Abstract
High temperature superconductor with nominal composition Bi1.6Pb0.4Sr1.8Ba0.2Ca2 Cu3O10+? was prepared by solid state reaction method. Two sets of samples have been prepared .The first one was quenched in air; the second set was quenched in liquid nitrogen. X-ray diffraction analyses showed an orthorhombic structure with two phases, high –Tc phase (2223) and low-Tc phase (2212) in addition to that impure phase was found. It has been observed that quenched in air samples display a sharp superconducting transition and a higher-Tc phase than that of the quenched in liquid nitrogen samples.
Highlights
Since the discovery of BiSrCaCuO superconductor system, which has three different superconducting phases with similar crystal structure, great efforts were achieved to obtain high quality of Bi-2223 monophase
It is possible to say that the volume fraction of the high Tc phase increases with increasing sintering time and it appears to be the dominant phase in these ceramics
Figs. indicate several peaks for high-Tc phase (Bi-2223) with amount of low-Tc phase (Bi-2212).with some impurity phases like Ca2PbO4 and Sr2Ca2Cu7Oδ are detected at 2θ equal to 17.8,31.96 and 36.8 respectively[8,9].The present of Ca2PbO4 was known to result in a liquid phase which accelerated the anisotropic growth of high Tc phase [8]
Summary
Since the discovery of BiSrCaCuO superconductor system, which has three different superconducting phases with similar crystal structure, great efforts were achieved to obtain high quality of Bi-2223 monophase. To get a nearly pure phase material, usually hundreds of hours were required (this involves repeated sintering steps). Such a long period of production is very disadvantageous for the practical application of this material. Kocabas [3] (1998) prepared the samples by used the solid state reaction, The sample (Bi1.5Pb0.4Sb0.1 Sr2Ca2Cu3Oy) were sintered at 850°C for 60, 80 and 100 hours in air and furnace cooled to room temperature. He was found the high Tc at 108, 110, and 112K, respectively. It is possible to say that the volume fraction of the high Tc phase increases with increasing sintering time and it appears to be the dominant phase in these ceramics
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