Temperature effects of defect formation in BeO ceramics during helium blistering

Abstract

The work is devoted to the study of the processes of defect accumulation in the near-surface layer of BeO ceramics associated with irradiation with low-energy He²⁺ ions, as well as to the establishment of the role of temperature effects on changes in thermal conductivity. Identification of the role of temperature effects in acceleration of the processes of distortion and disordering of the near-surface layers is one of the key tasks, the solution of which will allow more accurate prediction of the behavior of materials under extreme conditions combining the effects of high temperatures and radiation damage. During assessment of changes in structural parameters depending on variations in irradiation conditions, anisotropic distortion of the crystal lattice, the degree of deformation of which has a direct relationship with the temperature effect, was established. It has been determined that an increase in the irradiation temperature leads to an acceleration of the processes of accumulation of deformation distortions, the growth of which in the damaged layer leads to a more pronounced destabilization and broadening of the damaged layer depth. Such changes are associated with the acceleration of the diffusion processes of point and vacancy defects, the migration of which leads not only to an increase in deformation distortions and amorphous inclusions, but also to an increase in the damaged layer thickness. During determination of changes in the concentration of vacancy and structural defects in the damaged layer, relationships between the concentration of oxygen vacancies and the degradation of thermal conductivity, the reduction of which is due to an increase in the effects of phonon scattering and a decrease in the rate of heat transfer, were established.