Local structure of interstitial Zn in β-Zn4Sb3

• Published in: Physica status solidi. PSS-RRL. Rapid research letters 2007-11, Vol.1 (6), p.253-255
• Main Authors: Toberer, E. S., Sasaki, K. A., Chisholm, C. R. I., Haile, S. M., Goddard III, W. A., Snyder, G. J.
• Format: Article
• Language: English
• Subjects: 61.72.Ji; 66.30.Hs; 66.70.+f; 71.15.Mb
• ISSN: 1862-6254; 1862-6270
• DOI: 10.1002/pssr.200701168

The low thermal conductivity of the thermoelectric material β‐Zn4Sb3 has been linked to disorder arising from multiple interstitial Zn sites. Here we investigate the energetics and local distortions associated with these interstitial sites via DFT calculations. Our results show the β‐Zn4Sb3 structure is able to distort into many inequivalent geometries of similar energies, suggesting a topology rich with transport pathways through energetically accessible metastable states. The occurrence of such a shallow energy landscape may explain the recently discovered liquid‐like diffusivity of Zn in β‐Zn4Sb3 – comparable to that found in superionic conductors. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) Observations of exceptionally low lattice thermal conductivity and high Zn diffusion rates in the state‐of‐the‐art thermoelectric material β‐Zn4Sb3 have been attributed to high levels of interstitial Zn atoms. Here, density functional theory (DFT) calculations of interstitial energies in a relaxed lattice reveal a multitude of low energy positions which correspond to either vacancy–interstitial couplings or a concerted distortion of nearest neighbours. Such a flat energy landscape is in agreement with the observed properties.