Radiation effects on the T-c of bi-system superconductors by proton and gamma irradiation

Bi-system superconductors, prepared by the solid state reaction method and the nitrate method, were irradiated by 20 MeV protons and gamma-rays produc ed by nuclear reaction. The T-c0 and gamma-ray intensity were measured with the time after irradiation. The T-c0 increases on the gamma-ray irradiatio n, then the T-c0 decreases gradually with the gamma decay. The results indi cate that there are two competitive effects on the specimen's T-c0 during g amma irradiation. One is the coupling of excited electrons and holes to the superconductive carriers (such as Cooper-pairs) in which the energy gap is higher than normal one and induces the T-c0 to increase. The other is the defects produced by the irradiation, which induced the T-c0 to decrease. Th e proton irradiation causes the T-c0 to decrease monotonously. (C) 2000 Els evier Science B.V. All rights reserved.