Influence of Ag substrates on grain alignment and critical current density of Bi-2212 tape conductors

We investigated the influence of Ag substrate on the microstructure and J/sub c/ values of dip-coated Bi-2212/Ag tapes. The grain alignment of Bi-2212 in the oxide/Ag interface was much higher than that in the free surface of oxide. J/sub c/ increases with increasing oxide/Ag interface area and with decreasing oxide layer thickness, while J/sub c/ was almost independent of the free surface area. The smoothness of the Ag substrate is also an important factor. Micrometer-size roughness of the Ag substrate results in a decrease of Bi-2212 grain alignment and therefore J/sub c/. Addition of alloying elements to the Ag also degrades the grain alignment of Bi-2212 and decreased J/sub c/. Cold rolling before the heat treatment improved the grain alignment and enhanced J/sub c/.