Lattice Parameters and Surface Morphology of the High-T c Phase in Bi-Sr-Ca-Cu-O Superconducting Thin Films

Bi-Sr-Ca-Cu-O thin films with different T c values in the range from 110 K to 84 K were prepared on MgO(100) crystal by an rf-magnetron sputtering technology. The volume ratio of the high- T c phase, its lattice parameters and the surface morphology for these films were investigated. T c became higher as the c - and a -axes became shorter. The lattice parameters of the film with T c =110 K were c =37.15 Å and a =5.41 Å, which were the same as for bulk ceramics with T c =110 K. The grain size was larger for the higher- T c films.