STRUCTURES AND PROPERTIES OF F-DOPED BI-SYSTEM SUPERCONDUCTORS

In this paper, the possibility of F entering the superconducting phase, its position and the structure properties of the superconductors, and the mechanism of superconductivity in F-doped Bi-systems are studied based on experimental and theoretical results. It has been found that, because the ΔTc is narrowed and raised, the Tco of F-doped Bi-system superconductors increases obviously, with the highest Tco at 118 K, that F has entered into the superconducting phase, that generally F can reduce the potential barrier of forming high-Tc superconducting phase and improve the superconductivity of Bi-systems, but only if there exists certain amount of Pb in the system, and that with F-doping the weak linkage of superconductor is decreased, the flux pinning is enhanced, the carrier-hole concentration is increased, and the critical current is improved.