Physica Status Solidi a-Applied Research
The dc field dependencies of the ac susceptibility X'' have been studied in polycrystalline samples of YBa2+xCu3O7-y with x-values ranging from 0 to 0.2. Data on X'' versus T show the expected intergranular coupling peak at the temperature T-p. For a specific dc field T-p is found to increase with x varying from 0 to 0.10, and to decrease sharply at x > 0.10. Moreover, the transport critical current density J(ct) of samples increases with x up to 0.10. According to this evidence it can be concluded that a certain excess of barium in YBa2+xCu3O7-y improves the weak links at grain boundaries.
关键词:
high-temperature superconductors
