Experimental and Thermodynamic Study of Nonstoichiometry in 〈YBa ₂ Cu ₃ O 7‐x 〉

The dependence of the nonstoichiometry of 〈YBa 2 Cu 3 O 7−x 〉 (solid) has been studied over 5 orders of magnitude in oxygen pressure and from 573 to 1173 K. Hydrogen‐reduction methods for determining the absolute oxygen to‐metal ratio were developed. The resulting data were used to derive a chemical thermodynamic representation of the experimental variables. The data were used to derive a chemical thermodynamic representaltion of the experimental variables. The data were also compared with several other investigations to indentify the selfconsistent sets of data. The present data and thermodynamic data from the literature were correlated on an Ellingham diagram.