Thermal conductivity of the quasi-1D materials TaSe3 and ZrTe3

TL;DR

This study investigates the thermal conductivities and phonon properties of quasi-1D materials TaSe3 and ZrTe3 using density functional theory, revealing anisotropic behaviors and contributions of optical modes to heat transport.

Contribution

It provides detailed phonon dispersion and thermal conductivity tensors for TaSe3 and ZrTe3, highlighting their anisotropic properties and the role of optical modes in heat conduction.

Findings

TaSe3 exhibits more anisotropic thermal conductivity than ZrTe3.

Optical phonon modes significantly contribute to heat transport at room temperature.

TaSe3 has shorter phonon lifetimes and mean free paths compared to ZrTe3.

Abstract

The high breakdown current densities and resilience to scaling of the metallic transition metal trichalcogenides TaSe3 and ZrTe3 make them of interest for possible interconnect applications, and it motivates this study of their thermal conductivities and phonon properties. These crystals consist of planes of strongly bonded one-dimensional chains more weakly bonded to neighboring chains. Phonon dispersions and the thermal conductivity tensors are calculated using density functional theory combined with an iterative solution of the phonon Boltzmann transport equation. The phonon velocities and the thermal conductivities of TaSe3 are considerably more anisotropic than those of ZrTe3. The maximum LA velocity in ZrTe3 occurs in the cross-chain direction, and this is consistent with the strong cross-chain bonding that gives rise to large Fermi velocities in that direction. The thermal conductivities are similar to those of other metallic two-dimensional transition metal dichalcogenides. At room temperature, a significant portion of the heat is carried by the optical modes. In the low frequency range, the phonon lifetimes and mean free paths in TaSe3 are considerably shorter than those in ZrTe3. The shorter lifetimes in TaSe3 are consistent with the presence of lower frequency optical branches and zone-folding features in the acoustic branches that arise due to the doubling of the TaSe3 unit cell within the plane.