High-temperature order-disorder phase transition in the superconductor Y1Ba2Cu3O6+δ observed by electrical resistivity measurements

Abstract

The order-disorder transition involving oxygen atoms and vacancies in the Cu-O basal planes of the superconductor ${\mathrm{Y}}_1{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6+\delta }$ was studied under several oxygen partial pressures. The transition is second order in nature, shows small hysteresis probably due to twin boundary kinetics, and always occurs at the same oxygen concentration. The average site energy for an oxygen atom in the lattice is -3.41 eV. No superconductivity is found for a fully disordered sample.