2005 年 46 巻 7 号 p. 1502-1505
Polycrystalline samples of thallium compounds, Tl9BiTe6, TlBiTe2, TlSbTe2, and AgTlTe were prepared and the thermoelectric properties such as the electrical resistivity, Seebeck coefficient, and thermal conductivity were measured. The Seebeck coefficients of Tl9BiTe6, TlSbTe2, and AgTlTe are positive, while that of TlBiTe2 is negative. The thermal conductivities of these thallium compounds are very low compared with state-of-the-art thermoelectric materials. Especially, AgTlTe indicates extremely low value, 0.25 Wm−1K−1 at room temperature. The dimensionless figure of merit ZT of thallium compounds are relatively high due to their very low thermal conductivities. The maximum value of ZT is obtained for TlSbTe2 as 0.87 at 715 K.