Strain induced structural transformation, mechanical and phonon stability in silicene derived 2D-SiB

Abstract

Two-dimensional monolayer SiB is a silicene derivative exhibiting buckling of atoms similar to that seen in silicene. This manuscript presents a systematic study of the strain-dependent variation of the structural, mechanical, and dynamical properties of SiB. Strain was applied in the uniaxial armchair, uniaxial zigzag, and biaxial directions within the range of −0.2 to 0.3. The resultant strain energy plot indicates anisotropic behavior of SiB in these directions. The SiB showed a mechanical strength that was higher than its counterpart, silicene, by an order of 30%. The elastic constant data from the undeformed SiB indicated an anisotropic nature, which was also seen with all the strain directions. Charge density contours, along with Bader charge analysis, confirmed the ionic nature of SiB in its original form. This nature became covalent as the strain varied from the compressive to the tensile regime in the uniaxial zigzag and biaxial directions. The major finding described in this manuscript is a new flat conformation having orthorhombic symmetry in contrast to the buckled structure. In addition, this material was observed to attain stability with the application of uniaxial tensile armchair and zigzag directional strains. Ab-initio molecular dynamics simulation confirmed the thermal stability of SiB in its new conformation.