Resonant bonding leads to low lattice thermal conductivity

Abstract

Understanding the lattice dynamics and low thermal conductivities of IV-VI, V2 -VI3 and V materials is critical to the development of better thermoelectric and phase-change materials. Here we provide a link between chemical bonding and low thermal conductivity. Our first-principles calculations reveal that long-ranged interaction along the <100> direction of the rocksalt structure exist in lead chalcogenides, SnTe, Bi2 Te3, Bi and Sb due to the resonant bonding that is common to all of them. This long-ranged interaction in lead chalcogenides and SnTe cause optical phonon softening, strong anharmonic scattering and large phase space for three-phonon scattering processes, which explain why rocksalt IV-VI compounds have much lower thermal conductivities than zincblende III-V compounds. The new insights on the relationship between resonant bonding and low thermal conductivity will help in the development of better thermoelectric and phase change materials. © 2014 Macmillan Publishers Limited. All rights reserved.