Issue 65, 2014

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

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

Supplementary files

Article information

Article type
Paper
Submitted
23 May 2014
Accepted
31 Jul 2014
First published
14 Aug 2014

RSC Adv., 2014,4, 34552-34560

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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