Thermoelectric transport and microstructure of optimized Mg₂Si_0.8Sn_0.2

Abstract

Solid solutions from magnesium silicide and magnesium stannide exhibit excellent thermoelectric properties due to a favorable electronic band structure and a reduced thermal conductivity compared to the binary compounds. We have optimized the composition Mg2Si0.8Sn0.2 by Sb doping and obtained a thermoelectric figure of merit close to unity. The material comprises of several phases and exhibits intrinsic nanostructuring. Nevertheless, the main features of the electronic transport can be understood within the framework of a single parabolic band model. Compared to Mg2Si we observe a comparable power factor, a drastically reduced thermal conductivity and an increased effective mass.This journal is

Hybrid-Functional and Quasi-Particle Calculations of Band Structures of Mg2Si, Mg2Ge, and Mg2Sn

“…In this alloy, each phase can serve as a point-disorder region because it is a disordered solid solution, while the interface between Si-and Sn-rich regions can block the phonon transport. Thus, in Mg2Sirelated silicide alloys, the naturally formed superlattice-like structure is reported to be responsible for its low thermal conductivity of approximately 1-3 W/m/K [34,35]. Similarly, our recent work revealed Sb-induced microstructure inhomogeneities in Mg2(Si,Sn) alloys [36].…”

High efficiency Mg2(Si,Sn)-based thermoelectric materials: scale-up synthesis, functional homogeneity, and thermal stability

“…The best performing materials in the Mg 2 (Si,Sn) system usually contain $23 AE 3 at% Sn, which is where the conduction band convergence is taking place, 41,42 and all exhibit a maximum gure of merit, zT max , of 1.4 AE 0.2, satisfactory for the device applications. 43 As for industrial applications, in addition to the electrode development which is in good progress, [44][45][46] a large amount of material is required; thus, a scalable synthesis method that sustains the outstanding TE properties of the material needs to be established. The up-scaling process can be challenging due to occurrence of de-mixing phenomena such as the formation of Si-rich and Sn-rich regions induced by gravity.…”

Systematic analysis of the interplay between synthesis route, microstructure, and thermoelectric performance in p-type Mg2Si0.2Sn0.8

“…Among several thermoelectric materials, magnesium silicide based solid solutions are highly promising for thermoelectric applications in the middle temperature range (300-800 K) due to materials abundance, non-toxicity, low density and cost, good environmental compatibility, and high thermoelectric performance for n-type ( ≈ 1.4) [8,14,[22][23][24]. Compared to ntype Mg 2 (Si,Sn), p-type Mg 2 (Si,Sn) has inferior properties ( ≈ 0.6) and further optimization is highly desirable for a practical implementation of Mg 2 Si-based thermoelectric generators [25][26][27][28][29][30][31][32]. Both p-and n-type Mg 2 (Si,Sn) are synthesized using different synthesis techniques including high energy ball milling (BM) [14,32], or melt spinning combined with (spark plasma) sintering [25,26,29,30,33,34].…”