ABSTRACT
Half-Heusler (HH) compounds are named after Friedrich Heusler, a German chemist and mining engineer. More than 100 HH compounds can be found in Pearson's handbook and the Inorganic Crystal Structural Database. This chapter focuses on the classical n-type HH thermoelectric (TE) material-MNiSn. These defects can modify the band structure and affect the transport properties. For electrical conductivity and Seebeck coefficient, the determinant role is played by the band structure, which can be effectively tuned by dopants, structural disorder, and strain. The n-type HH compounds MNiSn usually have high thermal conductivity due to their high lattice thermal conductivity. Incorporating secondary phase nanoinclusions into the HH matrix can also create additional boundary scattering for phonons at the interface between the nanoinclusion and HH, leading to the reduction of lattice thermal conductivity. The p-type HH usually possesses very high power factors, with the high thermal conductivity being the only drawback.
