Reaction of rhenium and carbon at high pressures and temperatures

Abstract

Carbides / High pressures and temperatures / Synchrotron radiation / Analytical electron microscopy / Density functional theory (DFT) / X-ray diffraction / Powder diffraction structure analysis Abstract. A combined X-ray diffraction, EELS and DFT study of the reaction of rhenium with carbon at high-(P, T ) conditions up to P max ¼ 67 GPa and T max ¼ 3800 K is presented. A hexagonal rhenium carbide, ReC x , was identified as the stable phase at high-(P, T ) conditions. A composition of ReC 0:5 is proposed. No evidence for a cubic ReC polymorph with rocksalt structure, as suggested in the literature, or for any other phase was found at the P-T conditions explored. A preliminary P-T rhenium-carbon phase diagram has been derived and properties such as bulk moduli and elastic stiffness coefficients were obtained.

Thermodynamic stability and unusual strength of ultra-incompressible rhenium nitrides

“…Based on this prospect, recent design of new intrinsically superhard materials (H v ≥ 40 GPa) has concentrated on light-element (e.g., B, C, N, and O) TM compounds with high elastic moduli, 10 and PtC. 11 Although some of these ultraincompressible compounds, such as OsB 2 and ReB 2 , are expected to be intrinsically superhard,…”

Mechanical properties and electronic structure of the incompressible rhenium carbides and nitrides: A first-principles study

“…Among these compounds, Re 2 C, Re 2 N and Re 3 N have been prepared by experiments [2,3,5], as the negative E form value -74.24meV/atom for Re 3 C is calculated, it is expected that Re 3 C could be also obtained by experiments. Moreover, a phonon dispersion calculation along the high symmetry directions has been performed to further explore the dynamical stability of the new predicted compounds Re 3 C, which 5 is illustrated in Fig.…”

“…Recently, Re 2 C (P63/mmc) [2][3][4], Re 2 N (P63/mmc) and Re 3 N (P-6m2) [5] have been prepared and shown to be incompressible, which are placed for potential technological applications. Rather great bulk modulus of B=405±30 GPa for Re 2 C, B=401±10 GPa for Re 2 N and B=395±7 GPa for Re 3 N have been reported [2,3,5], respectively, which is comparable to that of the well-known incompressible materials c-BN. The unique property of these carbides and nitrides opens an interesting topic demanding of further exploration.…”

Электронная структура, механическая и динамическая стабильность гексагональных субкарбидов M-=SUB=-2-=/SUB=-C (M = Tc, Ru, Rh, Pd, Re, Os, Ir, Pt): ab initio расчеты

“…Далее, так как синтезированные карбиды тяжелых 4d-, 5d-металлов синтезируются и исследуются в каче-стве поликристаллической керамики [1,[6][7][8][9][10]29], полезно оценить упругие параметры для поликристаллических M 2 C. Для этой цели широко используется приближение Фойгта−Реусса−Хилла (VRH) [41] в пределе нулевой пористости M 2 C керамики. Таким образом, модули сжа-…”