Issue 13, 2013

Improved thermoelectric properties in Zn-doped Ca5Ga2Sb6

Abstract

Zintl compounds with the chemical formula Ca5M2Sb6 have attracted attention as candidates for use in thermoelectric applications due to their low thermal conductivity and promising high temperature performance (i.e., zT = 0.6 at 1000 K in Ca5Al2−xNaxSb6). We have shown previously that, relative to Ca5Al2Sb6, both Ca5Ga2Sb6 and Ca5In2Sb6 have reduced phonon velocities and improved carrier mobility, suggesting that improved zT can be achieved in these materials. Here we further investigate Ca5Ga2Sb6, which is an intrinsic semiconductor with a small concentration of p-type carriers. By substituting Zn2+ on the Ga3+ site, we show that it is possible to increase and control the carrier concentration in Ca5Ga2−xZnxSb6 and thus optimize its thermoelectric behavior. A single parabolic band model was used to estimate an effective mass of m* = 1.6me, which is slightly lower than Al-based compounds. Though the reduced m* leads to a lower Seebeck coefficient, it also leads to a much higher electronic mobility. The high mobility leads to increased thermoelectric figure of merit (zT) at low and intermediate temperatures relative to Zn-doped Ca5Al2Sb6. However, due to the decreased band gap in Ca5Ga2Sb6 relative to Ca5Al2Sb6, the maximum zT in optimally doped Ca5Ga2Sb6 is reduced (peak zT ∼ 0.35 at T = 775 K).

Graphical abstract: Improved thermoelectric properties in Zn-doped Ca5Ga2Sb6

Article information

Article type
Paper
Submitted
26 Oct 2012
Accepted
04 Feb 2013
First published
18 Feb 2013

J. Mater. Chem. A, 2013,1, 4244-4249

Improved thermoelectric properties in Zn-doped Ca5Ga2Sb6

S. I. Johnson, A. Zevalkink and G. J. Snyder, J. Mater. Chem. A, 2013, 1, 4244 DOI: 10.1039/C3TA00844D

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements