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Title: Strain effects on oxygen vacancy energetics in KTaO 3

Abstract

Due to lattice mismatch between epitaxial films and substrates, in-plane strain fields are produced in the thin films, with accompanying structural distortions, and ion implantation can be used to controllably engineer the strain throughout the film. Because of the strain profile, local defect energetics are changed. In this study, the effects of in-plane strain fields on the formation and migration of oxygen vacancies in KTaO 3 are investigated using first-principles calculations. In particular, the doubly positive charged oxygen vacancy (V 2+O) is studied, which is considered to be the main charge state of the oxygen vacancy in KTaO 3. We find that the formation energies for oxygen vacancies are sensitive to in-plane strain and oxygen position. The local atomic configuration is identified, and strong relaxation of local defect structure is mainly responsible for the formation characteristics of these oxygen vacancies. Based on the computational results, formation-dependent site preferences for oxygen vacancies are expected to occur under epitaxial strain, which can result in orders of magnitude differences in equilibrium vacancy concentrations on different oxygen sites. In addition, all possible migration pathways, including intra- and inter-plane diffusions, are considered. In contrast to the strain-enhanced intra-plane diffusion, the diffusion in the direction normalmore » to the strained plane is impeded under the epitaxial strain field. Lastly, these anisotropic diffusion processes can further enhance site preferences.« less

Authors:
ORCiD logo [1];  [1];  [2]; ORCiD logo [2]
  1. Univ. of Tennessee, Knoxville, TN (United States)
  2. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1345005
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 19; Journal Issue: 8; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Xi, Jianqi, Xu, Haixuan, Zhang, Yanwen, and Weber, William J. Strain effects on oxygen vacancy energetics in KTaO3. United States: N. p., 2017. Web. doi:10.1039/C6CP08315C.
Xi, Jianqi, Xu, Haixuan, Zhang, Yanwen, & Weber, William J. Strain effects on oxygen vacancy energetics in KTaO3. United States. doi:10.1039/C6CP08315C.
Xi, Jianqi, Xu, Haixuan, Zhang, Yanwen, and Weber, William J. Tue . "Strain effects on oxygen vacancy energetics in KTaO3". United States. doi:10.1039/C6CP08315C. https://www.osti.gov/servlets/purl/1345005.
@article{osti_1345005,
title = {Strain effects on oxygen vacancy energetics in KTaO3},
author = {Xi, Jianqi and Xu, Haixuan and Zhang, Yanwen and Weber, William J.},
abstractNote = {Due to lattice mismatch between epitaxial films and substrates, in-plane strain fields are produced in the thin films, with accompanying structural distortions, and ion implantation can be used to controllably engineer the strain throughout the film. Because of the strain profile, local defect energetics are changed. In this study, the effects of in-plane strain fields on the formation and migration of oxygen vacancies in KTaO3 are investigated using first-principles calculations. In particular, the doubly positive charged oxygen vacancy (V2+O) is studied, which is considered to be the main charge state of the oxygen vacancy in KTaO3. We find that the formation energies for oxygen vacancies are sensitive to in-plane strain and oxygen position. The local atomic configuration is identified, and strong relaxation of local defect structure is mainly responsible for the formation characteristics of these oxygen vacancies. Based on the computational results, formation-dependent site preferences for oxygen vacancies are expected to occur under epitaxial strain, which can result in orders of magnitude differences in equilibrium vacancy concentrations on different oxygen sites. In addition, all possible migration pathways, including intra- and inter-plane diffusions, are considered. In contrast to the strain-enhanced intra-plane diffusion, the diffusion in the direction normal to the strained plane is impeded under the epitaxial strain field. Lastly, these anisotropic diffusion processes can further enhance site preferences.},
doi = {10.1039/C6CP08315C},
journal = {Physical Chemistry Chemical Physics. PCCP (Print)},
number = 8,
volume = 19,
place = {United States},
year = {2017},
month = {2}
}

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Works referenced in this record:

From ultrasoft pseudopotentials to the projector augmented-wave method
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A climbing image nudged elastic band method for finding saddle points and minimum energy paths
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Enhancement of Ferroelectricity in Strained BaTiO3 Thin Films
journal, November 2004