Structures and thermoelectric properties of double-filled (CaxCe1-x)Fe4Sb12 skutterudites

Published

July 9, 2014

Author(s)

Yonggao Y. Yan, Winnie Wong-Ng, James A. Kaduk, Matthew Suchomel, Xiang Sun, Gangjian Tan, Xinfeng Tang, Lan (. Li, Igor Levin

Abstract

The structures and thermoelectric properties of double-filled (CaxCe1-x)Fe4Sb12 series (x=0, 0.25, 0.5, 0.75, and 1) have been investigated using the combination of experimental and computational approaches. Structural analysis shows that single phases of (CaxCe1-x)Fe4Sb12 only achieved with x=0. 0.5, and 1.0 under the current synthesis conditions. In other words, Ca and Ce prefer to fill the voids in the Fe4Sb12 framework with an approximate 1:1 atomic ratio, leading to the crystal structure of Ca0.5Ce0.5Fe4Sb12. These experimental observations are supported by density functional theory calculations for (CaxCe1-x)Fe4Sb12 (x=0, 0.5, 0.75 and 1.0), which provide detailed insights into the atomic structures and phase stability. Despite the fact that high hole concentration from Ca substitution in Ca0.5Ce0.5Fe4Sb12 causes a stronger semimetal transport than CeFe4Sb12, Ca0.5Ce0.5Fe4Sb12 still yields a slightly higher ZT value than CeFe4Sb12 likely due to its low lattice thermal conductivity. Phonon modes calculation adopting three-particle bending model shows that partly due to the large mass fluctuation between Ca and Ce, (71% mass difference), an additional new vibration mode involving both Ca and Ce occurs in Ca0.5Ce0.5Fe4Sb12, resulting in the low observed lattice thermal conductivity.

Citation

Physical Review B

Volume

218

Pub Type

Journals

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DOI Link

Citation

Yan, Y. , Wong-Ng, W. , Kaduk, J. , Suchomel, M. , Sun, X. , Tan, G. , Tang, X. , Li, L. and Levin, I. (2014), Structures and thermoelectric properties of double-filled (CaxCe1-x)Fe4Sb12 skutterudites, Physical Review B, [online], https://doi.org/10.1016/j.jssc.2014.06.042 (Accessed April 27, 2024)