Predicting the Lattice Thermal Conductivity in Nitride Perovskite LaWN<sub>3</sub> from ab initio Lattice Dynamics
Zhen Tong, Yatian Zhang, Alessandro Pecchia, ChiYung Yam, Liujiang Zhou, Traian Dumitrică, Thomas Frauenheim
Abstract
Abstract Using a density functional theory‐based thermal transport model, which includes the effects of temperature ( T )‐dependent potential energy surface, lattice thermal expansion, force constant renormalization, and higher‐order quartic phonon scattering processes, it is found that the recently synthesized nitride perovskite LaWN 3 displays strong anharmonic lattice dynamics manifested into a low lattice thermal conductivity ( κ L ) and a non‐standard κ L ∝ T −0.491 dependence. At high T , the departure from the standard κ L ∝ T −1 law originates in the dual particle‐wave behavior of the heat carrying phonons, which includes vibrations tied to the N atoms. While the room temperature κ L =2.98 W mK ‐1 arises mainly from the conventional particle‐like propagation of phonons, there is also a significant atypical wave‐like phonon tunneling effect, leading to a 20% glass‐like heat transport contribution. The phonon broadening effect lowers the particle‐like contribution but increases the glass‐like one. Upon T increase, the glass‐like contribution increases and dominates above T = 850 K. Overall, the low κ L with a weak T ‐dependence points to a new utility for LaWN 3 in energy technology applications, and motivates synthesis and exploration of nitride perovskites.