Thermoelectric properties of sintered type-II clathrates (K, Ba)24(Ga, Sn)136 with various carrier concentrations

We reported the thermoelectric properties of the sintered type-II clathrate K8Ba16Ga40Sn96 in a previous paper [S. Koda et al., J. Appl. Phys. 116, 023710 (2014)]. The clathrate had a high dimensionless figure of merit ZT, namely, 0.93. In this study, we optimized the carrier concentration n by modi...

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Veröffentlicht in:Journal of applied physics 2015-09, Vol.118 (12)
Hauptverfasser: Kishimoto, Kengo, Koda, Shota, Akai, Koji, Koyanagi, Tsuyoshi
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Sprache:eng
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Zusammenfassung:We reported the thermoelectric properties of the sintered type-II clathrate K8Ba16Ga40Sn96 in a previous paper [S. Koda et al., J. Appl. Phys. 116, 023710 (2014)]. The clathrate had a high dimensionless figure of merit ZT, namely, 0.93. In this study, we optimized the carrier concentration n by modifying the chemical compositions of (K, Ba)24(Ga, Sn)136 samples, and heat treated the sintered samples. The carrier mobilities μ were improved because of the reduction in potential barrier scattering at grain boundaries. The room-temperature (RT) n values varied from 7.7 × 1017 to 3.7 × 1019 cm−3; the maximum RT μ value was 170 cm2V−1s−1. Consequently, we obtained a high ZT value of 1.19 at 630 K for n = 2.5 × 1019 cm−3. This material therefore has good thermoelectric properties.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4931433