Nitrogen concentration driving the hardness of rhenium nitrides

Abstract

The structures and properties of rhenium nitrides are studied with density function based first principle method. New candidate ground states or high-pressure phases at Re:N ratios of 3:2, 1:3, and 1:4 are identified via a series of evolutionary structure searches. We find that the 3D polyhedral stacking with strong covalent N-N and Re-N bonding could stabilize Re nitrides to form nitrogen rich phases, meanwhile, remarkably improve the mechanical performance than that of sub-nitrides, as Re3N, Re2N, and Re3N2. By evaluating the trends of the crystal configuration, electronic structure, elastic properties, and hardness as a function of the N concentration, we proves that the N content is the key factor affecting the metallicity and hardness of Re nitrides.

Diverse ruthenium nitrides stabilized under pressure: a theoretical prediction

“…The chemical related compounds, including the corresponding nitrides IrN 3 27, CoN 3 28 and RhN 3 28 with the same type structure were also suggested by first-principles calculations. Besides, Imm 2-TcN 3 , P 4/ mmm -TcN 4 , Imm 2-ReN 3 and Cmmm -ReN 4 were also proposed by Zhao et al 2930,. together with ReN 4 , OsN 4 and WN 4 with ReP 4 -type structure by Aydin et al 31…”

Effect of sulfur concentration on structural, elastic and electronic properties of molybdenum sulfides from first-principles

“…To reveal the correlation between the S concentration and structural stability, the structural stability of Mo-S sulfides is examined by the formation enthalpy [36,37]. The equation of formation enthalpy is given by:…”

High-pressure Raman spectroscopy of Re 3 N crystals

“…In their works, the crystal structure and bulk modulus of Re 3 N were determined by high-pressure synchrotron radiation experiments [4], and the vibrational properties of Re 3 N were studied by ambient Raman experiments [5] as well as first principle calculations [5,6]. Subsequently, further theoretical studies using first principle calculations were performed to probe the physical and structural properties of rhenium nitrides [6][7][8][9][10][11].…”