First-principles Study of Metallic-atom Diffusion in Thermoelectric Material Mg${}_3$Sb${}_2$

Abstract

Mg${}_3$Sb${}_2$ is a promising thermoelectric material that consists of nontoxic and earth-abundant elements. We investigate metallic-atom diffusion in Mg${}_3$Sb${}_2$ by calculating the defect formation energy and the diffusion energy barrier for several kinds of metallic-atom impurities. We find that early transition metals, including $4d$ elements, with a large atomic radius have a high defect formation energy, whereas Mg and late transition metals such as Ni, Cu, and Zn have relatively low formation energies as interstitial impurities. Interstitial Ni, which is found to have a very low defect formation energy, might diffuse in the $ab$ plane at high temperatures with the energy barrier of 0.7 eV, while it seems difficult to diffuse in the $c$ direction. Interstitial Cu has a higher defect formation energy than Ni but has a low energy barrier of $\sim$0.4 eV for diffusion in the $ab$ plane. This study will offer important knowledge for developing a thermoelectric device of Mg${}_3$Sb${}_2$.

7 pages, 5 figures

References in corpus (8)

• Reversible Work Transiton State Theory: Application to Dissociative Adsorption of Hydrogen
• Relating chemical bonding to physical properties: The origin of unexpected isotropic properties in layered materials
• When Band Convergence is Not Beneficial for Thermoelectrics
• Growth and transport properties of Mg3X2 (X = Sb, Bi) single crystals
• Fermi surface complexity, effective mass, and conduction band alignment in n-type thermoelectric Mg3Sb2-xBix from first principles calculations
• Effective $n$-type Doping of Mg${}_3$Sb${}_2$ with Group-3 Elements
• Ab initio thermal conductivity of thermoelectric Mg${}_3$Sb${}_2$: evidence for dominant extrinsic effects
• First principles study on the thermoelectric performance of CaAl${}_2$Si${}_2$-type Zintl phase compounds