Sr3SbN and Sr3BiN: two anti-perovskite thermoelectric materials with low lattice thermal conductivity

This study comprehensively investigates the thermoelectric properties of anti-perovskite compounds Sr₃SbN and Sr₃BiN by combining first-principles calculations with the semi-classical Boltzmann theory framework, while incorporating the electron-phonon averaging (EPA) method. The results demonstrate that Sr₃SbN and Sr₃BiN exhibit excellent dynamical and mechanical stability, providing a solid theoretical foundation for their experimental synthesis. The calculated band gap values of Sr₃SbN and Sr₃BiN are 1.03 eV and 1.05 eV, respectively. Their conduction and valence band degeneracies (N_v) are 2 and 3, respectively, which facilitates the optimization of carrier transport properties. At 300 K, the lattice thermal conductivities (κ_L) of Sr₃SbN and Sr₃BiN are 2.28 and 2.67 W m⁻¹ K⁻¹, respectively, values comparable to that of the classical thermoelectric material PbTe (2.3 W m⁻¹ K⁻¹). At 400 K, the maximum ZT values for p-type doped Sr₃SbN and Sr₃BiN reach 0.63 and 0.71, respectively, providing valuable theoretical insights for the development of next-generation clean energy conversion devices.