Preparation of superconducting Ba2YCu3O7−y-Ag composite films on sapphire by the dipping pyrolysis process

Abstract
Superconducting Ba2YCu3O7−y(BYCO)‐Ag composite films were prepared on sapphire substrates without a buffer layer by the dipping pyrolysis process. Prefired films of a BaCO3‐Y2O3‐CuO‐Ag mixture (Ba:Y:Cu:Ag=2:1:3:0.2 in molar ratio) were heat treated at 740 °C under a low oxygen partial pressure [p(O2)=2×10−4 atm] followed by O2 annealing at 450 °C. The resulting 0.8–1.8 μm thick films showed high superconducting transition temperatures of Tc, zero=88–89 K.