Oxygenation of silver clad YBa2Cu3O7-δ

The effects of time, temperature, and coating thickness on the oxygenation of silver-coated YBa₂Cu₃O_7-δ wire during a postprocessing anneal were examined. Two different grades of silver-coated wire as well as bare ceramic fiber were subjected to a variety of isothermal and continuous-cooling oxygen anneals. DC transport J_c, AC magnetic susceptibility, optical microscopy, and scanning electron microscopy were used to characterize the samples. It is expected that a continuous-cooling anneal will be more efficient than an isothermal anneal for oxygenating YBa₂Cu₃O _7-δ. Reasons for this assumption are examined, and results of both types of anneals are presented. The superconducting behavior of sintered YBa₂Cu₃O_7-δ is limited by weak links. Both the J_c and AC susceptibility data measure flux motion in the weak links and therefore both of these measurements are appropriate means of assessing the efficiency of oxygenation. The rate of oxygenation at high temperatures is an important factor in determining optimal continuous-cooling anneals. Susceptibility measurements were used to characterize this oxygenation. The presence of a porous silver cladding slows the rate of oxygenation of YBa₂Cu₃O_7-δ but does not change its basic character