COLLISION CASCADE PROGRESS IN THE ORTHO-I AND ORTHO-II PHASES OF YBACUO

Computer simulation studies of collision cascade development in the or tho-I, ortho-II and tetragonal phases of the YBCO system after fast pa rticle irradiation are presented. The results of the computer simulati on show clearly that the sizes of the post-cascade defect regions as w ell as the defect forming power of cascades increase with increasing o xygen deficiency. This allows us to explain the different response of the ortho-I and the ortho-II phases to neutron irradiation observed in YBCO ceramics.