Tl2Ba2CaCu2O delta thin films on MgO annealed in a sealed capsule

High-quality c-axis oriented Tl2Ba2CaCu2Odelta thin films have been prepared on MgO, which is more suitable for high frequency applications than LaAlO3 because of its lower dielectric constant (epsilon) and smaller dielectric loss tangent (tan delta). Annealing of the thin films was carried out in an alumina capsule sealed with a gold gasket. It was revealed that preannealing of the pellets for Tl compensation is effective in improving the structural properties of the thin films. X-ray diffraction (XRD) rocking curve scans of Tl2Ba2CaCu2Odelta (0 0 12) reflection revealed that a full width of half maximum (FWHM) of thin films annealed with an unpreannealed pellet is 0.89 degrees, while that of thin films annealed with a preannealed pellet Is 0.22 degrees. The highest critical temperature (T-c) is 108 K and the highest critical current density J(c) is 2 x 10(6) A/cm(2) at 77 K.