Time evolution of copper defects in the mixed phase La0.5Gd0.5Ba2Cu3Oy
Guskos N, Likodimos V, Calamiotou M, Gantis A, Nabialek A, Szymczak H, Wabia M. Time evolution of copper defects in the mixed phase La0.5Gd0.5Ba2Cu3Oy. Radiation Effects and Defects in Solids [Internet]. 1999;151:151-157.
XRD, magnetic and EPR studies of the mixed phase La0.5Gd0.5Ba2Cu3Oy high-Tc superconductor after prolonged (one year) `aging' at room temperature are reported. Within this time period a pronounced change of the superconducting behavior and the homogeneity of the diamagnetic shielding signal accompanied by substantial structural changes, reduction of the impurity phase BaCuO2+x and increase of the EPR spectrum's intensity of Cu2+ magnetic defects is detected. The `aging' effects are related to strain-relaxation taking place during room temperature annealing that induces the formation of Cu2+ defect centers.