Reduced moisture-induced degradation of YBaCuO superconducting films by silver and high deposition temperatures

Abstract

Moisture-induced degradation of the YBaCuO superconducting films is studied using layer structures deposited at low temperatures with and without a silver covering layer, and using films deposited at high temperatures with a silver barrier layer. For the former, Ag/Cu/BaO/Y2O3/YSZ and Cu/BaO/Y2O3/YSZ are compared, where YSZ stands for yttria-stabilized zirconia substrate. Superconducting films with zero resistance between 80 and 87 K are obtained, depending on the annealing temperatures. Upon removing the samples from liquid nitrogen and warming in flowing nitrogen, a large rise in film resistivity is observed for the structures without silver, resulting in reduced temperatures for zero resistance and reduced critical current density at 77 K. Much less degradation is observed, however, with the samples containing a silver layer. For the samples deposited at high temperatures, no degradation is observed from similar moisture exposures.