Diverse lattice dynamics in ternary Cu-Sb-Se compounds.

Wujie Qiu,Wenqing Zhang,Jihui Yang,Lihua Wu,Xuezhi Ke

doi:10.1038/srep13643

Abstract

Searching and designing materials with extremely low lattice thermal conductivity (LTC) has attracted considerable attention in material sciences. Here we systematically demonstrate the diverse lattice dynamics of the ternary Cu-Sb-Se compounds due to the different chemical-bond environments. For Cu3SbSe4 and CuSbSe2, the chemical bond strength is nearly equally distributed in crystalline bulk, and all the atoms are constrained to be around their equilibrium positions. Their thermal transport behaviors are well interpreted by the perturbative phonon-phonon interactions. While for Cu3SbSe3 with obvious chemical-bond hierarchy, one type of atoms is weakly bonded with surrounding atoms, which leads the structure to the part-crystalline state. The part-crystalline state makes a great contribution to the reduction of thermal conductivity that can only be effectively described by including a rattling-like scattering process in addition to the perturbative method. Current results may inspire new approaches to designing materials with low lattice thermal conductivities for high-performance thermoelectric conversion and thermal barrier coatings.

Highlights

The first-principles calculations were performed in the framework of the density-function theory using the plane wave basis VASP code[32,33], implementing the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) form[34]
The interactions between the ions and electrons were described by the all-electron projector augmented wave (PAW) method[35,36], with plane waves up to a cutoff energy of 600 eV
To calculate the phonon dispersion curves, we used the direct ab initio force-constant approach, which is implemented in the PHONON software by Parlinski[23,38]

Summary

Introduction

The first-principles calculations were performed in the framework of the density-function theory using the plane wave basis VASP code[32,33], implementing the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) form[34]. The Brillouin-zone integrations were performed on the grid of Monkhorst-Pack procedure[37]. For the unit cell of Cu3SbSe3, CuSbSe2, and Cu3SbSe4, 4 × 3 × 4, 4 × 6 × 2 , and 5 × 5 × 3 k-point meshes were used, respectively.

Results

Conclusion