Oxygen order and charge-transfer mechanism in Zn-doped YBa2Cu3O7-?

The structural and electronic properties of YBa2(Cu1-xZnx)3O7-d have been investigated as a function of d and at 0<=x<=0.05. The oxygen-deficient compounds were obtained with the low-temperature Zr-gettering technique. It was found that the structural characteristics and anomalies, and the oxygen-ordering phenomena, observed in undoped YBa2Cu3O7-d, also occur in Zn-doped compounds at the same oxygen concentration, although they are not related to the corresponding electronic features. This seems to suggest that the charge-transfer mechanism, controlling Tc in pure YBa2Cu3O7-d, is modified by the presence of Zn.