Theoretical Investigation of Structural, Electronic, and Mechanical Properties of Two Dimensional C, Si, Ge, Sn

Abstract

In this article, we investigate the predictions of the first principles on structural stability, electronic and mechanical properties of 2D nanostructures: graphene, silicene, germanene and stenane. The electronic band structure and density of states in all these 2D materials are found to be generic in nature. A small band gap is generated in all the reported materials other than graphene. The linearity at the Dirac cone changes to quadratic, from graphene to stenane and a perfect semimetalicity is exhibited only by graphene. All other 2D structures tend to become semiconductors with an infinitesimal band gap. Bonding characteristics are revealed by density of states histogram, charge density contour, and Mulliken population analysis. Among all 2D materials graphene exhibits exotic mechanical properties. Analysis by born stability criteria and the calculation of formation enthalpies envisages the structural stability of all the structures in the 2D form. The calculated second order elastic stiffness tensor is used to determine the moduli of elasticity in turn to explore the mechanical properties of all these structures for the prolific use in engineering science. Graphene is found to be the strongest material but brittle in nature. Germanene and stenane exhibit ductile nature and hence could be easily incorporated with the existing technology in the semiconductor industry on substrates.

High performance photocatalytic and thermoelectric two-dimensional asymmetrically ordered Janus-like MXene alloys

“…A (hexagonal) 2D MXene possesses 3 independent non-zero elastic constants which are calculated to be: C 11 = 322.22 N m À1 , C 12 = 103.06 N m À1 , and C 66 = 109.58 N m À1 . These elastic constants fulfill the Born stability criteria according to Born-Huang's lattice dynamical theory for hexagonal 2D structures, 73,74 i.e., C 11 4 0, C 11 À C 12 4 0, and Fig. 3a illustrates the electronic band structure of the TiMoCO 2 ground-state configuration with a band gap of 0.60 eV.…”

Prediction of mechanical properties of 2D solids with related bonding configuration

“…3.1 Single-atomic graphene-like monolayers 3.1.1 Ratios of Young's moduli and fracture strengths. The mean values of the Young's moduli of the single-atomic monolayers of graphene, 4 boronitrene, 10 phosphorene, [11][12][13][14] silicene, 6,7,15,16 germanene, 6,7 and stanene 6,7,17 are collected in Table 1. From these values the ratios of the stiffness of the individual group members to that of the reference, graphene, is calculated.…”

“…Most of them possess promising properties of practical interest. [5][6][7] For other groups of 2D solids with related chemical and physical properties and similar bonding conguration, such as the group VI-B transition metal dichalcogenides (TMDs or TMDCs), even less is known, especially for the group members with high mass, despite increasing attention. 8,9 The main source of information on mechanical behavior comes from density functional theory (DFT) calculations and to some extent from molecular dynamics (MD) simulations.…”

Bonding, structure, and mechanical stability of 2D materials: the predictive power of the periodic table

“…Note that in stable low-buckled silicene, s-p orbital mixing is closer to sp 2 than to sp 3 hybridization with a small buckling effect of 0.041 nm. 73 For the larger Ge atoms, p bonding is further weakened and the contribution of sp 3 orbitals and thus buckling increases. This change in the bonding character is clearly visible in the bond angle, which decreases from 1201 in graphene to 116.91 in silicene, 112.61 in germanene, and 110.41 in stanene, which is near the bond angle of sp 3 hybridization of 109.51.…”