Optimizing the thermoelectric performance of FeVSb half-Heusler compound via Hf–Ti double doping

Abstract FeVSb-based half-Heusler (HH) compound has recently been identified as promising medium-high temperature thermoelectric (TE) materials for power generation applications. In this study, enhanced thermoelectric performance of Fe(V0.8Hf0.2)1-xTixSb (x = 0.0, 0.2, 0.4, 0.5, 0.6) HH alloys by Hf–Ti dual-doping was reported studied in a temperature range from 100 to 900 K. A high content of Ti doping not only optimized the carrier concentration but also reduced the lattice thermal conductivity, which all contribute to high zT. As a result, a zT value was increased by ~20% at 873 K for Fe(V0.8Hf0.2)0.8Ti0.2Sb compound. Hf–Ti dual doping significantly reduced the lattice thermal conductivity due to enhanced point defect scattering which is mainly attributed to mass fluctuations. Hence, suppressed the material's total thermal conductivity. A reduction of ~20% was obtained for the Fe(V0.8Hf0.2)0.8Ti0.2Sb sample, compared with the single Hf-doped FeVSb sample and of ~80% compared to FeVSb at room temperature.