A new defective 19-electron TiPtSb half-Heusler thermoelectric compound with heavy band and low lattice thermal conductivity. (June 2020) - Fang, T.
Abstract: Compared with widely studied 18-electron half-Heusler (HH) thermoelectric (TE) materials, cation-deficient 19-electron HH compounds have also been recently demonstrated to possess excellent TE performance, exhibiting high potential for TE application. Here, a new defective 19-electron HH compound Ti1- x PtSb is developed with high density-of-state effective mass and low lattice thermal conductivity. The former results from the band degeneracy and high band effective mass, and the latter results from the enhanced phonon scattering by substantial intrinsic Ti vacancies. The optimized carrier concentration, combined with the low lattice thermal conductivity, contributes to a maximum zT of 0.7 in pure-phase Ti1- x PtSb ( x = 0.14–0.18) samples, which is about 50% higher than that of the nominal TiPtSb sample, indicating that n -type Ti1- x PtSb HH compounds are promising TE materials. Graphical abstract: Image 1 Highlights: A new nominally 19-electron half-Heusler compound Ti1- x PtSb is reported. The heavy band is resulted from band degeneracy and high band effective mass. The low lattice thermal conductivity is mainly due to the strong phonon scattering by substantial intrinsic Ti vacancies. A maximum zT of 0.7 is obtained in pure-phase Ti1- x PtSb samples, about 50% higher than that of the nominal TiPtSb sample.