Microstructural and superconducting properties of Bi-2212 thick films melt-solidified with Bi2Al4O9

Bi2Sr2CaCu2Ox (Bi-2212) thick films were prepared via the screen-printing method and partial melting. We investigate the influence of the melt-solidification process with Bi2Al4O9 on microstructural and superconducting properties of Bi-2212 thick films. The vaporization of bismuth from Bi2Al4O9 during the melt-solidification suppresses the growth of the impurities such as (Sr, Ca)-Cu-O and Bi-Sr-Ca-O at the film surface. However, the appearance of Bi2Sr2CuOx (Bi-2201) is remarkably unstable to a variation of the maximum temperature. The result of ac susceptibility measurements shows that the melt-solidification with Bi2Al4O9 leads to a sample with superior qualities of superconductivity which are characterized as a small scattering of intergranular coupling strength and a high transport property at around liquid-nitrogen temperature. (author)