Synthesis of Superconducting Ceramics Hg0.82Re0.18Ba2Ca2Cu3O8+δ with Different Values of δ

2008 ◽  
Vol 591-593 ◽  
pp. 392-396 ◽  
Author(s):  
Luís Gallego Martinez ◽  
J.L. Rossi ◽  
M.T.D. Orlando ◽  
C.A.C. Passos ◽  
Francisco Cristóvão Lourenço de Melo ◽  
...  
Keyword(s):  
High Pressure ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Molar Ratio ◽  
High Tc ◽  
X Ray ◽  
Partial Pressures ◽  
Precursor Material ◽  
Superconducting Ceramics

Samples of the superconducting ceramics Hg0.82Re0.18Ba2Ca2Cu3O8+ were prepared by solid-vapor reaction technique. The preparation of the ceramic precursor started with a mixture of Ba2Ca2Cu3Ox and ReO2 powders with molar ratio 1:0.18. The precursor material was submitted to annealing under three different partial pressures of oxygen using a mixture of oxygen/argon at ratios: 5/95 (sample A), 10/90 (sample B) and 15/85 (sample C). X-ray powder diffraction analysis of the precursors identified the phases BaCuO2+x, Ba2Cu3O5+x, Ba4CaCu3O8+x, Ca2CuO3 and Ca5Re2O12 at different ratios in the samples, indicating an increment in the oxygen content from sample A to sample C. Finally, the precursors with different oxygen contents were blended with HgO at molar ratio 1:0.82 and treated in a sealed high pressure furnace to produce the high Tc superconducting ceramics. Rietveld refinement of XRD data showed differences in the crystal structures of the samples. The measurement of thermopower at room temperature resulted in distinct values, confirming the different oxygen sample doping.

High-resolution X-ray diffraction analysis of magnetically aligned high-Tc superconducting ceramics

1996 ◽  
Vol 265 (3-4) ◽  
pp. 233-242 ◽  
Author(s):  
J. Chrosch ◽  
C. Panagopoulos ◽  
N. Athanassopoulou ◽  
J.R. Cooper ◽  
E.K.H. Salje
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
Superconducting Ceramics ◽  
Magnetically Aligned

scholarly journals Comparative Compressibility of Smectite Group under Anhydrous and Hydrous Environments

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3784
Author(s):  
Yongmoon Lee ◽  
Pyosang Kim ◽  
Hyeonsu Kim ◽  
Donghoon Seoung
Keyword(s):  
High Pressure ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Environmental Changes ◽  
Silicone Oil ◽  
Distilled Water ◽  
X Ray ◽  
Water Conditions ◽  
Before And After ◽  
Cell Volumes

High-pressure synchrotron X-ray powder diffraction studies of smectite group minerals (beidellite, montmorillonite, and nontronite) reveal comparative volumetric changes in the presence of different fluids, as pressure transmitting media (PTM) of silicone oil and distilled water for anhydrous and hydrous environments at room temperature. Using silicone oil PTM, all minerals show gradual contraction of unit-cell volumes and atomistic interplane distances. They, however, show abrupt collapse near 1.0 GPa under distilled water conditions due to hydrostatic to quasi-hydrostatic environmental changes of water PTM around samples concomitant with the transition from liquid to ICE-VI and ICE-VII. The degrees of volume contractions of beidellite, montmorillonite, and nontronite up to ca. 3 GPa are ca. 6.6%, 8.9%, and 7.5% with bulk moduli of ca. 38(1) GPa, 31(2) GPa, and 26(1) GPa under silicone oil pressure, whereas 13(1) GPa, 13(2) GPa, and 17(2) GPa, and 17(1) GPa, 20(1) GPa, and 21(1) GPa under hydrostatic and quasi-hydrostatic environments before and after 1.50 GPa, respectively.

Effects of Oxygen Doping on the Transport Properties of Hg0.82Re0.18Ba2Ca2Cu3O8+d Superconducting Polycrystals

2014 ◽  
Vol 975 ◽  
pp. 95-100
Author(s):  
Carlos Auguto Cardoso Passos ◽  
Jefferson Rodrigues Rocha ◽  
Marcio de Sousa Bolzan
Keyword(s):  
Grain Morphology ◽  
Molar Ratio ◽  
Critical Temperatures ◽  
Sem Images ◽  
X Ray ◽  
Partial Pressures ◽  
Precursor Material ◽  
Gamma Density ◽  
Zero Resistance ◽  
Relationship Of

Hg0.82Re0.18Ba2Ca2Cu3O8+dpolycrystalline ceramic samples were prepared using a solid-vapour reaction technique. First, the ceramic precursor was prepared from a mixture of Ba2Ca2Cu3Oxand ReO2powders in a molar ratio of 1:0.18. The precursor material was annealed under three different partial pressures of oxygen that consisted of a mixture of oxygen/argon in the following ratios: 5/95 (sample A), 10/90 (sample B) and 15/85 (sample C). Secondly, the precursors prepared at different O2partial pressures were blended with HgO at a molar relationship of 1:0.82. The synthesis was carried out at 865 °C for 72 h. Moreover, analyses using X-ray powder diffraction, Scanning Electron Microscopy (SEM), and Energy Dispersion X-ray spectroscopy (EDS) were performed. These results demonstrated a similarity in the grain morphology within the samples. Using SEM images, a histogram of grain-boundary size was produced where the average junction size is represented by a gamma density distribution function. Finally, the samples were submitted to ac electrical resistivity ρ (T) under a low applied magnetic field (up to 400 Oe). Samples cut into bars approximately 7 × 1 × 1 mm3in size were studied using a four-probe technique. The zero-resistance critical temperatures (Tcj) were determined from ρ (T) curves. The results are compared and qualitatively explained in the framework of flux trapping by superconducting grains. In our opinion, the oxygen partial pressure has a strong influence on the grain junctions and causes island structures that form defects at the grain boundaries.

