Temperature effects in lattice dynamics of SnSe
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Date
2016-11-29
Journal Title
Journal ISSN
Volume Title
Publisher
Australian Institute of Nuclear Science and Engineering
Abstract
Tin selenide demonstrates a record high thermoelectric figure of merit. The distinctive feature of this material is very low thermal conductivity directly related to peculiarities of SnSe lattice dynamics. We studied the temperature dependence of the crystal structure, phonon dispersion curves and vibrational density of states (VDOS) of SnSe in temperature range from 300 to 750 K using neutron scattering instruments at ANSTO. We found that frequencies of longitudinal and transverse acoustic phonons in SnSe have remarkably low frequencies, in particular the TA [100] phonon branch. Another feature of SnSe is the presence of low-frequency optic phonons in close proximity to acoustic branches and softening of TOb [100] mode. Measurements of VDOS during heating reveal rather complex modifications of the spectrum showing a significant softening of phonon groups centred at ~ 7.5 and 16 meV related to displacive Pnma – Cmcm phase transition at 830 K. The high density of low-energy modes along with observed strong phonon damping is probably responsible for the low values of lattice component of thermal conductivity in this material.
Description
Keywords
Selenides, Thermoelectric properties, Thermal conductivity, Crystal structure, Temperature dependence, Neutron diffraction, ANSTO
Citation
Danilkin, S., Yu, D., Deng, G., Pomjakushina, E., Liu, H., & Kearley, G. (2016). Temperature effects in lattice dynamics of SnSe. Paper presented at 13th AINSE-ANBUG Neutron Scattering Symposium, Sydney, NSW, Australia, 29-30 November 2016.