ACTIVATED BEHAVIOR OF THE PHASE-SEPARATION IN LA2CUO4+DELTA

Investigation of the recovery of superconductivity by controlled annea ling and equlibration experiments in La2CuO4+delta samples quenched fr om room temperature to temperatures below the phase-separation tempera ture provides a tool to investigate time constants and activation ener gies governing phase separation in La2CuO4+delta. A series of differen t annealing experiments on ceramic samples of La2CuO4+delta (0.01 less than or equal to delta less than or equal to 0.04) is analyzed quanti tatively and activation energies determining the phase formation are e xtracted. We identify two separate activated processes between 150 and 250 K with activation energies of 0.36 (2) and 0.46 (3) eV which we a ttribute to activated interstititial oxygen atom or vacancy migration.