Effect of Oxygen Partial Pressure on Stability of High-Tc Phase in Sintered Bi-Pb-Sr-Ca-Cu-O Superconductos

1989 ◽  
Vol 169 ◽  
Author(s):  
H.K. Lee ◽  
K.W. Lee ◽  
D.H. Ha ◽  
J.C. Park
Keyword(s):  
Phase Transformation ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Superconducting Phase ◽  
Low Oxygen ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
High Tc Phase ◽  
Effect Of Oxygen

AbstractThe effect of oxygen partial pressure on stability of high-Tc phase in Bi-Pb-Sr-Ca-Cu-O system has been investigated using x-ray diffraction, resistivity and a.c. susceptibility measurements. It was found that part of the high-Tc phase in Bi-Pb-Sr-Ca-Cu-O system was transformed into the low-Tc phase (80 K) and insulating phases by heating in the temperature range 600 C to 880°C in O2 of one atmosphere. The original high-Tc phase was restored upon retreatment in a low oxygen partial pressure of 0.1 atmosphere. The reversible superconducting phase transformation is discussed in conjunction with the formation mechanism of the high-Tc phase in Bi-Pb-Sr-Ca-Cu-O system.

Synthesis and Properties of the High Tc Bi-Pb-Sr-Ca-Cu-O Superconductors

1989 ◽  
Vol 156 ◽  
Author(s):  
Utako Endo ◽  
J. Koyama ◽  
T. Kawai ◽  
N. Okazaki ◽  
K. Kitazawa ◽  
...  
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Hole Concentration ◽  
Composition Analysis ◽  
Low Oxygen ◽  
High Tc ◽  
Atomic Site ◽  
High Tc Phase

ABSTRACTA single high Tc phase of Bi-Pb-Sr-Ca-Cu-O superconductor was obtained by following proper synthetic conditions:(a)addition of Pb, (b)proper starting composition, (c)codecomposition method, (d)sintering under low oxygen partial pressure and (e)long sintering. The composition analysis showed that every atomic site might be occupied by some element and there might not be defects or excess atoms in the structure. The hole donor in these samples is considered to be Pb on the Bi site and hole concentration seems to be, to some extent, controlled by the Pb content. A phase with four CuO2 layers have possibly grown on the surface of the grains of thi high Tc phase.

In-situ analysis of chemical expansion and stability of SOFC cathodes

2014 ◽  
Vol 1655 ◽  
Author(s):  
Mirela Dragan ◽  
Scott Misture
Keyword(s):  
High Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Lattice Parameter ◽  
Low Oxygen ◽  
X Ray Diffraction ◽  
Chemical Expansion ◽  
X Ray ◽  
Reducing Conditions ◽  
The Stability

ABSTRACTIn this work high-temperature X-ray diffraction has been used to investigate thermal and chemical expansion as well as overall phase stability for various cathode materials: Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF), La0.3Sr0.7CoO3 (LSC37), La0.6Sr0.4CoO3 (LSC64) and La0.6Sr0.4Fe0.8Co0.2O3 (LSCF), as a function of temperature in reducing conditions. When perovskites materials are under a low oxygen partial-pressure condition, the lattice parameter and overall dimension increase. Their chemical expansion has comparable values. From the viewpoint of the stability of these phases, the high-temperature X-ray diffraction results indicate no phase decomposition can be one of the reasons for material failure at the current experimental oxygen partial pressure. LSF is most stable, while LSC and LSCF form oxygen vacancy-ordered phases and then decompose when heated to 1000°C under atmospheres with pO2 as low as 10-5 atm.

Effect of Oxygen Partial Pressure on Properties of ZnO Films Deposited on Freestanding Diamond Films

2013 ◽  
Vol 544 ◽  
pp. 230-233
Author(s):  
Ke Tang ◽  
Lin Jun Wang ◽  
Jian Huang ◽  
Bing Ren ◽  
Jie Zhou ◽  
...  
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Diamond Films ◽  
Flux Ratio ◽  
Zno Films ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
Effect Of Oxygen ◽  
Ar Gas

Highly c-axis-oriented ZnO films were deposited successfully on the nucleation sides of freestanding diamond (FSD) films by the direct current (DC) magnetron sputtering method in an oxygen (O2) + argon (Ar) gas mixture. The effect of oxygen partial pressure on properties of ZnO films was investigated by X-ray diffraction (XRD). The results showed that when flux ratio of argon to oxygen was 1, the ZnO films had a better crystalline quality.

EXPERIMENTAL STUDY OF THE HIGH Tc SUPERCONDUCTOR Y-Ba-Cu-O SYSTEM

1989 ◽  
Vol 03 (08) ◽  
pp. 661-664
Author(s):  
S.M.M.R. NAQVI ◽  
JAWAID ALAM ◽  
FIROZ AHMAD ◽  
MUSHEER HASAN KHAN
Keyword(s):  
Experimental Study ◽  
Superconducting Phase ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
High Tc Superconductor ◽  
Zero Resistance

Two batches of Y-Ba-Cu-O superconductors have been prepared. The zero resistance temperature is 90 K with Tc onset at 93 K and 95 K, respectively. Susceptibility measurements show superconducting phase at LN2. X-ray diffraction results indicates single phases.

