Electronic Structure Calculation of Cr3+ and Fe3+ in Phosphor Host Materials Based on Relaxed Structures by Molecular Dynamics Simulation
Electronic Structure Calculation of Cr3+ and Fe3+ in Phosphor Host Materials Based on Relaxed Structures by Molecular Dynamics Simulation
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DOI：
10.3390/technologies10030056
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发表时间：
2022-06-01
期刊：
影响因子：
3.6
通讯作者：
Matsushima, Yuta
中科院分区：
文献类型：
--
作者：
Ichikawa, Joichiro;Kominami, Hiroko;Matsushima, Yuta
采用DV-Xc方法计算了深红色荧光粉LiAl 5 O 8：Cr 3+、α-Al 2 O3：Cr 3+和γ-LiAlO 2：Fe 3+中发光中心离子Cr 3+和Fe 3+的电子结构，模拟结果再现了发光中心离子取代基质晶体中Al 3+位置引起的局域畸变.基于经典动力学的MD模拟允许处理超过1000个原子用于晶格弛豫计算，这有利于模拟其中少量外来原子（离子）分散在如磷光体中的主晶格中的情况，即使当应用典型的周期性边界条件时。MD后弛豫的晶格表明，Cr ~（3+）和Fe ~（3+）周围的配位多面体随着发光中心离子与基质晶体中Al ~（3+）之间的尺寸差异而扩展。孤立的Cr 3+和Fe 3+的3d轨道的偏态密度（p-DOS）的整体轮廓没有受到晶格弛豫的显着影响，而3d轨道的能量分裂的宽度减少。对γ-LiAlO 2中Fe-Fe对的电子结构计算表明，Fe 3+离子之间存在反平行电子自旋的反铁磁相互作用，特别是当Fe-Fe对位于第一近邻阳离子位置时，反铁磁相互作用更明显.
The electronic structures of the luminescent center ions Cr3+ and Fe3+ in the deep red phosphors LiAl5O8:Cr3+, alpha-Al2O3:Cr3+, and gamma-LiAlO2:Fe3+ were calculated by the DV-Xc method, in which the local distortion induced by the replacement of Al3+ sites in the host crystals by the luminescent center ions was reproduced by classical molecular dynamics (MD) simulation. The MD simulations based on classical dynamics allowed for the handling of more than 1000 atoms for the lattice relaxation calculations, which was advantageous to simulate situations in which a small number of foreign atoms (ions) were dispersed in the host lattice as in phosphors, even when typical periodic boundary conditions were applied. The relaxed lattices obtained after MD indicated that the coordination polyhedra around Cr3+ and Fe3+ expanded in accordance with the size difference between the luminescent center ions and Al3+ in the host crystals. The overall profiles of the partial density of states (p-DOSs) of the isolated Cr3+ and Fe3+ 3d orbitals were not significantly affected by the lattice relaxation, whereas the widths of the energy splitting of the 3d orbitals were reduced. The electronic structure calculations for Fe-Fe pairs in gamma-LiAlO2 showed that the antiferromagnetic interactions with antiparallel electron spins between the Fe3+ ions were preferred, especially when the Fe-Fe pair was on the first-nearest neighboring cation sites.