Distribution of the transport critical current in Ag-(Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ reinforced tape-form conductors

The spatial distribution of the transport critical current, I/sub c/, in the reinforced-tape-form, silver-clad (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ conductor manufactured by cold multistep rolling has been established by the in-situ measurements as a function of the thickness of the ceramic core. The measurements show that current is almost uniformly distributed through the whole cross-section of the core in the wire, almost independently of the initial I/sub c/ value of the tape. The effect of densification, texturing, and surface diffusion on the formation of the intergrain connectivity along the a-b plane of the core, at the silver-ceramic interface, and in the core has been investigated and is discussed in detail. The I/sub c/ anisotropy measurements and a study of magnetically aligned and randomly oriented samples lead to a functional relationship between the crystallographic orientation, morphology and connectivity of the grains in the tape. The variation of the hole concentration near the grain boundary region of the 2223 phase has been investigated by transmission electron energy loss spectroscopy.<
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