Thermoelectric properties of type-VIII clathrate Ba8Ga16Sn30 doped with Cu

► Single crystals of type-VIII clathrate Ba8Ga16Sn30 doped with Cu were grown. ► The size of p-type single crystals is twice as large as that grown without Cu. ► The thermoelectric figure of merit ZT was assessed for 300⩽T⩽600 K. ► The ZT values of the p- and n-type crystals reach 0.88 and 1.45, res...

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Bibliographic Details
Published in:Journal of alloys and compounds 2012-10, Vol.537, p.303-307
Main Authors: Saiga, Y., Du, B., Deng, S.K., Kajisa, K., Takabatake, T.
Format: Article
Language:English
Subjects:
Ba8Ga16Sn30
Clathrate
Clathrates
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Conductivity phenomena in semiconductors and insulators
Copper
Crystals
Doping
Electronic transport in condensed matter
Energy material
Exact sciences and technology
Flux
Gallium base alloys
Physics
Thermal conductivity
Thermoelectric and thermomagnetic effects
Thermoelectric material
Thermoelectricity
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Summary:► Single crystals of type-VIII clathrate Ba8Ga16Sn30 doped with Cu were grown. ► The size of p-type single crystals is twice as large as that grown without Cu. ► The thermoelectric figure of merit ZT was assessed for 300⩽T⩽600 K. ► The ZT values of the p- and n-type crystals reach 0.88 and 1.45, respectively. The intermetallic clathrate Ba8Ga16Sn30 with type-VIII structure is one of the promising thermoelectric materials. We report on significant effects of Cu doping on both the crystal growth and thermoelectric properties of type-VIII clathrate Ba8Ga16Sn30. By using the Ga flux and Sn flux, respectively, the carrier type could be tuned as p- and n-types. The p-type single crystals were grown to approximately 6mm in diameter, which is twice as large as that grown without Cu. The crystals were characterized by electron-probe microanalysis and powder X-ray diffraction and used for the measurements of the electrical resistivity, Seebeck coefficient, and thermal conductivity. The values of the dimensionless figure of merit ZT of the p- and n-type crystals reached 0.88 and 1.45 at around 500K, respectively, the latter of which is the highest among all substituted systems of type-VIII Ba8Ga16Sn30. This enhancement of ZT is discussed in relation with the charge balance and modification of the band structure caused by Cu doping.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2012.05.049