Ferroelectric phase transition and the lattice thermal conductivity of Pb1−xGexTe alloys

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Title: Ferroelectric phase transition and the lattice thermal conductivity of Pb1−xGexTe alloys
Author(s): Murphy, RM
Murray, ED
Fahy, S
Savic, I
Item Type: Journal Article
Abstract: We show how tuning the proximity to the soft optical mode phase transition via chemical composition affects the lattice thermal conductivity κ of Pb1−xGexTe alloys. Using first-principles virtual-crystal simulations, we find that the anharmonic contribution to κ is minimized at the phase transition due to the maximized acoustic-optical anharmonic interaction. Mass disorder significantly lowers and flattens the dip in the anharmonic κ over a wide composition range, thus shifting the κ minimum away from the phase transition. The total κ and its anharmonic contribution vary continuously between the rocksalt and rhombohedral phases as expected for the second-order phase transition. The actual phase and its strength of resonant bonding play a less prominent role in reducing the κ of Pb1−xGexTe alloys than the proximity to the phase transition and the atomic mass. Our results show that alloys with soft optical mode transitions are promising materials for achieving low thermal conductivity and possibly high thermoelectric efficiency.
Publication Date: 6-Apr-2017
Date of Acceptance: 20-Mar-2017
URI: http://hdl.handle.net/10044/1/45714
DOI: https://dx.doi.org/10.1103/PhysRevB.95.144302
ISSN: 1550-235X
Publisher: American Physical Society
Journal / Book Title: Physical Review B
Volume: 95
Copyright Statement: © 2017 American Physical Society
Keywords: Fluids & Plasmas
02 Physical Sciences
03 Chemical Sciences
Publication Status: Published
Article Number: 144302
Appears in Collections:Condensed Matter Theory
Physics
Faculty of Natural Sciences



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