Accurately predicting the thermal conductivity of boron arsenide considering the temperature-induced phonon anharmonic renormalization: a critical revisit

Abstract

Currently, theoretical works fail to accurately reproduce the experimental results for the lattice thermal conductivity of boron arsenides (BAs, the natural and isotopically enriched ones). We investigated the microscopic mechanisms of the ultrahigh lattice thermal conductivity (κ_L) and its unexpected strong temperature-dependence (T-dependence) in cubic ^natBAs using the first principles theory within the framework of the Wigner transport theory combined with temperature-dependent interatomic force constants (T-IFCs). The contributions of three- and four-phonon scattering processes to the phonon lifetime were included, and temperature-induced phonon renormalization was considered. We found that the κ_L of ^natBAs exhibited a strong T-dependence (κ_L ∼ T^−1.721), and T-IFCs played important roles in accurately predicting the κ_L, especially at high temperatures. We predicted a room-temperature κ_L of 1060.51 W m⁻¹ K⁻¹ for ^natBAs, which aligned more closely with the recently measured experimental value of 1000 ± 90 W m⁻¹ K⁻¹ [S. Li et al., High thermal conductivity in cubic boron arsenide crystals, Science, 361, 579–581 (2018)] than previously reported predictions. The superior accuracy of our prediction was attributed to the inclusion of T-IFCs in describing phonons and their scattering characteristics. Our results (i) resolved the discrepancy between the theoretically and experimentally obtained κ_L, (ii) explained the underlying mechanism of the ultra-high κ_L of ^natBAs, and (iii) highlighted the importance of considering the temperature-induced anharmonic renormalization effect at high temperatures. This work provides new insights into accurately predicting the κ_L for materials whose phonon dispersions appear harmonic but the κ_L are significantly affected by higher-order anharmonic interactions.