Lattice Thermal Conductivity in XMg2Sb2(X = Ca or Mg) Compounds: Temperature and High-Order Anharmonicity Effect.

ABSTRACT: The binary compound Mg3Sb2 (also written as MgMg2Sb2) exhibits a much lower lattice thermal conductivity (κL) than its ternary analog CaMg2Sb2, despite its relatively low mass density and simple crystalline structure. Here, we perform a comparative first-principles study of the lattice dynamics in MgMg2Sb2 and CaMg2Sb2 based on the density functional theory, together with the self-consistent phonon theory and the Boltzmann transport theory. We show that the modest anharmonicity of CaMg2Sb2 renders the three-phonon processes dominant, and the temperature dependence of κL approximately follows the T-1 relationship. In contrast, the strong quartic anharmonicity of MgMg2Sb2 leads to the ultralow κL and weak temperature dependence, in agreement with the experimental observations. A comprehensiv

SUBMITTER: Wu M 

PROVIDER: S-EPMC10707498 | biostudies-literature | 2023 Nov

REPOSITORIES: biostudies-literature