Vacancy-suppressed lattice conductivity of high-ZT In4Se3-x

Abstract

Anomalous, vacancy-induced anisotropic thermal conductivity is one of the important properties in the recently discovered high-ZT In4Se3-x compound. In this work, the lattice thermal conductivity of In4Se3-x is investigated using equilibrium molecular dynamics simulation, the point-defect model, and ab initio calculations. The charge density distribution shows highly anisotropic structure with strong bonding along In-Se-In chain direction. Se vacancy strongly suppresses the phonon propagation along the chain direction, with little change in other directions. We show that suppressed long-range acoustic phonon transport caused by the vacancy results in anisotropic change of lattice conductivity. We suggest controlling of vacancy in intrinsic low-dimensional compounds is critical in achieving optimal lattice thermal conductivity and other thermoelectric properties. DOI: 10.1103/PhysRevB.87.125111