Irradiation-Induced Amorphization and Order-DisorderTransformation in the Tungsten 8-phase Oxides Yb6W1O12and Y6W1012

摘要

Polycrystalline Yb6W1012 and Y6W1012 samples, which possess rhombohedral symmetry (structure knownas the 8-phase, closely related to cubic fluorite structure), were irradiated with 280 keV Kr++ ions to fluences up to2x1020 ions/m2 at cryogenic temperature (100 K). Ion irradiation damage effects in these samples were examined usinggrazing incidence X-ray diffraction (GIXRD) and cross-sectional transmission electron microscopy (TEM).Irradiation-induced amorphization in both compounds has been observed by GIXRD and TEM, while theamorphization dose for Yb6W1012 is lower than that for Y6W1012. Experimental results also revealed that bothirradiated samples experience an ordered rhombohedral to disordered cubic fluorite (0-D) transformation beforeamorphization. Factors influencing the irradiation damage response of these two compounds will be discussed in termsof cation radius ratio and cation antisite formation energy calculated by density functional theory (DFT).