Investigating the thermoelectric properties of p-type half-Heusler Hfx(ZrTi)1−xCoSb0.8Sn0.2 by reducing Hf concentration for power generation

Abstract

Based on the fact that Hf is much more expensive than other commonly used elements in HfCoSb-based half-Heusler materials, we studied the thermoelectric properties of the p-type half-Heusler Hf_x(ZrTi)_1−xCoSb_0.8Sn_0.2 by reducing Hf concentration. A peak ZT of ∼1.0 was achieved at 700 °C with the composition of Hf_0.19Zr_0.76Ti_0.05CoSb_0.8Sn_0.2 by keeping the Hf/Zr ratio at 1/4 and Hf/Ti at 4/1. This composition has much reduced cost and similar thermoelectric performance compared with our previously reported best p-type half-Heusler: Hf_0.44Zr_0.44Ti_0.12CoSb_0.8Sn_0.2. Due to the decreased usage of Hf, it is more favorable for consideration in applications. In addition, a higher output power is expected because of the higher power factor even though the conversion efficiency is the same due to the same ZT.