Solid-state diffusion in amorphous zirconolite

Yang, Chunlei; Zarkadoula, Eva; Dove, Martin T.; Todorov, Ilian T.; Geisler, T.; Бражкин, В. В.; Trachenko, Kostya

doi:10.1063/1.4901326

Cited by 4 publications

(4 citation statements)

References 26 publications

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“…While computational studies of radiation damage are quite common, the application of atomic‐scale simulation methodology has generally focused on either elemental metals or semiconductors [ Stoller , ]. Recently, there have been significant efforts to use atomic‐scale simulation to study the evolution of radiation damage in binary and more complex oxides including MgO [ Aidhy et al , ], UO 2 [ Aidhy et al , ], CeO 2 [ Aidhy et al , ], ZrO 2 [ Zarkadoula et al , ], and ZrCaTi 2 O 7 [ Yang et al , ]. The general picture which has emerged is that radiation damage generates Frenkel defects (interstitial‐vacancy pairs), although more severe damage can lead to amorphization [ Golubov , ].…”

Section: Introductionmentioning

confidence: 99%

Atomic‐scale simulation of space weathering in olivine and orthopyroxene

Quadery

Pacheco

et al. 2015

JGR Planets

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(2015), Atomic-scale simulation of space weathering in olivine and orthopyroxene, J. Geophys. Res. Planets, 120, 643-661, doi:10.1002 Abstract Classical molecular dynamics was used to study the annealing of anion and cation Frenkel defects in olivine and orthopyroxene minerals. While it was found that for both minerals, reorganization of the Si-O bonds, often accompanied by large Si displacements, occurs to maintain the fourfold coordination of the SiO 4 tetrahedra, important differences are observed in their annealing behavior. Specifically, cation defects are substantially more mobile in olivine than in orthopyroxene leading to rapid annihilation of cation Frenkel defects and formation of extended defects in olivine. By contrast, the diffusion rate of anion defects in orthopyroxene is much higher than that in olivine and also exhibits large anisotropy. Consequently, it was found that diffusion in orthopyroxene occurs without significant annihilation of anion Frenkel defects or trapping of anion interstitials or vacancies into clusters. The results obtained here are discussed in the context of space weathering of olivine and orthopyroxene. Specifically, two important observations are made which may explain previous experimental results. First, ion irradiation experiments that show reduced tolerance for radiation damage in orthopyroxene may be explained by the rapid, one-dimensional anion mobility which prevents healing of the lattice. Second, laser heating experiments which show that orthopyroxene has enhanced tolerance to reduction and the evolution of nanophase Fe inclusions could be due to the observed rapid anion diffusion in orthopyroxene, which might allow the bulk to act as a reservoir for the surface.

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Section: Introductionmentioning

confidence: 99%

Atomic‐scale simulation of space weathering in olivine and orthopyroxene

Quadery

Pacheco

et al. 2015

JGR Planets

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“…As well as continual change to the local PDFs a continued increase in the number of coordination defects was also observed in the overlapped damaged region. The persistence of PDF peaks at the cations' crystalline peak positions have been also observed in amorphous zirconolite 29 . We will return to this point below when we discuss the variation of activation energies with the degree of introduced disorder.…”

Section: A Diffusion In Zirconmentioning

confidence: 62%

Radiation damage effects on helium diffusion in zircon

Diver,

Dicks,

Elena

et al. 2021

Preprint

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We report the effects of radiation damage on helium diffusion in zircon using data from molecular dynamics simulations. We observe an increase in activation energy for helium diffusion as a result of radiation damage and increasing structural disorder. The activation energy in a heavily damaged region is smaller than in a completely amorphous system which is correlated with remaining order in the cation sublattices of the damaged structure not present in the fully amorphized system. The reduction of activation energy is related to the disappearance of fast diffusion pathways that present in the crystal. Consistent with the change in activation energy, we observe the accumulation of helium atoms in the damaged structure and discuss the implications of this effect for the formation of helium bubbles and zircon's performance as an encapsulation material for nuclear waste.

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“…As well as continual change to the local PDFs a continued increase in the number of coordination defects was also observed in the overlapped damaged region. The persistence of PDF peaks at the cations' crystalline peak positions have been also observed in amorphous zirconolite [27]. We will return to this point below when we discuss the variation of activation energies with the degree of introduced disorder.…”

Section: Diffusion In Zirconmentioning

confidence: 72%

Radiation damage effects on helium diffusion in zircon

Diver

Dicks

Elena

et al. 2021

Journal of Materials Research

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We report the effects of radiation damage on helium diffusion in zircon using data from molecular dynamics simulations. We observe an increase in activation energy for helium diffusion as a result of radiation damage and increasing structural disorder. The activation energy in a heavily damaged region is smaller than in a completely amorphous system which is correlated with remaining order in the cation sublattices of the damaged structure not present in the fully amorphized system. The increase in activation energy is related to the disappearance of fast diffusion pathways that are present in the crystal. Consistent with the change in activation energy, we observe the accumulation of helium atoms in the damaged structure and discuss the implications of this effect for the formation of helium bubbles and zircon’s performance as an encapsulation material for nuclear waste. Graphic abstract

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Solid-state diffusion in amorphous zirconolite

Cited by 4 publications

References 26 publications

Atomic‐scale simulation of space weathering in olivine and orthopyroxene

Atomic‐scale simulation of space weathering in olivine and orthopyroxene

Radiation damage effects on helium diffusion in zircon

Radiation damage effects on helium diffusion in zircon

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