Structures and thermoelectric properties of double-filled (Ca{sub x}Ce{sub 1−x})Fe{sub 4}Sb{sub 12} skutterudites

Journal Article · Wed Oct 15 00:00:00 EDT 2014 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2014.06.042· OSTI ID:22443432

Yan, Y. G. ^[1]; Wong-Ng, W.; Li, L.; Levin, I. ^[2]; Kaduk, J. A. ^[3]; Suchomel, M. R. ^[4]; Sun, X.; Tan, G. J. ^[1]

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1. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, Hubei 430070 (China)
2. Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)
3. Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, IL 60616 (United States)
4. Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States)

The structures and thermoelectric properties of the double-filled (Ca{sub x}Ce{sub 1−x})Fe{sub 4}Sb{sub 12} series (x=0, 0.25, 0.5, 0.75, and 1) have been studied using a combined experimental and computational methods. Compounds of (Ca{sub x}Ce{sub 1−x})Fe{sub 4}Sb{sub 12} were obtained only for x=0, 0.5, and 1. Composition with x=0.25 was found to be a mixture of x=0 and 0.5 compounds, and composition with x=0.75 was found to be a mixture of x=1 and 0.5 compounds, respectively. Our conclusions on phase formation are supported by density functional theory (DFT) calculations. In Ca{sub 0.5}Ce{sub 0.5}Fe{sub 4}Sb{sub 12,} Ca substitution in the Ce site of CeFe{sub 4}Sb{sub 12} leads to high hole concentrations, resulting in stronger semimetal transport as compared to CeFe{sub 4}Sb{sub 12}. Ca{sub 0.5}Ce{sub 0.5}Fe{sub 4}Sb{sub 12} yields a slightly higher ZT value than that of CeFe{sub 4}Sb{sub 12}, which is attributed to its lower lattice thermal conductivity. Phonon mode calculations adopting a three-particle bending model suggest that thermal conductivity is reduced upon Ca substitution because of an additional vibration mode which involves both Ca and Ce atoms. - Graphical abstract: Detailed structural information to correlate with thermoelectric properties in a series of double-filled (Ca{sub x}Ce{sub 1−x})Fe{sub 4}Sb{sub 12} skutterudite samples were obtained using synchrotron X-ray diffraction and first principle calculations. - Highlights: • Research focus on phase stability of CaCe double-filled p-type skutterudite. • Stable structure forms for an equiatomic occupancy of the voids by Ca and Ce. • Samples feature two-phase mixtures with variations of filling atoms ratio. • Phase stablility is investigated by DFT total energy calculations. • Sample with Equiatomic occupancy of Ca and Ce show higher ZT.

• OSTI ID: 22443432
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. 218; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
DENSITY FUNCTIONAL METHOD
MIXTURES
OSCILLATION MODES
PARTICLES
PHASE STABILITY
PHONONS
SYNCHROTRONS
THERMAL CONDUCTIVITY
THERMOELECTRIC PROPERTIES
X-RAY DIFFRACTION