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Title: A theoretical study of the stability of anionic defects in cubic ZrO 2 at extreme conditions

Abstract

Using first principles density functional theory calculations, we present a study of the structure, mobility, and the thermodynamic stability of anionic defects in the high-temperature cubic phase of ZrO 2. Our results suggest that the local structure of an oxygen interstitial depends on the charge state and the cubic symmetry of the anionic sublattice is unstable at 0 K. In addition, the oxygen interstitials and the vacancies exhibit symmetry breaking transitions to low-energy structures with tetragonal distortion of the oxygen sublattice at 0 K. However, the vibrational entropy stabilizes the defect structures with cubic symmetry at 2600–2980 K. The formation free energies of the anionic defects and Gibbs free energy changes associated with different defect reactions are calculated by including the vibrational free energy contributions and the effect of pressure on these defect structures. By analyzing the defect chemistry, we obtain the defect concentrations at finite temperature and pressure conditions using the zero temperature ab initio results as input and find that at low oxygen partial pressures, neutral oxygen vacancies are most dominant and at high oxygen partial pressures, doubly charged anionic defects are dominant. As a result, the relevance of the results to the thermal protective coating capabilities ofmore » zirconium-based ceramic composites is elucidated.« less

Authors:
 [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1253684
Report Number(s):
LLNL-JRNL-681102
Journal ID: ISSN 0022-2461
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Materials Science
Additional Journal Information:
Journal Volume: 51; Journal Issue: 10; Journal ID: ISSN 0022-2461
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Samanta, Amit. A theoretical study of the stability of anionic defects in cubic ZrO2 at extreme conditions. United States: N. p., 2016. Web. doi:10.1007/s10853-016-9788-8.
Samanta, Amit. A theoretical study of the stability of anionic defects in cubic ZrO2 at extreme conditions. United States. doi:10.1007/s10853-016-9788-8.
Samanta, Amit. Fri . "A theoretical study of the stability of anionic defects in cubic ZrO2 at extreme conditions". United States. doi:10.1007/s10853-016-9788-8. https://www.osti.gov/servlets/purl/1253684.
@article{osti_1253684,
title = {A theoretical study of the stability of anionic defects in cubic ZrO2 at extreme conditions},
author = {Samanta, Amit},
abstractNote = {Using first principles density functional theory calculations, we present a study of the structure, mobility, and the thermodynamic stability of anionic defects in the high-temperature cubic phase of ZrO2. Our results suggest that the local structure of an oxygen interstitial depends on the charge state and the cubic symmetry of the anionic sublattice is unstable at 0 K. In addition, the oxygen interstitials and the vacancies exhibit symmetry breaking transitions to low-energy structures with tetragonal distortion of the oxygen sublattice at 0 K. However, the vibrational entropy stabilizes the defect structures with cubic symmetry at 2600–2980 K. The formation free energies of the anionic defects and Gibbs free energy changes associated with different defect reactions are calculated by including the vibrational free energy contributions and the effect of pressure on these defect structures. By analyzing the defect chemistry, we obtain the defect concentrations at finite temperature and pressure conditions using the zero temperature ab initio results as input and find that at low oxygen partial pressures, neutral oxygen vacancies are most dominant and at high oxygen partial pressures, doubly charged anionic defects are dominant. As a result, the relevance of the results to the thermal protective coating capabilities of zirconium-based ceramic composites is elucidated.},
doi = {10.1007/s10853-016-9788-8},
journal = {Journal of Materials Science},
number = 10,
volume = 51,
place = {United States},
year = {2016},
month = {2}
}

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