Bi-based superconductors with nanosized silver dopant

The effect of nanosized silver on formation and transport properties of Bi-2223 phase was studied. Samples with nominal composition Bi3.2Pb0.8Sr4Ca5Cu7Ox were prepared by solid state synthesis. Ag as additive was used in three different weight percentage 5, 10 and 15. Ag powder was added to the initial mixture or after second calcination. All samples have critical temperature Tc in the range 108-109 K. An increase of the Bi-2223 phase content was observed at Ag concentration 10 wt%. Prolonged sintering time (400 h) improved critical current density Jc(77) above the value of the undoped sample. The values of porosity and density of the long sintered samples demonstrated their densification. The SEM micrographs have shown that addition of the silver improves the connectivity between the grains. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)