Radiation damage effects in δ-Sc4Zr3O12 irradiated with Kr2+ ions under cryogenic conditions

Abstract

Radiation damage effects in polycrystalline pellets of the oxide Sc4Zr3O12 irradiated with 300keV Kr2+ ions were studied by combining grazing incidence X-ray diffraction (GIXRD) with transmission electron microscopy (TEM). Kr2+ ion irradiations were performed to a maximum fluence of 3×1020Krm−2 at cryogenic temperature (100K). GIXRD and cross-sectional TEM observations revealed that the crystal structure of the irradiated Sc4Zr3O12 was unchanged by irradiation to a dose of ∼23 displacements per atom (dpa). However, by a dose of ∼70dpa, much of the irradiated Sc4Zr3O12 experienced an order-to-disorder transformation. The structure of pristine Sc4Zr3O12 possesses rhombohedral symmetry and is referred to as the delta (δ) phase. However, this rhombohedral structure is closely related to the cubic fluorite structure. Following high dose ion irradiation the δ-Sc4Zr3O12 experienced a rhombohedral-to-cubic transformation. This transformation is discussed in terms of a new, layered atom description for compounds with the δ-Sc4Zr3O12 structure.