Densification of Highly Defective Ceria by High Temperature Controlled Re-Oxidation

De Wei Ni, Julie Glasscock, Aénor Pons, Wei Zhang, Aditya Prasad, Simone Sanna, Nini Pryds, Vincenzo Esposito

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Highly enhanced densification and grain growth of Ce0.9Gd0.1O1.95-δ (CGO, gadolinium-doped ceria, with 10 mol% Gd) is achieved in low oxygen activity atmospheres. However, the material can suffer mechanical failures during cooling when the re-oxidation process is not controlled due to the large volume changes. In this work, the redox process of CGO is investigated using dilatometry, microscopy, electrochemical impedance spectroscopy and thermodynamic analysis. In addition, the conditions allowing controlled re-oxidation and cooling in order to preserve the mechanical integrity of the CGO component are defined: this can be achieved over a wide temperature range (800−1200◦C) by gradually increasing the oxygen content of the atmosphere. It is found that the electrical conductivity of the CGO, particularly at low temperature (<450◦C) is influenced by the sintering and controlled re-oxidation conditions. An increase in activation energy for conduction at low temperature is observed as the re-oxidation temperature decreases. Moreover it was observed that the ionic conductivity blocking effect, usually associated with grain boundary contributions, is not influenced by the grain size but rather by the chemical history of the material. © 2014 The Electrochemical Society.
Original languageEnglish
JournalJournal of The Electrochemical Society
Volume161
Issue number11
Pages (from-to)F3072-F3078
ISSN0013-4651
DOIs
Publication statusPublished - 2014

Cite this

Ni, De Wei ; Glasscock, Julie ; Pons, Aénor ; Zhang, Wei ; Prasad, Aditya ; Sanna, Simone ; Pryds, Nini ; Esposito, Vincenzo. / Densification of Highly Defective Ceria by High Temperature Controlled Re-Oxidation. In: Journal of The Electrochemical Society. 2014 ; Vol. 161, No. 11. pp. F3072-F3078.
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title = "Densification of Highly Defective Ceria by High Temperature Controlled Re-Oxidation",
abstract = "Highly enhanced densification and grain growth of Ce0.9Gd0.1O1.95-δ (CGO, gadolinium-doped ceria, with 10 mol{\%} Gd) is achieved in low oxygen activity atmospheres. However, the material can suffer mechanical failures during cooling when the re-oxidation process is not controlled due to the large volume changes. In this work, the redox process of CGO is investigated using dilatometry, microscopy, electrochemical impedance spectroscopy and thermodynamic analysis. In addition, the conditions allowing controlled re-oxidation and cooling in order to preserve the mechanical integrity of the CGO component are defined: this can be achieved over a wide temperature range (800−1200◦C) by gradually increasing the oxygen content of the atmosphere. It is found that the electrical conductivity of the CGO, particularly at low temperature (<450◦C) is influenced by the sintering and controlled re-oxidation conditions. An increase in activation energy for conduction at low temperature is observed as the re-oxidation temperature decreases. Moreover it was observed that the ionic conductivity blocking effect, usually associated with grain boundary contributions, is not influenced by the grain size but rather by the chemical history of the material. {\circledC} 2014 The Electrochemical Society.",
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Densification of Highly Defective Ceria by High Temperature Controlled Re-Oxidation. / Ni, De Wei; Glasscock, Julie; Pons, Aénor; Zhang, Wei; Prasad, Aditya; Sanna, Simone; Pryds, Nini; Esposito, Vincenzo.

In: Journal of The Electrochemical Society, Vol. 161, No. 11, 2014, p. F3072-F3078.

Research output: Contribution to journalJournal articleResearchpeer-review

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T1 - Densification of Highly Defective Ceria by High Temperature Controlled Re-Oxidation

AU - Ni, De Wei

AU - Glasscock, Julie

AU - Pons, Aénor

AU - Zhang, Wei

AU - Prasad, Aditya

AU - Sanna, Simone

AU - Pryds, Nini

AU - Esposito, Vincenzo

PY - 2014

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N2 - Highly enhanced densification and grain growth of Ce0.9Gd0.1O1.95-δ (CGO, gadolinium-doped ceria, with 10 mol% Gd) is achieved in low oxygen activity atmospheres. However, the material can suffer mechanical failures during cooling when the re-oxidation process is not controlled due to the large volume changes. In this work, the redox process of CGO is investigated using dilatometry, microscopy, electrochemical impedance spectroscopy and thermodynamic analysis. In addition, the conditions allowing controlled re-oxidation and cooling in order to preserve the mechanical integrity of the CGO component are defined: this can be achieved over a wide temperature range (800−1200◦C) by gradually increasing the oxygen content of the atmosphere. It is found that the electrical conductivity of the CGO, particularly at low temperature (<450◦C) is influenced by the sintering and controlled re-oxidation conditions. An increase in activation energy for conduction at low temperature is observed as the re-oxidation temperature decreases. Moreover it was observed that the ionic conductivity blocking effect, usually associated with grain boundary contributions, is not influenced by the grain size but rather by the chemical history of the material. © 2014 The Electrochemical Society.

AB - Highly enhanced densification and grain growth of Ce0.9Gd0.1O1.95-δ (CGO, gadolinium-doped ceria, with 10 mol% Gd) is achieved in low oxygen activity atmospheres. However, the material can suffer mechanical failures during cooling when the re-oxidation process is not controlled due to the large volume changes. In this work, the redox process of CGO is investigated using dilatometry, microscopy, electrochemical impedance spectroscopy and thermodynamic analysis. In addition, the conditions allowing controlled re-oxidation and cooling in order to preserve the mechanical integrity of the CGO component are defined: this can be achieved over a wide temperature range (800−1200◦C) by gradually increasing the oxygen content of the atmosphere. It is found that the electrical conductivity of the CGO, particularly at low temperature (<450◦C) is influenced by the sintering and controlled re-oxidation conditions. An increase in activation energy for conduction at low temperature is observed as the re-oxidation temperature decreases. Moreover it was observed that the ionic conductivity blocking effect, usually associated with grain boundary contributions, is not influenced by the grain size but rather by the chemical history of the material. © 2014 The Electrochemical Society.

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