Identification of a potential superhard compound ReCN

Abstract

We identify a new ternary compound, ReCN and characterize its properties including structural stability and indicators of hardness using first principles calculations. We find that there are two stable structures with space groups P63mc (HI) and P3m1 (HII), in which there are no CC and N-N bonds. Both structures, H1 and III are elastically and dynamically stable. The electronic structures show that ReCN is a semiconductor, although the parent compounds, ReC 2 and ReN 2 are both metallic. ReCN is found to possess the outstanding mechanical properties with the large bulk modulus, shear modulus and excellent ideal strengths. In addition, ReCN may perhaps be synthesized relatively easily because it becomes thermodynamic stable with respect to decomposition at very low pressures.

Ab-initio study of ReCN in the bulk and as a new two dimensional material

“…1(b)), which indicates good agreement with previous calculations 29 . The Re-C, Re-N, and C-N distances were found also in agreement with previously reported data, as seen in Table 1.

Figure 1( a ) ReCN bulk structure, and ( b ) Total energy as function of lattice parameter for bulk ReCN.

…”

“…Previous calculations of bulk ReCN have found a stable tetragonal structure with lattice parameters: a = 2.897 Å and c = 7.851 Å 29 , and a semiconductor behavior with a calculated energy gap of ~0.6 eV 29 . Before studying the ReCN 2D system, we have reproduced the ReCN bulk structure, as shown in Fig.…”

“…To begin with the calculations, we have optimized the ReCN bulk structure in a tetragonal structure, with space group P63mc (186) 29 . The monolayer has been simulated by taking only a Re-C-N unit with an empty space large enough (~15 Å) to account for the surface effects in the 2D system as well as to eliminate undesirable interactions between adjacent monolayers.…”

“…Keeping in mind the interest that 2D materials have generated in the past years, we have turned our attention to the ReCN compound. This is a super hard material with an orthogonal bulk structure with two ReCN tri-layers in the unit cell 29 . Since two consecutive tri-layers are not bonded by weak van der Waals forces, it is not possible to obtain 2D ReCN by exfoliation.…”

Mechanochemical synthesis and annealing of tungsten di‐ and tetra‐boride

“…Superhard materials (Vickers hardness > 40 GPa) have attracted considerable attention of scientists and researchers all around the world attributed to their high hardness, good wear resistance, high-compression resistance, and excellent thermal conductivity, etc. 1,2 Diamond and cubic boron nitride (cBN) are well-known and commonly used surperhard materials, but they are failed to satisfy the need of some emerging industrial applications. For example, diamond is unusable for cutting ferrous materials and cBN is very expensive to synthesize and difficult to shape.…”