CeO2 Nanorods and Nanocubes: Impact of Nanoparticle Shape on Dilatometry and Electrical Properties

Philippe Knauth; George F. Harrington; Sean R. Bishop; Howard Saltsburg; Harry L. Tuller

doi:10.1111/jace.14257

CeO₂ Nanorods and Nanocubes: Impact of Nanoparticle Shape on Dilatometry and Electrical Properties

Philippe Knauth, George F. Harrington, Sean R. Bishop, Howard Saltsburg, Harry L. Tuller

Department of Chemistry

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

4 Citations (SciVal)

Abstract

The electrical and dilatometric properties of CeO₂ nanopowders were examined as function of particle shape and size, including nanorods and nanocubes. Nanorods show continuous irreversible shrinkage, linked to particle reordering and compaction. Thermal expansion of CeO₂ nanocubes was analyzed and was found to be consistent with literature data for microcrystalline ceria with no apparent nanosize effects. The electrical properties of the loosely compacted nanopowders were generally found to be characterized by n-type electronic conduction, except for proton conductivity contributions associated with adsorbed moisture at temperatures below 400°C. The P_O2 and temperature dependences of the conductivity were examined in terms of defect chemical models. The lower effective enthalpy of reduction for nanorods (1.5 eV) in comparison with nanocubes (1.8 eV), both being much smaller than the value found for “bulk” ceria (4.7 eV), can be related to the larger surface to volume ratio of the nanorods, where oxide ion removal is more facile and less energy costly.

Original language	English
Pages (from-to)	2415-2421
Number of pages	7
Journal	Journal of the American Ceramic Society
Volume	99
Issue number	7
DOIs	https://doi.org/10.1111/jace.14257
Publication status	Published - 31 Jul 2016

Bibliographical note

Funding Information:
The authors acknowledge the US Department of Energy – Basic Energy Sciences, Grant DE-SC0002633, for financial support. This work made use of the MRSEC Shared Experimental Facilities at MIT, supported by the National Science Foundation under award number DMR-0819762, including the assistance of Dr. Scott Speakman with the XRD analysis. P. K. thanks H. L. T. for the kind hospitality during his sabbatical at the Massachusetts Institute of Technology and H. L.T likewise thanks P. K. for his kind hospitality during a week-long visit to Aix-Marseille University during the preparation of this manuscript. G. F. H. acknowledges financial support from the Progress-100 program at Kyushu University.

Publisher Copyright:
© 2016 The American Ceramic Society

Funding

The authors acknowledge the US Department of Energy – Basic Energy Sciences, Grant DE-SC0002633, for financial support. This work made use of the MRSEC Shared Experimental Facilities at MIT, supported by the National Science Foundation under award number DMR-0819762, including the assistance of Dr. Scott Speakman with the XRD analysis. P. K. thanks H. L. T. for the kind hospitality during his sabbatical at the Massachusetts Institute of Technology and H. L.T likewise thanks P. K. for his kind hospitality during a week-long visit to Aix-Marseille University during the preparation of this manuscript. G. F. H. acknowledges financial support from the Progress-100 program at Kyushu University.

Keywords

defects
nonstoichiometry
oxides
reduction
thermodynamics

ASJC Scopus subject areas

Ceramics and Composites
Materials Chemistry

Access to Document

10.1111/jace.14257

Cite this

@article{b0d7047f4e904dd3aaf9de37568785cb,

title = "CeO2 Nanorods and Nanocubes: Impact of Nanoparticle Shape on Dilatometry and Electrical Properties",

abstract = "The electrical and dilatometric properties of CeO2 nanopowders were examined as function of particle shape and size, including nanorods and nanocubes. Nanorods show continuous irreversible shrinkage, linked to particle reordering and compaction. Thermal expansion of CeO2 nanocubes was analyzed and was found to be consistent with literature data for microcrystalline ceria with no apparent nanosize effects. The electrical properties of the loosely compacted nanopowders were generally found to be characterized by n-type electronic conduction, except for proton conductivity contributions associated with adsorbed moisture at temperatures below 400°C. The PO2 and temperature dependences of the conductivity were examined in terms of defect chemical models. The lower effective enthalpy of reduction for nanorods (1.5 eV) in comparison with nanocubes (1.8 eV), both being much smaller than the value found for “bulk” ceria (4.7 eV), can be related to the larger surface to volume ratio of the nanorods, where oxide ion removal is more facile and less energy costly.",

