Insight into the structures, melting points, and mechanical properties of NbSi₂ from first‐principles calculations

Abstract

Studies are carried out on the equilibrium structural, mechanical properties, and melting points of NbSi 2 with four ground-state crystal structures (C40, C11 b , C54, and C49) using first-principles approach. By means of the calculated formation enthalpies and phonon dispersion, it is found that these NbSi 2 phases are thermodynamically and dynamically stable. C54-NbSi 2 is uncovered to possess the lowest energy and formation enthalpy, implying that it is expected to be the most favorite structure for NbSi 2 . The results of the calculated elastic constants reveal that four NbSi 2 phases are mechanically stable. We further find that the mechanical properties of C54-NbSi 2 are superior to those of the other NbSi 2 phases. The melting points of these NbSi 2 phases are calculated to examine their thermal stability. The elastic anisotropy is calculated and discussed using three patterns. The results prove that C54-and C40-NbSi 2 have good elastic isotropy, as confirmed by the given three-dimensional plots of elastic moduli. Analyzing the difference charge density and Mulliken overlap population provides the explanation about the relationship between bonding characteristics and mechanical properties. K E Y W O R D Sfirst-principles theory, mechanical properties, NbSi 2 , structure

Exploring the novel structure, transportable capacity and thermodynamic properties of TiH 2 hydrogen storage material

“…The mechanical properties of a solid are measured by the elastic modulus: bulk modulus ( B ), shear modulus ( G ) and Young modulus ( Y ), respectively. The elastic modulus of hydrogen storage materials are calculated by the elastic constants ( C ij ) …”

Thermodynamic, lattice dynamical, and elastic properties of iron‐vanadium oxides from experiments and first principles

“…Meanwhile, ν reflects the degree of transverse deformation. Generally, if ν < 0.26, it exhibits a brittle characteristic, otherwise it corresponds to ductile nature . The B / G ratio and ν of Fe 2 V 4 O 13 are <0.26 and <1.75, respectively, indicating it is intrinsically brittle.…”

The influence of high pressure on the structural stability, Vickers hardness and mechanical properties of Re and Ru dodecaborides

“…According to the first-principles calculations, the calculated lattice parameter is a = 7.329 Å for ReB 12 and a = 7.366 Å for RuB 12 [47][48][49][50] According to the first-principles calculations, the elastic modulus of TMB 12 is obtained by the elastic constants. [51][52][53] For the TMB, the elastic constants are calculated by using variations of the equilibrium energy with respect to applied strain, which is defined as [54] : [51][52][53] For the TMB, the elastic constants are calculated by using variations of the equilibrium energy with respect to applied strain, which is defined as [54] :…”