Exploring the Lattice Dynamics of the Lead Chalcogenides

J M Skelton, A Walsh

Research output: Contribution to conferencePoster


Lead chalcogenides are promising candidates for high-temperature thermoelectric materials, with lattice thermal conductivities several times lower than those of typical rock-salt structures [1]. Indeed, a number of recent high-profile studies have achieved record zT values, the figure of merit for thermoelectrics, using nanostructured PbTe-based materials [1, 2].

There has been intense research into the microscopic origin of the unusually low thermal conductivity in the PbX family of compounds, which has suggested anharmonicity and thermal disorder to be key factors [3, 4]. The recently-published experimental study in Ref. 4 observed a large cation disorder, with the Pb atomic positions showing significant fluctuations even at very low temperatures [4].

We have carried out density-functional theory modelling of the lattice dynamics of PbS, PbSe and PbTe within the quasi-harmonic approximation, using the VASP code [5] in conjunction with the Phonopy package [6]. These calculations allow the structural and vibrational properties of the materials to be examined over a broad temperature range, and very good agreement with experimental data is obtained using the PBEsol functional, compared with other studies carried out using LDA or other GGA functionals (e.g. [7]).

Our studies provide first-principles insight into the atomic-level behaviour of the PbX compounds and shed light on the origin of their unique properties, which we hope will contribute to the design and optimisation of future ferroelectrics for a broad range of applications.

[1] N. Biswas et al., Nature 489, 414 (2012)
[2] J. R. Sootsman et al., Angew. Chem. Int. Ed. 47 (45), 8618 (2008)
[3] O. Delaire et al., Nat. Mater. 10, 614 (2011)
[4] S. Kastbjerg et al., Adv. Func. Mater., DOI: 10.1002/adfm.201300722 (2013)
[5] G. Kresse and J. Hafner, Phys. Rev. B 47, 558 (1993)
[6] A. Togo, F. Oba and I. Tanaka, Phys. Rev. B 78 (13), 134106 (2008)
[7] Y. Zhang et al., Phys. Rev. B 80, 024304 (2009)
Original languageEnglish
Publication statusPublished - 18 Dec 2013
EventRSC Solid State Chemistry Group Christmas Meeting 2013 - University of Bath, Bath, UK United Kingdom
Duration: 18 Dec 201319 Dec 2013


ConferenceRSC Solid State Chemistry Group Christmas Meeting 2013
Country/TerritoryUK United Kingdom


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