Inhibition of Lattice Thermal Conductivity of ZrNiSn-based Half-Heusler Thermoelectric Materials by Entropy Adjustment

The thermoelectric properties of ZrNiSn-based half-Heusler materials were hindered due to their high thermal conductivity. In order to reduce the lattice thermal conductivity, the high-entropy alloys ZrNiSn and Zr0.5Hf0.5Ni1-xPtxSn (x=0, 0.1, 0.15, 0.2, 0.25, 0.3) were prepared by levitation melting and spark plasma sintering. Configurational entropy of the alloys was manipulated by Hf substitution for Zr and Pt substitution for Ni. Effects of configuration entropy on the thermoelectric properties were investigated. The reslults showed that the minimum sum of lattice thermal conductivity and bipolar thermal conductivity (kappa(l)+kappa(b)) at 673 K for Zr0.5Hf0.5Ni0.85Pt0.15Sn was optimized at 2.1 W.m(-1).K-1, which was significantly reduced by about 58% when compared with ZrNiSn. This finding provides an effective strategy for reducing lattice thermal conductivity of ZrNiSn-based alloy to offer great potential for further improvement of thermoelectrics.