Electrical conductivity and grain boundary composition of Gd-doped and Gd/Pr co-doped ceria

William J. Bowman; Jiangtao Zhu; Renu Sharma; Peter Crozier

doi:10.1016/j.ssi.2014.12.006

Electrical conductivity and grain boundary composition of Gd-doped and Gd/Pr co-doped ceria

William J. Bowman, Jiangtao Zhu, Renu Sharma, Peter Crozier

Research output: Contribution to journal › Article › peer-review

76 Scopus citations

Abstract

We characterize electrical conductivity, microstructure, nano-scale grain boundary structure and chemistry of ceria electrolytes with nominal compositions of Gd_0.2Ce_0.8O_2-δ (GDC) and Gd_0.11Pr_0.04Ce_0.85O_2-δ (GPDC). The electrolytes are fabricated using mixed oxide nanopowders synthesized by spray drying. AC impedance spectroscopy was performed from 150 °C to 700 °C in air to determine grain-interior electrical conductivity. Grain-boundary conductivity was determined below 300 °C. The grain-interior conductivity of the GPDC was higher than that of GDC by as much as 10 times, depending on the temperature. The GPDC specific grain-boundary conductivity was measured to be approximately 100 times higher than that of GDC. Energy dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) confirmed the grain-to-grain compositional uniformity of both materials following heat treatments. Grain boundaries were free of glassy intergranular phases; dopant concentration and Ce oxidation state were found to vary significantly near grain boundaries. Boundary core composition was estimated from STEM EELS to be Gd_0.62Ce_0.38O_2-δ, and Gd_0.29Pr_0.16Ce_0.55O_2-δ in GDC and GPDC, respectively. Pr segregation to grain boundaries in the GPDC is hypothesized to enhance conductivity by both decreasing oxygen vacancy migration energy, and inducing mixed ionic-electronic conductivity in the near-boundary region.

Original language	English (US)
Pages (from-to)	9-17
Number of pages	9
Journal	Solid State Ionics
Volume	272
DOIs	https://doi.org/10.1016/j.ssi.2014.12.006
State	Published - Apr 2015

Keywords

Doped ceria
Electron energy-loss spectroscopy
Grain boundary
Impedance spectroscopy
Scanning transmission electron microscopy
Spray drying

ASJC Scopus subject areas

Chemistry(all)
Materials Science(all)
Condensed Matter Physics

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10.1016/j.ssi.2014.12.006

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@article{54a40a483c5844b280505ac7c769c308,

title = "Electrical conductivity and grain boundary composition of Gd-doped and Gd/Pr co-doped ceria",

abstract = "We characterize electrical conductivity, microstructure, nano-scale grain boundary structure and chemistry of ceria electrolytes with nominal compositions of Gd0.2Ce0.8O2-δ (GDC) and Gd0.11Pr0.04Ce0.85O2-δ (GPDC). The electrolytes are fabricated using mixed oxide nanopowders synthesized by spray drying. AC impedance spectroscopy was performed from 150 °C to 700 °C in air to determine grain-interior electrical conductivity. Grain-boundary conductivity was determined below 300 °C. The grain-interior conductivity of the GPDC was higher than that of GDC by as much as 10 times, depending on the temperature. The GPDC specific grain-boundary conductivity was measured to be approximately 100 times higher than that of GDC. Energy dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) confirmed the grain-to-grain compositional uniformity of both materials following heat treatments. Grain boundaries were free of glassy intergranular phases; dopant concentration and Ce oxidation state were found to vary significantly near grain boundaries. Boundary core composition was estimated from STEM EELS to be Gd0.62Ce0.38O2-δ, and Gd0.29Pr0.16Ce0.55O2-δ in GDC and GPDC, respectively. Pr segregation to grain boundaries in the GPDC is hypothesized to enhance conductivity by both decreasing oxygen vacancy migration energy, and inducing mixed ionic-electronic conductivity in the near-boundary region.",

keywords = "Doped ceria, Electron energy-loss spectroscopy, Grain boundary, Impedance spectroscopy, Scanning transmission electron microscopy, Spray drying",

author = "Bowman, {William J.} and Jiangtao Zhu and Renu Sharma and Peter Crozier",

note = "Funding Information: The authors wish to thank the Fulton Undergraduate Research Initiative at Arizona State University , the National Institute of Standards and Technology's Summer Undergraduate Research Fellowship , Arizona State University's Doctoral Enrichment Fellowship , and the National Science Foundation's Graduate Research Fellowship Program for their gracious support without which this work would not have been possible. We also gratefully acknowledge the staff that assisted this work, as well as the use of facilities in the LeRoy Eyring Center for Solid State Science and the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1311230 , and NSF DMR-1308085 . Publisher Copyright: {\textcopyright} 2014 Elsevier B.V. Copyright: Copyright 2015 Elsevier B.V., All rights reserved.",

year = "2015",

month = apr,

doi = "10.1016/j.ssi.2014.12.006",

language = "English (US)",

volume = "272",

pages = "9--17",

journal = "Solid State Ionics",

issn = "0167-2738",

publisher = "Elsevier",

}

TY - JOUR

T1 - Electrical conductivity and grain boundary composition of Gd-doped and Gd/Pr co-doped ceria

AU - Bowman, William J.

