T-C ENHANCEMENT IN SILVER SUBSTITUTED BI1.7PB0.3SR2-XAGXCA2CU3OY

The superconductor Bi1.7Pb0.3Sr2-xAgxCu3Oy has been synthesied under t he ambient pressure. These specimens show the presence of only 2212 ph ase when x < 0.4, and the T-c achieved 104 K. With the x increase, the structure of sample transfers to 2223 phase with T-c at 106 K. The in vestigations show that Silver does not seem to be incorporated in the lattice. It is argued that Ag doping produces Sr vacancies in SrO plan es at a certain condition. This changes oxidation state of Cu thus cau sing the unusual high T-c of Br-2212 phase.