Experimental Insight into the Radiation Resistance of Zirconia-Based Americium Ceramics

Abstract

Our works shows that the americium pyrochlore (241)Am(2)Zr(2)O(7) undergoes a phase transition to a defect-fluorite structure along with an unusual volume contraction when subjected to internal radiation from alpha-emitting actinides. Disorder relaxation proceeds through the simultaneous formation of cation antisites and oxygen Frenkel pairs. X-ray absorption spectroscopy at the Am-L(II) and the Zr-K edges reveals that Am-O polyhedra show an increasing disorder with increasing exposure. In contrast, the Zr-O polyhedral units remain highly ordered, while rotating along edges and corners, thereby reducing the structural strain imposed by the growing disorder around americium. We believe it is this particular property of the compound that provides the remarkable resistance to radiation (>9.4 x 10(18) alpha-decay events g(-1) or 0.80 dpa).

Investigation of NdxY0.25–xZr0.75O1.88 inert matrix fuel materials made by a co-precipitation synthetic route

“…In all cases, the Zr-O scattering path length was found to be 2.16 Å, which is consistent with previously reported results. 24,27,36,60 The Zr-Zr/Y scattering path length was 3.56 Å, which is also in agreement with previously reported results. 24,27,36,60 The Zr-Nd path lengths determined from the EXAFS fit varied from 3.18 to 3.77 Å, depending on composition and annealing temperature.…”

“…24,27,36,60 The Zr-Zr/Y scattering path length was 3.56 Å, which is also in agreement with previously reported results. 24,27,36,60 The Zr-Nd path lengths determined from the EXAFS fit varied from 3.18 to 3.77 Å, depending on composition and annealing temperature. The most significant change occurred when the Nd 0.25 Zr 0.75 O 1.88 material made by co-precipitation was annealed at both 1400 and 1500°C, as the Zr-Nd scattering path decreased from 3.77 to 3.36 Å (Table S1) The spectra from the materials made at 800°C via a co-precipitation method and made at 1500°C via a ceramic method are compared.…”

“…[19][20][21][22] The tetragonal and monoclinic structures are formed by distorting the cubic fluorite structure. [23][24][25][26] The cubic structure can be stabilized by adding an aliovalent cation, and Y 3+ has been commonly used as the dopant ion. 22,[27][28][29][30] The size difference between Y 3+ and Zr 4+ as well as oxygen vacancies generated by charge balancing requirements act to stabilize the fluorite structure.…”

Structural studies of the phase separation in the UO2–PuO2–Pu2O3 ternary system

“…The procedure is described in [35]. XRD measurements of 0.25 6 y 6 0.65 compositions were performed at room temperature with a Bragg-Brentano Bruker D8 X-ray diffractometer with no monochromator (Ka 1 radiation, k = 1.5406 Å and Ka 2 radiation, k = 1.5443 Å), a rotating sample-holder and a LynX'Eye fast counting detector.…”

Structure and performance evolution of the system (Gd1−Nd )2(Zr1−Ce )2O7 (0 ≤x, y≤ 1.0)

“…While recently Gregg et al has shown that Pu can be exchanged for both the A and B site within lanthanum zirconate pyrochlore [17]. As Zhang et al focus on the formation of high actinide valence states during fabrication [18], other teams devotes to the radiation performance and mechanism in A 2 Zr 2 O 7 pyrochlores (A = La, Nd, Sm, Gd, and 241 Am) [4,19]. Moreover, the evaluation and even prediction about radiation damage tolerance properties for systems that contain pyrochlore or fluorite phases have been processed [20,21].…”