FIXED TRIANGLE IN Bi2-XPbXSr2CaCu2O8+Y AND Bi2-XPbXSr2Ca2Cu3O10+Y SYSTEMS

2013 ◽  
Vol 27 (15) ◽  
pp. 1362015 ◽  
Author(s):  
C. Q. GUO ◽  
C. Y. ZHANG ◽  
S. J. HAO ◽  
W. T. JIN ◽  
H. ZHANG
Keyword(s):  
High Temperature ◽  
Rietveld Refinement ◽  
Chemical Bond ◽  
Rock Salt ◽  
Local Structure ◽  
High Temperature Superconductivity ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Close Relationship

The structural characteristics of Bi 2-x Pb x Sr 2 CaCu 2 O 8+y( Bi -2212) and Bi 2-x Pb x Sr 2 Ca 2 Cu 3 O 10+y( Bi -2223) with x changing from 0 to 0.8 were studied by X-ray diffraction and Rietveld refinement. By careful calculation of chemical bond lengths and angles, it is found that there exists a fixed triangle on the Cu–O planes in the two systems, and then makes the Cu–O planes stable. The fluctuations of this fixed triangle were investigated, and it is found that there is a close relationship between it and Tc's. In addition, we discussed the origin of this special local structure. It may be caused by the interaction between the perovskite block and the rock salt block in a unit cell, which may play an important role in the mechanism of high temperature superconductivity.

The high-pressure cadmium borate Cd6B22O39·H2O

2015 ◽  
Vol 70 (3) ◽  
pp. 183-190 ◽  
Author(s):  
Gerhard Sohr ◽  
Nina Ciaghi ◽  
Klaus Wurst ◽  
Hubert Huppertz
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Cell Dimensions ◽  
Temperature Experiment ◽  
Unit Cell Dimensions ◽  
Ir And Raman

AbstractSingle crystals of the hydrous cadmium borate Cd6B22O39·H2O were obtained through a high-pressure/high-temperature experiment at 4.7 GPa and 1000 °C using a Walker-type multianvil apparatus. CdO and partially hydrolyzed B2O3 were used as starting materials. A single crystal X-ray diffraction study has revealed that the structure of Cd6B22O39·H2O is similar to that of the type M6B22O39·H2O (M=Fe, Co). Layers of corner-sharing BO4 groups are interconnected by BO3 groups to form channels containing the metal cations, which are six- and eight-fold coordinated by oxygen atoms. The compound crystallizes in the space group Pnma (no. 62) [R1=0.0379, wR2=0.0552 (all data)] with the unit cell dimensions a=1837.79(5), b=777.92(2), c=819.08(3) pm, and V=1171.00(6) Å3. The IR and Raman spectra reflect the structural characteristics of Cd6B22O39·H2O.

Elucidating the structure, redox properties and active entities of high-temperature thermal aged CuOx-CeO2 catalysts for CO-PROX

2021 ◽  
Author(s):  
Zhihuan Qiu ◽  
Xiaolin Guo ◽  
Jianxin Mao ◽  
Renxian Zhou
Keyword(s):  
High Temperature ◽  
Rietveld Refinement ◽  
Copper Content ◽  
Redox Properties ◽  
Coprecipitation Method ◽  
Desorption Isotherm ◽  
X Ray Diffraction ◽  
N2 Adsorption ◽  
X Ray ◽  
Adsorption Desorption

CuOx-CeO2 catalysts with different copper content are synthesized via a coprecipitation method and thermal treated at 700 oC. Various characterization techniques including X-ray diffraction (XRD) Rietveld refinement, N2 adsorption-desorption isotherm,...

Synthesis, Thermal and X-Ray Investigations of the High-Temperature Phase of Copper(I) Cyanide

2003 ◽  
Vol 58 (1) ◽  
pp. 155-158 ◽  
Author(s):  
Olaf Reckeweg ◽  
Cora Lind ◽  
Arndt Simon ◽  
J. Salvo
Keyword(s):  
High Temperature ◽  
Ir Spectroscopy ◽  
Chemical Analysis ◽  
Rietveld Refinement ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray

Abstract CuCN was investigated by chemical analysis, IR spectroscopy and powder X-ray diffraction. A high-temperature phase of CuCN was identified and structurally characterized by Rietveld refinement. HT-CuCN is isotypic to AgCN (R3m (No. 166), Z = 3, a = 597.109(8), c = 484.33(5) pm, Cu (3a), C/N (6c), z = 0.3915(10) at 77 K) with head-tail disorder of the cyanide anions.

Single Crystals: What They Tell About High Temperature Superconductivity

MRS Bulletin ◽  
1991 ◽  
Vol 16 (5) ◽  
pp. 31-35 ◽  
Author(s):  
Merwyn B. Brodsky
Keyword(s):  
New York ◽  
High Temperature ◽  
Single Crystal ◽  
Single Crystals ◽  
High Temperature Superconductivity ◽  
Scattering Length ◽  
X Ray Diffraction ◽  
Society Meeting ◽  
X Ray ◽  
American Physical

From the beginning of the activity in high temperature superconductivity (near the end of 1986), there were efforts to grow single crystals of the compounds. The push for single crystals arose because earlier work on Chevrelphase superconductors (e.g., PbMo6S8) or re-entrant superconductors (ErRh4B4) showed that the properties of complex superconductors were easily masked by impurities, grain boundaries, imperfectly averaged properties, etc.As early as the so-called “Woodstock of Physics” (the American Physical Society Meeting in New York, March 1987), a single-crystal, x-ray diffraction structure was given for YBa2Cu3O7-x (YBCO-123, with Tc = 93 K), the composition of which had been announced only three weeks earlier. The sample qualified as a single crystal because a single grain had been separated out for the x-ray study, although it was too small for any other measurements.But, single crystal studies are not infallible, and may not always be the best route. For instance, the aforementioned x-ray work on YBCO gave the wrong structure because the x-ray scattering length from oxygen atoms is too small to yield enough scattering intensity to locate them. It remained for neutron-scattering work with large powdered samples to give the correct orthorhombic structure, having Cu-O chains and warped Cu-O planes (see Figure 1).

