CRITICAL-CURRENT DENSITIES IN NEUTRON-IRRADIATED TI2CA2BA2CU3O10 SINGLE-CRYSTALS

A Tl2Ca2Ba2Cu3O10 single crystal with a transition temperature of 117. 5 K was subjected to fast neutron irradiation to fluences of 2.10(21), 4.10(21), 8.10(21), and 1.6.10(22) m(-2) (E>0.1 MeV). The superconduc ting transition temperatures T-c, the hysteresis loops and the irrever sibility lines were measured before and after each irradiation step. T he critical current densities J(c) were calculated from the magnetizat ion loops using an anisotropic Bean model. With increasing fluence we find a decrease of T-c, as observed in YBCO-123 and other high tempera ture superconductors, and an increase of J(c). The irreversibility lin e is shifted to higher fields and temperatures.