Influence of chemical composition on the stability of YBa2Cu3O y in a humid atmosphere

The influence of replacements of yttrium and barium in YBa₂Cu₃O _y and doping of this compound with CeO₂, ZrO₂, and Pr₂O₃ on the capability of absorbing water from the annealing atmosphere at T = 200°C has been studied. The complication of the chemical composition of the 123-type compounds leads to an enhancement of their stability to aggressive components of the gaseous phase (H₂O, CO₂). These compounds have a variable chemical composition both in oxygen and water and can exist in three modifications: the oxygen-ordered ortho-phase, the oxygen-disordered tetra-phase, and the pseudocubic phase with a variable water content, which at T = 200°C separates into an oxygen-deficient water-enriched phase and an oxygen-rich anhydrous phase.