Abstract The transition metal silicide W3Si was suggested to be a promising candidate for ultrahigh-temperature materials due to its good strength and ductility. However, the crystal structure of W3Si still remains unclear. Using an unbiased structure searching method, we explored the ground-state structures of W3Si up to 200 GPa. Two new tetragonal phases, P4/nmm and I-42m, are found to be energetically more favorable than the previous proposed cubic phase even at zero pressure. Electronic structure analysis reveals that both the predicted phases are metallic, and the W-5d states of which are mostly responsible for bond formations. Compared with the cubic W3Si, stronger W-Si covalent bonds are formed in the two predicted phases. The P4/nmm phase has a large shear modulus G, indicating a strong shear deformation resistance. The Vickers hardness of P4/nmm phase is larger than that of the I-42m phases. In addition, the P4/nmm phase shows slightly brittle behavior, while I-42m phase exhibits good ductility. Furthermore, the two predicted phases show isotropy character. The stress-strain calculations reveal that the ideal strengths of P4/nmm and I42-m phases are 19.6 and 12.1 GPa, respectively.

中文翻译：

---

从第一性原理计算探索 W3Si 硅化物的真实基态结构

摘要 过渡金属硅化物W3Si由于其良好的强度和延展性被认为是一种很有前途的超高温材料候选材料。然而，W3Si 的晶体结构仍不清楚。使用无偏结构搜索方法，我们探索了高达 200 GPa 的 W3Si 的基态结构。发现两个新的四方相 P4/nmm 和 I-42m 即使在零压力下也比先前提出的立方相在能量上更有利。电子结构分析表明，预测的两个相都是金属相，其 W-5d 态主要是形成键的原因。与立方 W3Si 相比，在两个预测相中形成了更强的 W-Si 共价键。P4/nmm 相具有较大的剪切模量 G，表明具有较强的抗剪切变形能力。P4/nmm 相的维氏硬度大于 I-42m 相。此外，P4/nmm 相表现出轻微的脆性，而 I-42m 相表现出良好的延展性。此外，两个预测的相位显示出各向同性的特征。应力应变计算表明，P4/nmm 和 I42-m 相的理想强度分别为 19.6 和 12.1 GPa。