Strong decrease of anisotropy by lead-substitution in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+y/

The in-plane ( rho /sub ab/) and out-of-plane ( rho /sub c/)/sub c/ resistivities were measured above the critical temperature, T/sub c/, in several lead-substituted single crystals of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+y/ and compared to the results obtained for lead-free samples. It was found that the lead substitution induces an important decrease of rho /sub c/, resulting in a lowering of the anisotropy rho /sub c// rho /sub ab/ by two orders of magnitude near T/sub c/. Moreover, rho /sub c/ changes its behavior from a semiconducting type of behavior to a metallic one. These results are related to the role of lead, which was recently inferred from structural considerations. The possibility of improving the out-of-plane critical current by lead substitution is discussed.<
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