Energetics of carbon and nitrogen impurities and their interactions with vacancy in vanadium

Abstract

We studied the energetic behaviors of interstitial and substitution carbon (C)/nitrogen (N) impurities as well as their interactions with the vacancy in vanadium by first-principles simulations. Both C and N impurities prefer the octahedral site (O-site). N exhibits a lower formation energy than C. Due to the hybridization between vanadium-d and N/C-p, the N-p states are located at the energy from −6.00 eV to −5.00 eV, which is much deeper than that from −5.00 eV to −3.00 eV for the C-p states. Two impurities in bulk vanadium, C-C, C-N, and N-N can be paired up at the two neighboring Osites along the 111 direction and the binding energies of the pairs are 0.227 eV, 0.162 eV, and 0.201 eV, respectively. Further, we find that both C and N do not prefer to stay at the vacancy center and its vicinity, but occupy the O-site off the vacancy in the interstitial lattice in vanadium. The possible physical mechanism is that C/N in the O-site tends to form a carbide/nitride-like structure with its neighboring vanadium atoms, leading to the formation of the strong C/N-vanadium bonding containing a covalent component.

Tailored modifications of the electronic properties of g-C3N4/C2N-h2D nanoribbons by first-principles calculations

“…4. 41 The conduction band minimum (CBM) of g-C 3 N 4 /C 2 N-h2D nanoribbons is located at point M, and its valence band maximum (VBM) is located at point G. It is significant that g-C 3 N 4 /C 2 N-h2D nanoribbons have a narrow band gap. This indicates that the excited electrons can easily cross the forbidden band.…”

Strain rate and cold rolling dependence of tensile strength and ductility in high nitrogen nickel-free austenitic stainless steel

“…The investigations on the metals and alloys have attracted extensive attention in the past years because of their good performance. [32][33][34][35][36][37][38][39] For the purpose of optimizing the microstructure and mechanical properties of the metals and alloys and extending their practical applications, it is of particular importance to analyze their plastic deformation behavior or stress-strain curves. One of the earliest attempts is the empirical mathematical equation proposed by Hollomon (termed as the Hollomon equation).…”

Prediction of a Stable Organic Metal-Free Porous Material as a Catalyst for Water-Splitting

“…[4][5][6][7][8][9][10][11][12], which belong to inorganic materials. Inorganic photocatalysts materials have some drawbacks, for example limited concentration of active sites and heavy metal toxicity [13][14][15]. However, organic photocatalysts have some merits, for example low cost, ease of fabrication and mechanical flexibility [16,17].…”