Ding Li-Ping, Tiandong Yun Hao, Shao Peng, Tang Yan, Zhao Zi-Li, Lu Haiyan
Department of Optoelectronic Science & Technology, School of Electronic Information and Artificial Intelligence, Shaanxi University of Science & Technology, Xi'an 710021, China.
Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 9-35, Jiangyou 621908, China.
J Phys Chem Lett. 2021 Jun 10;12(22):5423-5429. doi: 10.1021/acs.jpclett.1c01300. Epub 2021 Jun 3.
Yttrium borides have attracted much attention for their superconducting and high chemical stability. However, the fundamental knowledge of the mechanical properties and hardness of yttrium borides is rather lack. Here, we performed a systematic investigation on yttrium borides with various stoichiometries based on an unbiased CALYPSO structure search method and first-principles calculations. A new YB compound with 3 hexagonal structure is observed, which is more stable than the experimental synthesized 3̅ phase. The calculated formation enthalpy, elastic constants, and phonon dispersions distinctly show that the 3-YB is energetically, mechanically, and dynamically stable. The density of states and electronic band structure reveal that all the stable yttrium borides are metallic. Based on a semiempirical method, the Vicker hardness of 3-YB is expectant to be 37.0 GPa, indicating it is a potential ultrahard metal. Our results provide insights for future synthesis and design of new type functional materials.
硼化钇因其超导性和高化学稳定性而备受关注。然而，关于硼化钇力学性能和硬度的基础知识却相当匮乏。在此，我们基于无偏CALYPSO结构搜索方法和第一性原理计算，对具有不同化学计量比的硼化钇进行了系统研究。观察到一种具有六方结构的新型YB化合物，它比实验合成的3̅相更稳定。计算得到的生成焓、弹性常数和声子色散明显表明3-YB在能量、力学和动力学上都是稳定的。态密度和电子能带结构表明，所有稳定的硼化钇都是金属性的。基于半经验方法，预计3-YB的维氏硬度为37.0 GPa，表明它是一种潜在的超硬金属。我们的结果为新型功能材料的未来合成和设计提供了见解。