AU - Zhu, Jiangtao

AU - Sharma, Renu

AU - Crozier, Peter

N1 - Funding Information: The authors wish to thank the Fulton Undergraduate Research Initiative at Arizona State University , the National Institute of Standards and Technology's Summer Undergraduate Research Fellowship , Arizona State University's Doctoral Enrichment Fellowship , and the National Science Foundation's Graduate Research Fellowship Program for their gracious support without which this work would not have been possible. We also gratefully acknowledge the staff that assisted this work, as well as the use of facilities in the LeRoy Eyring Center for Solid State Science and the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1311230 , and NSF DMR-1308085 . Publisher Copyright: © 2014 Elsevier B.V. Copyright: Copyright 2015 Elsevier B.V., All rights reserved.

PY - 2015/4

Y1 - 2015/4

N2 - We characterize electrical conductivity, microstructure, nano-scale grain boundary structure and chemistry of ceria electrolytes with nominal compositions of Gd0.2Ce0.8O2-δ (GDC) and Gd0.11Pr0.04Ce0.85O2-δ (GPDC). The electrolytes are fabricated using mixed oxide nanopowders synthesized by spray drying. AC impedance spectroscopy was performed from 150 °C to 700 °C in air to determine grain-interior electrical conductivity. Grain-boundary conductivity was determined below 300 °C. The grain-interior conductivity of the GPDC was higher than that of GDC by as much as 10 times, depending on the temperature. The GPDC specific grain-boundary conductivity was measured to be approximately 100 times higher than that of GDC. Energy dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) confirmed the grain-to-grain compositional uniformity of both materials following heat treatments. Grain boundaries were free of glassy intergranular phases; dopant concentration and Ce oxidation state were found to vary significantly near grain boundaries. Boundary core composition was estimated from STEM EELS to be Gd0.62Ce0.38O2-δ, and Gd0.29Pr0.16Ce0.55O2-δ in GDC and GPDC, respectively. Pr segregation to grain boundaries in the GPDC is hypothesized to enhance conductivity by both decreasing oxygen vacancy migration energy, and inducing mixed ionic-electronic conductivity in the near-boundary region.

AB - We characterize electrical conductivity, microstructure, nano-scale grain boundary structure and chemistry of ceria electrolytes with nominal compositions of Gd0.2Ce0.8O2-δ (GDC) and Gd0.11Pr0.04Ce0.85O2-δ (GPDC). The electrolytes are fabricated using mixed oxide nanopowders synthesized by spray drying. AC impedance spectroscopy was performed from 150 °C to 700 °C in air to determine grain-interior electrical conductivity. Grain-boundary conductivity was determined below 300 °C. The grain-interior conductivity of the GPDC was higher than that of GDC by as much as 10 times, depending on the temperature. The GPDC specific grain-boundary conductivity was measured to be approximately 100 times higher than that of GDC. Energy dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) confirmed the grain-to-grain compositional uniformity of both materials following heat treatments. Grain boundaries were free of glassy intergranular phases; dopant concentration and Ce oxidation state were found to vary significantly near grain boundaries. Boundary core composition was estimated from STEM EELS to be Gd0.62Ce0.38O2-δ, and Gd0.29Pr0.16Ce0.55O2-δ in GDC and GPDC, respectively. Pr segregation to grain boundaries in the GPDC is hypothesized to enhance conductivity by both decreasing oxygen vacancy migration energy, and inducing mixed ionic-electronic conductivity in the near-boundary region.

KW - Doped ceria

KW - Electron energy-loss spectroscopy

KW - Grain boundary

KW - Impedance spectroscopy

KW - Scanning transmission electron microscopy

KW - Spray drying

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U2 - 10.1016/j.ssi.2014.12.006

DO - 10.1016/j.ssi.2014.12.006

M3 - Article

AN - SCOPUS:84920683179

SN - 0167-2738

VL - 272

SP - 9

EP - 17

JO - Solid State Ionics

JF - Solid State Ionics

ER -

Electrical conductivity and grain boundary composition of Gd-doped and Gd/Pr co-doped ceria

Abstract

Keywords

ASJC Scopus subject areas

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