Orbital facilitated charge transfer originated phonon mode in Cr‐substituted PrFeO3: A brief Raman study,Journal of Raman Spectroscopy

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Orbital facilitated charge transfer originated phonon mode in Cr‐substituted PrFeO3: A brief Raman study
Journal of Raman Spectroscopy ( IF 2.4 ) Pub Date : 2020-04-27 , DOI: 10.1002/jrs.5894
Anil Kumar ₁ , Sima Umrao ₂ , Pankaj R. Sagdeo ₁

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We report the possible origin of orbital facilitated new Raman mode in orthorhombic perovskite PrFe_1‐xCr_xO₃. For this purpose, resonance and power‐dependent Raman spectroscopy measurements have been carried out to understand the origin of local oxygen breathing mode in the mixed Fe–Cr orthorhombic perovskites through the orbital mediated charge transfer mechanism. It has been observed that multi‐phonon scattering is highly sensitive to the presence of mixed Fe–Cr ions and is absent in pure iso‐structural vacuum annealed PrFeO₃. The Raman spectroscopy results infer a scaling in the intensity of octahedral breathing Raman mode around 660 cm⁻¹, which is attributed to the lattice rearrangement due to the transfer of an electron from Cr³⁺(d³) to Fe³⁺(d⁵) and results to d²–d⁶ (Cr⁴⁺–O⁻²–Fe²⁺) configuration. The interactions of d²–d⁶ configuration are different from d³–d⁵ configuration, which leads to the octahedral lattice rearrangement and activates the new Raman mode. The charge transfer phenomenon is supported through first‐principle calculations and valence band spectroscopy.

中文翻译：

Cr取代的PrFeO3中的轨道促进的电荷转移起源于声子模：拉曼的简要研究

我们报告了正交晶系钙钛矿PrFe _1-x Cr _x O ₃中轨道促进的新拉曼模式的可能起源。为此，已经进行了共振和依赖功率的拉曼光谱测量，以了解通过轨道介导的电荷转移机制在混合的Fe-Cr斜方钙钛矿中局部氧气呼吸模式的起源。已经观察到，多声子散射对混合的Fe-Cr离子高度敏感，在纯等结构真空退火的PrFeO _3中却不存在。拉曼光谱学结果推断八面体呼吸拉曼模式强度在660 cm ^-1附近发生缩放，这归因于电子从Cr ³⁺（d ³）转移到Fe ³⁺（d ⁵）导致的晶格重排，并导致d ²-d ⁶（Cr ⁴⁺ -O ^-2 -Fe ^{2 +}）配置。d ²-d ⁶配置的相互作用不同于d ³-d ⁵配置，这导致八面体晶格重排并激活新的拉曼模式。电荷转移现象通过第一性原理计算和价带光谱得到支持。

更新日期：2020-04-27

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