The electronic structure of newly synthesized marcasite-type cobalt pernitride (CoN₂) is investigated using X-ray absorption and photoelectron spectroscopy (XAS and XPS), in combination with the electronic band structure calculation within the scheme of the density functional theory under a generalized gradient approximation. N K-edge XAS spectra and unoccupied electronic structures of the marcasite-type RuN₂ and pyrite-type PtN₂ are also studied. The N K-edge XAS and valence-band XPS spectra are well explained using the calculated valence-band and conduction-band densities of states, which agree well with the XAS spectra calculated using the electric dipole approximation. The physical properties of these pernitrides are discussed in terms of the obtained electronic structures. In contrast to the Pt⁴⁺ 5d-t_2g⁶ configuration, which leads to the strong covalent nature and insulating superhard properties of the pyrite-type PtN₂, the ferromagnetic metal of the marcasite-type CoN₂ can be derived from the Co²⁺ 3d-t_2g⁶e_g¹ configuration instead of the Co⁴⁺ 3d-t_2g⁵ configuration. The difference in the electronic configurations of the Co pernitride is attributed to the spatial extent of the 3d states.

中文翻译：

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X射线吸收和光电子能谱研究过渡金属氮化物的电子结构

利用X射线吸收和光电子能谱（XAS和XPS），结合密度泛函理论框架下的电子能带结构计算，研究了新合成的镁铁矿型过氧化钴（CoN ₂）的电子结构。梯度近似。还研究了马氏体型RuN ₂和黄铁矿型PtN _2的N K边缘XAS光谱和未占据的电子结构。N K利用计算得到的态价带和导带密度很好地解释了边缘XAS和价带XPS光谱，这与使用电偶极近似法计算出的XAS光谱非常吻合。根据获得的电子结构讨论了这些氮化物的物理性质。与Pt ⁴⁺ 5 d - t _2g ⁶构型相反，Pt ⁴⁺ 5 d - t _2g ⁶构型导致黄铁矿型PtN ₂具有很强的共价性和绝缘超硬性，而镁铁矿型CoN ₂的铁磁性金属可以从Co ²⁺ 3 d - t _2g ⁶ e _g¹配置而不是Co ⁴⁺ 3 d - t _2g ⁵配置。钴氮化物的电子构型的差异归因于3d状态的空间范围。