The influence of Zn vacancy on thermal conductivity of β-Zn4Sb3: A molecular dynamics study

The influence of Zn vacancy on lattice thermal conductivity of β-Zn4Sb3 is studied by non-equilibrium molecular dynamics approach. The lattice thermal conductivity of single-crystal bulk β-Zn4Sb3 decreases rapidly when there is Zn vacancy, and then when the vacancy grows, the lattice thermal conductivity decreases further but rather slowly, which suggests a scaling law of kv∼nv−α of Zn atom vacancy (nv) to lattice thermal conductivity (kvac). This phenomenon is attributed to the fact that the existence of vacancy scattering can significantly decrease the mean free path. When the Zn atom vacant proportion reaches 10%, that is the vacancy model of β-Zn4Sb3, the lattice thermal conductivity is 1.32 W/mk along the x-axis and 1.62 W/mk along the z-axis, respectively, which drops by ∼90% that of its full occupancy model. Therefore, our calculations show that the 10% Zn atom vacancy in β-Zn4Sb3 is the main reason for its exceptionally low thermal conductivity, and the interstitial Zn atoms have little effect on the thermal conductivity of single-crystal β-Zn4Sb3.