Phase Stability and Pressure Dependence of Defect Formation in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Gd</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Ti</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>7</mml:mn></mml:msub></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Gd</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Zr</mml:mi><mml:m

Zhang, F.X.; Wang, J. W.; Lian, Jie; Lang, Maik; Becker, Udo; Ewing, Rodney C.

doi:10.1103/physrevlett.100.045503

Cited by 121 publications

(103 citation statements)

References 30 publications

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“…It is found that the threshold displacement energies for both cations and anions in La 2 order-disorder transition to form a defect-fluorite structure. Since the defect-fluorite structure is extremely stable under ion-irradiation and structural amorphization cannot be induced, our calculations suggest that Nd 2 Zr 2 O 7 and Sm 2 Zr 2 O 7 are more radiation resistant than La 2 Zr 2 O 7 , which is in good agreement with the experiments.…”

Section: Discussionmentioning

confidence: 97%

“…Zirconate pyrochlores, with the chemical formula A 2 Zr 2 O 7 (where A is a rare earth element), have attracted considerable attention because of their potential use as solid oxide fuel cell electrode materials, fluorescence screens, thermal-barrier coatings, high-temperature heating elements, oxidation catalysts, and refractory ceramic materials for use in magnetohydrodynamic power generation [1][2][3][4][5][6][7][8]. Because they exhibit remarkable resistance to structural amorphization under ion-beam irradiation [6] and high chemical durability (release rates typically <10 À5 g m À2 d À1 based on zirconium) [9], as well as the fact that zirconium has a low neutron absorption cross-section [7], zirconate pyrochlores have also been proposed as inert matrix materials for actinide burning [7,9] and host matrices for high level radioactive waste, especially for long half-life actinides [10].…”

Section: Introductionmentioning

confidence: 99%

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Ab initio molecular dynamics simulations of ion–solid interactions in zirconate pyrochlores

et al. 2015

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In this study, an ab initio molecular dynamics method is employed to study low energy recoil events in zirconate pyrochlores (A 2 Zr 2 O 7 , A = La, Nd and Sm). It shows that both cations and anions in Nd 2 Zr 2 O 7 and Sm 2 Zr 2 O 7 are generally more likely to be displaced than those in La 2 Zr 2 O 7 . The damage end states mainly consist of Frenkel pair defects, and the Frenkel pair formation energies in Nd 2 Zr 2 O 7 and Sm 2 Zr 2 O 7 are lower than those in La 2 Zr 2 O 7 . These results suggest that the order-disorder structural transition more easily occurs in Nd 2 Zr 2 O 7 and Sm 2 Zr 2 O 7 resulting in a defect-fluorite structure, which agrees well with experimental observations. Our calculations indicate that oxygen migration from 48f and 8b to 8a sites is dominant under low energy irradiation. A number of new defects, including four types of cation Frenkel pairs and six types of anion Frenkel pairs, are revealed by ab initio molecular dynamics simulations. The present results may help to advance the fundamental understanding of the irradiation response behavior of zirconate pyrochlores.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Ab initio molecular dynamics simulations of ion–solid interactions in zirconate pyrochlores

et al. 2015

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“…Polycrystalline samples of Gd 2 Ti 2 O 7 and La 2 Ti 2 O 7 were synthesized by a sol-gel method, the details of which have been reported elsewhere [21]. The typical grain size of the samples was several microns, and the measured densities of Gd 2 Ti 2 O 7 and La 2 Ti 2 O 7 were 6.56 g/cm 3 and 5.82 g/ cm 3 , respectively.…”

Section: Methodsmentioning

confidence: 99%

Response of Gd2Ti2O7 and La2Ti2O7 to swift-heavy ion irradiation and annealing

et al. 2015

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Swift heavy ion (2 GeV 181 Ta) irradiation-induced amorphization and temperature-induced recrystallization of cubic pyrochlore Gd 2 Ti 2 O 7 (Fd 3m) are compared with the response of a compositionally-similar material with a monoclinic-layered perovskite-type structure, La 2 Ti 2 O 7 (P2 1 ). The averaged electronic energy loss, dE/dx, was 37 keV/nm and 35 keV/nm in Gd 2 Ti 2 O 7 and La 2 Ti 2 O 7 , respectively. Systematic analysis of the structural modifications was completed using transmission electron microscopy, synchrotron X-ray diffraction, Raman spectroscopy, and small-angle X-ray scattering. Increasing ion-induced amorphization with increasing ion fluence was evident in the X-ray diffraction patterns of both compositions by a reduction in the intensity of the diffraction maxima concurrent with the growth in intensity of a broad diffuse scattering halo. Transmission electron microscopy analysis showed complete amorphization within ion tracks (diameter: $10 nm) for the perovskite-type material; whereas a concentric, core-shell morphology was evident in the ion tracks of the pyrochlore, with an outer shell of disordered yet still crystalline material with the fluorite structure surrounding an amorphous track core (diameter: $9 nm). The radiation response of both titanate oxides with the same stoichiometry can be understood in terms of differences in their structures and compositions. While the radiation damage susceptibility of pyrochlore A 2 B 2 O 7 materials decreases as a function of the cation radius ratio r A /r B , the current study correlates this behavior with the stability field of monoclinic structures, where r La /r Ti > r Gd /r Ti . Isochronal annealing experiments of the irradiated materials showed complete recrystallization of La 2 Ti 2 O 7 at 775°C and of Gd 2 Ti 2 O 7 at 850°C. The annealing behavior is discussed in terms of enhanced damage recovery in La 2 Ti 2 O 7 , compared to the pyrochlore compounds Gd 2 Ti 2 O 7 . The difference in the recrystallization behavior may be related to structural constraints, i.e., reconstructing a low symmetry versus a high symmetry phase.

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“…[31][32][33], and in many other ternary compounds, e.g. CaTiO 3 and A 2 B 2 O 7 compounds [34][35][36][37][38]. Tang et al [31] studied the irradiation response in rare earth sesquioxides and found the phase transformation from cubic phase to the monoclinic phase which is closely related to the temperature.…”

Section: The Formation and Growth Of The Irradiation-induced Fcc Phasementioning

confidence: 97%