A Novel Silicon Allotrope in the Monoclinic Phase

作者：Bai, Chaogang; Chai, Changchun; Fan, Qingyang^*; Liu, Yuqian; Yang, Yintang

来源：Materials, 2017, 10(4): 441.

DOI：10.3390/ma10040441

• silicon allotrope
• first-principles calculations
• mechanical properties
• thermal properties

This paper describes a new silicon allotrope in the P2/m space group found by first-principles calculations using the Cambridge Serial Total Energy Package (CASTEP) plane-wave code. The examined P2/m-Si belongs to the monoclinic crystal system. P2/m-Si is an indirect band-gap semiconductor with a band gap of 1.51 eV, as determined using the HSE06 hybrid functional. The elastic constants, phonon spectra and enthalpy indicate that P2/m-Si is mechanically, dynamically, and thermodynamically stable. P2/m-Si is a low-density (2.19 g/cm(3)) silicon allotrope. The value of B/G is less than 1.75, which indicates that the new allotrope is brittle. It is shown that the difference in the elastic anisotropy along different orientations is greater than that in other phases. Finally, to understand the thermodynamic properties of P2/m-Si, the thermal expansion coefficient a, the Debye temperature circle minus(D), and the heat capacities C-P and C-V are also investigated in detail.

• 出版日期2017-4
• 单位西安电子科技大学