2012 Volume 53 Issue 11 Pages 1976-1980
InSb is known to be a good candidate as a thermoelectric (TE) material owing to its high carrier mobility and narrow band gap of around 0.18 eV. However, a high ZT value has not been achieved in InSb because of its high lattice thermal conductivity (κlat). In order to reduce the κlat of InSb, In3+ ions in InSb were partly replaced by Zn2+ and Ge4+ ions to form the ZnIn18GeSb20 alloy. Polycrystalline samples of ZnIn18GeSb20 were prepared by a powder metallurgy process combining mechanical alloying and hot pressing followed by water quenching or slow cooling. The TE properties of the quenched and slow-cooled samples were examined over the temperature range of room temperature to 723 K. The κlat values of the quenched and slow-cooled samples at room temperature were 2.70 and 2.83 W m−1 K−1, respectively. These values were approximately 6 times lower than that of InSb, presumably due to grain refinement through MA and effective alloy scattering from the multi-component system. The present study confirmed that the relatively large secondary phase would played an important role for the decreased the thermal conductivity in the Zn–In–Ge–Sb system unlike the AgPbmSbTem+2 (LAST-m) system, in which nano-sized Ag–Sb inclusion are embedded in the PbTe matrix.