Preparation and heavy-ion irradiation effects of Gd2CexZr2−xO7 ceramics

Abstract

A number of compositions with the general stoichiometry of Gd₂Ce_xZr_2−xO₇ (0 ≤ x ≤ 2) ceramics have been synthesized and received irradiation tests at room temperature with Xe²⁰⁺ ions in a broad fluence range. X-ray diffraction (XRD) measurements shows that Gd₂Ce_xZr_2−xO₇ (0 ≤ x ≤ 0.2) samples adopt the pyrochlore structure, whereas Gd₂Ce_xZr_2−xO₇ (0.2 ≤ x ≤ 2.0) samples predominantly displayed an anion deficient fluorite structure, indicating that the structures of Gd₂Ce_xZr_2−xO₇ are determined by the content of doped Ce⁴⁺ ions. XRD results of irradiated samples (Gd₂Zr₂O₇, Gd₂Ce₂O₇) indicate that Gd₂Zr₂O₇ was transformed into a radiation resistant anion deficient fluorite structure with increasing fluence, whereas the Gd₂Ce₂O₇ was partially amorphized. It was found that the structural evolutions induced by irradiation are strongly dependent on the samples composition and ions fluence. In addition, SEM results show that the density and hardness of waste forms play an important role in the morphology modifications induced by irradiation. These results would be considered for design and elaboration of future matrices for actinide immobilization or transmutation.