Direct Determination of the Local Structure in Molten Alumina by High Temperature X-Ray Diffraction

1995 ◽  
Vol 50 (8) ◽  
pp. 770-774 ◽  
Author(s):  
Y. Waseda ◽  
K. Sugiyama ◽  
J. M. Toguri
Keyword(s):  
High Temperature ◽  
Diffraction Study ◽  
Local Structure ◽  
Direct Determination ◽  
X Ray Diffraction ◽  
Interference Function ◽  
X Ray ◽  
Local Ordering

Abstract A high temperature X-ray diffraction study of molten alumina has been carried out at 2363 K (2090°C). The local ordering parameters in molten alumina were estimated by using the interference function refining technique. Octahedrally coordinated aluminum is suggested to remain in the melt as the fundamental local structure.

A44_ Effect of Nano-Sized ZnO on Electrical & Structural Properties of High Temperature Tl2-x HgxBa2Ca2Cu3O10-δ Superconductors

2014 ◽  
Vol 925 ◽  
pp. 436-441
Author(s):  
Sabah Jalal Fathi
Keyword(s):  
Electrical Resistivity ◽  
High Temperature ◽  
Critical Temperature ◽  
Structural Properties ◽  
High Temperature Superconductivity ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Nano Zno ◽  
X Ray ◽  
Tetragonal Type

The electrical resistivity of high temperature superconductivity Tl2-xHgxBa2Ca2Cu3O10-δhas been measured in the temperature range from 90K to 330K. These results showed that the critical temperature of the zero resistivity increases from 127K to 138K ,when the Hg concentration increased from 0 to 0.5. The structure of the Tl2-xHgxBa2Ca2Cu3O10-δcompound has also investigated by using X- ray diffraction technique. This compound has tetragonal type structure with a=b=5.36A & c=36.09A and the magnitude of c-axis increases to 37.8A when x increased to 0.5. Nano ZnO was add to the sample with concentration (0-1) wt% of the ( Tl2-xHgxBa2Ca2Cu3O10-δ) samples mass. The effect of the nano ZnO concentration substitution on the samples investigated on structure and critical temperature of the best sample properties (when x=0.5)and showed that the structure remains tetragonal and c-axis increased to 39.2A when nano sized concentration 0.8% and Tcincrease to 146K but c-axis decreased to 38.4A and Tcdecreased to 143K when the ZnO concentration 1%.

The Local Ordering of Molten LiNbO3 by X-ray Diffraction

1990 ◽  
Vol 45 (11-12) ◽  
pp. 1325-1327 ◽  
Author(s):  
K. Sugiyama ◽  
K. Nomura ◽  
Y. Waseda ◽  
P. Andonov ◽  
S. Kimura ◽  
...  
Keyword(s):  
High Temperature ◽  
Local Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Local Ordering

Abstract The structure of molten LiNbO3 has been studied in the range 1550-1600 K by high temperature X-ray diffraction. Octahedrally coordinated niobium is suggested to exist in the melt as a fundamental local structure.

A NEW HIGH-Tc SUPERCONDUCTOR YBa2Ca2Cu3Ox

1989 ◽  
Vol 03 (16) ◽  
pp. 1233-1236
Author(s):  
A. SHIMA ◽  
T. SHOJI ◽  
M. UKAKU ◽  
Y. WATANABE ◽  
Y. TAZAWA ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
High Temperature Superconductivity ◽  
Liquid Nitrogen Temperature ◽  
X Ray Diffraction ◽  
Oxide Compound ◽  
High Tc ◽  
X Ray ◽  
High Tc Superconductor ◽  
New Superconductor

We report that the high temperature superconductivity observed in a new ceramic Y–Ba–Ca–Cu oxide compound which exhibited the onset of superconductivity clearly at above 90 K and became completely superconductive at liquid nitrogen temperature (77 K). Powder X-ray diffraction analysis showed that the crystal structure of this new superconductor had the same one as a YBa 2 Cu 3 O x.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

X-ray microprobe for materials science

1994 ◽  
Vol 52 ◽  
pp. 56-57
Author(s):  
G.E. Ice
Keyword(s):  
Crystallographic Orientation ◽  
Local Structure ◽  
Materials Science ◽  
Chemical Information ◽  
X Ray Diffraction ◽  
Ray Optics ◽  
X Ray ◽  
Novel Materials ◽  
New Information ◽  
Elemental Sensitivity

The increasing availability of synchrotron x-ray sources has stimulated the development of advanced hard x-ray (E≥5 keV) microprobes. With new x-ray optics these microprobes can achieve micron and submicron spatial resolutions. The inherent elemental and crystallographic sensitivity of an x-ray microprobe and its inherently nondestructive and penetrating nature will have important applications to materials science. For example, x-ray fluorescent microanalysis of materials can reveal elemental distributions with greater sensitivity than alternative nondestructive probes. In materials, segregation and nonuniform distributions are the rule rather than the exception. Common interfaces to whichsegregation occurs are surfaces, grain and precipitate boundaries, dislocations, and surfaces formed by defects such as vacancy and interstitial configurations. In addition to chemical information, an x-ray diffraction microprobe can reveal the local structure of a material by detecting its phase, crystallographic orientation and strain.Demonstration experiments have already exploited the penetrating nature of an x-ray microprobe and its inherent elemental sensitivity to provide new information about elemental distributions in novel materials.

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