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This work is devoted to the study of the effect of irradiation with Kr 15? and Xe 23? heavy ions with energies of 147 and 220 MeV, respectively, on the change in the optical, structural and strength properties of ceramics ZrO 2 . Polycrystalline ZrO 2 ceramics with a tetragonal type of crystal structure, which are highly resistant to external influences, mechanical strength to cracking, and hardness were chosen as the object of research. The choice of heavy ions Kr 15? and Xe 23? is due to the possibility of simulating the effect of nuclear fission fragments in an atomic reactor, and the choice of irradiation doses of 1 9 10 13 -1 9 10 14 ion/cm 2 is due to the possibility of simulating the effects of overlapping defect regions arising along the trajectory of ions in the material. Using the X-ray diffraction method, it was found that in the case of irradiation with heavy ions, an increase in the radiation dose leads to phase transformations of the tetragonal type of the crystal lattice into a cubic one. In this case, for the samples irradiated with Xe 23? ions at an irradiation dose of 1 9 10 14 ion/cm 2 , an almost complete phase transformation is observed. Dependences of changes in strength and optical characteristics on the type of irradiation and dose load have been established.

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The aim of this work was to study the mechanisms of polymorphic transformations in ZrO2 ceramics under irradiation with heavy ions, as well as to determine the nature of structural distortions in the case of t-ZrO2 → c-ZrO2 type transformations and associated anisotropic deformations. The samples of ZrO2 ceramics were irradiated with Kr15+ heavy ions with an energy of 150 MeV and fluences of 1011–1016 ion/cm2. During evaluation of the structural changes depending on the irradiation fluence, it was found that at low irradiation fluences (1011–1012 ion/cm2), the main role is played by deformation distortions of the crystal lattice, which have a pronounced anisotropic character. Meanwhile, at fluences above 1013 ion/cm2, the main role is played by polymorphic transformations of the t-ZrO2 → c-ZrO2 type, followed by amorphization of the damaged layer at fluences above 1015 ion/cm2. It was established that the anisotropic distortion of the crystal lattice is more pronounced along the crystallographic a axis, as well as the (011) texture orientation, which is characteristic of t-ZrO2. The polymorphic transformation processes of the t-ZrO2 → c-ZrO2 type occur at irradiation fluences of 1013–1014 ions/cm2, which are characterized by the formation of an overlap of local areas of defects that appear along the trajectory of ions in the material. The dependences of changes in the strength and thermophysical properties of ZrO2 ceramics on the irradiation fluence were obtained. The mechanisms of influence of the structural disorder and polymorphic transformations on the decrease in strength and crack resistance were established.

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