کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1681056 | 1518693 | 2014 | 6 صفحه PDF | دانلود رایگان |
Both experimental approach and atomistic simulations are performed in order to investigate the influence of the composition of pyrochlores on their radiation tolerance. Therefore, Gd2Ti2O7 and Gd2Zr2O7 were irradiated with 4 MeV Au and 92 MeV Xe ions in order to study the structural changes induced by low and high-energy irradiations. XRD results show that, for both irradiations, the structural modifications are strongly dependent on the sample composition: Gd2Ti2O7 is readily amorphized, whereas Gd2Zr2O7 is transformed into a radiation-resistant anion-deficient fluorite structure. Using atomistic simulations with new interatomic potentials derived from the SMTB-Q model, the lattice properties and the defect formation energies were calculated in Gd2Ti2O7 and Gd2Zr2O7. Calculations show that titanates have a more covalent character than zirconates. Moreover, in Gd2Ti2O7 the formation of cation antisite defects leads to strong local distortions around Ti-defects and to a decrease of the Ti coordination number, which are not observed in Gd2Zr2O7. Thus, the radiation resistance is related to the defect stability: the accumulation of structural distortions around Ti-defects could drive the Gd2Ti2O7 amorphization induced by irradiation.
Journal: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms - Volume 326, 1 May 2014, Pages 228–233