LAUSR

MNiSn (M = Ti, Zr, and Hf) half-Heusler (HH) compounds are widely studied n-type thermoelectric (TE) materials for power generation. Most studies focus on Zr- and Hf-based compounds due to their high thermoelectric performance. However, these kinds of compositions are not cost-effective. Herein, the least expensive alloy in this half-Heusler family—TiNiSn—is investigated. Modulation doping of half-metallic MnNiSb in the TiNiSn system is realized by using spark plasma sintering. It is found that MnNiSb dissolves into the TiNiSn matrix and forms a heavily doped Ti1–xMnxNiSn1–xSbx phase, which leads to largely enhanced carrier concentration and also slight increase of carrier mobility. As a result, the electrical conductivity and power factor of the modulation doped compounds are greatly improved. A maximum power factor of 45 × 10–4 W K–2 m–1 is obtained at 750 K for the modulation doping system (TiNiSn)1–x + (MnNiSb)x with x = 0.05, which is one of the highest reported values in literature for TiNiSn system...