Suppressed phonon transport and strong four-phonon scattering in zeolite-like SOD-MO (M = Mg, Zn, Cd)

Abstract

By using the self-consistent charge density-functional tight-binding method combined with iterative solutions of the Boltzmann transport equation, we systematically investigated the thermal transport properties of zeolite-like semiconductor SOD-MO (M = Mg, Zn, Cd) assembled from cage clusters (MO)12. Our results reveal that at room temperature, when both three-phonon (3ph) scattering and four-phonon (4ph) scattering are considered, the lattice thermal conductivities (κlat) of SOD-MgO, SOD-ZnO, and SOD-CdO are 16.45, 2.17, and 0.53 W/mK, respectively. These are significantly lower than those of conventional MO semiconductors, which can be attributed to the localized phonon modes in SOD-MO. Further analysis demonstrates that the intensity of 4ph scattering in SOD-MO is notably stronger than that of 3ph scattering, due to the interaction between the lone-pair electrons and the bonding electrons. This anomalous phenomenon, not reported in conventional materials, indicates that SOD-MO exhibits unique thermal transport properties. Our study paves the way for designing the low κlat materials by cluster assemblies.