Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study

Autores
Murgida, Gustavo Ezequiel; Ferrari, Valeria Paola; Ganduglia Pirovano, Maria Veronica; Llois, Ana Maria
Año de publicación
2014
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
The importance of ceria (CeO2) in many applications originates from the ease of oxygen vacancy formation and healing. The ordering of vacancies and the whereabouts of the excess charge in bulk CeO2 are of no less significance than at ceria surfaces, but they have not received the same attention. In this work, the formation of neutral oxygen vacancies in bulk CeO2 is investigated using density-functional theory (DFT) in the DFT + U (U is an effective onsite Coulomb interaction parameter) approach for a broad range of vacancy concentrations Θ (1/64 ≤ Θ ≤ 1/4 ). We find that the excess charge prefers to be localized in cation sites such that the mean Ce3+ coordination number is maximized, and if nearest-neighbor cation sites are reduced, they rather be nonuniformly distributed. Furthermore, we show that a vacancy repels other vacancies from its nearest-neighbor shell and that the [110] and [111] directions are possible directions for clustering of second- and third-neighbor vacancies, respectively. Vacancies prefer not to share cations. The results are discussed in a simple physical picture which enables the separation of the different contributions to the averaged vacancy formation energy. We also consider cells with fluorite structure and same stoichiometries as in existing bulk phases, i.e., Ce11O20 (Θ = 1/11), Ce7 O12 (Θ = 1/7), and Ce2O3 (Θ = 1/4), as well as the corresponding real structures. We find that the vacancy ordering and the location of the excess electrons are consistent with the results for single-phase reduced CeO2, but the Ce11O20, Ce7O12, and Ce2O3 structures are substantially more stable. The stability of these phases as a function of pressure and temperature is discussed. Vacancy-induced lattice relaxation effects are crucial for the interpretation of the results.
Fil: Murgida, Gustavo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); Argentina
Fil: Ferrari, Valeria Paola. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); Argentina
Fil: Ganduglia Pirovano, Maria Veronica. Consejo Superior de Investigaciones Científicas; España
Fil: Llois, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); Argentina
Materia
Ceria
Oxygen Vacancies
Charge Localization
Phase Stability
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/35955

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spelling Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U studyMurgida, Gustavo EzequielFerrari, Valeria PaolaGanduglia Pirovano, Maria VeronicaLlois, Ana MariaCeriaOxygen VacanciesCharge LocalizationPhase Stabilityhttps://purl.org/becyt/ford/1.3https://purl.org/becyt/ford/1The importance of ceria (CeO2) in many applications originates from the ease of oxygen vacancy formation and healing. The ordering of vacancies and the whereabouts of the excess charge in bulk CeO2 are of no less significance than at ceria surfaces, but they have not received the same attention. In this work, the formation of neutral oxygen vacancies in bulk CeO2 is investigated using density-functional theory (DFT) in the DFT + U (U is an effective onsite Coulomb interaction parameter) approach for a broad range of vacancy concentrations Θ (1/64 ≤ Θ ≤ 1/4 ). We find that the excess charge prefers to be localized in cation sites such that the mean Ce3+ coordination number is maximized, and if nearest-neighbor cation sites are reduced, they rather be nonuniformly distributed. Furthermore, we show that a vacancy repels other vacancies from its nearest-neighbor shell and that the [110] and [111] directions are possible directions for clustering of second- and third-neighbor vacancies, respectively. Vacancies prefer not to share cations. The results are discussed in a simple physical picture which enables the separation of the different contributions to the averaged vacancy formation energy. We also consider cells with fluorite structure and same stoichiometries as in existing bulk phases, i.e., Ce11O20 (Θ = 1/11), Ce7 O12 (Θ = 1/7), and Ce2O3 (Θ = 1/4), as well as the corresponding real structures. We find that the vacancy ordering and the location of the excess electrons are consistent with the results for single-phase reduced CeO2, but the Ce11O20, Ce7O12, and Ce2O3 structures are substantially more stable. The stability of these phases as a function of pressure and temperature is discussed. Vacancy-induced lattice relaxation effects are crucial for the interpretation of the results.Fil: Murgida, Gustavo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); ArgentinaFil: Ferrari, Valeria Paola. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); ArgentinaFil: Ganduglia Pirovano, Maria Veronica. Consejo Superior de Investigaciones Científicas; EspañaFil: Llois, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); ArgentinaAmerican Physical Society2014-09info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/35955Murgida, Gustavo Ezequiel; Ferrari, Valeria Paola; Ganduglia Pirovano, Maria Veronica; Llois, Ana Maria; Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study; American Physical Society; Physical Review B: Condensed Matter and Materials Physics; 90; 11; 9-2014; 1-121098-0121CONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/url/https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.115120info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevB.90.115120info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-03T09:50:54Zoai:ri.conicet.gov.ar:11336/35955instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-03 09:50:54.429CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study
title Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study
spellingShingle Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study
Murgida, Gustavo Ezequiel
Ceria
Oxygen Vacancies
Charge Localization
Phase Stability
title_short Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study
title_full Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study
title_fullStr Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study
