Structural Changes Accompanying the Low-Temperature Annealing of YBa2Cu3O7-δ (0.3 ≤ δ ≤ 0.4) : Transformation of the 123 Phase to a 124-Type Structure

Abstract

Superconducting YBa2Cu3O7-δ (0.3 ≤ δ ≤ 0.4) compositions seem to transform to a metastable YBa2Cu4O8 (124)-like phase with a c parameter of 27.2 Å on annealing at 473 K for a few hours.