Rapid Prediction of Anisotropic Lattice Thermal Conductivity: Application to Layered Materials

Thermal
conductivity plays a crucial role in many applications;
the use of single-crystal and textured polycrystalline materials in
such applications necessitates understanding the anisotropy in thermal
transport. The measurement of anisotropic lattice thermal conductivity
κL(θ,ϕ) is quite challenging. To address
this need through computations, we build upon our previously developed
isotropic model for κL and incorporate the directional
(angular) dependence by using the elastic tensor obtained from ab
initio calculations and the Christoffel equations for the speed of
sound. With the anisotropic speed of sound and intrinsic material
properties as input parameters, we can predict the direction-dependent
κL(θ,ϕ). We validate this new model by
comparing with the experimental data from the literaturethe
predicted κL is within an average factor difference
of 1.8 of experimental measurements, spanning 5 orders of magnitude
in κL. To demonstrate the utility and computational
tractability of this model, we calculate κL(θ,ϕ)
of ∼2200 layered materials that are expected to exhibit anisotropic
thermal transport. We consider both van der Waals and ionic layered
structures with binary and ternary chemistries and analyze the anisotropy
in their κL. The large-scale study has revealed many
layered structures with interesting anisotropy in κL.