Author(s)

Shen Li^1*, Clas Persson^1,2

¹Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm, Sweden.
²Department of Physics, University of Oslo, Oslo, Norway.

The narrow-gap semiconductor CsBi₄Te₆ is a promising material for low temperature thermoelectric applications. Its thermoelectric property is significantly better than the well-explored, high-performance thermoelectric material Bi₂Te₃ and related alloys. In this work, the thermal expansion and the heat capacity at constant pressure of CsBi₄Te₆ are determined within the quasiharmonic approximation within the density functional theory. Comparisons are made with available experimental data, as well as with calculated and measured data for Bi₂Te₃. The phonon band structures and the partial density of states are also investigated, and we find that both CsBi₄Te₆ and Bi₂Te₃ exhibit localized phonon states at low frequencies. At high temperatures, the decrease of the volume expansion with temperature indicates the potential of a good thermal conductivity in this temperature region.

Quasi Harmonic Approximation, Thermal Expansion, Heat Capacity, Phonon Dispersion

Li, S. and Persson, C. (2015) Thermal Properties and Phonon Dispersion of Bi₂Te₃ and CsBi₄Te₆ from First-Principles Calculations. Journal of Applied Mathematics and Physics, 3, 1563-1570. doi: 10.4236/jamp.2015.312180.