Santos Cledson, Attah-Baah John M, Junior Romualdo S Silva, Mâcedo Marcelo A, Rezende Marcos V S, Matos Robert S, Ţălu Ştefan, Trong Dung Nguyen, da Paz Simone P A, Angélica Rômulo S, Ferreira Nilson S
Department of Physics, Federal University of Sergipe, São Cristóvão 49100-000, SE, Brazil.
Laboratory of Corrosion and Nanotechnology (LCNT), Federal University of Sergipe, São Cristóvão 49100-000, SE, Brazil.
Nanomaterials (Basel). 2023 Mar 8;13(6):980. doi: 10.3390/nano13060980.
Herein, we carefully investigated the Fe doping effects on the structure and electron distribution of CrO nanoparticles using X-ray diffraction analysis (XRD), maximum entropy method (MEM), and density functional theory (DFT) calculations. We showed that increasing the Fe doping induces an enlargement in the axial ratio of /, which is associated with an anisotropic expansion of the unit cell. We found that as Fe replaces Cr in the CrO lattice, it caused a higher interaction between the metal 3 states and the oxygen 2 states, which led to a slight increase in the Cr/Fe-O1 bond length followed by an opposite effect for the Cr/Fe-O2 bonds. Our results also suggest that the excitations characterize a well-localized bandgap region from occupied Cr to unoccupied Fe states. The CrO and Fe-doped CrO nanoparticles behave as Mott-Hubbard insulators due to their band gap being in the - gap, and Cr 3 orbitals dominate the conduction band. These findings suggest that the magnitude and the character of the electronic density near the O atom bonds in CrO nanoparticles are modulated by the Cr-Cr distances until its stabilization at the induced quasi-equilibrium of the CrO lattice when the Fe doping values reaches the saturation level range.
在此，我们使用X射线衍射分析（XRD）、最大熵方法（MEM）和密度泛函理论（DFT）计算，仔细研究了铁掺杂对CrO纳米颗粒结构和电子分布的影响。我们表明，增加铁掺杂会导致/轴比增大，这与晶胞的各向异性膨胀有关。我们发现，当铁在CrO晶格中取代铬时，会导致金属3态和氧2态之间产生更强的相互作用，这使得Cr/Fe - O1键长略有增加，而Cr/Fe - O2键长则产生相反的变化。我们的结果还表明，激发表现出从占据的Cr态到未占据的Fe态的一个局域良好的带隙区域。由于CrO和铁掺杂的CrO纳米颗粒的带隙处于 - 间隙，它们表现为莫特 - 哈伯德绝缘体，并且Cr 3轨道主导导带。这些发现表明，CrO纳米颗粒中O原子键附近电子密度的大小和特征受到Cr - Cr距离的调制，直到当铁掺杂值达到饱和水平范围时，在CrO晶格的诱导准平衡状态下达到稳定。
