Thermoelectric and electrical transport properties of Mg<sub>2</sub>Si multi-doped with Sb, Al and Zn

Zhao, Jianbao; Liu, Zhenxian; Reid, Joel W.; Takarabe, Kenichi; Iida, Tsutomu; Wang, Bosen; Uwatoko, Yoshiya; Tse, John S.

doi:10.1039/c5ta03751d

Cited by 39 publications

(17 citation statements)

References 41 publications

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“…A further material class specific advantage is their low density which is a factor of 2-3 lower than that ofskutteruditesor PbTe. This holds especially for the binary or Si-rich compositions [15][16][17] and gives magnesium silicides an advantage where weight is crucial, i.e., in airborne or mobile applications.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric performance of Li doped, p-type Mg2(Ge,Sn) and comparison with Mg2(Si,Sn)

et al. 2016

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Solid solutions with chemical formulaMg 2 (Si,Ge,Sn) are promising thermoelectric materials with very good properties for the n-type material but significantly worse for the p-type. For power generation applications good n-and p-type materials are required and it has been shown recently that Li doping can enhance the carrier concentration and improve the thermoelectric properties for p-type Mg 2 Si 1x Sn x .We have investigated the potential of p-type Mg 2 (Ge,Sn) by optimizing Mg 2 Ge 0.4 Sn 0.6 using Li as dopant. We were able to achieve high carrier concentrations (1.4 × 10 20 cm −3) and relatively high hole mobilities resulting in high power factors of 1.7 × 10 −3 W m −1 K −2 at 700 K, the highest value reported so far for this class of material. Exchanging Ge by Si allows for a systematic comparison of Mg 2 (Ge,Sn) with Mg 2 (Si,Sn) and shows that Si containing samples exhibit a lower power factor but also a lower thermal conductivity resulting in comparable thermoelectric figure-of-merit. The data is furthermore analyzed in the framework of a single parabolic band model to gain insight on the effect of composition on band structure. 2 , here is the electrical conductivity, the thermal conductivity, the Seebeck coefficient, and the absolute temperature. A large fraction of the potentially available waste heat can be found in the mid-temperature region

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Section: Introductionmentioning

confidence: 99%

Thermoelectric performance of Li doped, p-type Mg2(Ge,Sn) and comparison with Mg2(Si,Sn)

et al. 2016

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“…However, the environmentally hazardous Pb element prevents them from widespread application. Therefore, it is of signifi cance to develop eco-friendly TE materials for middle temperature application, such as Mg 2 Si, [ 13 ] Half-Heusler, [ 14 ] and BiCuSeO [ 15 ] based TE materials.More recently, chalcopyrite CuInTe 2 is being considered as a promising p-type TE material because of the merits of environmentally friendly chemical component, intrinsically high electrical conductivity, and high Seebeck coeffi cient owing to the degenerate energy bands near the valence band maximum (VBM). [ 16 ] Thus many efforts have been made theoretically and experimentally [17][18][19][20][21][22] to enhance its TE performance already, such as Cu defi ciency and cation substitution.…”

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confidence: 99%

Progressive Regulation of Electrical and Thermal Transport Properties to High‐Performance CuInTe₂ Thermoelectric Materials

Luo

Jiang

et al. 2016

Advanced Energy Materials

128

133

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In addition, it is of importance to note that a high power factor ( S 2 / ρ ) is also indispensable for a given TE material to maximize its output power. [ 3 ] Therefore, by taking account of the practical application, a simultaneously optimization in the electrical and thermal transport properties of TE materials is imperative to maximize the output power and conversion efficiency concurrently. Recently, some strategies have been proved to be effective and even high ZT values greater than 2.0 have been achieved in the Pb-based TE materials, [ 4,5 ] such as the band convergence, [ 6 ] electronic density of states (DOS) distortion, [ 7 ] carrier energy barrier fi ltering, [ 8 ] and the conduction (valence) band modifi cation [ 9 ] to enhance Seebeck coefficient for high power factor; while defect engineering, [ 10 ] nanostructuring, [ 11 ] and multiscale hierarchical architecturing [ 12 ] to enhance the scattering of phonons for low thermal conductivity. However, the environmentally hazardous Pb element prevents them from widespread application. Therefore, it is of signifi cance to develop eco-friendly TE materials for middle temperature application, such as Mg 2 Si, [ 13 ] Half-Heusler, [ 14 ] and BiCuSeO [ 15 ] based TE materials.More recently, chalcopyrite CuInTe 2 is being considered as a promising p-type TE material because of the merits of environmentally friendly chemical component, intrinsically high electrical conductivity, and high Seebeck coeffi cient owing to the degenerate energy bands near the valence band maximum (VBM). [ 16 ] Thus many efforts have been made theoretically and experimentally [17][18][19][20][21][22] to enhance its TE performance already, such as Cu defi ciency and cation substitution. However, since there are two cation sites (Cu and In) in CuInTe 2 , cation substitution often lacks specifi city and may generate both electron and hole simultaneously, making it diffi cult to enhance the electrical transport properties substantially. Besides, the less phonon scattering, mainly by point defects originated from chemical component regulation, rendering its thermal conductivity is still relatively high. It is well known that refi ning the microstructure into nanoscale is often effective in optimizing thermal transport properties, yet the electrical transport properties are usually deteriorated due to the inevitably scattering of carriers, as typical shown in the CuInTe 2 /graphene [ 23 ] and our

