Study of the radiation disordering mechanisms of AlN ceramic structure as a result of helium swelling

In this work, using X-ray diffraction patterns recording method in a scan phi = 0 degrees-360 degrees, the kinetics of changes in geometry of crystallites, as well as crystal lattice deformation along the a and c axes of aluminum nitride ceramic as a result of helium swelling, is shown. The degradation kinetics of AlN ceramic was modeled by irradiation with low-energy He2+ ions (40 keV) with radiation doses of 10(16)-10(18) ion/cm(2). The choice of energies, doses and type of ions is due to the possibility of modeling the processes of helium swelling and subsequent destruction of the near-surface layer up to 0.5 mu m thick. During the experiments, it was shown that the main structural distortions occur at doses above 10(17) ions/cm(2) and are associated with the occurrence of anisotropy of the form of crystallites, as well as deformation of the crystal lattice along both axes. The anisotropy of the crystallite shape that occurs under large dose irradiation is due to grain crushing processes, the formation of amorphous inclusions in the structure of the near-surface layer, as well as the processes of destruction and subsequent corrosion of the near-surface layer exposed to radiation. It has been found that an increase in radiation dose above 10(17) ion/cm(2) results in a large number of helium bubbles in the structure of the near-surface layer, which led to surface degradation and swelling. At the same time, the results obtained made it possible to assess radiation swelling resistance degree of AlN ceramic during irradiation with helium ions and its subsequent accumulation, which showed that the critical radiation doses causing the irreversible catastrophic nature of structural deformations are doses of 5-7 x 10(17) ions/cm(2).

Automated summary

Using X-ray diffraction patterns, the study investigated the effects of helium swelling on the crystal structure of aluminum nitride ceramics, revealing distortions in crystallite shape and crystal lattice deformation at higher radiation doses, leading to the formation of helium bubbles and surface degradation. The results showed that the critical radiation doses causing irreversible structural deformations are 5-7 x 10(17) ions/cm(2).