Phase transition in the electron subsystem of high-Tc YBa₂Cu₃O₇

Abstract

Time-dependent XRD and resistivity data on the orthorhombic high-Tc (T_c≥90K) YBa₂Cu₃O₇ (123) phase at the low temperature transformation YBa₂Cu₃O₇→YBa₂Cu₄O₈ (124) are presented. This transformation is accompanied by the phase separation of mother’s 123 structure into two 123 structures. We analyse the difference in the tructures and the electrophysical features of these two phases and reveal that two qualitatively different HTS states of the electron subsystem may exist in the orthorhombic 123 structure as function of the type and a degree of its cation subsystem imperfection.