Effect of silver on the water‐degradation of YBaCuO superconducting films

Degradation of YBaCuO superconducting films by water is studied using different starting structures with or without a silver layer. Several layer structures are compared, including Cu/BaO/Y2O3 substrate, Ag/Cu/BaO/Y2O3/substrate, Cu/BaO/Y2O3/Ag/substrate, and Ag/Cu/BaO/Y2O3/Ag/substrate, deposited either at room temperature or at high temperatures. Superconducting films were formed from these structures, with a zero resistance between 81 and 88 K. Upon exposing to moisture or immersing in water, a large difference in film degradation is observed, being much less for the structures containing a silver layer. Changes in film properties are analyzed, including decreasing critical current densities at 77 K, decreasing temperatures for zero resistance, increasing contact resistance at low temperatures, increasing film resistance at room temperatures, and changes in film structures. The possible mechanisms involved are also discussed.