A study of the YxBa1-xCuOy superconductors for 0.3

A series of compositions in the region of the YBa2Cu3O7- delta superconducting phase have been studied exhaustively. These materials show significant changes in the X-ray diffraction line intensities which are closely correlated with variations in both the electrical conductivity and the thermoelectric properties as a function of composition. Evidence exists to suggest that these changes may correspond to a change in the hole concentration with increasing x. It is proposed that these effects are associated with the continuous introduction of yttrium planar stacking faults which automatically compensate for the yttrium-barium imbalance and at the same time generate an increased oxygen concentration.