"Understanding and Manipulating Lattice Instability of PbTe for Improved Thermoelectric Performance"

will be given by Dr Ivana Savic (Tyndall National Institute, Cork, Ireland).

Abstract of the talk:

Thermoelectric materials could play an important role in energy harvesting and solid state cooling applications since they enable conversion between thermal and electrical energy [1]. The key physical properties for good thermoelectric performance are high electrical conductivity, high Seebeck coefficient and low thermal conductivity [1]. In many materials the improvement of one of these characteristics leads to a disimprovement of others, and the optimization of the overall thermoelectric performance is highly challenging.

It has been recently proposed that the proximity to a structural phase transition of PbTe is one of the key factors leading to its low thermal conductivity and high thermoelectric efficiency [2]. In this talk, using first principles calculations, I will show that driving PbTe closer to the structural phase transition via strain or alloying could substantially suppress its thermal conductivity [3]. Furthermore, using a combination of ultrafast X-ray scattering measurements and first principles calculations, I will show that the coupling of the electronic states near the band edges to transverse optical phonons drives PbTe near the structural instability [4]. These insights may open new opportunities for the development of more efficient thermoelectric materials.

[1] G. J. Snyder and E. S. Toberer, Nat. Mater. 7, 105 (2008).
[2] O. Delaire et al., Nat. Mater. 10, 614 (2011).
[3] R. M. Murphy, E. D. Murray, S. Fahy, and I. Savic, Phys. Rev. B 93, 104304 (2016)
[4] M. P. Jiang, M. Trigo, I. Savic et al., submitted.