MICROSTRUCTURAL STUDY OF Y1B2CU3O7-X AG SAMPLES IRRADIATED WITH CO-60GAMMA-RAYS AT HIGH-DOSES/

We have investigated the damage induced by irradiation in Y1Ba2Cu3O7-x silver added samples. The samples were prepared with 0 and 6.5 wt% of silver and irradiated by high-energy gamma irradiation (50-150 Mrad). The roles of silver and dosage irradiation are discussed in terms of their effects on microstructure, crystallinity, critical temperature ( T-c) and zero-resistance temperature (T-0). After irradiation, T-c dec reased while the room-temperature electrical resistance increased by a factor of 8 for some of the samples. The difference in T-0 between ir radiated and non-irradiated YBCO samples was of the order of 10 K. We have found that the difference is bigger for silver-added samples. We have also observed several changes in diffraction patterns of YBCO and YBCO-silver samples. SEM images, EDS and XPS analysis showed that sil ver resided inside the grains as single atoms and as metallic clusters . The relative concentrations of the elements in samples were quantifi ed by Auger electron spectroscopy. The J(c) values showed a gradual in crease for radiation doses ranging between 0 and 100 Mrad. For doses u p to 100 Mrad, J(c) decreased because of the weak-link breakage induce d by high doses of gamma rays.