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

In this study, an ab initio molecular dynamics method is employed to study low energy recoil events in zirconate pyrochlores (A2Zr2O7, A=La, Nd and Sm). It shows that both cations and anions in Nd2Zr2O7 and Sm2Zr2O7 are generally more likely to be displaced than those in La2Zr2O7. The damage end sta...

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Bibliographic Details
Published in:Acta materialia 2015-04, Vol.87, p.273-282
Main Authors: Xiao, H.Y., Weber, W.J., Zhang, Y., Zu, X.T.
Format: Article
Language:English
Subjects:
Anions
Cations
Charge transfer
Computer simulation
Defects
Low energy
MATERIALS SCIENCE
Molecular dynamics
Pyrochlores
RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
Radiation effects
Simulation
Zirconate pyrochlores
Zirconates
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Summary:In this study, an ab initio molecular dynamics method is employed to study low energy recoil events in zirconate pyrochlores (A2Zr2O7, A=La, Nd and Sm). It shows that both cations and anions in Nd2Zr2O7 and Sm2Zr2O7 are generally more likely to be displaced than those in La2Zr2O7. The damage end states mainly consist of Frenkel pair defects, and the Frenkel pair formation energies in Nd2Zr2O7 and Sm2Zr2O7 are lower than those in La2Zr2O7. These results suggest that the order-disorder structural transition more easily occurs in Nd2Zr2O7 and Sm2Zr2O7 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.
ISSN:1359-6454
1873-2453
DOI:10.1016/j.actamat.2015.01.019