Akademik Veri Yönetim Sistemi
JOURNAL OF PHYSICS-CONDENSED MATTER, cilt.9, sa.5, ss.1105-1121, 1997 (SCI-Expanded)
Systematic substitution of V in the Bi2-deltaVdeltaSr2Ca2Cu3O10+y system (delta = 0, 0.2, 0.4, 0.6, 0.8 and 1) was carried out in order to determine the effect of V ions on the phase formation and on the physical properties of the BSCCO 2223 system. The most interesting observation was structural transformation of the system from tetragonal to orthorhombic after delta = 0.6. A solid solubility limit for V was also found to exist. Resistivity and susceptibility studies have shown that high-T-c superconductivity exists up to delta = 0.6 and that the semiconducting-to-metallic transition or fully semiconducting behaviour occurs after this limit. A fractionally small but very-high-T-c transition at around 210 K was also observed, but it was not reproducible. Among the V-substituted samples the best electrical properties were obtained for delta = 0.2; T-c and T-0 were found to be 112 K and 92 K, respectively, the calculated value of J(c) was found to be 1.11 x 10(5) A cm(2) at 4.5 K and the thermal conductivity parameter kappa was found to be 6.4 mW cm(-1) K-1. By substituting the higher-valence state V5+ ions for Bi3+, the thermal treatment time is significantly reduced. The magnetic properties, IR and thermal conductivity results showed evidence of a strong coupling mechanism in the Bi2-deltaVdeltaSr2Ca2Cu3O10+y system.