BI-PB-CA-CU-O SUPERCONDUCTOR FILMS ON SINGLE-CRYSTAL GARNET SUBSTRATES

The use of garnet as substrates for growing high temperature supercond uctor films of Bi-Pb-Sr-Ca-Cu-O (BPSCCO) system is reported here. Thic k films of BPSCCO with a prevalently high T(c). phase were successfull y prepared on Gadolinium Gallium Garnet (GGG) substrates using the scr een printing technique. The formation of superconducting phase on thes e substrates needed much lower heat treatment temperatures (30-40C low er than used for most known substrates) and heating time. Heat treatme nt at 800C for 2-6 hours was sufficient to give good a-b oriented film s with a single sharp transition at 100K, having mostly a high T(c) ph ase. Films annealed at higher temperature showed two step transition a nd mixed phases. The microstructural, electrical, superconducting and cross sectional studies for interaction between film and substrate and their dependence on heat treatment temperatures are also reported her e.