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Proceedings Paper

Amorphous-to-superconducting transformation in bismuth-based high-Tc superconducting rods
Author(s): Mohammad N. Khan; A. Memon; Shawqi Al-Dallal; Anwar Ul Haq
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Paper Abstract

The transformation of high-resistivity amorphous Bi1.68Pb0.32Ca1.85Sr1.75Cu2.85Oy to superconductive material has been characterized by structural, thermochemical, transport and SEM measurements. X-ray powder diffraction confirmed that rapid solidification of Bi-Pb-Ca-Sr-Cu-Oy yields amorphous material. In further heat treatments the sequential crystallization of 2201, 2212, 2223 phases have been identified. The differential scanning calorimetry indicated an exothermic crystallization peak at 520 degrees Celsius with corresponding enthalpy of 62 J/g. SEM studies revealed that the grain size increases with sintering time and formation mechanism in the interior of the bulk is different from that at the edges of the superconducting glass ceramic rods. Thermal cycling of the insulating glass to a temperature above that required for crystallization results in a transformation from an insulating to a superconducting material with a Tc (R equals 0) of 105 K. It is also shown that the glass ceramic rods obtained by re-heating glass rods at 850 degrees Celsius for 120 hours have a Tc (R equals 0) of 105 K while the disk specimens obtained by re-heating the powdered glass compacts in the same way do not exhibit superconductivity above 85 K. This difference in superconductivity between the specimens is discussed in terms of the crystallization process and the amount of oxygen absorption of the specimens during heating.

Paper Details

Date Published: 8 April 1996
PDF: 4 pages
Proc. SPIE 2780, Metal/Nonmetal Microsystems: Physics, Technology, and Applications, (8 April 1996); doi: 10.1117/12.238122
Show Author Affiliations
Mohammad N. Khan, Univ. of Bahrain (Bahrain)
A. Memon, Univ. of Bahrain (Bahrain)
Shawqi Al-Dallal, Univ. of Bahrain (Bahrain)
Anwar Ul Haq, Dr. A.Q. Khan Research Labs. (Pakistan)


Published in SPIE Proceedings Vol. 2780:
Metal/Nonmetal Microsystems: Physics, Technology, and Applications

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