Bi_(2)Sr_(2)CaCu_(2)O_(y) single crystals were air-annealed at 300,400,600 and 750℃ for 20h in consequence.Measurements of ac susceptibility and x-ray diffraction showed that at annealing temperature below 400℃,the ...Bi_(2)Sr_(2)CaCu_(2)O_(y) single crystals were air-annealed at 300,400,600 and 750℃ for 20h in consequence.Measurements of ac susceptibility and x-ray diffraction showed that at annealing temperature below 400℃,the change of Tc was dominated by oxygen-diffusion involved in pervoskite unit and was strongly sample-dependent.This diffusion from pervoskite unit occurred earlier than that from Bi-O layers.At annealing temperature over 400℃,with the intercalation of excess oxygen into Bi-O layers,the hole concentration in the crystal was redistributed so that Bi-O reservoir fully determined superconductivity.From the changes of non-uniform strain in annealing process,it was found that structural modification was also closely correlated to superconductivity.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.59425008the NationalCenter for Research&Development on Superconductivity under Grant No.AJ103.
文摘Bi_(2)Sr_(2)CaCu_(2)O_(y) single crystals were air-annealed at 300,400,600 and 750℃ for 20h in consequence.Measurements of ac susceptibility and x-ray diffraction showed that at annealing temperature below 400℃,the change of Tc was dominated by oxygen-diffusion involved in pervoskite unit and was strongly sample-dependent.This diffusion from pervoskite unit occurred earlier than that from Bi-O layers.At annealing temperature over 400℃,with the intercalation of excess oxygen into Bi-O layers,the hole concentration in the crystal was redistributed so that Bi-O reservoir fully determined superconductivity.From the changes of non-uniform strain in annealing process,it was found that structural modification was also closely correlated to superconductivity.
