Ternary thermoelectric AB2C2 Zintls

As derivatives of Mg3Sb2, ternary CaAl2Si2-structured AB2C2 Zintl compounds (A = Mg, Ca, Sr, Ba, Eu, Yb; BMg, Zn, Cd; CP, As, Sb, Bi) have been intensively demonstrated as promising p-type candidates for thermoelectric applications. This largely stems from the strong lattice anharmonicity for intrinsically low lattice thermal conductivity and tunable valence-band structure for superior electronic performance. Moreover, the richness in constituent of this Zintl family enables a diversified manipulation of composition in a broad range for optimizing both electronic and thermal transport properties. Utilization of proven strategies of band and defects engineering, a significant enhancement in thermoelectric figure of merit, zT, has been achieved in these compounds in recent 20 years. Here, synthesis techniques, band structure, electronic transport properties, lattice thermal conductivity and other fundamental material parameters of ternary AB2C2 Zintls, as well as successful strategies for manipulating the thermoelectric properties, are summarized with opportunities for further advancements as the perspectives. These strategies involved are believed to be in principle applicable for advancing many other thermoelectrics.