Abstract Usually, the thermal conductivity is predominantly contributed by electrons in metals. In this work, by using first-principles calculations we find that in tungsten carbide (WC) the phonon-contributed thermal conductivities ( κ ph ) are 131 and 158 W m − 1 K − 1 along the a and c axes, respectively, three times as much as the electronic contribution ( κ e ). In isotopically pure samples, κ ph can be further increased to 204 and 249 W m − 1 K − 1 along the a and c axes, respectively, which is comparable to the κ e of Al. The anomalously large κ ph is attributed to the weak phonon-phonon and electron-phonon scattering, both of which have their origin in the electronic structure of the group-VI carbides. The Fermi energy falls within the pseudogap between the bonding and antibonding states, suggesting stronger interatomic bonding and weaker electron-phonon scattering than in group-IV and V carbides. The unique combination of strong interatomic bonding and large atomic mass of W results in a large acoustic-optical gap in the phonon dispersion, suppressing phonon-phonon scattering. In contrast, in another group-VI carbide, MoC, also with strong interatomic bonding, the smaller atomic mass of Mo increases the acoustic phonon frequencies and reduces the acoustic-optical gap. Furthermore, electron-phonon scattering, though not very strong in absolute magnitude, also plays an important role in phonon scattering, leading to a weak temperature dependence of κ ph in WC. The large thermal conductivity, persisting at high temperatures, facilitates the use of this material in applications such as cutting tools.

中文翻译：

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金属碳化钨的异常大晶格热导率及其在电子结构中的起源

摘要 通常，金属中的热导率主要由电子贡献。在这项工作中，通过使用第一性原理计算，我们发现在碳化钨 (WC) 中，声子贡献的热导率 (κ ph ) 沿 a 轴和 c 轴分别为 131 和 158 W m - 1 K - 1，三个是电子贡献 (κ e ) 的倍数。在同位素纯样品中，沿 a 和 c 轴的 κ ph 可以进一步增加到 204 和 249 W m - 1 K - 1，这与 Al 的 κ e 相当。异常大的 κ ph 归因于弱声子 - 声子和电子 - 声子散射，这两者都起源于 VI 族碳化物的电子结构。费米能量落在键合状态和反键​​合状态之间的赝隙内，表明与 IV 族和 V 族碳化物相比，原子间键合更强，电子-声子散射更弱。W 的强原子间键合和大原子质量的独特组合导致声子色散中的大声光间隙，抑制声子 - 声子散射。相比之下，在另一种 VI 族碳化物 MoC 中，同样具有强原子间键合，较小的 Mo 原子质量会增加声学声子频率并减小声光间隙。此外，电子-声子散射虽然在绝对幅度上不是很强，但在声子散射中也起着重要作用，导致 WC 中 κ ph 的温度依赖性较弱。在高温下持续的大热导率促进了这种材料在切削工具等应用中的使用。