Abstract
Abstract The paper presents the results of a study of the formation and evolution of radiation defects under the irradiation of nuclear materials based on beryllium oxide with the heavy ions Ni12+. The irradiation with 100-MeV Ni12+ ions was carried out on a DC-60 accelerator, and the irradiation fluence was 1013–1014 ion/cm2. It has been established that the crystal lattice parameter changed insignificantly at low irradiation fluences typical of the formation of single defects. An increase in the irradiation fluence led to a sharp change in the parameter value and a root-mean-square displacement of atoms from lattice sites due to an increase in the concentration of distortions in the structure. It has been found that the magnitude of the displacements of atoms from lattice sites exponentially changed due to the occurrence of defect overlap areas at a fluence (1014 ion/cm2) with the subsequent formation of a large number of migrating defects, which lead to crystal structure distortion and deformation, because of the rupture of chemical bonds in the structure.