In-Plane Mechanically Gradated 2D Materials: Exploring Graphene/SiC/Silicene Transition via Full Atomistic Simulation

HM Zhang and SW Cranford, ADVANCED THEORY AND SIMULATIONS, 2, 1800126 (2019).

DOI: 10.1002/adts.201800126

The emergence of 2D materials has resulted in many platforms with promising applications. One possibility is to combine two (or more) systems in a multilayered structure. However, can such materials transition in-plane? Here, the potential of graded transition from graphene to silicene, via 2D silicon carbide is explored. The work focuses on mechanical performance of a two-phase gradated system under uniaxial stress. The percentage of the carbon/silicon in-plane, to explore the resulting effects on strength and stiffness using full atomistic molecular dynamics (MD) is varied. Carbon atom placement of 0% to 100% in nine increments with random substitution, is tested using both single-bond and mixed-bond homogeneous and two-phase gradated models. Stiffness and strength can be predicted by a simple model accounting for proportional bond distributions. It is demonstrated that the inclusion of nominal amounts of Si-C bonding results in drastic changes in mechanical response when compared to graphene, tolerant to change across a wide range of distributions, suggesting a "weakest link" effect. For the two-phase gradated systems, stress contour plots correlate with changes in silicon-to-carbon ratios. The work demonstrates the feasibility of a new class of 2D in-plane gradated materials with tunable stiffness, predictable strength, and controlled failure.

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