Thermal and superconducting properties of glass-ceramic HTc BiSrCa(CuPr)O system

In this study, the glass samples with nominal composition of Bi2Sr2Ca2Cu3-xPrxO10+y, where x=0.5, were fabricated using conventional melt quenching technique. After appropriate heat treatments, the glass-ceramic samples obtained showed a deformed and multiphase structure. While the a(=b)-axis was nearly unchanged, the c-axis was obtained to be smaller than that of the unsubstituted Bi-2223 system. From the resistance versus temperature measurements, a semiconducting type behavior down to T-c was observed. The best T-c value was obtained to be 46 K and T-zero 29 K for the sample heat treated at 1123 K (850 degrees C) for 60 h. The Pr-substituted Bi-2223 glass-ceramic samples showed negative thermoelectric power, indicating that the dominant carriers are electrons in the samples. Two-band model with linear T-term was used to analyze the TEP data. A rapid rise in thermal conductivity, k, was obtained just below T-c .This suggests an enhancement of the quasiparticle contribution to the heat conductivity and so an increase of the quasiparticle mean free path. (c) 2007 Elsevier B.V. All rights reserved.