Electronic behavior of oxygen-deficientYBa2Cu3O7−δ

Abstract

We have measured the resistivity, Meissner effect, and neutron powder diffraction on a series of samples of $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ quenched into liquid nitrogen from temperatures between 400 and 900°C in order to study the dependence of the electronic and structural properties on oxygen content. The normal-state resistivity is linear only for samples with high superconducting transition temperatures, becoming concave upward for samples with low $T_c$, and semiconducting for nonsuperconducting samples quenched from high temperatures. Structural analysis shows dramatic movements of the bridging oxygen atom [O(4)] and the copper atom [Cu(2)] in the two-dimensional planes as the oxygen stoichiometry is reduced.