Fabrication and Thermoelectric Properties of Al/Mg₂Si Composite Materials

Abstract

Mg 2 Si has attracted interest as a potential thermoelectric material that can convert waste heat into electricity. To improve thermoelectric performance of Mg 2 Si, Al/Mg 2 Si composite materials with nominal composition of xAl/Mg 2 Si (x = 0.25, 0.5, 0.75, 1.0, or 1.5) were fabricated, i.e., an Al metal phase was introduced to an Mg 2 Si matrix. Reflecting an increase in the electrical conductivity and a decrease in the Seebeck coefficient with increasing x, the power factor was successfully enhanced by the incorporation of the Al phase. The increase in electrical conductivity was discussed in terms of electron carrier density and carrier mobility.

Chemical-Pressure-Induced Point Defects Enable Low Thermal Conductivity for Mg2Sn and Mg2Si Single Crystals

“…Mg-based compounds such as Mg 2 (Si,Ge,Sn), − Mg 3 Sb 2 , − and others with a complex crystal structure − have attracted considerable attention as state-of-the-art thermoelectric (TE) materials that can effectively convert waste heat into electricity. These compounds exhibit high TE performance, which is evaluated by the dimensionless figure of merit, zT = S 2 σ T /κ tot , and power factor, PF = S 2 σ, where S , σ, T , and κ tot denote the Seebeck coefficient (thermopower), electrical conductivity, absolute temperature, and total thermal conductivity, respectively.…”

Realizing p-type Mg2Sn Thermoelectrics via Ga-Doping and Point Defect Engineering

“…Mg 2 Sn and its derivatives Mg 2 (Si, Ge, Sn), which are composed of cheap, environmentally friendly, and abundant elements, are potential TE materials for operation at moderate temperatures between 400 K and 800 K. ,− Recently, we prepared Mg 2 Sn single crystals (SCs) by melting under an Ar atmosphere, which contained Mg vacancies (V Mg ) as point defects that scattered phonons and gave the prepared Mg 2 Sn SCs a lower κ lat than that of a previously reported Mg 2 Sn polycrystals (PCs) . Such point defect engineering has recently been used to improve the zT value of bulk materials. − We enhanced the n-type characteristics of the Mg 2 Sn SC containing V Mg by increasing its electron carrier concentrations via Sb doping .…”

Enhanced thermoelectric performance of p-type Mg2Sn single crystals via multi-scale defect engineering

“…Among the considered materials, Mg 2 Sn and its derivatives Mg 2 (Si,Ge,Sn) are potential TE materials for operation at moderate temperatures between 400 K and 800 K. 5–34 Good TE performances ( zT ∼ 0.9 at 750 K) have been reported for n-type Mg 2 Sn utilizing point defects and carrier optimization. 26,27 Among the n-type Mg 2 Sn samples, undoped, B-doped, and Sb-doped Mg 2 Sn single crystals (SCs), 22–24,34 Bi-doped Mg 2 Sn polycrystals (PCs), 26 and Sb-doped Mg 2 Sn PCs 27 prepared by applying physical and chemical pressure were found to contain Mg vacancy (V Mg ) as a point defect.…”