Point defect chemistry of YBa2Cu3O6.5+δ

A novel mathematical approach for defect concentration calculations proposed by Poulsen [F.W. Poulsen, Solid State Ionics, 129 (2000) 145] for oxides with rather small deviations from stoichiometry also applies to perovskite-type oxides with large ranges of oxygen nonstoichiometry. Point defect chemistry calculations have been performed for YBa 2 Cu 3 O 6.5 + δ for which experimental equilibrium oxygen partial pressure isotherms are well known. The model applied in this work describes experimental results very well in the p O 2 range of 1 0 − 5 to 10  bar and for temperatures between 450 and 800  ° C.