Amorphous silicon hexaboride at high pressure


DURANDURDU M.

PHILOSOPHICAL MAGAZINE, vol.100, no.14, pp.1818-1833, 2020 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 100 Issue: 14
  • Publication Date: 2020
  • Doi Number: 10.1080/14786435.2020.1741060
  • Title of Journal : PHILOSOPHICAL MAGAZINE
  • Page Numbers: pp.1818-1833

Abstract

We investigate the pressure-induced structural phase transformation of amorphous silicon hexaboride (a-SiB6) using a constant pressure first principles approach. a-SiB6 is found to undergo a gradual phase transformation to a high-density amorphous phase (HDA) in which the average coordination number of both B and Si atoms is about 6. The HDA phase consists of differently coordinated motifs ranging from 4 to 8. B-12 icosahedra are found to persist during compression of a-SiB6 and the structural modifications primarily occur around Si atoms and in the regions linking pentagonal pyramid-like configurations to each other. Upon pressure release, an amorphous structure, similar to the uncompressed one, is recovered, indicating a reversible amorphous-to-amorphous phase change in a-SiB6. When the electronic structure is considered, the HDA phase is perceived to have a wider forbidden band gap than the uncompressed one.