Activated Lone-Pair Electrons Lead to Low Lattice Thermal Conductivity: A Case Study of Boron Arsenide

Abstract

Reducing thermal conductivity (κ) is of great significance to lots of applications, such as thermal insulation, thermoelectrics, etc. In this study, we propose an effective approach for realizing low κ by introducing lone-pair electrons or making the lone-pair electrons stereochemically active through bond nanodesigning. By cutting at the (111) cross section of the three-dimensional cubic boron arsenide (c-BAs), the κ is lowered by more than 1 order of magnitude in the resultant two-dimensional graphenelike BAs (g-BAs). The underlying mechanism of activating lone-pair electrons is analyzed based on the comparative study on the thermal transport properties and electronic structures of g-BAs, c-BAs, graphene, and diamond (c-BAs → g-BAs vs diamond → graphene). The proposed approach for realizing low κ and the underlying mechanism uncovered in this study would largely benefit the design of advanced thermal functional materials, especially in future research involving novel materials for energy applications.

Importance of Four-Phonon Interactions in Lattice Thermal Conductivity and Thermoelectrics: A Case Study

“…Second, the lone pair–lone pair repulsions in the interlayer increase the anharmonicity of the system. These factors can potentially decrease the thermal conductivity of the system . The presence of Ge–Ge interactions (indicated in green color) has been observed in the two different layers of the h-GeS bilayer.…”

“…These factors can potentially decrease the thermal conductivity of the system. 55 The presence of Ge−Ge interactions (indicated in green color) has been observed in the two different layers of the h-GeS bilayer.…”