Thermoelectric performance of n-type Mg2Ge

Abstract Magnesium-based thermoelectric materials (Mg2X, X = Si, Ge, Sn) have received considerable attention due to their availability, low toxicity, and reasonably good thermoelectric performance. The synthesis of these materials with high purity is challenging, however, due to the reactive nature...

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Autores principales:	Rafael Santos, Mitchell Nancarrow, Shi Xue Dou, Sima Aminorroaya Yamini
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/96773189978e43a48af55b7e39245a74
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spelling	oai:doaj.org-article:96773189978e43a48af55b7e39245a742021-12-02T11:40:14ZThermoelectric performance of n-type Mg2Ge10.1038/s41598-017-04348-72045-2322https://doaj.org/article/96773189978e43a48af55b7e39245a742017-06-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-04348-7https://doaj.org/toc/2045-2322Abstract Magnesium-based thermoelectric materials (Mg2X, X = Si, Ge, Sn) have received considerable attention due to their availability, low toxicity, and reasonably good thermoelectric performance. The synthesis of these materials with high purity is challenging, however, due to the reactive nature and high vapour pressure of magnesium. In the current study, high purity single phase n-type Mg2Ge has been fabricated through a one-step reaction of MgH2 and elemental Ge, using spark plasma sintering (SPS) to reduce the formation of magnesium oxides due to the liberation of hydrogen. We have found that Bi has a very limited solubility in Mg2Ge and results in the precipitation of Mg2Bi3. Bismuth doping increases the electrical conductivity of Mg2Ge up to its solubility limit, beyond which the variation is minimal. The main improvement in the thermoelectric performance is originated from the significant phonon scattering achieved by the Mg2Bi3 precipitates located mainly at grain boundaries. This reduces the lattice thermal conductivity by ~50% and increases the maximum zT for n-type Mg2Ge to 0.32, compared to previously reported maximum value of 0.2 for Sb-doped Mg2Ge.Rafael SantosMitchell NancarrowShi Xue DouSima Aminorroaya YaminiNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-7 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Rafael Santos Mitchell Nancarrow Shi Xue Dou Sima Aminorroaya Yamini Thermoelectric performance of n-type Mg2Ge
description	Abstract Magnesium-based thermoelectric materials (Mg2X, X = Si, Ge, Sn) have received considerable attention due to their availability, low toxicity, and reasonably good thermoelectric performance. The synthesis of these materials with high purity is challenging, however, due to the reactive nature and high vapour pressure of magnesium. In the current study, high purity single phase n-type Mg2Ge has been fabricated through a one-step reaction of MgH2 and elemental Ge, using spark plasma sintering (SPS) to reduce the formation of magnesium oxides due to the liberation of hydrogen. We have found that Bi has a very limited solubility in Mg2Ge and results in the precipitation of Mg2Bi3. Bismuth doping increases the electrical conductivity of Mg2Ge up to its solubility limit, beyond which the variation is minimal. The main improvement in the thermoelectric performance is originated from the significant phonon scattering achieved by the Mg2Bi3 precipitates located mainly at grain boundaries. This reduces the lattice thermal conductivity by ~50% and increases the maximum zT for n-type Mg2Ge to 0.32, compared to previously reported maximum value of 0.2 for Sb-doped Mg2Ge.
format	article
author	Rafael Santos Mitchell Nancarrow Shi Xue Dou Sima Aminorroaya Yamini
author_facet	Rafael Santos Mitchell Nancarrow Shi Xue Dou Sima Aminorroaya Yamini
author_sort	Rafael Santos
title	Thermoelectric performance of n-type Mg2Ge
title_short	Thermoelectric performance of n-type Mg2Ge
title_full	Thermoelectric performance of n-type Mg2Ge
title_fullStr	Thermoelectric performance of n-type Mg2Ge
title_full_unstemmed	Thermoelectric performance of n-type Mg2Ge
title_sort	thermoelectric performance of n-type mg2ge
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/96773189978e43a48af55b7e39245a74
work_keys_str_mv	AT rafaelsantos thermoelectricperformanceofntypemg2ge AT mitchellnancarrow thermoelectricperformanceofntypemg2ge AT shixuedou thermoelectricperformanceofntypemg2ge AT simaaminorroayayamini thermoelectricperformanceofntypemg2ge
_version_	1718395659916148736

Thermoelectric performance of n-type Mg2Ge

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