Hexa ↔ tetra silicene crystal–crystal phase transition

ABSTRACT

Formation of confined crystalline tetra-silicene (t-silicene) from crystalline hexa-silicene (h-silicene) via compression, and the reverse transition from the obtained t-silicene to h-silicene via heating, are studied by molecular dynamics (MD) simulations. Models contain 6400 Si atoms interacted via the new version of the Stillinger-Weber potential. While t-silicene can be obtained via compression of the crystalline h-silicene at various temperatures, we find that the best quality samples (with the highest fraction of tetragons) are obtained at high temperatures but still well below the melting point. Such t-silicene is stable over a wide range of pressure and temperature. Evolution of the structural characteristics of samples and various thermodynamic quantities upon compression is studied. Detailed analysis of the structure of t-silicene at 300 K is presented via radial distribution function, coordination number and bond-angle distributions, ring statistics and interatomic distance distribution, as well as 2D visualisation of the atomic configurations. Various types of structural defects of t-silicene are found and discussed. In addition, heating of the obtained t-silicene is shown to lead first to the reverse tetra-to-hexa silicene phase transition, and then to the melting of h-silicene. Evolution of the structural characteristics of the samples and of the thermodynamic quantities upon heating are considered. Atomic mechanism underlaying the tetra$\leftrightarrow$hexa phase transitions is discussed.

KEYWORDS:

• Hexa-tetra silicene phase transition
• compression-induced crystal–crystal transition
• tetra-hexa silicene phase transition
• heating-induced phase transition

Acknowledgements

We acknowledge the use of New Zealand eScience Infrastructure (NeSI) supercomputer facilities.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Nguyen Hoang Giang http://orcid.org/0000-0003-4766-7243

Additional information

Funding

This work was supported by National Foundation for Science and Technology Development [grant number 103.01-2017.01].