Effect of substitutional doping on the thermal conductivity of Ti-based Half-Heusler compounds

Abstract

ABSTRACTHalf-Heusler alloys with the general formula TiNiSn1-XSbXare currently being investigated for their potential as thermoelectric (TE) materials.1,2,3,4These materials exhibit high thermopower (40–250μV/K) and low electrical resistivity values (0.1 - 8mΩ-cm) which yields a relatively large power factor (α2σT) of (0.2 - 1.0) W/m♦K at room temperature. The challenge is to reduce the relatively high thermal conductivity (≈ 10 W/m♦K) that is evident in these materials. The focus of this research is to investigate the effect of Sb-doping on the Sn site and Zr doping on the Ti site on the thermal conductivity of TiNiSn. Highly doped half-Heusler alloys have shown marked reduction in thermal conductivity to values on the order of 3.5 - 4.5 W/m♦K. Systematic determination of thermal conductivity in a variety of these doped materials as well as Sb and Zr doped TiNiSn are presented and discussed.