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Title: Evidence for percolation diffusion of cations and reordering in disordered pyrochlore from accelerated molecular dynamics

Diffusion in complex oxides is critical to ionic transport, radiation damage evolution, sintering, and aging. In complex oxides such as pyrochlores, anionic diffusion is dramatically affected by cation disorder. However, little is known about how disorder influences cation transport. Here, we report results from classical and accelerated molecular dynamics simulations of vacancy-mediated cation diffusion in Gd 2Ti 2O 7 pyrochlore, on the microsecond timescale. We find that diffusion is slow at low levels of disorder, while higher disorder allows for fast diffusion, which is then accompanied by antisite annihilation and reordering, and thus a slowing of cation transport. Cation diffusivity is therefore not constant, but decreases as the material reorders. We also show that fast cation diffusion is triggered by the formation of a percolation network of antisites. This is in contrast with observations from other complex oxides and disordered media models, suggesting a fundamentally different relation between disorder and mass transport.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ;  [1] ;  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-16-25519
Journal ID: ISSN 2041-1723
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); LANL Laboratory Directed Research and Development (LDRD) Program
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; Material Science
OSTI Identifier:
1402615

Perriot, Romain, Uberuaga, Blas P., Zamora, Richard J., Perez, Danny, and Voter, Arthur F.. Evidence for percolation diffusion of cations and reordering in disordered pyrochlore from accelerated molecular dynamics. United States: N. p., Web. doi:10.1038/s41467-017-00708-z.
Perriot, Romain, Uberuaga, Blas P., Zamora, Richard J., Perez, Danny, & Voter, Arthur F.. Evidence for percolation diffusion of cations and reordering in disordered pyrochlore from accelerated molecular dynamics. United States. doi:10.1038/s41467-017-00708-z.
Perriot, Romain, Uberuaga, Blas P., Zamora, Richard J., Perez, Danny, and Voter, Arthur F.. 2017. "Evidence for percolation diffusion of cations and reordering in disordered pyrochlore from accelerated molecular dynamics". United States. doi:10.1038/s41467-017-00708-z. https://www.osti.gov/servlets/purl/1402615.
@article{osti_1402615,
title = {Evidence for percolation diffusion of cations and reordering in disordered pyrochlore from accelerated molecular dynamics},
author = {Perriot, Romain and Uberuaga, Blas P. and Zamora, Richard J. and Perez, Danny and Voter, Arthur F.},
abstractNote = {Diffusion in complex oxides is critical to ionic transport, radiation damage evolution, sintering, and aging. In complex oxides such as pyrochlores, anionic diffusion is dramatically affected by cation disorder. However, little is known about how disorder influences cation transport. Here, we report results from classical and accelerated molecular dynamics simulations of vacancy-mediated cation diffusion in Gd2Ti2O7 pyrochlore, on the microsecond timescale. We find that diffusion is slow at low levels of disorder, while higher disorder allows for fast diffusion, which is then accompanied by antisite annihilation and reordering, and thus a slowing of cation transport. Cation diffusivity is therefore not constant, but decreases as the material reorders. We also show that fast cation diffusion is triggered by the formation of a percolation network of antisites. This is in contrast with observations from other complex oxides and disordered media models, suggesting a fundamentally different relation between disorder and mass transport.},
doi = {10.1038/s41467-017-00708-z},
journal = {Nature Communications},
number = ,
volume = 8,
place = {United States},
year = {2017},
month = {9}
}