Magnetic, X-ray diffraction and electron paramagnetic resonance studies were made of a Cu3Ba2La0.5Gd0.5Oy high-temperature superconductor after annealing for 1 year at room temperature. During this time, appreciable structural changes occurred. These included an increase in the electron paramagnetic resonance spectrum intensity of Cu2+ magnetic defects. This was attributed to a strain-relaxation which took place during room-temperature annealing and induced the formation of such defect centres.

Time Evolution of Copper Defects in the Mixed Phase. N.Guskos, V.Likodimos, M.Calamiotou, A.Gantis, A.Nabialek, H.Szymczak, M.Wabia: Radiation Effects and Defects in Solids, 1999, 151[1-4], 963-9