C-axis oriented (Hg,Ti)-based superconducting films with T-c>125 K

Thin films with mostly (Hg,T1)(1)Ba2Ca3Cu2O8+delta[(Hg,T1)-1223] phase have been fabricated by radio frequency magnetron sputtering of precursor films and post-annealing method. The doping of a small amount of thallium in the film is helpful to the formation of the three-layer CuO2 compound. These films have a highly oriented structure with the c-axis perpendicular to the film surface. Resistivity measurements show that the films after annealing at 300 degrees C for 1 h in O-2 have the superconducting transition temperature of T-c(onset)=133 K and T-c(zero)=127 K. Scanning electron micrographs of the film reveal platelike micrometer-size grains coalesce to cover the substrate surface. (C) 1996 American Institute of Physics.