A first-principles investigation of a new hard multi-layered MnB2 structure

Abstract

ReB₂-type MnB₂ has always been considered to be the ground-state structure of MnB₂. However, subsequent theoretical study has revealed that this structure is easy to decompose into elemental Mn and B under ambient conditions, which motivated us to look for a stable MnB₂ structure at high pressures. Using structure prediction algorithm USPEX and density functional theory calculations, we found a stable multi-layered MnB₂ structure with space group Immm at high pressure. The calculated hardness of Immm-MnB₂ is 22.5 GPa, which makes it a potential hard multifunctional material along with its conductive and magnetic properties. The hexagonal graphene-like boron networks of Immm-MnB₂ contribute to its hardness and stability.