keywords = "defects, nonstoichiometry, oxides, reduction, thermodynamics",

author = "Philippe Knauth and Harrington, {George F.} and Bishop, {Sean R.} and Howard Saltsburg and Tuller, {Harry L.}",

note = "Funding Information: The authors acknowledge the US Department of Energy – Basic Energy Sciences, Grant DE-SC0002633, for financial support. This work made use of the MRSEC Shared Experimental Facilities at MIT, supported by the National Science Foundation under award number DMR-0819762, including the assistance of Dr. Scott Speakman with the XRD analysis. P. K. thanks H. L. T. for the kind hospitality during his sabbatical at the Massachusetts Institute of Technology and H. L.T likewise thanks P. K. for his kind hospitality during a week-long visit to Aix-Marseille University during the preparation of this manuscript. G. F. H. acknowledges financial support from the Progress-100 program at Kyushu University. Publisher Copyright: {\textcopyright} 2016 The American Ceramic Society",

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AU - Saltsburg, Howard

AU - Tuller, Harry L.

N1 - Funding Information: The authors acknowledge the US Department of Energy – Basic Energy Sciences, Grant DE-SC0002633, for financial support. This work made use of the MRSEC Shared Experimental Facilities at MIT, supported by the National Science Foundation under award number DMR-0819762, including the assistance of Dr. Scott Speakman with the XRD analysis. P. K. thanks H. L. T. for the kind hospitality during his sabbatical at the Massachusetts Institute of Technology and H. L.T likewise thanks P. K. for his kind hospitality during a week-long visit to Aix-Marseille University during the preparation of this manuscript. G. F. H. acknowledges financial support from the Progress-100 program at Kyushu University. Publisher Copyright: © 2016 The American Ceramic Society

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N2 - The electrical and dilatometric properties of CeO2 nanopowders were examined as function of particle shape and size, including nanorods and nanocubes. Nanorods show continuous irreversible shrinkage, linked to particle reordering and compaction. Thermal expansion of CeO2 nanocubes was analyzed and was found to be consistent with literature data for microcrystalline ceria with no apparent nanosize effects. The electrical properties of the loosely compacted nanopowders were generally found to be characterized by n-type electronic conduction, except for proton conductivity contributions associated with adsorbed moisture at temperatures below 400°C. The PO2 and temperature dependences of the conductivity were examined in terms of defect chemical models. The lower effective enthalpy of reduction for nanorods (1.5 eV) in comparison with nanocubes (1.8 eV), both being much smaller than the value found for “bulk” ceria (4.7 eV), can be related to the larger surface to volume ratio of the nanorods, where oxide ion removal is more facile and less energy costly.

AB - The electrical and dilatometric properties of CeO2 nanopowders were examined as function of particle shape and size, including nanorods and nanocubes. Nanorods show continuous irreversible shrinkage, linked to particle reordering and compaction. Thermal expansion of CeO2 nanocubes was analyzed and was found to be consistent with literature data for microcrystalline ceria with no apparent nanosize effects. The electrical properties of the loosely compacted nanopowders were generally found to be characterized by n-type electronic conduction, except for proton conductivity contributions associated with adsorbed moisture at temperatures below 400°C. The PO2 and temperature dependences of the conductivity were examined in terms of defect chemical models. The lower effective enthalpy of reduction for nanorods (1.5 eV) in comparison with nanocubes (1.8 eV), both being much smaller than the value found for “bulk” ceria (4.7 eV), can be related to the larger surface to volume ratio of the nanorods, where oxide ion removal is more facile and less energy costly.

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