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Decisive role of mixed-valence structure in colossal dielectric constant of LaFeO3

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Authors
Ni, W.
Ye, J.
Guo, Y.
Cheng, C.
Lin, Z.
Li, Y.
Wang, H.
Yu, Y.
Li, Q.
Huang, S.
Shao, Zongping
Wang, C.
Date
2017
Type
Journal Article

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Ni, W. and Ye, J. and Guo, Y. and Cheng, C. and Lin, Z. and Li, Y. and Wang, H. et al. 2017. Decisive role of mixed-valence structure in colossal dielectric constant of LaFeO3. Journal of the American Ceramic Society. 100 (7): pp. 3042-3049.
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Journal of the American Ceramic Society
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Department of Chemical Engineering
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Abstract

The role of mixed-valence structure in colossal dielectric constant (CDC) behavior has been investigated in LaFeO 3 ceramics by tuning the ratio of Fe 2+ /Fe 3+ through substituting Al for Fe. The ratio of Fe 2+ /Fe 3+ is decreased gradually from 1.0 to 0.0 by increasing the concentration of Al 3+ . Two clear-cut correlations have been found: (i) the relationship between the CDC behavior and the ratio of Fe 2+ /Fe 3+ follows an exponential function and (ii) the activation energy of the polaron relaxation is proportional to 1/? 2 0 , where ? 0 is the intrinsic dielectric constant. These findings underscore the role of the mixed-valence structure in CDC behavior and suggest that adjusting the mixed-valence structure through doping/alloying can be a promising strategy to achieve superior CDC behavior in transition-metal oxides.