HIGH-Tc SUPERCONDUCTIVITY AND STRUCTURE OF Y-Ba-Cu OXIDES REPLACED PARTIALLY BY La AND Li

1987 ◽  
Vol 01 (02) ◽  
pp. 253-256 ◽  
Author(s):  
Yuhuan Xu ◽  
Zhongrong Li ◽  
Chaorui Li ◽  
Hong Wang ◽  
Wu Li ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Room Temperature ◽  
Sem Analysis ◽  
Main Phase ◽  
Orthorhombic Crystal ◽  
Middle Point ◽  
High Tc ◽  
High Tc Superconductivity ◽  
X Ray ◽  
Crystal Class

The compounds with the composition Ba(Y1−xLax)(Cu1−yLiy)2On have been prepared in ceramic form. It has been discovered that this ceramic (x=0.33, y=0.10) exhibits high- Tc superconductivity with Tc (middle point) of 90K and T R=zero of 82K. By SEM analysis, it was shown that the main phase is some rectangle grains with size of 2−10μm. From X-ray powder diffraction, the structure of main phase, which belongs to orthorhombic crystal class with the lattice parameters of a=3.895Å, b=3.888Å, and c=11.598Å at room temperature, was determinated.

Notizen: Preparation and Crystal Structure of NiHg

1977 ◽  
Vol 32 (4) ◽  
pp. 479 ◽  
Author(s):  
M. Pušelj ◽  
Z. Ban
Keyword(s):  
Crystal Structure ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Single Phase ◽  
Extended Period ◽  
Structure Type ◽  
X Ray

A single phase binary amalgam of the composition NiHg was found to form at room temperature after an extended period of time (approx. 2 years).X-ray powder diffraction analysis enabled us to determine the crystal structure. The compound crystallizes tetragonally with a = 4.22 Å and c = 3.14 Å. It belongs to L 10 crystal structure type.

High-pressure phases in the system W–O. II. Structure determination of WO2.625 by HRTEM and X-ray powder diffraction analysis

1993 ◽  
Vol 49 (2) ◽  
pp. 169-171 ◽  
Author(s):  
Yu. A. Barabanenkov ◽  
N. D. Zakharov ◽  
I. P. Zibrov ◽  
V. P. Filonenko ◽  
P. Werner ◽  
...  
Keyword(s):  
High Pressure ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Structure Determination ◽  
X Ray

scholarly journals Stoichiometric evolutions of PH3 under high pressure: implication for high-Tc superconducting hydrides

2019 ◽  
Vol 6 (3) ◽  
pp. 524-531 ◽  
Author(s):  
Ye Yuan ◽  
Yinwei Li ◽  
Guoyong Fang ◽  
Guangtao Liu ◽  
Cuiying Pei ◽  
...  
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
Recent Observation ◽  
Theoretical Calculations ◽  
Ambient Pressure ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Elemental Phosphorus ◽  
High Tc ◽  
X Ray

Abstract The superconductivity of hydrides under high pressure has attracted a great deal of attention since the recent observation of the superconducting transition at 203 K in strongly compressed H2S. It has been realized that the stoichiometry of hydrides might change under high pressure, which is crucial in understanding the superconducting mechanism. In this study, PH3 was studied to understand its superconducting transition and stoichiometry under high pressure using Raman, IR and X-ray diffraction measurements, as well as theoretical calculations. PH3 is stable below 11.7 GPa and then it starts to dehydrogenate through two dimerization processes at room temperature and pressures up to 25 GPa. Two resulting phosphorus hydrides, P2H4 and P4H6, were verified experimentally and can be recovered to ambient pressure. Under further compression above 35 GPa, the P4H6 directly decomposed into elemental phosphorus. Low temperature can greatly hinder polymerization/decomposition under high pressure and retains P4H6 up to at least 205 GPa. The superconductivity transition temperature of P4H6 is predicted to be 67 K at 200 GPa, which agrees with the reported result, suggesting that it might be responsible for superconductivity at higher pressures. Our results clearly show that P2H4 and P4H6 are the only stable P–H compounds between PH3 and elemental phosphorus, which is helpful for shedding light on the superconducting mechanism.

Synthesis and X-ray powder diffraction analysis of the high-Tc superconductor HgBa2Ca2Cu3O8+δ

1994 ◽  
Vol 92 (7) ◽  
pp. 595-599 ◽  
Author(s):  
H.M. Shao ◽  
K. Zhou ◽  
Y. Rui ◽  
J.C. Shen ◽  
X.N. Xu ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Powder Diffraction ◽  
High Tc ◽  
X Ray ◽  
High Tc Superconductor
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