Abstract
We prepared polycrystalline Tl-1223 films without impurity phases and with a c-axis orientation by heat treatment and intermediate pressing of precursor films using a laser ablation process on Ag substrates. The critical temperature (Tc) of Tl1223 films on Ag was 120 K and the critical current density (Jc) was 15 kA/cm2 at 77 K, 0 T. The strong field dependence of Jc of the Tl-1223 films in a low magnetic field showed that the grain boundaries of the Tl-1223 films behaved like a weak link. The temperature dependence of Jc of the Tl-1223 films was proportional to (1-T/Tc)n with n=2.0 for 0.08 ?? 1-T/Tc ?? 0.38. These results confirm that grain boundaries in Tl-1223 films act as superconductor-normal metal-superconductor (SNS) junctions.
