LOW-DOSE IRRADIATION EFFECTS PRODUCED BY 14 MEV NEUTRONS IN DIFFERENTQUALITY Y-BASED AND TL-BASED HIGH-T(C) CERAMICS

Various changes in the microwave absorption signals of irradiated samp les of different quality YBa2Cu3O7 and Tl2CaBa2Cu2O8 target materials by low-dose (10(14) n/cm2) monoenergetic neutrons have been observed a nd studied. The irradiation induced changes of the shape of microwave absorption lines together with transport measurements show that the lo w-dose irradiation in poor quality samples increases, while in good qu ality ones, decreases the superconducting volume fraction. Low quality (non-percolative) samples are more sensitive to irradiation than the high quality ones. These observations indicate that the consequences o f irradiation are determined mainly by the preirradiation structure of the samples.