Structural, electronic and thermoelectric performance of narrow gap LuNiSb half Heusler compound: Potential thermoelectric material

Abstract

We report the band structure calculations of rare earth based half Heusler LuNiSb compound for thermoelectric performance. A narrow energy gap of 0.227 eV is opened using TB-mBJ approximation. The value of Seebeck coefficient 288 (μVK −1) at room temperature using mBJ scheme is quite large as compared to the experiment as well as well known thermoelectric material PbTe at same temperature. The observed highest value (6.1 × 10 10 Wm −1 K −2 s −1) at 647 K is close to our calculated value 9.93 × 10 10 Wm −1 K −2 s −1 at 650 K using GGA + U approximations. We found the Lu-4 f flat bands lie in conduction band along Γ– X direction are mainly responsible for maximum peaks of Power factor. The high value 0.804 of ZT and value of other thermoelectric parameters indicate that LuNiSb would be a favourable material for room temperature thermo electric applications.