Superconducting YBCO thin film on multicrystalline Ag film evaporated on MgO substrate

Superconducting YBa2Cu3O7-delta films were grown by resistive evaporation o n multicrystalline silver film which was evaporated on MgO substrate. A sim ple inexpensive vacuum system equipped with resistively heated boat was use d for the whole process. Silver film was first evaporated on MgO substrate kept at 400 degreesC during the evaporation after which with no further ann ealing a precursor mixture of yttrium small grains and Cu and BaF2 in powde r form weighed in the atomic proportion to yield stoichiometric YBa2Cu3O7 w as evaporated. The films thus obtained were annealed at 740 degreesC under low oxygen part ial pressure of about 1Pa for 30 minutes to form the superconducting phase. X-ray diffraction and scanning electron microscopy techniques were used fo r texture and surface analysis. Electrical properties were determined using a standard de four-probe for electrical measurements. The physical and electrical properties of the YBCO films are discussed in l ight of the fact that X-ray diffraction measurements done on the silver fil m have revealed a multicrystalline structure.