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Er-stuffed pyrochlore series Er 2 (Ti 2− x Er x )O 7− x /2 ( x = 0, 0.162, 0.286, 0.424 and 0.667) were synthesized using conventional ceramic processing procedures. The structure of Er 2 (Ti 2− x Er x )O 7− 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 400 keV Ne 2+ ions to fluences ranging from 5 × 10 14 to 3.0 × 10 15 ions/cm 2 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 Er 2 (Ti 2− x Er x )O 7− x /2 undergoes significant lattice disordering and swelling at fluences of ⩽1.5 × 10 15 ions/cm 2 and amorphization at fluences of ⩾1.5 × 10 15 ions/cm 2 . 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 Er 2 (Ti 2− x Er x )O 7− x /2 under 400 keV Ne 2+ ion irradiation. [ABSTRACT FROM AUTHOR]

Abstract: In this report, we present results of an irradiation damage study on a pyrochlore compound, Er2Ti2O7. Polycrystalline Er2Ti2O7 was irradiated with 400keV Ne2+ ions at cryogenic temperature (∼77K) to fluences ranging from 2×1018 to 2×1019 ions/m2. Irradiation-induced microstructural evolution was examined using grazing incidence X-ray diffraction (GIXRD) at angles of γ =0.25° and 3°. It was found that the irradiated Er2Ti2O7 undergoes significant lattice swelling before succumbing to a radiation-induced partial amorphization transformation. Both of the extent of the lattice swelling and the lattice disorder of the Er2Ti2O7 increase with increasing Ne ion fluence prior to partial amorphization. We present here a detailed discussion regarding the nature of the defects responsible for the observed lattice swelling and disorder in Er2Ti2O7. [Copyright &y& Elsevier]

Abstract: We have recently synthesized “stuffed” (i.e., excess Lu) Lu2(Ti2− x Lu x )O7− x /2 (x =0, 0.4 and 0.67) compounds using conventional ceramic processing. X-ray diffraction measurements indicate that stuffing more Lu3+ cations into the oxide structure leads eventually to an order-to-disorder (O–D) transition, from an ordered pyrochlore to a disordered fluorite crystal structure. At the maximum deviation in stoichiometry (x =0.67), the Lu3+ and Ti4+ ions become completely randomized on the cation sublattices, and the oxygen “vacancies” are randomized on the anion sublattice. Samples were irradiated with 400keV Ne2+ ions to fluences ranging from 1×1015 to 1×1016 ions/cm2 at cryogenic temperatures (∼77K). Ion irradiation effects in these samples were examined by using grazing incident X-ray diffraction. The results show that the ion irradiation tolerance increases with disordering extent in the non-stoichiometric Lu2(Ti2− x Lu x )O7− x /2. [Copyright &y& Elsevier]