OXYGEN ORDERING, PEROXIDE-ION FORMATION, AND POLARIZATION FLUCTUATIONS IN YBA2CU3O7-DELTA

This paper considers four aspects of the oxide system YBa//2Cu//3O//7// minus // delta , 0 less than delta less than equivalent to 1. These are the location of the redox species associated with oxygen intercalation/disintercalation, two types of ordering of the mobile oxygen, peroxide-ion formation between intercalated oxygen in contact at oxidation levels delta less than 0. 5, and how the overlap of partially filled sigma * and pi * bands could give rise to a polarization-fluctuation mechanism for the enhancement of T//c.