y3Al5−x Ga x O12 (0 ≤ x ≤ 5) garnet solid solutions with the compositions x = 0.0, 1.0, 2.0, 3.0 and 4.0 were synthesized using a flux method. The compositional dependence of the lattice constants of the garnet solid solutions shows a large deviation from Vegard's law. Investigation of the cation distributions of these garnets using single-crystal X-ray diffraction shows that Ga3+, which is larger than Al3+, preferentially occupies the tetrahedral (four-coordinate) site rather than the octahedral (six-coordinate) site. On the basis of the results obtained from structure refinements, geometric analyses of the polyhedral distortions were carried out. The results imply that the cation–cation repulsive force across the polyhedral shared edges decreases with increasing substitution of Ga3+. Moreover, the proportion of covalent bonding in the cation–oxygen bonds was estimated from the bond strength; the results indicate that the covalency of the Ga—O bond is greater than that of the Al—O bond. The peculiar cation distributions observed in the Y3Al5−x Ga x O12 garnet solid solutions are most probably caused by the strong covalency of the Ga—O bond and also simultaneously induced by the need to decrease the cation–cation repulsive force. Crystal data: cubic, Ia3¯d, Z = 8, Mo Kα, λ = 0.71069 Å; at x = 0.0 (triyttrium pentaaluminium dodecaoxide): a 0 = 12.0062 (5) Å, V = 1730.7 (2) Å3, D x = 4.56 Mg m−3, M r = 593.613, μ = 21.21 mm−1, F(000) = 2224, R = 0.029 for 294 reflections; at x = 1.0 (triyttrium tetraaluminium gallium dodecaoxide): a 0 = 12.0432 (7) Å, V = 1746.7 (3) Å3, D x = 4.84 Mg m−3, M r = 636.351, μ = 24.09 mm−1, F(000) = 2368, R = 0.022 for 124 reflections; at x = 2.0 (triyttrium trialuminium digallium dodecaoxide): a 0 = 12.0926 (9) Å, V = 1768.3 (4) Å3, D x = 5.10 Mg m−3, M r = 679.089, μ = 26.85 mm−1, F(000) = 2512, R = 0.018 for 144 reflections; at x = 3.0 (triyttrium dialuminium trigallium dodecaoxide): a 0 = 12.1552 (6) Å, V = 1795.9 (3) Å3, D x = 5.34 Mg m−3, M r = 721.827, μ = 29.43 mm−1, F(000) = 2656, R = 0.018 for 184 reflections; at x = 4.0 (triyttrium aluminium tetragallium dodecaoxide): a 0 = 12.2123 (8) Å, V = 1821.3 (4) Å3, D x = 5.58 Mg m−3, M r = 764.565, μ = 31.97 mm−1, F(000) = 2800, R = 0.014 for 159 reflections.

scholarly journals X-ray Determination of Compressive Residual Stresses in Spring Steel Generated by High-Speed Water Quenching

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1154
Author(s):  
Diego E. Lozano ◽  
George E. Totten ◽  
Yaneth Bedolla-Gil ◽  
Martha Guerrero-Mata ◽  
Marcel Carpio ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
High Speed ◽  
Spring Steel ◽  
X Ray Diffraction ◽  
Laboratory Equipment ◽  
X Ray ◽  
Water Chamber ◽  
Hardened Case ◽  
Compressive Residual Stresses

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about −700 MPa were obtained.

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