Structure and radiation effect of Er-stuffed pyrochlore Er2(Ti2−xErx)O7−x/2 (x = 0–0.667)

Abstract

Er-stuffed pyrochlore series Er2(Ti2−xErx)O7−x/2 (x=0, 0.162, 0.286, 0.424 and 0.667) were synthesized using conventional ceramic processing procedures. The structure of Er2(Ti2−xErx)O7−x/2 is effectively tailored by the Er stuffing level (x). In order to study the radiation effect of Er-stuffed pyrochlores, irradiation experiments were performed with 400keV Ne2+ ions to fluences ranging from 5×1014 to 3.0×1015ions/cm2 at cryogenic condition. Irradiation induced microstructural evolution was examined using a grazing incidence X-ray diffraction technique. It is found that the irradiated layer of Er2(Ti2−xErx)O7−x/2 undergoes significant lattice disordering and swelling at fluences of ⩽1.5×1015ions/cm2 and amorphization at fluences of ⩾1.5×1015ions/cm2. The radiation effect depends strongly on the chemical compositions of the samples. Both the lattice swelling percentage and the amorphous fraction decrease with increasing x. The experimental results are discussed in the context of cation antisite defect. The defect formation energy which varies as a function of x is responsible for the difference in the structural behaviors of Er2(Ti2−xErx)O7−x/2 under 400keV Ne2+ ion irradiation.