Analyzing transport properties of p-type Mg2Si–Mg2Sn solid solutions: optimization of thermoelectric performance and insight into the electronic band structure

Hasbuna Kamila; Prashant Sahu; Aryan Sankhla; Mohammad Yasseri; Hoang-Ngan Pham; Titas Dasgupta; Eckhard Mueller; Johannes de Boor

doi:10.1039/C8TA08920E

Analyzing transport properties of p-type Mg₂Si–Mg₂Sn solid solutions: optimization of thermoelectric performance and insight into the electronic band structure†

Hasbuna Kamila,

*^a Prashant Sahu,^c Aryan Sankhla,

^a Mohammad Yasseri,^ab Hoang-Ngan Pham,^a Titas Dasgupta,^c Eckhard Mueller^ab and Johannes de Boor

*^a

Author affiliations

* Corresponding authors

^a Institute of Materials Research, German Aerospace Center, Linder Hoehe, Cologne 51147, Germany
E-mail: Hasbuna.kamila@dlr.de, Johannes.deBoor@dlr.de

^b Institute of Inorganic and Analytical Chemistry, Justus Liebig University Giessen, Giessen 35392, Germany

^c Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400 076, India

Abstract

We have synthesized the complete stoichiometric range of p-Mg₂Si_1−xSn_x, striving to optimize the thermoelectric properties of p-type Mg₂(Si,Sn) with respect to composition. The experimental data are analyzed in the framework of a single parabolic band (SPB) model and we can show that the thermoelectric properties can be well presented if acoustic phonon scattering and alloy scattering are taken into account. We find that the maximum achievable carrier concentration and power factor increase with higher Sn content. Also, the carrier mobility increases strongly from Mg₂Si to Mg₂Sn due to the changing density of states effective mass for the valence band which decreases from Image ID:c8ta08920e-t1.gif to Image ID:c8ta08920e-t2.gif . Retrieval of the acoustic phonon scattering potential (E_Def = 9 eV) and the alloy scattering parameter (E_AS = 0.5 eV) allows for modelling the thermoelectric properties for any arbitrary composition. Hence, we can predict the optimum zT for x ≈ 0.65–0.7 and the maximum power factor for Sn-rich compositions. Furthermore, we reveal that a significant improvement of the thermoelectric properties of Si-rich compositions can be achieved by increasing the carrier concentration experimentally and that the disparity between n- and p-type Mg₂(Si,Sn) is due to the differences between the valence and the conduction bands and not the interaction potentials.

This article is part of the themed collection: 2019 Journal of Materials Chemistry A HOT Papers

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Article information

DOI: https://doi.org/10.1039/C8TA08920E
Article type: Paper
Submitted: 13 Sep 2018
Accepted: 26 Nov 2018
First published: 28 Nov 2018

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J. Mater. Chem. A, 2019,7, 1045-1054

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Analyzing transport properties of p-type Mg₂Si–Mg₂Sn solid solutions: optimization of thermoelectric performance and insight into the electronic band structure

H. Kamila, P. Sahu, A. Sankhla, M. Yasseri, H. Pham, T. Dasgupta, E. Mueller and J. de Boor, J. Mater. Chem. A, 2019, 7, 1045 DOI: 10.1039/C8TA08920E

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Journal of Materials Chemistry A