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Thermodynamics of mono- and di-vacancies in barium titanate

Erhart, Paul and Albe, Karsten (2007):
Thermodynamics of mono- and di-vacancies in barium titanate.
In: Journal of Applied Physics, American Institute of Physics, pp. 084111-1, 102, (8), ISSN 00218979,
[Online-Edition: http://dx.doi.org/10.1063/1.2801011],
[Article]

Abstract

The dependence of the electrical conductivity on the oxygen partial pressure is calculated for the prototypical perovskite BaTiO3 based on data obtained from first-principles calculations within density functional theory. The equilibrium point defect concentrations are obtained via a self-consistent determination of the electron chemical potential. This allows one to derive charge carrier concentrations for a given temperature and chemical environment and eventually the electrical conductivity. The calculations are in excellent agreement with experimental data if an accidental acceptor dopant level of 1017 cm3 is assumed. It is shown that doubly charged oxygen vacancies are accountable for the high-temperature n-type conduction under oxygen-poor conditions. The high-temperature p-type conduction observed at large oxygen pressures is due to barium vacancies and titanium-oxygen divacancies under Ti- and Ba-rich conditions, respectively. Finally, the connection between the present approach and the mass-action law approach to point defect thermodynamics is discussed.

Item Type: Article
Erschienen: 2007
Creators: Erhart, Paul and Albe, Karsten
Title: Thermodynamics of mono- and di-vacancies in barium titanate
Language: English
Abstract:

The dependence of the electrical conductivity on the oxygen partial pressure is calculated for the prototypical perovskite BaTiO3 based on data obtained from first-principles calculations within density functional theory. The equilibrium point defect concentrations are obtained via a self-consistent determination of the electron chemical potential. This allows one to derive charge carrier concentrations for a given temperature and chemical environment and eventually the electrical conductivity. The calculations are in excellent agreement with experimental data if an accidental acceptor dopant level of 1017 cm3 is assumed. It is shown that doubly charged oxygen vacancies are accountable for the high-temperature n-type conduction under oxygen-poor conditions. The high-temperature p-type conduction observed at large oxygen pressures is due to barium vacancies and titanium-oxygen divacancies under Ti- and Ba-rich conditions, respectively. Finally, the connection between the present approach and the mass-action law approach to point defect thermodynamics is discussed.

Journal or Publication Title: Journal of Applied Physics
Volume: 102
Number: 8
Publisher: American Institute of Physics
Uncontrolled Keywords: ab initio calculations, barium compounds, carrier density, chemical potential, density functional theory, electrical conductivity, vacancies (crystal)
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
Zentrale Einrichtungen
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > C - Modelling
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > C - Modelling > Subproject C1: Quantum mechanical computer simulations for electron and defect structure of oxides
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres
DFG-Collaborative Research Centres (incl. Transregio)
Date Deposited: 15 Aug 2011 12:47
Official URL: http://dx.doi.org/10.1063/1.2801011
Additional Information:

SFB 595 C1

Identification Number: doi:10.1063/1.2801011
Funders: This project was funded by the Sonderforschungsbereich 595 “Fatigue in functional materials” of the Deutsche Forschungsgemeinschaft.
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