Structural, mechanical and electronic properties of Rh2B and RhB2: first-principles calculations

Abstract

The crystal structures of Rh2B and RhB2 at ambient pressure were explored by using the evolutionary methodology. A monoclinic P21/m structure of Rh2B was predicted and donated as Rh2B-I, which is energetically much superior to the previously experimentally proposed Pnma structure. At the pressure of about 39 GPa, the P21/m phase of Rh2B transforms to the C2/m phases. For RhB2, a new monoclinic P21/m phase was predicted, named as RhB2-II, it has the same structure type with Rh2B. Rh2B-I and RhB2-II are both mechanically and dynamically stable. They are potential low compressible materials. The analysis of electronic density of states and chemical bonding indicates that the formation of strong and directional covalent B-B and Rh-B bonds in these compounds contribute greatly to their stabilities and high incompressibility.

Stability and the Electronic Structure of XB2(X = Pt, Ir, Pd, Rh, Os) Diborides

“…Two different structures, the Pmmn orthorhombic [9] and the C2/m monoclinic [10] have been reported in IrB 2 through ab initio density-functional theory calculations. The structure of RhB 2 has also been proposed to be monoclinic at ambient pressure [11].…”