PROPERTIES AND STRUCTURE OF THE F-DOPED (BI,PB)-SR-CA-CU-O SUPERCONDUCTOR

Using transmission electron microscopy, x-ray photoelectron spectrosco py, infrared, positron annihilation, and differential specific-heat me asurements, we have studied the properties and structure of the F-dope d (Bi,Pb)-Sr-Ca-Cu-O superconductor. The results show that the fluorin e atoms are homogeneously distributed in the superconducting phase and substituted for the oxygen atoms at O(2) crystallographic sites; the Pb-F and Cu-F bonds are formed. F-doping results in the variance of th e incommensurate modulation structure, the increase of the point defec ts and chemical pressure, the enhancement of the flux-pinning effect, and the change of the electronic structure and chemical bond, and grea tly improves the superconductive properties of the 2223 phase of (Bi,P b)-Sr-Ca-Cu-O.