ELECTROCHEMICAL INVESTIGATION INTO THE ENVIRONMENTAL DEGRADATION OF YBA2CU3O7 SUPERCONDUCTORS

YBa2Cu3O7(YBC) high-T(c) superconductors degrade rapidly when exposed to humidity or water. In an attempt to gain a better understanding of the degradation behavior and to study the effect of porosity on degrad ation susceptibility, small amplitude cyclic voltammetry (SACV) is per formed. Microelectrodes are fabricated from YBC superconducting pellet s of porosities approximately 50% and <1%. SACV is performed in methyl alcohol saturated with sodium chloride and 1 M NaCl in distilled wate r before and after exposure to water. It is found that the corrosion r ate of bulk superconductors increases with exposure time. The dense sp ecimens seem to stabilize after 36 h while the porous specimens contin ue to deteriorate at first rapidly and after 24 h slowly. The BaCO3 fi lm produced by corrosion is non-protective.