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Issue 65, 2014
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Enhancing thermoelectric properties of a p-type Mg3Sb2- based Zintl phase compound by Pb substitution in the anionic framework

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Abstract

Mg3Sb2-based Zintl compounds have recently attracted attention as a potential candidate for thermoelectric applications due to their low thermal conductivity and promising thermoelectric performance (i.e. ZT = 0.6 at 773 K in Mg3Sb2−xBix). We have reported previously that isoelectronic Bi3− substitution of Sb3− leads to a moderate increase in the electrical conductivity, enhanced Seebeck coefficient and reduced thermal conductivity. Herein, we report a large enhancement of the electrical conductivity while maintaining the Seebeck coefficient by substituting Pb4− on Sb3− sites in Mg3Sb2−xPbx (0 ≤ x ≤ 0.3) alloys. Transport measurements reveal that optimum doping of 10 at% Pb4− on Sb3− enhances the ZT to 0.84 at 773 K which is comparable to bismuth telluride and selenide industrial materials which are toxic and expensive. The enhancement in ZT is attributed to a decrease in lattice thermal conductivity and simultaneously an increase in the power factor resulting from the significant increase in the electrical conductivity. We observe that Pb4− substitutions on Sb3− sites in Mg3Sb2−xPbx (0 ≤ x ≤ 0.3) increase the hole carrier concentration. Electronic transport data of Mg3Sb2−xPbx (0 ≤ x ≤ 0.3) alloys have been analyzed using a single parabolic band model and have been compared to Mg3Sb2. The relatively high figure of merit and affordable material ingredients coupled with one step synthesis process makes these materials a promising cost effective solution as thermoelectric materials.

Graphical abstract: Enhancing thermoelectric properties of a p-type Mg3Sb2- based Zintl phase compound by Pb substitution in the anionic framework

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Supplementary files

Article information


Submitted
23 May 2014
Accepted
31 Jul 2014
First published
14 Aug 2014

RSC Adv., 2014,4, 34552-34560
Article type
Paper
Author version available

Enhancing thermoelectric properties of a p-type Mg3Sb2- based Zintl phase compound by Pb substitution in the anionic framework

A. Bhardwaj and D. K. Misra, RSC Adv., 2014, 4, 34552
DOI: 10.1039/C4RA04889J

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