Tensile Properties and Creep Behavior of SiC-Based Fibers under Various Oxygen Partial Pressures

2005 ◽  
Vol 475-479 ◽  
pp. 1333-1336 ◽  
Author(s):  
Jan Ji Sha ◽  
J.S. Park ◽  
Tatsuya Hinoki ◽  
Akira Kohyama ◽  
J. Yu
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Tensile Properties ◽  
Creep Behavior ◽  
Elevated Temperatures ◽  
Low Oxygen ◽  
X Ray Diffraction ◽  
Sic Fibers ◽  
Partial Pressures ◽  
Ar Gas

Three kinds of atmospheres (air, highly-pure Ar and ultra highly-pure Ar gas) with different oxygen partial pressures were applied to investigate the tensile properties and creep behavior of SiC fibers such as Hi-NicalonTM and TyrannoTM-SA. These fibers were annealed and crept at elevated temperatures ranging from1273-1773 K in such environments. After annealing at 1773 K, the room temperature tensile strengths of SiC-based fibers decreased with decreasing the oxygen partial pressure and the near stoichiometric fiber TyrannoTM-SA shows excellent strength retention. At temperatures above the 1573 K, the creep resistance of SiC fibers evaluated by bending stress relaxation (BSR) method under high oxygen partial pressure was lower than that of in low oxygen partial pressure. The microstructural features on these fibers were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

scholarly journals Process-Parameter-Dependent Structural, Electrical, and Optical Properties of Reactive Magnetron Sputtered Ag-Cu-O Films

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
P. Narayana Reddy ◽  
A. Sreedhar ◽  
M. Hari Prasad Reddy ◽  
S. Uthanna ◽  
J. F. Pierson
Keyword(s):  
Optical Properties ◽  
Substrate Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Rf Magnetron Sputtering ◽  
Low Oxygen ◽  
Electrical And Optical Properties ◽  
Partial Pressures ◽  
Effect Of Oxygen ◽  
Parameter Dependent

Silver-copper-oxide thin films were formed by RF magnetron sputtering technique using Ag80Cu20target at various oxygen partial pressures in the range 5 × 10−3–8 ×10−2 Pa and substrate temperatures in the range 303–523 K. The effect of oxygen partial pressure and substrate temperature on the structure and surface morphology and electrical and optical properties of the films were studied. The Ag-Cu-O films formed at room temperature (303 K) and at low oxygen partial pressure of 5 × 10−3 Pa were mixed phase of Ag2Cu2O3and Ag, while those deposited at 2 × 10−2 Pa were composed of Ag2Cu2O4and Ag2Cu2O3phases. The crystallinity of the films formed at oxygen partial pressure of 2 × 10−2Pa increased with the increase of substrate temperature from 303 to 423 K. Further increase of substrate temperature to 523 K, the films were decomposed in to Ag2O and Ag phases. The electrical resistivity of the films decreased from 0.8 Ωcm with the increase of substrate temperature from 303 to 473 K due to improvement in the crystallinity of the phase. The optical band gap of the Ag-Cu-O films increased from 1.47 to 1.83 eV with the increase of substrate temperature from 303 to 473 K.

SUPERCONDUCTING PROPERTIES OF THE HIGH Tc SUPERCONDUCTING Er-Ba-Cu-O COMPOUND

1989 ◽  
Vol 03 (03) ◽  
pp. 441-444 ◽  
Author(s):  
S. M. M. R. NAQVI ◽  
FIROZ AHMAD ◽  
JAWAID ALAM ◽  
SHARFUDDIN AHMAD
Keyword(s):  
Superconducting Phase ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
Zero Resistance ◽  
Two Phases

Two batches of Er-Ba-Cu-O superconductors have been prepared. The zero resistance temperature is 86 K with T c onsets at 99 K and 92 K respectively. Susceptibility measurements show superconducting phase at LN 2. X-ray diffraction results indicates two phases, the superconducting being the major one.

High temperature X-ray diffraction studies of the decomposition mechanism of YBa2Cu3O7−δ at an oxygen partial pressure less than 10 Pa

1995 ◽  
Vol 10 (3) ◽  
pp. 165-169 ◽  
Author(s):  
W. Pitschke ◽  
W. Bieger ◽  
G. Krabbes ◽  
U. Wiesner
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Solid State Reaction ◽  
Peritectic Reaction ◽  
Decomposition Reaction ◽  
Primary Decomposition ◽  
X Ray Diffraction ◽  
X Ray

The crystallographic data of YBa2Cu3O7−δ, Y2BaCuO5, BaCu2O2, and YBa4Cu3O9 at high temperatures and p(O2)<10 Pa have been derived on the basis of HT-XRD measurements. Whereas Y2BaCuO5 expands nearly isotropically, YBa2Cu3O7−δ and BaCu2O2 show anisotropic expansions. Furthermore, the first decomposition step of the considered compounds at p(O2)<10 Pa was observed. BaCu2O2 melts congruently at T ≍ 1273 K and Y2BaCuO5 decomposes via a peritectic reaction into Y2O3, Y2BaO4 and melts at T ≍ 1323 K. A solid-state reaction into Y2BaCuO5 and BaCu2O2 was indicated for YBa2Cu3O7−δ at T ≍ 1123 K. Because YBa4Cu3O9 becomes unstable at T ≍ 1123 K, this compound cannot be formed by the primary decomposition reaction of YBa2Cu3O7−δ

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