Oxygen stoichiometry of YBa2Cu2.82Zn0.18O7-δ between 25 and 930°C

Article abstract of DOI:10.1016/0025-5408(89)90042-1

This paper presents a new methodology for determining the oxygen stoichiometry of YBa₂(Cu_1-xZn_x)₃O_7-δ type of compounds, taking x=0.06 as an example. The method involves heating the sample up to 930°C and slow cooling (1°C/min) under pure oxygen up to 25°C followed by hydrogen reduction in a thermobalance. Both the copper and zinc contents of the oxide reduced to the metallic state under hydrogen at about 900°C. In the present method the sample was kept at 980°C for a sufficiently long period such that zinc was completely removed by volatalization. This helped in establishing the composition of the reduced product and thereby the oxygen stoichiometry of the oxide. The oxygen stoichiometry (7-δ values) as a function of temperature under an equilibrium of pure oxygen at 1.0 atm was found to vary from 6.84 ± 0.03 to 6.27 ± 0.03 from 25 to 930°C, respectively.