First principles study on the structural, electronic and magnetic properties of Ni4C

Abstract

a b s t r a c tThe first-principles calculations were performed based on density functional theory to study the structural, electronic and magnetic properties of Ni 4 C resulting from carbon atom diffusion in a conventional Ni unit cell. Firstly, geometry optimization was performed to reach the equilibrium state of Ni 4 C. The lattice constant of the stable Ni 4 C crystal structure was larger than that of the Ni unit cell. Then the electronic and magnetic properties of Ni 4 C were determined, and the results showed that the magnetic moment was 0.46 m B per unit cell, and the calculated local magnetic moment of carbon atoms was 0. There were two occupied sites for Ni atoms with different local magnetic moments, which was about 0.64 m B (close to that of nickel unit cell) for Ni a atoms at the top corners and a negative value of À0.06 m B for Ni b atoms at the face center. The magnetic moment increased abruptly to 1.89 m B at 3.79 Å due to the changes of lattice parameters with external factors, and fluctuated slowly from 3.5 Å to 3.78 Å.

First-principles study of magnetism in some novel MXene materials

“…Cu and Zn, which have 10 d electrons, cannot have unpaired electrons, and the magnetic moment for Ni is zero due to electron transfer and rearrangement in the electronic conguration. 50 Since phonon dispersion can be used to measure the dynamic stability of a material, the phonon dispersion plots of the lowestenergy congurations of the M 2 C MXenes along the highsymmetry directions in the Brillouin zone are given in Fig. S1.…”

A “One-Pot” Route for the Synthesis of Snowflake-like Dendritic CoNi Alloy-Reduced Graphene Oxide-Based Multifunctional Nanocomposites: An Efficient Magnetically Separable Versatile Catalyst and Electrode Material for High-Performance Supercapacitors

“…These facts clearly indicate the metallic nature and the ferromagnetic nature of Co-Ni-graphene. 46,47 The band structure of graphene (Figure S12) clearly shows its zero band gap nature. 48 The band structures of Co, Ni, Co-Ni, and Co-Ni-graphene also indicates their metallic character.…”

Parameters of crystal and electronic structure and magnetic properties of mechanically alloyed Ni3C cubic carbide

“…J. Yang et al [8] and C.M. Fang et al [16] have speculated on the formation of cubic carbide on the basis of fcc or hpc Ni crystal lattices.…”

“…Portnoi et al [7] have synthesized the well-known metastable hexagonal hpc Ni3C carbide by mechanical alloying of Ni-graphite charge (3:1). Previously, J. Yang et al [8] have predicted the existence of cubic carbide Ni4C under certain conditions by the first-principles calculations based on density functional theory. However, our experimental data on the tetrahedral displacement of carbon atoms in the synthesized fcc Ni3C carbide [6] contradicts the theoretical model of cubic Ni4C carbide [8], in which carbon atoms demonstrate the octahedral displacement.…”

“…Previously, J. Yang et al [8] have predicted the existence of cubic carbide Ni4C under certain conditions by the first-principles calculations based on density functional theory. However, our experimental data on the tetrahedral displacement of carbon atoms in the synthesized fcc Ni3C carbide [6] contradicts the theoretical model of cubic Ni4C carbide [8], in which carbon atoms demonstrate the octahedral displacement. However, it should be noted that both studies [6,8] deal with the formation of a supersaturated solid solution on the base of fcc nickel lattice.…”