Effect of HCl on the normal magnetic susceptibility of YBa2Cu3O/sub 7-//sub δ/

Normal static magnetic-susceptibility measurements have been carried out for the high-T/sub c/ superconductor YBa2Cu3O/sub 7-//sub δ/ which was annealed at temperatures between 100 and 500 0C in the presence of HCl gas at a pressure of 100 Torr. The magnetic susceptibility data strongly depend on the change in the proportion of Cu/sup 2+/ to Cu/sup 3+/ during the reaction of YBa2Cu3O/sub 7-//sub δ/ with HCl. The Curie-Weiss susceptibility arises from the localized Cu/sup 2+/ spins and the Pauli paramagnetic susceptibility arises from conduction electrons in Cu/sup 3+/ states. These data can be interpreted in terms of the two-dimensional ordering of oxygen-vacancy sites in the one-dimensional chains in CuO layers. The one-dimensional chains have a stoichiometry of Cu3+/sub 1-//sub x/Cu2+/sub x/O/sub 1-//sub x//sub /2/ with δ = x/2