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Title: Insights into dynamic processes of cations in pyrochlores and other complex oxides

Abstract

Complex oxides are critical components of many key technologies, from solid oxide fuel cells and superionics to inert matrix fuels and nuclear waste forms. In many cases, understanding mass transport is important for predicting performance and, thus, extensive effort has been devoted to understanding mass transport in these materials. However, most work has focused on the behavior of oxygen while cation transport has received relatively little attention, even though cation diffusion is responsible for many phenomena, including sintering, radiation damage evolution, and deformation processes. Here, we use accelerated molecular dynamics simulations to examine the kinetics of cation defects in one class of complex oxides, A₂B₂O₇ pyrochlore. In some pyrochlore chemistries, B cation defects are kinetically unstable, transforming to A cation defects and antisites at rates faster than they can diffuse. When this occurs, transport of B cations occurs through defect processes on the A sublattice. Further, these A cation defects, either interstitials or vacancies, can interact with antisite disorder, reordering the material locally, though this process is much more efficient for interstitials than vacancies. Whether this behavior occurs in a given pyrochlore depends on the A and B chemistry. Pyrochlores with a smaller ratio of cation radii exhibit this complexmore » behavior, while those with larger ratios exhibit direct migration of B interstitials. Similar behavior has been reported in other complex oxides such as spinels and perovskites, suggesting that this coupling of transport between the A and B cation sublattices, while not universal, occurs in many complex oxide.« less

Authors:
 [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1221616
Report Number(s):
LA-UR-15-24397
Journal ID: ISSN 1463-9076; PPCPFQ
Grant/Contract Number:  
2013LANL8400; AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP
Additional Journal Information:
Journal Volume: 17; Journal Issue: 37; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Uberuaga, Blas Pedro, and Perriot, Romain. Insights into dynamic processes of cations in pyrochlores and other complex oxides. United States: N. p., 2015. Web. doi:10.1039/c5cp03372a.
Uberuaga, Blas Pedro, & Perriot, Romain. Insights into dynamic processes of cations in pyrochlores and other complex oxides. United States. https://doi.org/10.1039/c5cp03372a
Uberuaga, Blas Pedro, and Perriot, Romain. 2015. "Insights into dynamic processes of cations in pyrochlores and other complex oxides". United States. https://doi.org/10.1039/c5cp03372a. https://www.osti.gov/servlets/purl/1221616.
@article{osti_1221616,
title = {Insights into dynamic processes of cations in pyrochlores and other complex oxides},
author = {Uberuaga, Blas Pedro and Perriot, Romain},
abstractNote = {Complex oxides are critical components of many key technologies, from solid oxide fuel cells and superionics to inert matrix fuels and nuclear waste forms. In many cases, understanding mass transport is important for predicting performance and, thus, extensive effort has been devoted to understanding mass transport in these materials. However, most work has focused on the behavior of oxygen while cation transport has received relatively little attention, even though cation diffusion is responsible for many phenomena, including sintering, radiation damage evolution, and deformation processes. Here, we use accelerated molecular dynamics simulations to examine the kinetics of cation defects in one class of complex oxides, A₂B₂O₇ pyrochlore. In some pyrochlore chemistries, B cation defects are kinetically unstable, transforming to A cation defects and antisites at rates faster than they can diffuse. When this occurs, transport of B cations occurs through defect processes on the A sublattice. Further, these A cation defects, either interstitials or vacancies, can interact with antisite disorder, reordering the material locally, though this process is much more efficient for interstitials than vacancies. Whether this behavior occurs in a given pyrochlore depends on the A and B chemistry. Pyrochlores with a smaller ratio of cation radii exhibit this complex behavior, while those with larger ratios exhibit direct migration of B interstitials. Similar behavior has been reported in other complex oxides such as spinels and perovskites, suggesting that this coupling of transport between the A and B cation sublattices, while not universal, occurs in many complex oxide.},
doi = {10.1039/c5cp03372a},
url = {https://www.osti.gov/biblio/1221616}, journal = {Physical Chemistry Chemical Physics. PCCP},
issn = {1463-9076},
number = 37,
volume = 17,
place = {United States},
year = {Wed Aug 26 00:00:00 EDT 2015},
month = {Wed Aug 26 00:00:00 EDT 2015}
}

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Cited by: 17 works
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