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“…4,5 Production techniques for Mg 2 Si are numerous, among them spark plasma sintering (SPS) 11 or fieldactivated and press-assisted sintering (FAPAS). 12,13 In this study, bulk Mg 2 Si-based TE materials are produced through hot extrusion. 14,15 This approach has many advantages over SPS or FAPAS, not only by lowering the sintering temperature, which decreases the chance of contamination, but also by providing a lower cost route to industrial-scale production.…”

Section: Introductionmentioning

confidence: 99%

Hot Extruded Polycrystalline Mg2Si with Embedded XS2 Nano-particles (X: Mo, W)

Bercegol

Christophe

Keshavarz

et al. 2016

Journal of Elec Materi

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Due to their abundant, inexpensive and non-toxic constituent elements, magnesium silicide and related alloys are attractive for large-scale thermoelectric (TE) applications in the 500-800 K temperature range, in particular for energy conversion. In this work, we propose a hot extrusion method favorable for large-scale production, where the starting materials (Mg 2 Si and XS 2 , X: W, Mo) are milled together in a sealed vial. The MoS 2 nano-particles (0.5-2 at.%) act as solid lubricant during the extrusion process, thus facilitating material densification, as confirmed by density measurements based on Archimedes' method. Scanning electron microscopy images of bulk extruded specimens show a wide distribution of grain size, covering the range from 0.1 lm to 10 lm, and energy dispersive spectroscopy shows oxygen preferentially distributed at the grain boundaries. X-ray diffraction analysis shows that the major phase is the expected cubic structure of Mg 2 Si. The TE properties of these extruded alloys have been measured by the Harman method between 300 K and 700 K. Resistivity values at 700 K vary between 370 lX m and 530 lX m. The ZT value reaches a maximum of 0.26 for a sample with 2 at.% MoS 2 . Heat conductivity is reduced for extruded samples containing MoS 2 , which most likely behave as scattering centers for phonons. The reason why the WS 2 particles do not bring any enhancement, for either densification or heat transfer reduction, might be linked to their tendency to agglomerate. These results open the way for further investigation to optimize the processing parameters for this family of TE alloys.

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Thermoelectric and electrical transport properties of Mg₂Si multi-doped with Sb, Al and Zn

Abstract: A maximum ZT of 0.964 was found for Sb0.5%Zn0.5% doped Mg2Si, which is comparable to those of PbTe based thermoelectric materials.

Cited by 39 publications

References 41 publications

Thermoelectric performance of Li doped, p-type Mg2(Ge,Sn) and comparison with Mg2(Si,Sn)

Thermoelectric performance of Li doped, p-type Mg2(Ge,Sn) and comparison with Mg2(Si,Sn)

Progressive Regulation of Electrical and Thermal Transport Properties to High‐Performance CuInTe₂ Thermoelectric Materials

Hot Extruded Polycrystalline Mg2Si with Embedded XS2 Nano-particles (X: Mo, W)

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Thermoelectric and electrical transport properties of Mg2Si multi-doped with Sb, Al and Zn

Abstract: A maximum ZT of 0.964 was found for Sb0.5%Zn0.5% doped Mg2Si, which is comparable to those of PbTe based thermoelectric materials.

Cited by 39 publications

References 41 publications

Thermoelectric performance of Li doped, p-type Mg2(Ge,Sn) and comparison with Mg2(Si,Sn)

Thermoelectric performance of Li doped, p-type Mg2(Ge,Sn) and comparison with Mg2(Si,Sn)

Progressive Regulation of Electrical and Thermal Transport Properties to High‐Performance CuInTe2 Thermoelectric Materials

Hot Extruded Polycrystalline Mg2Si with Embedded XS2 Nano-particles (X: Mo, W)

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Thermoelectric and electrical transport properties of Mg₂Si multi-doped with Sb, Al and Zn

Progressive Regulation of Electrical and Thermal Transport Properties to High‐Performance CuInTe₂ Thermoelectric Materials