Phonon hardening and the effect of phonon transport in cubic antiperovskites [formula omitted] (A = Li, Na; B = Se, Te) induced by quartic anharmonicity

Abstract

In this article, we aim at the structural stability, lattice thermal conductivity, transport properties of four cubic antiperovskites A3FB using first-principle calculations combined with self-consistent phonon theory(SCP), compressive sensing techniques (CS), and Boltzmann transport equation (BTE), with a particular focus on the 4 phonon scattering rates and phonon frequency shifts caused by quartic anharmonicity. The results indicate that the strong quartic anharmonicity of alkali metal atoms Na atom harden low-frequency phonon branch to ensure dynamic stability of the material. We also find that the quartic anharmonicity play a crucial role in obtaining the reasonable temperature dependence of κL. In addition, we analyze the impact of phonon group velocities, the scattering rate and scattering phase space of 3ph and 4ph on phonon transport, revealing that the low κL of Na3FSe is due to the strong 4ph SRs which is dominated by redistribution and Umklapp processes. Our studies provide the microscopic understanding of the quartic anharmonicity together with their impact on lattice dynamics and phonon transport is not only of indispensable interest but also essential to design and explore materials with ultralow thermal conductivity.