Development of microstructure in Tl-2212 thin films and possible influence on microwave surface resistance values

Abstract

The microstructures of Tl2Ba2Ca1Cu2O8 (Tl-2212) films are very strongly influenced by the processing parameters used to synthesize the superconducting phase and also control the microwave surface resistance values that are of key importance in the application of these materials in high-frequency devices. We report here on detailed studies of how the mesotexture of Tl-2212 films develops during synthesis at 820 and 855 °C. Our key observation is that the microstructure, and hence the superconducting properties, are controlled by the mechanism by which stress is relieved in the films and that apparently perfectly epitaxial films do not have the best microwave performance because in these samples the stress is relieved by macroscopic defects rather than local, low-angle grain misorientations.