标题：Strong electron-phonon coupling induced anomalous phonon transport in ultrahigh temperature ceramics ZrB2 and TiB2
作者：Yang, Jia-Yue ;Zhang, Wenjie ;Xu, Chengying ;Liu, Jun ;Liu, Linhua ;Hu, Ming
作者机构：[Yang, Jia-Yue ;Zhang, Wenjie ;Liu, Linhua ] School of Energy and Power Engineering, Shandong University, Jinan; Shandong; 250061, China;[Xu, Chengyin 更多
来源：International Journal of Heat and Mass Transfer
摘要：Ultrahigh temperature ZrB2- and TiB2-based ceramics are widely used in extreme thermal environment. Yet, open questions remain pertaining to their lattice thermal conductivity (кph). In this work we investigate the phonon transport of ZrB2 and TiB2 by systematically evaluating the phonon-phonon interaction (PPI), electron-phonon interaction (EPI) and grain boundary scattering (GBS) from the atomistic level using first-principles. Upon including EPI, the room-temperature кph of ZrB2 and TiB2 is significantly reduced by 38.16% and 52.34%, respectively, and agrees excellently with experimental measurement. Such giant reduction arises from the strong EPI for the heat-carrying acoustic phonons due to phonon anomaly and the existence of Fermi nesting vectors along high symmetry line in the Brillouin zone. Following the Casimir model, the GBS further decreases кph of ZrB2 even by 49.27% for small grain boundary spacing of 50 nm and theoretical calculations agree well with experiments. Thus, GBS crucially influences phonon transport, which explains the large deviation of previous experimental measurements on кph for ZrB2-based ceramics. Moreover, the combined influence of EPI and GBS results in the anomalous phonon transport where кph is almost temperature-independent over a large temperature range, consistent with experimental observations. This work directly reveals the phonon transport mechanism for high temperature ceramics ZrB2 and TiB2, gains deep insight into the large variation in the previously reported кph and provides guidance to engineer it for practical applications.