The irradiation effects of Gd2Hf2O7 and Gd2Ti2O7

In this report, we present dramatically different behavior between isostructural Gd2Hf2O7 and Gd2Ti2O7 pyrochlore using 400 keV Ne2+ irradiation under cryogenic conditions (similar to 77 K), in which the lattice volume of the irradiated layer of Gd2Ti2O7 increased with ion fluence up to 1 x 10(15) ions/cm(2), whereas, the lattice volume of the irradiated layer of Gd2Hf2O7 decreased with increasing fluence from 1 x 10(15) to 6 x 10(16) ions/cm(2). The cation radius ratio r(A)/r(B), the bond-type of A-O and B-O bonds, the order-to-disorder transition energy of Gd2Hf2O7 and Gd2Ti2O7, temperature-composition (T-C) phase diagrams of HfO2-Gd2O3 and TiO2-Gd2O3 mixtures were used to explain the response of Gd2Hf2O7 and Gd2Ti2O7 to ion irradiation-induced structure transformation. (C) 2012 Elsevier B.V. All rights reserved.