TEM observation of neutron-induced collision cascades in Bi-2212 single crystals

Several high-quality single crystals of the superconductor Bi2Sr2CaCu2O8 (Bi-2212) were exposed to three different neutron fluences in the central irradiation facility of the Triga Mark II reactor in Vienna in the form of pre-prepared and pre-characterized transmission electron microscopy (TEM) samples as well as in full crystalline form. We find that the radiation damage produced in Bi-2212 is very similar to that found previously in YBa2Cu3O7-delta (Y-123) single crystals. The diameter of the amorphous cascade volume is 3.5 nm, the inwardly directed strain field is of approximately the same size, the density of cascades is 3.7 x 10(22) m(-3) per 10(22) neutrons m(-2) (E > 0.1 MeV) and their concentration scales linearly with neutron fluence. Based on these results and in view of the similar displacement cross-sections of the constituents of other high temperature superconductors, we conclude that the neutron-induced defects in high-T-c materials will generally have a diameter (including the strain field) of 5-7 nm. (C) 1998 Elsevier Science B.V.