Superconductive (Y1−xCax)Ba2Cu4O8 (x = 0.0 and 0.05) ceramics prepared by low and high oxygen partial pressure techniques

1991 ◽  
Vol 6 (1) ◽  
pp. 18-27 ◽  
Author(s):  
Takahiro Wada ◽  
Nobuo Suzuki ◽  
Koji Yamaguchi ◽  
Ataru Ichinose ◽  
Yuji Yaegashi ◽  
...  
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Thermal Analyses ◽  
Annealed Sample ◽  
Crystallographic Structure ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Post Annealing ◽  
Transmission Electron ◽  
Diffraction Patterns

Both YBa2Cu4O8 and (Y0.95Ca0.05)Ba2Cu4O8 were successfully prepared by firing for 160 h at 850 °C and at oxygen partial pressure of 3 atm without using any catalysts. These samples were characterized in terms of the crystallographic structure and thermal and superconducting properties. The x-ray powder diffraction patterns and superconducting properties for these samples were little changed after post-annealing for 6 h at 1070 °C and at oxygen partial pressure of 400 atm. However, when heat-treated at 700 °C in air and then quenched into liquid nitrogen, samples without post-annealing showed broader superconducting transitions than those post-annealed. Actually, the sharpness of the superconducting transition for a post-annealed sample was little affected by quenching. These observations were in agreement with the results of both transmission electron microscopy and thermal analyses.

Growth Mechanisms of YBa2Cu3O7-δ Thin Films Post Annealed at a Low Oxygen Partial Pressure

1993 ◽  
Vol 312 ◽  
Author(s):  
S. Y. Hou ◽  
D. J. Werder ◽  
Julia M. Phillips ◽  
J. H. Marshall
Keyword(s):  
Thin Films ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Early Stage ◽  
Growth Mechanisms ◽  
Low Oxygen ◽  
Cross Sectional ◽  
Annealing Conditions ◽  
Post Annealing ◽  
Transmission Electron

AbstractThe growth mechanism of YBa2Cu3O 7-= thin films grown by the BaF2 post annealing process at low oxygen partial pressure have been studied by transmission electron microscopy. Under the annealing conditions of po2 = 4 Torr and 700°C, BaCuO2 and Y2 Cu2O5 precipitates develop from stoichiometric film precursors of YBCO during annealing. A growth model is proposed based on the observations. In addition, early stage nucleation and growth of both c- and a-axis oriented grains at the substrate interface were observed in quench annealed cross-sectional samples. 90° [100] symmetrical boundaries form between the a- and c-axis oriented grains. The possible effects of these boundaries are discussed.

Formation of Superconducting La2−xSrxCaCu2O6−δ Ceramic with Application of O2-HIP Technique

1991 ◽  
Vol 251 ◽  
Author(s):  
Kiyoshi Oshima ◽  
Yuichi Watanabe ◽  
Masasuke Takata ◽  
Kozo Ishizaki
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Strong Correlation ◽  
Hot Isostatic Pressing ◽  
Lattice Parameters ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Isostatic Pressing ◽  
Diffraction Patterns

ABSTRACTSuperconducting La2−xSrxCaCu2O6−δ ceramics (x=0−0.6) were prepared with application of the oxygen-hot-isostatic pressing (O2-HIP) technique. The Tc of various samples was found to depend on both the Sr content and the applied oxygen partial pressure in the HIP treatment. The maximum Tc onset of 50K was observed for samples of the composition x=0.3 and 0.4 HIPped at 1050°C under 60atm oxygen partial pressure, and x=0.1 and 0.2 HIPped at 1050°C under 400atm oxygen partial pressure, respectively. From the analysis of x-ray diffraction patterns for superconducting substances, it was found that there existed a strong correlation between superconducting properties and the lattice parameters.

