Bonding Nature, Structural Optimization, and Energetics studies of SiC Graphitic-Like layer Structures and Single/Double Walled Nanotubes

TL;DR

This study uses DFT simulations to explore the structure, bonding, and energetics of SiC graphitic-like layers and nanotubes, revealing flexible bonding and stability features similar to carbon structures.

Contribution

It provides a detailed theoretical analysis of SiC-based layered and nanotube structures, highlighting their bonding nature and energetic stability, which was not extensively studied before.

Findings

SiC graphitic-like layers exhibit sp2 bonding, unlike bulk SiC.

Interlayer spacing depends on atomic ordering and Coulomb interactions.

Different interlayer distances are observed in SiC nanotubes based on their chirality.

Abstract

The structural optimization and energetics studies of SiC graphitic-like structures have been investigated theoretically in the context of formations of stable graphitic-like layer structures, single- and multi-walled nanotubes using the DFT-based Vienna ab-inito simulation package. The bonding nature of atoms in the optimized structures has been examined using a local analysis technique based on a self-consistent and environment-dependent semi-empirical Hamiltonian. Results of our studies reveal that stabilized SiC graphitic-like layer structures possess the sp2 bonding nature, different from the sp3 bonding nature in bulk SiC. Such flexibility in bonding configurations between Si and C atoms holds the possibility for a wide range of stable SiC-based structures, similar to those for carbon-based structures. In the case of SiC-based nanotubes, we have calculated quantities such as the strain energy, the degree of buckle in the cylindrical shell, and bond charges between Si and C atoms, to obtain an understanding of the optimized structures. The optimized interlayer spacing of SiC graphitic-like multilayer sheets has been found to depend on the ordering of atoms in different layers of the SiC graphitic-like structure (0.37 nm for the Si-C sequence of bilayer arrangement versus 0.48 nm for either the Si-Si or the C-C sequence of bilayer arrangement). These observations may be attributed to the Coulomb interactions due to the charge redistribution among Si and C atoms. On the other hand, the existence of two different ranges of interlayer separation in SiC double-walled nanotubes (0.38 nm for zigzag and 0.48 nm for armchair) is found to be related to whether the dominant interlayer neighbors are of the Si-C type or the Si-Si and C-C types.