First-principles calculations of the structural, elastic, vibrational and electronic properties of YB6 compound under pressure-猫眼课题宝

DOI：

10.1140/epjb/e2019-100080-1

发表时间：

2019-07

期刊：

The European Physical Journal B

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

M. Romero;A. Benítez-Rico;E. Arévalo-López;R. Gómez;M. Marquina;J. Rosas;R. Escamilla

本文报道了富硼二元化合物YB_6在0 ~ 50 GPa压力下的理论预测。采用基于Perdew-Wang（PW 91）提出的广义梯度近似（GGA）的平面波赝势方法，采用密度泛函理论（DFT），进行了第一性原理计算，研究了体系的弹性、振动和电子结构性质.我们讨论了结构稳定性的基础上的弹性常数分析（Cij）与静态有限应变技术。采用Voigt-Reuss近似方法，从多晶集合体出发，计算了体积模量（BH）、剪切模量（GH）、杨氏模量（EH）和泊松比（ν）。其它参数如维氏硬度（Hv）、普氏比（GH/BH）、声速（vm）和德拜温度（θD）由弹性模量给出。结果表明，随着压力的增大，C11和C12的弹性常数和弹性模量单调增大，而C44减小，因此，该结构除了硬度随压力的增大而减小外，还具有动态稳定性和韧性。声子色散曲线表明，在压力作用下，整个布里渊区（BZ）内没有虚声子频率，表现出稳定的Pm ~ 3空间群。最后，费米能级上的态密度（DOS）随着压力的增加而减小，这是由于B 2-p态的贡献减小。图形摘要

AbstractIn this paper, we report our theoretical prediction of a boron-rich binary compound, YB6, withPm3̅mspace group subjected to pressures from 0 to 50 GPa. Calculations of first principles are performed to investigate the elastic, vibrational and electronic structural properties using the Density Functional Theory (DFT) within the plane-wave pseudopotential method based on the generalized gradient approximation (GGA) proposed by Perdew-Wang (PW91). We discuss the structural stability based on elastic constants analysis (Cij) obtained with static finite strain technique. Bulk (BH), Shear (GH) and Young’s modulus (EH) as well as Poisson’s ratio (ν), were calculated with the Voigt-Reuss approximation derived from ideal polycrystalline aggregate. Other parameters such as Vickers Hardness (Hv), Pugh’s ratioGH/BH, the speed of sound (vm) and Debye temperature (θD) were given by elastic modules. We found thatC11andC12elastic constants and elastic modulus monotonically increase whileC44decrease as a function of pressure; consequently, the structure is dynamically stable and ductile besides that hardness decreases under pressure. The phonon dispersion curves showed no imaginary phonon frequency in the entire Brillouin Zone (BZ) under pressure, showing stablePm3̅mspace group. Finally, the density of states (DOS) at the Fermi level decreases with increasing pressure, due to the decrease of the contribution of B 2-p states.Graphical abstract

First-principles calculations of the structural, elastic, vibrational and electronic properties of YB6 compound under pressure

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