title_full_unstemmed Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study
title_sort Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study
dc.creator.none.fl_str_mv Murgida, Gustavo Ezequiel
Ferrari, Valeria Paola
Ganduglia Pirovano, Maria Veronica
Llois, Ana Maria
author Murgida, Gustavo Ezequiel
author_facet Murgida, Gustavo Ezequiel
Ferrari, Valeria Paola
Ganduglia Pirovano, Maria Veronica
Llois, Ana Maria
author_role author
author2 Ferrari, Valeria Paola
Ganduglia Pirovano, Maria Veronica
Llois, Ana Maria
author2_role author
author
author
dc.subject.none.fl_str_mv Ceria
Oxygen Vacancies
Charge Localization
Phase Stability
topic Ceria
Oxygen Vacancies
Charge Localization
Phase Stability
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.3
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv The importance of ceria (CeO2) in many applications originates from the ease of oxygen vacancy formation and healing. The ordering of vacancies and the whereabouts of the excess charge in bulk CeO2 are of no less significance than at ceria surfaces, but they have not received the same attention. In this work, the formation of neutral oxygen vacancies in bulk CeO2 is investigated using density-functional theory (DFT) in the DFT + U (U is an effective onsite Coulomb interaction parameter) approach for a broad range of vacancy concentrations Θ (1/64 ≤ Θ ≤ 1/4 ). We find that the excess charge prefers to be localized in cation sites such that the mean Ce3+ coordination number is maximized, and if nearest-neighbor cation sites are reduced, they rather be nonuniformly distributed. Furthermore, we show that a vacancy repels other vacancies from its nearest-neighbor shell and that the [110] and [111] directions are possible directions for clustering of second- and third-neighbor vacancies, respectively. Vacancies prefer not to share cations. The results are discussed in a simple physical picture which enables the separation of the different contributions to the averaged vacancy formation energy. We also consider cells with fluorite structure and same stoichiometries as in existing bulk phases, i.e., Ce11O20 (Θ = 1/11), Ce7 O12 (Θ = 1/7), and Ce2O3 (Θ = 1/4), as well as the corresponding real structures. We find that the vacancy ordering and the location of the excess electrons are consistent with the results for single-phase reduced CeO2, but the Ce11O20, Ce7O12, and Ce2O3 structures are substantially more stable. The stability of these phases as a function of pressure and temperature is discussed. Vacancy-induced lattice relaxation effects are crucial for the interpretation of the results.
Fil: Murgida, Gustavo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); Argentina
Fil: Ferrari, Valeria Paola. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); Argentina
Fil: Ganduglia Pirovano, Maria Veronica. Consejo Superior de Investigaciones Científicas; España
Fil: Llois, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); Argentina
description The importance of ceria (CeO2) in many applications originates from the ease of oxygen vacancy formation and healing. The ordering of vacancies and the whereabouts of the excess charge in bulk CeO2 are of no less significance than at ceria surfaces, but they have not received the same attention. In this work, the formation of neutral oxygen vacancies in bulk CeO2 is investigated using density-functional theory (DFT) in the DFT + U (U is an effective onsite Coulomb interaction parameter) approach for a broad range of vacancy concentrations Θ (1/64 ≤ Θ ≤ 1/4 ). We find that the excess charge prefers to be localized in cation sites such that the mean Ce3+ coordination number is maximized, and if nearest-neighbor cation sites are reduced, they rather be nonuniformly distributed. Furthermore, we show that a vacancy repels other vacancies from its nearest-neighbor shell and that the [110] and [111] directions are possible directions for clustering of second- and third-neighbor vacancies, respectively. Vacancies prefer not to share cations. The results are discussed in a simple physical picture which enables the separation of the different contributions to the averaged vacancy formation energy. We also consider cells with fluorite structure and same stoichiometries as in existing bulk phases, i.e., Ce11O20 (Θ = 1/11), Ce7 O12 (Θ = 1/7), and Ce2O3 (Θ = 1/4), as well as the corresponding real structures. We find that the vacancy ordering and the location of the excess electrons are consistent with the results for single-phase reduced CeO2, but the Ce11O20, Ce7O12, and Ce2O3 structures are substantially more stable. The stability of these phases as a function of pressure and temperature is discussed. Vacancy-induced lattice relaxation effects are crucial for the interpretation of the results.
publishDate 2014
dc.date.none.fl_str_mv 2014-09
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/35955
Murgida, Gustavo Ezequiel; Ferrari, Valeria Paola; Ganduglia Pirovano, Maria Veronica; Llois, Ana Maria; Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study; American Physical Society; Physical Review B: Condensed Matter and Materials Physics; 90; 11; 9-2014; 1-12
1098-0121
CONICET Digital
CONICET
url http://hdl.handle.net/11336/35955
identifier_str_mv Murgida, Gustavo Ezequiel; Ferrari, Valeria Paola; Ganduglia Pirovano, Maria Veronica; Llois, Ana Maria; Ordering of oxygen vacancies and excess charge localization in bulk ceria: A DFT+U study; American Physical Society; Physical Review B: Condensed Matter and Materials Physics; 90; 11; 9-2014; 1-12
1098-0121
CONICET Digital
CONICET
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.115120
info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevB.90.115120
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
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eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
application/pdf
application/pdf
dc.publisher.none.fl_str_mv American Physical Society
publisher.none.fl_str_mv American Physical Society
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
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repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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