Tensile strength and fracture mechanics of two-dimensional nanocrystalline silicon carbide

Two-dimensional Silicon Carbide (SiC) has opened the route to a cornucopia of advanced functionalities in the realm of quantum condensed matter. It holds great promise for highly efficient nanoelectronic, optoelectronic, renewable energy, and spintronic applications thanks to the confluence of a wide spectrum of mesmerizing physical properties like a wide direct bandgap with high exciton binding energy, robust spin-orbit-coupling, excellent photoluminescence, suitable mechanical strength, and thermodynamic stability. Nonetheless, it is still a daunting challenge to incorporate SiC in functional systems since extensive analyses of the mechanical properties, and fracture mechanism of nanocrystalline (NC)-SiC is still obscure. In this light, this work is an attempt to report detailed information concerning the room-temperature tensile mechanical properties and fracture phenomena of NC-SiC executing Molecular Dynamics (MD) simulations. In particular, effects of grain size on the stress-strain profile, fracture strength, fracture strain, and Young's modulus of the NC-SiC have been thoroughly investigated. It has been found that the strength as a function of grain size can be characterized by the inverse pseudo Hall-Petch relation. Increasing grain size brings about more elasticity in the structure, albeit at the price of fracture strain. The NC-SiC encounters a substantial degradation in mechanical properties relative to its singlecrystal counterpart. Afterward, we performed an exhaustive fracture analysis on two NC-SiC samples of different grain sizes. The single-crystal SiC can endure more tensile strain before rupture compared to that of the NC-SiC. At last, the nanosheet exhibits more immunity to fracture with decreasing grain size. This study would lay the groundwork for NC-SiC to be successfully realized in functional systems as well as serving as a solid roadmap for engineering the mechanical properties of nanocrystalline materials.