Oxygen Processing of Hg and Tl Based Cuprate Superconductors

Abstract

The effect that oxygen stoichiometry has on the physical properties of high critical temperature superconductors is well documented. For a general understanding of the conditions necessary for processing high critical temperature superconducting materials, phase equilibrium diagrams have been quite useful; however, such diagrams provide no information concerning the time required to oxygenate superconducting structures. In this paper, we present experimental results that clearly demonstrate the relationships among phase equilibrium diagrams, oxygen diffusion coefficients and grain sizes with the time required to “adequately” oxygenate high critical temperature superconducting materials and device structures. While oxygen processing of the high critical temperature superconductor, YBa2Cu3O7−δ, is emphasized throughout this paper, the concepts and relationships discussed herein, in general, can be applied to the oxygen processing of other high critical temperature superconductors including the Hg and TI based systems.