Mg<sub>2</sub>Sn: a potential mid-temperature thermoelectric material

Jin, Yu; Feng, Zhen; Ye, Ling Yun; Yan, Yu; Wang, Yuanxu

doi:10.1039/c6ra04986a

Cited by 21 publications

(21 citation statements)

References 51 publications

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“…The trend of increasing carrier concentration with higher Sn content can be understood from the interplay between Fermi level and density of states or effective mass. Similar DOS shape and values for the VB have been reported [29,45,49,50], our results using hybrid-DFT, and with an exact-exchange mixing parameter of 25%, are shown in figures S1 and S2 of the SI. However, the VB-DOS close to the band edge differs between the two binaries, which determines the transport properties via the density of states effective mass (m * D ).…”

Section: Discussionsupporting

confidence: 85%

Understanding the dopability of p-type Mg₂(Si,Sn) by relating hybrid-density functional calculation results to experimental data

Kamila¹,

Ryu²,

Ayachi³

et al. 2022

J. Phys. Energy

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Reaching a sufficiently high carrier concentration is crucial for thermoelectric material optimization in developing Mg2X (X = Si, Ge, and Sn)-based thermoelectric generators (TEGs). While n-type Mg2(Si,Sn) has excellent thermoelectric properties, p-type shows suboptimal thermoelectric performance because of insufficient carrier concentration, in particular for Mg2Si and Si-rich Mg2(Si,Sn). A systematic investigation of Li-doped Mg2Si1-xSnx has been performed as Li, in contrast to other typical dopants, has a high solubility in the material system and has been shown to yield the highest reported carrier concentrations. We observe that the carrier concentration increases with Li content, but the dopant efficiency decreases. With respect to the Si:Sn ratio, we find a clear increase in maximum achievable carrier concentration and dopant efficiency with increasing Sn content. The trends can be understood employing defect formation energies obtained within the hybrid-density functional theory (DFT) for the binaries. We furthermore use a linear interpolation of the hybrid-DFT results from the binaries to the ternary Mg2(Si,Sn) compositions and a simple single parabolic band model to predict the maximal achievable carrier concentration for the solid solutions, providing a simple guideline for experimental work. Finally, we show that the approach is transferable to other material classes. This work highlights that besides dopant solubility the interplay between intrinsic and extrinsic defects determines the achievable carrier concentration.

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Section: Discussionsupporting

confidence: 85%

Understanding the dopability of p-type Mg₂(Si,Sn) by relating hybrid-density functional calculation results to experimental data

Kamila¹,

Ryu²,

Ayachi³

et al. 2022

J. Phys. Energy

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“…In the present study, we focus on Mg 2 Sn with the same crystal structure as Mg 2 Si. Mg 2 Sn has been studied extensively as a potential TE material [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] . Xin et al 31 reported that an Sb-doped n-type polycrystalline Mg 2 Sn, Mg 2.15 Sn 0.98 Sb 0.02 exhibited a zT value of 0.53 at 650 K (κ and PF are 4.7 W/mK and 3.9 W/mK 2 , respectively).…”

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confidence: 99%

Control of the Thermoelectric Properties of Mg2Sn Single Crystals via Point-Defect Engineering

Saito

Hayashi

Dong

et al. 2020

Sci Rep

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is a potential thermoelectric (te) material that can directly convert waste heat into electricity. in this study, Mg 2 Sn single-crystal ingots are prepared by melting under an Ar atmosphere. the prepared ingots contain Mg vacancies (V Mg) as point defects, which results in the formation of two regions: an Mg 2 Sn single-crystal region without V Mg (denoted as the single-crystal region) and a region containing V Mg (denoted as the V Mg region). the V Mg region is embedded in the matrix of the single-crystal region. the interface between the V Mg region and the single-crystal region is semi-coherent, which does not prevent electron carrier conduction but does increase phonon scattering. furthermore, electron carrier concentration depends on the fraction of V Mg , reflecting the acceptor characteristics of V Mg. The maximum figure of merit zT max of 1.4(1) × 10 −2 is realised for the Mg 2 Sn single-crystal ingot by introducing V Mg. these results demonstrate that the te properties of Mg 2 Sn can be optimised via pointdefect engineering.

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“…So to optimise the thermoelectric properties, main focus is the reduction of thermal conductivity. Due to the low lattice thermal conductivity, zT value of 1.1 was observed in p-type Mg 2 Sn at 800 K [192] which is more than Mg 2 Si(0.8) and Mg 2 Ge(1). The low lattice thermal conductivity is due to low velocity of optical modes caused by the large mass density [192].…”

Section: Sige Alloysmentioning

confidence: 95%

“…Due to the low lattice thermal conductivity, zT value of 1.1 was observed in p-type Mg 2 Sn at 800 K [192] which is more than Mg 2 Si(0.8) and Mg 2 Ge(1). The low lattice thermal conductivity is due to low velocity of optical modes caused by the large mass density [192]. zT reached the value of 0.46 in Mg2Si microstructure via Yb and Bi doping because Yb doping lowers the thermal conductivity and Bi doping adjusts the electronic transport properties [193].…”

Section: Sige Alloysmentioning

confidence: 95%

Odyssey of thermoelectric materials: foundation of the complex structure

et al. 2018

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Growing energy crises and pollution are the major issues of the modern world. The thermoelectric concept seems to be the promising solution to deal with these problems, because of the ability of thermoelectric materials to convert waste heat into electricity without adding more pollution to the atmosphere. The development of thermoelectric materials (TE) is driven by fundamental interest and their potential applications. To replace the conventional techniques, the figure of merit (zT) of the thermoelectric materials should be higher than 2 for power generation and greater than 3 for cooling. Recently, there have been significant advances in enhancing the figure of merit of thermoelectric materials and also to find new materials for the thermoelectric purpose. Low thermal conductivity is the key for a promising thermoelectric material that can be achieved through the complex structures. This review provides insights into the recent advancements in improving the efficiency of thermoelectric systems, complex nature of thermoelectric materials, with a concise introduction to preparative approaches for thermoelectric (TE) materials.

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Mg₂Sn: a potential mid-temperature thermoelectric material

Abstract: The Mg2X (X = Si, Ge, and Sn) with X = Sn has the highest ZT value due to its large mass density.

Cited by 21 publications

References 51 publications

Understanding the dopability of p-type Mg₂(Si,Sn) by relating hybrid-density functional calculation results to experimental data

Understanding the dopability of p-type Mg₂(Si,Sn) by relating hybrid-density functional calculation results to experimental data

Control of the Thermoelectric Properties of Mg2Sn Single Crystals via Point-Defect Engineering

Odyssey of thermoelectric materials: foundation of the complex structure

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Mg2Sn: a potential mid-temperature thermoelectric material

Abstract: The Mg2X (X = Si, Ge, and Sn) with X = Sn has the highest ZT value due to its large mass density.

Cited by 21 publications

References 51 publications

Understanding the dopability of p-type Mg2(Si,Sn) by relating hybrid-density functional calculation results to experimental data

Understanding the dopability of p-type Mg2(Si,Sn) by relating hybrid-density functional calculation results to experimental data

Control of the Thermoelectric Properties of Mg2Sn Single Crystals via Point-Defect Engineering

Odyssey of thermoelectric materials: foundation of the complex structure

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Mg₂Sn: a potential mid-temperature thermoelectric material

Understanding the dopability of p-type Mg₂(Si,Sn) by relating hybrid-density functional calculation results to experimental data

Understanding the dopability of p-type Mg₂(Si,Sn) by relating hybrid-density functional calculation results to experimental data