OXYGEN PROCESSING OF HG AND TL BASED CUPRATE SUPERCONDUCTORS

The effect that oxygen stoichiometry has on the physical properties of high critical temperature superconductors is well documented. For a g eneral understanding of the conditions necessary for processing high c ritical temperature superconducting materials, phase equilibrium diagr ams have been quite useful; however, such diagrams provide no informat ion concerning the time required to oxygenate superconducting structur es. In this paper, we present experimental results that clearly demons trate the relationships among phase equilibrium diagrams, oxygen diffu sion coefficients and grain sizes with the time required to ''adequate ly'' oxygenate high critical temperature superconducting materials and device structures. While oxygen processing of the high critical tempe rature superconductor, YBa2Cu3O7-delta, is, is emphasized throughout t his paper, the concepts and relationships discussed herein, in general , can be applied to the oxygen processing of other high critical tempe rature superconductors including the Hg and Tl based systems.