Thermoelectric devices are useful to directly convert heat into electricity. A range of material systems such as half-Heuslers, skutterudites, silicides, chalcogenides, and Zintl compounds are thoroughly investigated to enhance their thermoelectric properties [1]. The Mg3Sb2 based Zintl compounds are promising thermoelectric materials due to the non-toxicity and the abundance of the constituent elements. However, the main hindrance in realizing the full potential of Mg3Sb2 based compounds for thermoelectric applications is their low energy conversion efficiency, which is often quantified by the dimensionless figure of merit (zT). The zT of p-type Mg3Sb2 is much lower in comparison with its n-type counterpart owing to its reduced electronic properties [1]. Density functional theory calculations of p-type Mg3Sb2 suggest that doping of suitable elements at the Mg sites can tailor the carrier density and optimize the electronic properties. In the present work, p-type Mg3Sb2 has been synthesized by careful doping at the Mg site following a solid-state synthesis route. The co-doping of Ag and Cu at the Mg site of Mg3Sb2 is found to significantly enhance the thermoelectric figure of merit [2]. The enhancement of zT also comes from a drastic reduction of the lattice thermal conductivity aided by the rattling of co-doped atoms in the Mg3Sb2 lattice. Further, the strategy to enhance the thermoelectric properties of Mg3Sb2 through a combined approach of experiments and theory will be presented in detail.

[1] A Das, A Chauhan, V Trivedi, M Tiadi, Ravi Kumar, M Battabyal, D K Satapathy,
Physical Chemistry Chemical Physics, 23, 4230 (2021).
[2] M Tiadi, M Battabyal, P K Jain, A Chauhan, D K Satapathy, R Gopalan, Sustainable
Energy and Fuels, 5, 4104 (2021).