Wang Yi X, Liu Ying Y, Yan Zheng X, Liu W, Gu Jian B
College of Science, Xi'an University of Science and Technology Xi'an 710054 People's Republic of China
School of Materials and Chemical Engineering, Zhongyuan University of Technology Zhengzhou People's Republic of China.
RSC Adv. 2020 Oct 7;10(61):37142-37152. doi: 10.1039/d0ra07633c.
The phase stabilities, elastic anisotropies, and thermal conductivities of ReB diborides under ambient conditions have been investigated by using density functional theory calculations. It was found that 6/ (hP6-ReB), (oP6-ReB), 3̄ (hR3-ReB), 3̄ (hR6-ReB), and 2/ (mC12-ReB) of ReB are both mechanically and dynamically stable, and the order of phase stability is hP6 > oP6 > hR3 > hR6 > mC12. Moreover, the calculated Vickers hardness showed that hP6-ReB, oP6-ReB, hR3-ReB, and mC12-ReB were potential hard materials, while hR6-ReB could not be used as a candidate hard material. In addition, the elastic-dependent anisotropy properties of ReB in different crystal structures were also investigated. The results show that the anisotropic order of the Young's modulus and shear modulus of ReB is hR6 > mC12 > oP6 > hP6 > hR3, while that of the bulk modulus is mC12 > hR3 > hP6 > oP6 > hR6. Finally, by means of Clarke's and Cahill's models, the minimum thermal conductivities of ReB in different crystal structures were further evaluated, and the order of them is hR3 > hP6 > mC12 > oP6 > hR6. Moreover, the results show that all these ReB diborides exhibit relatively low thermal conductivities and are suitable for thermal insulation materials.
利用密度泛函理论计算研究了环境条件下二硼化铼（ReB）的相稳定性、弹性各向异性和热导率。研究发现，ReB的6/（hP6-ReB）、（oP6-ReB）、3̄（hR3-ReB）、3̄（hR6-ReB）和2/（mC12-ReB）在力学和动力学上均稳定，相稳定性顺序为hP6＞oP6＞hR3＞hR6＞mC12。此外，计算得到的维氏硬度表明，hP6-ReB、oP6-ReB、hR3-ReB和mC12-ReB是潜在的硬质材料，而hR6-ReB不能用作候选硬质材料。另外，还研究了不同晶体结构中ReB的弹性相关各向异性性质。结果表明，ReB的杨氏模量和剪切模量的各向异性顺序为hR6＞mC12＞oP6＞hP6＞hR3，而体模量的各向异性顺序为mC12＞hR3＞hP6＞oP6＞hR6。最后，借助克拉克模型和卡希尔模型，进一步评估了不同晶体结构中ReB的最小热导率，其顺序为hR3＞hP6＞mC12＞oP6＞hR6。此外，结果表明，所有这些二硼化铼都表现出相对较低的热导率，适合用作隔热材料。
