Oxygen ordering and superconductivity in YBa2Cu3O7-δ

Samples of YBa₂Cu₃O_7-δ in which concentration of oxygen was varied by annealing at different temperatures between 200 and 900C followed by quenching to 77 K have been investigated by carrying out measurements of oxygen stoichiometry, room temperature resistivity, superconductivity and crystal structure. It is shown that the overall oxygen stoichiometry alone does not adequately characterize the superconducting and normal state behaviour;T _c, ΔT _cand room temperature resistivity also vary with the heat treatment conditions. This implies a dependence of the physical properties on the details of the distribution of the oxygen atoms. The results show a definite correlation betweenT _cand resistivity hitherto not reported.