Size of oxide vacancies in fluorite and perovskite structured oxides

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Abstract

An analysis of the effective radii of vacancies and the stoichiometric expansion coefficient is performed on metal oxides with fluorite and perovskite structures. Using the hard sphere model with Shannon ion radii we find that the effective radius of the oxide vacancy in fluorites increases with increasing ion radius of the host cation and that it is significantly smaller than the radius of the oxide ion in all cases, from 37% smaller for HfO2 to 13 % smaller for ThO2. The perovskite structured LaGaO3 doped with Sr or Mg or both is analyzed in some detail. The results show that the effective radius of an oxide vacancy in doped LaGaO3 is only about 6 % smaller than the oxide ion. In spite of this the stoichiometric expansion coefficient (a kind of chemical expansion coefficient) of the similar perovskite, LaCrO3, is significantly smaller than the stoichiometric expansion coefficient of the fluorite structured CeO2. Our analysis results indicate that the smaller stoichiometric expansion coefficient of the perovskites is associated with the restraining action of the A-O sub-lattice to dimensional changes in the B-O sub-lattice and vice versa.
Original languageEnglish
JournalJournal of Electroceramics
Volume34
Issue number1
Pages (from-to)100-107
Number of pages8
ISSN1385-3449
DOIs
Publication statusPublished - 2015

Bibliographical note

© The Author(s) 2014. This article is published with open access at Springerlink.com

Keywords

  • Oxide vacancy
  • Stoichiometric expansion
  • Volume effects of doping

Cite this

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title = "Size of oxide vacancies in fluorite and perovskite structured oxides",
abstract = "An analysis of the effective radii of vacancies and the stoichiometric expansion coefficient is performed on metal oxides with fluorite and perovskite structures. Using the hard sphere model with Shannon ion radii we find that the effective radius of the oxide vacancy in fluorites increases with increasing ion radius of the host cation and that it is significantly smaller than the radius of the oxide ion in all cases, from 37{\%} smaller for HfO2 to 13 {\%} smaller for ThO2. The perovskite structured LaGaO3 doped with Sr or Mg or both is analyzed in some detail. The results show that the effective radius of an oxide vacancy in doped LaGaO3 is only about 6 {\%} smaller than the oxide ion. In spite of this the stoichiometric expansion coefficient (a kind of chemical expansion coefficient) of the similar perovskite, LaCrO3, is significantly smaller than the stoichiometric expansion coefficient of the fluorite structured CeO2. Our analysis results indicate that the smaller stoichiometric expansion coefficient of the perovskites is associated with the restraining action of the A-O sub-lattice to dimensional changes in the B-O sub-lattice and vice versa.",
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author = "Christodoulos Chatzichristodoulou and Poul Norby and Hendriksen, {Peter Vang} and Mogensen, {Mogens Bjerg}",
note = "{\circledC} The Author(s) 2014. This article is published with open access at Springerlink.com",
year = "2015",
doi = "10.1007/s10832-014-9916-2",
language = "English",
volume = "34",
pages = "100--107",
journal = "Journal of Electroceramics",
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Size of oxide vacancies in fluorite and perovskite structured oxides. / Chatzichristodoulou, Christodoulos; Norby, Poul; Hendriksen, Peter Vang; Mogensen, Mogens Bjerg.

In: Journal of Electroceramics, Vol. 34, No. 1, 2015, p. 100-107.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Size of oxide vacancies in fluorite and perovskite structured oxides

AU - Chatzichristodoulou, Christodoulos

AU - Norby, Poul

AU - Hendriksen, Peter Vang

AU - Mogensen, Mogens Bjerg

N1 - © The Author(s) 2014. This article is published with open access at Springerlink.com

PY - 2015

Y1 - 2015

N2 - An analysis of the effective radii of vacancies and the stoichiometric expansion coefficient is performed on metal oxides with fluorite and perovskite structures. Using the hard sphere model with Shannon ion radii we find that the effective radius of the oxide vacancy in fluorites increases with increasing ion radius of the host cation and that it is significantly smaller than the radius of the oxide ion in all cases, from 37% smaller for HfO2 to 13 % smaller for ThO2. The perovskite structured LaGaO3 doped with Sr or Mg or both is analyzed in some detail. The results show that the effective radius of an oxide vacancy in doped LaGaO3 is only about 6 % smaller than the oxide ion. In spite of this the stoichiometric expansion coefficient (a kind of chemical expansion coefficient) of the similar perovskite, LaCrO3, is significantly smaller than the stoichiometric expansion coefficient of the fluorite structured CeO2. Our analysis results indicate that the smaller stoichiometric expansion coefficient of the perovskites is associated with the restraining action of the A-O sub-lattice to dimensional changes in the B-O sub-lattice and vice versa.

AB - An analysis of the effective radii of vacancies and the stoichiometric expansion coefficient is performed on metal oxides with fluorite and perovskite structures. Using the hard sphere model with Shannon ion radii we find that the effective radius of the oxide vacancy in fluorites increases with increasing ion radius of the host cation and that it is significantly smaller than the radius of the oxide ion in all cases, from 37% smaller for HfO2 to 13 % smaller for ThO2. The perovskite structured LaGaO3 doped with Sr or Mg or both is analyzed in some detail. The results show that the effective radius of an oxide vacancy in doped LaGaO3 is only about 6 % smaller than the oxide ion. In spite of this the stoichiometric expansion coefficient (a kind of chemical expansion coefficient) of the similar perovskite, LaCrO3, is significantly smaller than the stoichiometric expansion coefficient of the fluorite structured CeO2. Our analysis results indicate that the smaller stoichiometric expansion coefficient of the perovskites is associated with the restraining action of the A-O sub-lattice to dimensional changes in the B-O sub-lattice and vice versa.

KW - Oxide vacancy

KW - Stoichiometric expansion

KW - Volume effects of doping

U2 - 10.1007/s10832-014-9916-2

DO - 10.1007/s10832-014-9916-2

M3 - Journal article

VL - 34

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JO - Journal of Electroceramics

JF - Journal of Electroceramics

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