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1992 electric properties, superconductors, semiconductors electric properties, superconductors, semiconductors D 8000 -004Stability of YBa2Cu3O7-δ in Alkaline Solution.-Degradation of high Tc superconductors is one of the most important problems in practical applications and, therefore, the behavior of the title superconductor in alkaline solution is investigated. It is shown that in a decarbonated solution (pH ≥ 7), YBa2Cu3O7-δ is relatively stable for several days but a slight degradation occurs through formation of hydroxides. This process is more quickly at higher pH. In the presence of CO2-3 anions the degradation is strongly accelerated due to formation of highly insoluble BaCO3, CuO, and amorphous Y compounds. -(PARK, J. C.; WATTIAUX, A.; GRENIER, J. C.; POUCHARD, M.; HAGENMULLER, P.; Eur. J. Solid State Inorg. Chem. 29 (1992) 2, 361-370; Lab. Chim. Solide, CNRS, Univ. Bordeaux I, 33405 Talence, Fr.; EN)

An appropriate treatment called “Vacuum‐Oxygen Cycle” (V.O.C.) has been carried out in order to obtain highly densified YBa2Cu3O7‐δceramics. The obtained materials exhibit a homogeneous oxygen distribution and their feature have been characterized using relevant physical measurements. Preliminary electrochemical experiments have been performed and this treatment seems to improve their superconducting properties.