The crystal structures, mechanical properties and electronic structures of HfC_xN_1-x have been predicted by using evolutionary structure search followed by the first-principles calculations in this study. The crystal structures predicted indicate that there are 10 thermodynamic stable phases for HfC_xN_1-x, of which 8 are newly discovered crystal structures and 2 are already known. We investigated the mechanical properties, including the bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio and Vickers hardness, of all 10 stable phases, and further established the relationship between such properties and the ratio of nitrogen to carbon content. Besides, the Fermi energy level and electronic density of states of these 10 stable phases are calculated as well, and the results reveal the fundamental reason why the mechanical properties change with the ratio of nitrogen to carbon. The predictions of this study agree well with both the experimental data and the previous theoretical evaluations.

通过使用进化结构搜索，然后通过第一性原理计算，对HfC _x N _1-x的晶体结构，力学性能和电子结构进行了预测。预测的晶体结构表明HfC _x N _1-x有10个热力学稳定相，其中8个是新发现的晶体结构，而2个是已知的。我们研究了所有10个稳定相的机械性能，包括体积模量，剪切模量，杨氏模量，泊松比和维氏硬度，并进一步建立了这些性能与氮碳含量比之间的关系。此外，还计算了这10个稳定相的费米能级和态的电子密度，结果揭示了机械性能随氮碳比变化的根本原因。这项研究的预测与实验数据和先前的理论评估都很好地吻合。