First-principles study on the preferential sites of Cr in Co₇W₆

Abstract

The preferential sites of Cr in the μ-Co7W6 phase and its influence on electronic properties were studied by first-principles calculations based on density functional theory. The calculation results of the formation energy and defect formation energy show that the stability of the system is enhanced when Cr occupies the Co site, which indicates that Cr tends to occupy the Co site of the system. By calculating the density of states, the Hamilton population of crystal orbital, the electron location function and the Bader charge distribution, the reason why Cr preferentially occupied the Co sites is further explained. This is primarily owing to the hybridization of the d-d orbitals of the Cr atom to its adjacent atoms.

Multiple Function Synchronous Optimization by PbS Quantum Dots for Highly Stable Planar Perovskite Solar Cells with Efficiency Exceeding 23%

“…The E g of PbS QDs increases as the content of Eu doping raises. [ 68 ] This situation indicates that the concentration of free charge in the conduction band will change the Fermi level and its position, and the bandgap is related to the excitation of the charge from the valence band to the Fermi level. The reason why the bandgap needs to be adjusted is that energy level matching between each layer is also an essential factor for high‐performance PSCs.…”

Machine Learning-Aided High-Throughput First-Principles Calculations to Predict the Formation Energy of μ Phase

“…The μ phase belongs to TCP, and its space group is R 3̅ m (No. 166) . To elucidate the atomic interactions within the μ phase, it is commonly described using its equivalent structure, A 21 B 18 , characterized by a hexagonal lattice structure containing 39 atoms distributed among five distinct lattice sites, as shown in Figure , where different colors represent different sites.…”

“…Hexagonal crystal structure of the μ phase with five distinct sites: 3a (blue), 6c 1 (gray), 6c 2 (black), 6c 3 (green), and 18h (red). , …”

“…166). 25 To elucidate the atomic interactions within the μ phase, it is commonly described using its equivalent structure, A 21 B 18 , characterized by a hexagonal lattice structure containing 39 atoms distributed among five distinct lattice sites, as shown in Figure 1 , where different colors represent different sites. The lattice parameters of the μ phase are a = 4.72∼4.80 Å, c = 25.679∼25.90 Å, α = 90°, β = 90°, γ = 120°.…”

“…First-principles calculations based on density functional theory (DFT) are commonly used for calculating the formation energy of the μ phase. , The μ phase is a hexagonal structure with 39 atoms occupying five inequivalent sites, namely 3a, 6c 1 , 6c 2 , 6c 3 , and 18h. − Composite energy formalism (CEF) is typically employed in thermodynamic models to handle multicomponent and nonstoichiometric phases . Nevertheless, calculating the formation energy of the μ phase is challenging due to the vast number of possible configurations.…”