Effect of /spl gamma/-irradiation on silver-sheathed Bi/sub 1.6/Pb/sub 0.4/Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ tapes

Specimens with nominal composition Bi/sub 1.6/Pb/sub 0.4/Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10/ were prepared using the powder-in tube technique. The effect of /spl gamma/-irradiation at room temperature on the superconducting properties have been investigated using x-ray diffraction, resistivity measurements and I-V characteristics. The intensities of the main diffraction peaks decrease by about 25%, however, the peak positions do not change with /spl gamma/-irradiation up to a dose of 400 MR. The normal state resistance R(T) increases gradually up to a dose of 100 MR, whereas at higher doses, the effect of irradiation becomes rather negligible. The transition temperature T/sub c/ decrease slightly and the transition temperature width /spl Delta/T broadens at doses below 100 MR with almost no change at higher doses up to 400 MR. At relatively low magnetic fields and low /spl gamma/ doses, the critical current densities J/sub c/(B) increase with /spl gamma/-irradiation, while the effect of /spl gamma/-irradiation at relatively high magnetic fields is hardly observable. These results are discussed and explained in terms of the effect of /spl gamma/-rays on the weak links grain boundaries and Josephson junctions between the grains.