Bian Liang, Xu Jin-bao, Song Mian-xin, Dong Fa-qin, Dong Hai-liang, Shi Fa-Nian, Zhang Xiao-Yan, Duan Tao
Xinjiang Key Laboratory of Electronic Information Materials and Devices, CAS, Urumqi, 830011, Xinjiang, China,
J Mol Model. 2015 Apr;21(4):91. doi: 10.1007/s00894-015-2583-7. Epub 2015 Mar 19.
Understanding how temperature affects the electronic transitions of BFO is important for design of BiFeO3 (BFO)-based temperature-sensitive device. Hitherto, however, there have been only very limited reports of the quantitative simulation. Here, we used density functional theory (DFT) and two-dimensional correlation analysis (2D-CA) techniques to calculate the systematic variations in electronic transitions of BFO crystal, over a range of temperature (50~1500 K). The results suggest that the heat accumulation accelerates the O-2p(4) orbital splitting, inducing the Fe(3+)-3d(5) → Fe(2+)-3d(5)d(0) charge disproportionation. The origin is observed as the temperature-dependent electron transfer process changes from threefold degeneracy to twofold degeneracy. Additionally, the crystallographic orientation (111) can be used to control the 2p-hole-induced electronic transition as O → unoccupied Fe(3+)-3d(5), in comparison to the O → Bi-6p(3) + Fe(3+)-3d(5)d(0) on the orientations (001) and (101). This study offers new perspective on the improvement of BFO-based temperature-sensitive device.
了解温度如何影响BiFeO₃（BFO）的电子跃迁对于基于BiFeO₃（BFO）的温度敏感器件的设计至关重要。然而，迄今为止，关于定量模拟的报道非常有限。在此，我们使用密度泛函理论（DFT）和二维相关分析（2D-CA）技术来计算BFO晶体在一定温度范围（50~1500 K）内电子跃迁的系统变化。结果表明，热量积累加速了O-2p(4)轨道分裂，诱导了Fe(3+)-3d(5) → Fe(2+)-3d(5)d(0)电荷歧化。其起源表现为与温度相关的电子转移过程从三重简并变为二重简并。此外，与（001）和（101）晶向上的O → Bi-6p(3) + Fe(3+)-3d(5)d(0)相比，晶体取向（111）可用于控制O → 未占据的Fe(3+)-3d(5)的2p空穴诱导的电子跃迁。本研究为改进基于BFO的温度敏感器件提供了新的视角。
