Analysis of the relation between structure and the superconducting transition in YBa2Cu3O∼7

Abstract
It is shown that in the high-Tc YBa2 Cu3 O∼7 superconductor the critical temperature is a function of the orthorhombic distortion (b–a)/a of the unit cell. From the extrapolation of the (b - a)/a ratio against Tc , a maximum critical temperature of 66 K for the tetragonal phase of YBa2 Cu3 O∼7 was predicted. From the correlation between the transition width δTc and the orthorhombic distortion there was deduced an upper limit for Tc , in the orthorhombic phase of YBa2 Cu3 O∼7 of 94·5K.