Critical currents of (Tl0.5Pb0.5)(Sr0.85Ba0.15)2Ca2Cu3Oz films on untextured silver substrates

Superconducting (Tl0.5Pb0.5)(Sr0.85Ba0.15)2Ca2Cu3Oz films were prepared on highly polished, untextured silver substrates. A superconducting transition temperature (Tc) of 114.9 ± 0.1 K was obtained from the resistivity versus temperature measurements for different applied ac currents. The temperature dependence of the critical current was fitted with a power law: Jc(T) = Jc(0)[1 − T/Tc]n with n = 2. The critical current in self-field at 77 K was found to be 8 × 103 A/cm2. The temperature dependence of the real and imaginary parts of ac susceptibility was measured for different amplitudes of ac magnetic field. Only a small differences of the ac susceptibility for parallel and perpendicular fields with respect to the film surface were observed.