DFT Predictions of Crystal Structure, Electronic Structure, Compressibility, and Elastic Properties of Hf-Al-C Carbides
DFT Predictions of Crystal Structure, Electronic Structure, Compressibility, and Elastic Properties of Hf-Al-C Carbides
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Hf-Al-C 碳化物晶体结构、电子结构、压缩性和弹性性能的 DFT 预测
DOI：
10.1111/jace.14361
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发表时间：
2016-10-01
影响因子：
3.9
通讯作者：
Lee, William Edward
中科院分区：
文献类型：
--
作者：
Bai, Yuelei;Duff, Andrew;Lee, William Edward
为了了解Hf-Al-C三元化合物的应用潜力，采用密度泛函理论研究了（HfC）（n）Al 3C 2（Hf 2Al 3C 4和Hf 3Al 3C 5）和（HfC）（n）Al 4C 3（Hf 2Al 4C 5和Hf 3Al 4C 6）的晶体结构、电子结构、压缩性和弹性性质。（HfC）（n）Al 3C 2的理论密度（4.10-4.16 g/cm（3））高于（HfC）（n）Al 4C 3的理论密度（3.92-3.98 g/cm（3）），这是由于较轻的Al-C层的数量较少。随着Hf-C层数的增加，Hf-C和Al-C键长几乎保持不变。在这些化合物中，费米能（E-f）周围没有间隙，这意味着它们是类金属导体。随着压力的增加，沿着c轴的收缩比沿a轴的收缩大。粘结刚度随着压力的增加而增加。通常，（HfC）（n）Al 3C 2具有比（HfC）（n）Al 4C 3更高的弹性刚度，其中模量随着Hf-C层的数目而增加。Hf-Al-C化合物以及脆性Zr-Al-C化合物都具有从0.71至0.78的低剪切模量/体积模量比（G/B），这表明G/B比并不总是延性的合适量度。
To understand the potential for use of the Hf-Al-C ternary compounds, (HfC)(n)Al3C2 (Hf2Al3C4 and Hf3Al3C5) and (HfC)(n)Al4C3 (Hf2Al4C5 and Hf3Al4C6) were investigated using density functional theory, including crystal structure, electronic structure, compressibility, and elastic properties. The theoretical density of (HfC)(n)Al3C2 (4.10-4.16 g/cm(3)) is higher than that of (HfC)(n)Al4C3 (3.92-3.98 g/cm(3)), due to the smaller number of lighter Al-C layers. With increasing numbers of Hf-C layers, the Hf-C and Al-C bond lengths remain almost unchanged. In none of the compounds is there a gap around the Fermi energy (E-f), which implies they are metal-like conductors. With increasing pressure, there is greater shrinkage along the c axis than the a axis. The bond stiffness increases with increasing pressure. In general, (HfC)(n)Al3C2 has higher elastic stiffness than (HfC)(n)Al4C3, with the moduli increasing with the number of Hf-C layers. The Hf-Al-C compounds as well as the brittle Zr-Al-C compounds all have low shear moduli/bulk moduli ratio (G/B) from 0.71 to 0.78, suggesting that the G/B ratio is not always a suitable measure of ductility.