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Title: Dissociated vacancies and screw dislocations in MgO and UO 2: atomistic modeling and linear elasticity analysis

Abstract

Understanding the effect of dislocations on the mass transport in ionic ceramics is important for understanding the behavior of these materials in a variety of contexts. In particular, the dissociated nature of vacancies at screw dislocations, or more generally, at a wide range of low-angle twist grain-boundaries, has ramifications for the mechanism of defect migration and thus mass transport at these microstructural features. In this paper, a systematic study of the dissociated vacancies at screw dislocations in MgO is carried out. The important role of stress migration in the atomistic modeling study is identified. Another aspect of the current work is a rigorous treatment of the linear elasticity model. As a result, good agreement between the atomistic modeling results and the linear elasticity model is obtained. Furthermore, we demonstrate that the proposed vacancy dissociation mechanism can also be extended to more complicated ionic ceramics such as UO 2, highlighting the generality of the mechanism.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1511623
Report Number(s):
LA-UR-18-31444
Journal ID: ISSN 2045-2322
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING

Citation Formats

Liu, Xiang -Yang, Martinez, Enrique, and Uberuaga, Blas P. Dissociated vacancies and screw dislocations in MgO and UO2: atomistic modeling and linear elasticity analysis. United States: N. p., 2019. Web. doi:10.1038/s41598-019-42926-z.
Liu, Xiang -Yang, Martinez, Enrique, & Uberuaga, Blas P. Dissociated vacancies and screw dislocations in MgO and UO2: atomistic modeling and linear elasticity analysis. United States. doi:10.1038/s41598-019-42926-z.
Liu, Xiang -Yang, Martinez, Enrique, and Uberuaga, Blas P. Wed . "Dissociated vacancies and screw dislocations in MgO and UO2: atomistic modeling and linear elasticity analysis". United States. doi:10.1038/s41598-019-42926-z. https://www.osti.gov/servlets/purl/1511623.
@article{osti_1511623,
title = {Dissociated vacancies and screw dislocations in MgO and UO2: atomistic modeling and linear elasticity analysis},
author = {Liu, Xiang -Yang and Martinez, Enrique and Uberuaga, Blas P.},
abstractNote = {Understanding the effect of dislocations on the mass transport in ionic ceramics is important for understanding the behavior of these materials in a variety of contexts. In particular, the dissociated nature of vacancies at screw dislocations, or more generally, at a wide range of low-angle twist grain-boundaries, has ramifications for the mechanism of defect migration and thus mass transport at these microstructural features. In this paper, a systematic study of the dissociated vacancies at screw dislocations in MgO is carried out. The important role of stress migration in the atomistic modeling study is identified. Another aspect of the current work is a rigorous treatment of the linear elasticity model. As a result, good agreement between the atomistic modeling results and the linear elasticity model is obtained. Furthermore, we demonstrate that the proposed vacancy dissociation mechanism can also be extended to more complicated ionic ceramics such as UO2, highlighting the generality of the mechanism.},
doi = {10.1038/s41598-019-42926-z},
journal = {Scientific Reports},
number = 1,
volume = 9,
place = {United States},
year = {2019},
month = {4}
}

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