Accurately predicting the thermal conductivity of boron arsenide due to phonon anharmonic renormalization: A critical revisit

Abstract

Currently theoretical works fail to accurately reproduce experimental results of lattice thermal conductivity of boron arsenide (BAs, both the nature one or the isotopically enriched one). We investigate the microscopic mechanisms of ultrahigh lattice thermal conductivity (κ_L) and its unexpectedly strong temperature dependence (T-dependence) in cubic ^natBAs by a first principles theory in the framework of the Wigner transport theory combined with temperature-dependent interatomic force constants (T-IFCs). We include the contributions of three- and four-phonon scattering processes to the phonon lifetime, and consider the phonon renormalization due to temperature. We find that κ_L of ^natBAs has a strong T-dependence (κ_L~T^-1.721) and T-IFCs play important roles in accurately predicting κ_L especially at high temperatures. We predict a room-temperature κ_L of 1060.51 W/mK of ^natBAs, which aligns more closely with the recently measured value of 1000 ± 90 W/mK [Science, 361, 579-581 (2018)] than previously reported predictions. The superior accuracy of our predictions is attributed to the inclusion of T-IFCs in describing phonons and their scattering characteristics. Our results (i) resolve the discrepancy between theoretical and experimental κ_L, (ii) explain the underlying mechanism of the ultra-high κ_L of ^natBAs, and (iii) highlight the importance of considering the temperature-induced anharmonic renormalization effect at high temperatures. This work provides new insights into accurately predicting κ_L for materials with relatively harmonic phonon dispersion but having strong high-order anharmonic effects.