Abstract:
Given paper presents study results of radiation defect formation and development processes in materials based on beryllium oxide under Ni$^{12+}$ ion irradiation in order to study the possibility of using them as structural materials for nuclear facilities. The irradiation was carried out at the DC-60 accelerator by Ni$^{12+}$ ions with an energy of 100 MeV and irradiation fluence of 10$^{13}$-10$^{14}$ ions/cm$^2$. It is shown that for small irradiation fluences, which are characterized by single defect formation in the structure, the value of crystal lattice parameter varies slightly. An increase in fluence of Ni$^{12+}$ ions determines a sharp change in values of lattice parameter and root-mean-square (rms) atomic displacement from lattice sites, caused by a significant increase in concentration of distortions in the structure. An exponential character of changes in the rms atomic displacements is established, which is explained by formation of defect overlap areas at irradiation fluence of 10$^{14}$ ions/cm$^2$ with following appearance in crystal structure of a huge number of migrating defects inducing distortion and deformation of the structure due to chemical bonds breakage.
