Effects of interlayer electrons and high-order anharmonicity on phonon thermal transport of electride Sc2C

Electrides have attracted considerable research interest over the past four decades owing to their rich physical properties. However, their phonon thermal transport behavior, which is critical for thermal management applications, remains relatively unexplored. In this work, we systematically investigate the influence of high-order anharmonicity and interlayer electrons on the lattice thermal conductivity (κL) of Sc2C using density functional theory calculations combined with the phonon Boltzmann transport equation. Our results reveal that four-phonon scattering processes substantially suppress the κL of Sc2C, leading to remarkable reductions of 61.5% in the in-plane and 58.6% in the out-of-plane directions at 300 K due to the strong quartic anharmonicity. Furthermore, the removal of interlayer electrons markedly reduces the in-plane κL, while its effect on the out-of-plane component remains minimal. This anisotropic behavior is attributed to a competition between two opposing effects: an increase in phonon group velocity due to lattice contraction, and enhanced phonon scattering rates resulting from increased anharmonicity upon the removal of interlayer electrons. This work deepens our understanding of the phonon thermal transport property of Sc2C and provides a theoretical guidance for regulating the κL of electride materials.