Confined tetra-silicene obtained by cooling from the melt

VV Hoan and NH Giang and TQ Dong, COMPUTATIONAL MATERIALS SCIENCE, 158, 406-413 (2019).

DOI: 10.1016/j.commatsci.2018.11.034

Formation of confined tetra-silicene (t-silicene) from the melt is studied by molecular dynamics (MD) simulation. Models containing 6066 atoms interacted via Stillinger-Weber potential are obtained by cooling from 5000 K to 300 K. We find that t-silicene is formed with the broad buckling distribution ranged from 0.60 angstrom to 1.49 angstrom differed from unique buckling of 1.49 angstrom predicted by DFT calculations. Depending on the cooling rate used in simulations one can obtain crystalline or amorphous samples. Crystallization and glass transition temperatures are defined, namely, T-X approximate to 1950 K and T-g approximate to 1350 K. These temperatures are higher than those found for hexasilicene. Structural characteristics of models are studied in details via radial distribution functions (RDFs), coordination number, bond-angle, interatomic distance and buckling distributions plus ring statistics. In addition, 2D visualization of atomic configurations plus diffraction pattern of the models at 300 K is done in order to see in more details structure of the models. Main types of structural defects are defined and their role in chemicophysical performance of t-silicene is discussed. Although main structural units are tetragons, both amorphous and crystalline t-silicenes contain many rings differed from tetragons. According to our calculations, the Poisson ratio for the obtained t-silicene is positive. In order to clarify interatomic potential effects on the formation of t-silicene, the same simulation procedure is done with the reactive force field and intensive comparison is given.

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