Jump to main content
Jump to site search


A two-dimensional CaSi monolayer with quasi-planar pentacoordinate silicon

Author affiliations

Abstract

The prediction of new materials with peculiar topological properties is always desirable to achieve new properties and applications. In this work, by means of density functional theory computations, we extend the rule-breaking chemical bonding of planar pentacoordinate silicon (ppSi) into a periodic system: a C2v Ca4Si22− molecular building block containing a ppSi center is identified first, followed by the construction of an infinite CaSi monolayer, which is essentially a two-dimensional (2D) network of the Ca4Si2 motif. The moderate cohesive energy, absence of imaginary phonon modes, and good resistance to high temperature indicate that the CaSi monolayer is a thermodynamically and kinetically stable structure. In particular, a global minimum search reveals that the ppSi-containing CaSi monolayer is the lowest-energy structure in 2D space, indicating its great promise for experimental realization. The CaSi monolayer is a natural semiconductor with an indirect band gap of 0.5 eV, and it has rather strong optical absorption in the visible region of the solar spectrum. More interestingly, the unique atomic configuration endows the CaSi monolayer with an unusually negative Poisson's ratio. The rule-breaking geometric structure together with its exceptional properties makes the CaSi monolayer quite a promising candidate for applications in electronics, optoelectronics, and mechanics.

Graphical abstract: A two-dimensional CaSi monolayer with quasi-planar pentacoordinate silicon

Back to tab navigation

Supplementary files

Publication details

The article was received on 22 Jun 2017, accepted on 22 Jan 2018 and first published on 22 Jan 2018


Article type: Communication
DOI: 10.1039/C7NH00091J
Citation: Nanoscale Horiz., 2018, Advance Article
  •   Request permissions

    A two-dimensional CaSi monolayer with quasi-planar pentacoordinate silicon

    Y. Wang, M. Qiao, Y. Li and Z. Chen, Nanoscale Horiz., 2018, Advance Article , DOI: 10.1039/C7NH00091J

Search articles by author

Spotlight

Advertisements