Fabrication of double-sided Tl2Ba2CaCu2O8 thin films on 2-in. LaAlO3 substrates by pulsed laser deposition and post-annealing

Double-sided Tl2Ba2CaCu2O8 (Tl-2212) thin films have been prepared on 2-in. LaAlO3 substrates by a two-step method in which Tl-free amorphous Ba2CaCu2Ox precursor films were first deposited on the substrates by pulsed laser deposition and the subsequent thallination, crystallization and oriented growth of the superconducting Tl-2212 films were obtained in a long-duration annealing process in argon atmosphere at temperature around 720-740 deg. C. The films were characterized by means of X-ray diffraction, scanning electron microscopy and transport measurements. The results show that the as-prepared films are predominately single phase with c-axis perpendicular to the substrate surface, except for the presence of some submicron particles on the film surface. For the both sides of the films, the zero-resistance transition temperature TC0 is about 105 K and the critical current density JC is in excess of 106 A/cm2. The microwave surface resistance RS is below 0.5 mΩ