Extended Data Table 1 Transverse (TA/TA’) and longitudinal (LA) Debye temperatures (Θ), phonon velocities (v) and Grüneisen parameters (γ) along a, b and c axes in the low-temperature SnSe phase.
From: Ultralow thermal conductivity and high thermoelectric figure of merit in SnSe crystals
- Values are calculated from the phonon and Grüneisen dispersions (Fig. 4a, b). The Debye temperature is calculated using Θ = ωD/kB (ωD is the largest acoustic frequency in each direction); the phonon velocity is the slope of the acoustic phonon dispersion around the Γ point; the Grüneisen parameter of each acoustic dispersion is evaluated from the root-mean-square value of γi along each direction:
. Additionally, average acoustic values of Debye temperatures, phonon velocities and Grüneisen parameters are given, which are the above quantities, averaged over the three acoustic branches.
. Additionally, average acoustic values of Debye temperatures, phonon velocities and Grüneisen parameters are given, which are the above quantities, averaged over the three acoustic branches.