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Combined homo-hetero doping for enhancement of ionic conductivity

Akila, R and Jacob, KT (1987) Combined homo-hetero doping for enhancement of ionic conductivity. In: Solid State Ionics, 25 (2-3). pp. 217-221.

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Electrical conductivity of $Na_{0.005}Ca_{0.995}F_{1.995}$ and $Y_{0.008}Ca_{0.992}F_{2.008}$ samples containing 2 mol% $CeO_{2-x}$ as the dispersed phase has been measured in the range 630 to 1030 K using an ac bridge at 1 kHz. The presence of the dispersed phase enhanced the conductivity of $CaF_2$ homogeneously doped with NaF. However, heterogeneous doping with $CeO_{2-x}$ decreased the conductivity of $YF_3$-doped $CaF_2$. This suggests that preferential adsorption of $F^-$ ions to the $CeO_{2-x}$ interface and the consequent creation of a space charge region with increased fluorine vacancies near the interface is the primary mechanism responsible for the enhancement of the conductivity of $CaF_2$ heterogeneously doped with $CeO_{2-x}$. By the synergetic effect of homogeneous and heterogeneous doping, the conductivity of polycrystalline $CaF_2$ can be enhanced by 4.5 orders of magnitude at 630 K.

Item Type: Journal Article
Publication: Solid State Ionics
Publisher: Elsevier Science B.V.
Additional Information: Copyright of this article belongs to Elsevier Science B.V.
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 10 Apr 2008
Last Modified: 19 Sep 2010 04:44
URI: http://eprints.iisc.ac.in/id/eprint/13720

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