Atomic structure of ion tracks in fluorite structure oxides; Comparison with CeO and ZrO

Takaki, Seiya  

Oxide ceramics with fluorite-structure have been studied as advanced nuclear application, so it is important to clarify the irradiation-induced microstructure. Especially, radiation damage induced by fission fragments with 70-100 MeV, induce high-density electronic excitation in the materials to result in forming cylindrical defect, so called ion track. This study aims to clarify and compare with the structure of ion tracks in CeO and cubic ZrO (YSZ) irradiated with swift heavy ions. It was shown that the density of vacancy at the core damage region of ion tracks is increased and the O anion lattice is preferentially disordered at such region. On the other hand, the size and the areal density of ion tracks in YSZ is smaller than those of CeO. The difference of ion tracks between CeO and YSZ is presumably due to the difference in the recovery process from the thermal spike regime, which is influenced by the presence of structural vacancy in oxide sublattice.