Structural, mechanical and dynamical stabilities of K2NaMCl6 (M: Cr, Fe) halide perovskites along with electronic and thermal properties

Abstract

The properties of K2NaMCl6 (M: Cr, Fe) are simulated using density functional theory. The exchange-correlation potential of halide perovskites is projected by generalized gradient approximation and integration of modified Becke–Johnson potential. The structure's stability is defined by optimizing total energy and using the tolerance factor. In contrast, the enthalpy of formation and elastic constants are used to predict the thermodynamical and mechanical stabilities, while phonon calculations for dynamical stability, respectively. The conventional lattice constant obtained is consistent with those reported for similar halide perovskites. Spin-polarized band structure and energy state distribution plots portray these materials' semiconducting behavior in both spin states. The magnetic moment of 3µB and 5µB is obtained for Cr and Fe-based materials, respectively. The magnetic moment is mainly from transition-metal-based constituents. The thermoelectric figure of merit suggests that these materials could be potential candidates for waste heat recovery.