Abstract
The superconducting low Tc Bi2Sr2CaCu2Oy films of 1 μm in thickness have been prepared on Sr2Ca2Cu4Oy substrates by thermal evaporation of metallic Bi layer and heat treatment at 830 ° C for a few minutes in air. The transition behavior and morphology of the films were studied by resistivity measurements and scanning electron microscopy. The zero resistance temperature Tcz and critical current density Jc at 70 K were observed to be 78 K and 103 A/cm2, respectively. It is found that the superconducting films are formed by the reaction between liquid phase (Bi2O3) and solid phase (substrate), and that the dendrite structure is produced in the cross section of the films as it is generally observed in the liquid phase sintering.