Serrano-Sánchez, FedericoFedericoSerrano-SánchezLuo, TingTingLuoYu, JunjieJunjieYuXie, WenjieWenjieXieLe, CongcongCongcongLeAuffermann, GudrunGudrunAuffermannWeidenkaff, AnkeAnkeWeidenkaffZhu, TiejunTiejunZhuZhao, XinbingXinbingZhaoAlonso, José A.José A.AlonsoGault, BaptisteBaptisteGaultFelser, ClaudiaClaudiaFelserFu, ChenguangChenguangFu2022-03-062022-03-062020https://publica.fraunhofer.de/handle/publica/26951910.1039/d0ta04644bHalf-Heusler compounds with a valence electron count of 18, including ZrNiSn, ZrCoSb, and NbFeSb, are good thermoelectric materials owing to favorable electronic structures. Previous computational studies had predicted a high electrical power factor in another half-Heusler compound NbCoSn, but it has not been extensively investigated experimentally. Herein, the synthesis, structural characterization, and thermoelectric properties of the heavy-element Pt-substituted NbCoSn compounds are reported. Pt is found to be an effective substitute enabling the optimization of electrical power factor and simultaneously leading to a strong point defect scattering of phonons and the suppression of lattice thermal conductivity. Post-annealing significantly improves the carrier mobility, which is ascribed to the decreased grain boundary scattering of electrons. As a result, a maximum power factor of ∼3.4 mW m−1 K−2 is obtained at 600 K. In conjunction with the reduced lattice thermal conductivity, a maximum figure of merit zT of ∼0.6 is achieved at 773 K for the post-annealed NbCo0.95Pt0.05Sn, an increase of 100% compared to that of NbCoSn. This work highlights the important roles that the dopant element and microstructure play in the thermoelectric properties of half-Heusler compounds.enannealingchemical elementcobalt alloyscomputational studiescrystal latticeselectric power factorelectronic structuregrain boundarygrain boundary scatteringHalf-Heusler compoundhall mobilityhigh electrical powerhole mobilityiron alloyslattice thermal conductivityniobium alloyplatinum compoundsstructural characterizationternary alloythermal conductivitythermoelectric equipmentthermo-electric materialsthermoelectric propertiesthermoelectricitytin alloysZircaloy541journal article