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Influence of porosity on the bulk and grain-boundary electrical properties of Gd-doped ceria
The effects of porosity on the grain and grain-boundary transport properties of the solid-state electrolyte Ce 0.9Gd 0.1O 1.95 (CGO) have been analysed with a modified brick-layer model. Ceramics of CGO with varying degrees of densification were obtained on sintering compacted green bodies of commer...
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Published in: | Solid state ionics 2010-07, Vol.181 (21), p.1033-1042 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that cite this one |
Online Access: | Get full text |
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Summary: | The effects of porosity on the grain and grain-boundary transport properties of the solid-state electrolyte Ce
0.9Gd
0.1O
1.95 (CGO) have been analysed with a modified brick-layer model. Ceramics of CGO with varying degrees of densification were obtained on sintering compacted green bodies of commercially produced powder in the range 1200
≤
T
s
≤
1500
°C. Impedance spectroscopy was employed to determine the transport properties of the microstructural components in the range 150–1000
°C for samples pertaining to the sintering regimes of densification (
T
s
=
1200–1300
°C) and grain growth (1300–1500
°C). The bulk resistance is dependent only on porosity throughout the sintering process and decreases monotonously with increasing relative density (r.d.). The grain-boundary transport is dependent, however, on both porosity and grain size, which is reflected by a sharp increase in conductance on crossing from densification to grain-growth regimes. Since the effect of porosity on capacitance is opposite to that of resistance, neither bulk nor grain-boundary “specific” conductivity is affected by densification for levels above 75% r.d. Accordingly, activation energies for the conductance of both components are independent of the degree of porosity. The total conductivity could be well correlated with the bulk and grain-boundary components by means of a porosity factor introduced in the brick-layer model. |
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ISSN: | 0167-2738 1872-7689 |
DOI: | 10.1016/j.ssi.2010.06.006 |