The electronic structure and properties of Fe _6(N _(1-x)C _x) _2 carbonitrides by first-principles calculations

摘要

Electronic structure and properties of Fe _6(N _(1-x)C _x) _2 carbonitrides with 0≤x≤1, i.e. the concentrations of N and C elements are respectively in range of 0～7.69 wt% and 0～6.67 wt%, have been studied by first-principles calculations based on density functional theory (DFT) implemented in the Cambridge Serial Total Energy Package (CASTEP) code. The calculated results show that the Fe _6(N _(1-x)C _x) _2 carbonitrides are thermodynamically and mechanically stable. Lattice parameters and stability of the carbonitrides increase when C atoms replace N atoms in Fe _6N _2 unit cell. In Fe _6(N _(1-x)C _x) _2 unit cell, the hybridization effect between C-2p and Fe-3d states is stronger than that between N-2p and Fe-3d states. Elastic properties and melting points of the carbonitrides change slightly with the substitution of C atoms for N atoms in Fe _6(N _(1-x)C _x) _2 carbonitrides.