Effect of hydration on the structure of perovskite-like cuprates

The effect of hydration at $T$ = 150 and 200$^\circ$C on the structures of YBa$_{2}$Cu$_{3}$O$_{y}$ (123) and a number of binary cuprates has been studied. It has been shown that the compounds containing oxygen vacancies in their structures interact with hydrogen significantly more strongly than cuprates without vacancies. Depending on the cuprate structure, hydrogen can be embedded in interstitial sites with the formation of hydrides and be attached to oxygen with the formation of hydroxides. The phase transition of the 123 phase to a defect tetragonal 124-type phase occurs only for the compounds with a high oxygen content. All the cuprates under study are more stable to reduction as compared to CuO.