Microstructure and superconducting properties of attrition-milled Bi2Sr2CaCu2Ox

1994 ◽  
Vol 9 (2) ◽  
pp. 297-304 ◽  
Author(s):  
J.S. Luo ◽  
H.G. Lee ◽  
S.N. Sinha
Keyword(s):  
Electron Microscopy ◽  
Milled Powder ◽  
High Energy ◽  
Double Layers ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Steel Tank ◽  
Practical Implications

The microstructure and superconducting properties of Bi2Sr2CaCu2Ox (Bi-2212) during high-energy attrition milling were investigated in detail by a combination of x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and magnetization techniques. The starting superconducting powder was milled in a standard laboratory attritor using yttria-stabilized ZrO2 balls and a stainless steel tank. After selected time increments, the milling was interrupted and a small quantity of milled powder was removed for further analysis. It was found that the deformation process rapidly refines Bi-2212 into nanometer-size crystallites, increases atomic-level strains, and changes the plate-like morphology of Bi-2212 to granular submicron clusters. At short milling times, the deformation seems localized at weakly linked Bi-O double layers, leading to twist/cleavage fractures along the {001} planes. The Bi-2212 phase decomposes into several bismuth-based oxides and an amorphous phase after excessive deformation. The superconducting transition is depressed by about 10 K in the early stages of milling and completely vanishes upon prolonged deformation. A deformation mechanism is proposed and correlated with the evolution of superconducting properties. The practical implications of these results are presented and discussed.

Improvement in D-E Hysteresis Curve Squareness of PZT Thin Films - Effect of Oxygen Partial Pressure in High-Pressure Post-Annealing

2003 ◽  
Vol 52 (1) ◽  
pp. 137-145
Author(s):  
Junichi Karasawa ◽  
Taku Aoyama ◽  
Takeshi Kijima ◽  
Eiji Natori ◽  
Tatsuya Shimoda
Keyword(s):  
Thin Films ◽  
High Pressure ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Hysteresis Curve ◽  
Pzt Thin Films ◽  
Post Annealing ◽  
Effect Of Oxygen

scholarly journals Electrical Characterization of La2-xSrxCuO4-y Superconductors

1989 ◽  
Vol 44 (1) ◽  
pp. 26-28 ◽  
Author(s):  
G. Chiodelli ◽  
G. Campari-Viganò ◽  
V. Massarotti ◽  
G. Flor
Keyword(s):  
Electrical Resistivity ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Solid Solutions ◽  
Electrical Characterization ◽  
Superconducting Transition ◽  
Electrical Behaviour ◽  
Temperature Range

Abstract The electrical behaviour of La2-xSrxCuO4-y solid solutions (with x = 0, x = 0.025, x = 0.05, and x = 0.15) at temperatures between 10 and 900 K and under different oxygen partial pressure pO2 = 1 ÷ 10-6 atm) has been investigated. The samples prepared and measured under an O2 flux (i.e., with y = 0) show a superconducting transition with Tc = 46, 29. 37 K for x = 0. 0.05 and 0.15, respectively. The samples with x = 0.025, y = 0, and x = 0, y ≠ 0 exhibit no sign of superconductivity. In the temperature range 100-900 K. La2CuO4 is semiconducting, whereas the electrical resistivity is independent of temperature for the x =0.025 sample, and the x = 0.05 and x = 0.15 are metallic.

Superior microwave properties by post‐annealing YBa2Cu3O7thin films at low oxygen partial pressure

1992 ◽  
Vol 60 (26) ◽  
pp. 3310-3312 ◽  
Author(s):  
A. Mogro‐Campero ◽  
L. G. Turner ◽  
A. M. Kadin ◽  
D. S. Mallory
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Microwave Properties ◽  
Low Oxygen ◽  
Post Annealing

Resistivity measurement of an a-axis-oriented YBa2Cu3O7–δ thin film at 450-650 °C

1993 ◽  
Vol 8 (4) ◽  
pp. 705-708 ◽  
Author(s):  
Toshio Usui ◽  
Akira Oishi ◽  
Hidekazu Teshima ◽  
Kazumi Ohata ◽  
Tadataka Morishita
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Ybco Film ◽  
Resistivity Measurement ◽  
Ambient Atmosphere ◽  
Reversible Change ◽  
Superconducting Properties ◽  
Ybco Thin Film

Resistivity measurement of an a-axis-oriented YBa2Cu3O7-δ (YBCO) thin film was carried out in a stream of O2/Ar mixtures at 450–650 °C. Rapidly reversible change in the resistivity of the YBCO film was observed as a function of the oxygen partial pressure in the ambient atmosphere due to the oxygen in-/out-diffusion in the YBCO film. Resistivity measurement of YBCO thin films at higher temperatures of 450–650 °C was found to be quite effective to predict the influence of fabricating processes on the superconducting properties of YBCO films.

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