Positron annihilation and magnetization studies of proton irradiated polycrystalline textured Bi2Sr2CaCu2O8+delta and Bi1.84Pb0.34Sr1.91Ca2.03Cu3.06O10+delta superconductors

Proton irradiations on polycrystalline textured Bi2Sr2CaCu2O8+delta (Bi-221 2) and Bi1.84Pb0.34Sr1.91Ca2.03Cu3.06O10+delta (Bi-2223) samples have been carried out. The irradiation induced defect size increases with dose up to 5x10(15) protons/cm(2) in Bi-2212, but remains effectively constant in Bi-2 223 as revealed from positron Lifetime measurements. Magnetization studies show that at moderate dose, there is no significant change in intergranular critical current density (J(c)(int)) in both systems. But intragranular cr itical current density (J(c)) increases with dose in Bi-2212. A drastic fal l in both J(c)(int) and J(c) is observed at high dose in Bi-2223 as compare d to Bi-2212. (C) 1999 Elsevier Science B.V. All rights reserved.