Gd/W共掺杂La2Mo2O9中的Gd-4f交换分裂与Mo-4d晶体场重新分布：DFT+U研究
Gd-4f Exchange Splitting and Mo-4d Crystal-Field Redistribution in Gd/W Co-doped La2Mo2O9: A DFT+U Study
- Advanced Materials Research Laboratory (AMRL)（先进材料研究实验室）
- Department of Physics（物理系）
- Rashtrasant Tukadoji Maharaj Nagpur University（拉什特拉桑特·图库吉·马哈拉杰纳格浦尔大学）
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AI总结：
本研究通过DFT+U方法研究Gd/W共掺杂La2Mo2O9的电子结构，揭示其Gd-4f交换分裂与Mo-4d晶体场重新分布机制，为改善固体氧化物燃料电池材料提供设计原则。
AI中文摘要：
La2Mo2O9（LAMOX）是一种有望用于中温固体氧化物燃料电池的氧化物离子导体，但其一阶单斜相向立方相（α相向β相）的相变限制了其实际应用。本研究采用考虑局域Gd-4f态的在位哈伯德修正的自旋极化密度泛函理论，探究了纯相La2Mo2O9及Gd/W共掺杂组成La1.6Gd0.4Mo1.7W0.3O9的电子结构。投影态密度显示，纯相La2Mo2O9是O-2p/Mo-4d电荷转移氧化物，La在带边附近的贡献可忽略不计。Gd/W共掺杂引入了具有约1011 eV多数-少数自旋分离的强交换分裂Gd-4f多重态，通过使晶体场分裂增加两倍显著重新分布了Mo-4d电子态，并将价带顶附近的O-2p贡献从78%降至66%。这些电子特征与实验观测到的晶格收缩、MoO拉曼模式软化以及共掺杂系列中氧化物离子电导率的非单调演化一致。特别是，最高掺杂水平下显著的晶体场分裂和局域Gd磁性为观测到的离子电导率抑制提供了微观电子层面的解释。本研究结果为理解Gd/W共掺杂LAMOX电解质中掺杂剂诱导的相稳定和氧化物离子传输建立了原子级电子结构框架，为开发改进的固体氧化物燃料电池材料提供了设计原则。
英文摘要：
La2Mo2O9 (LAMOX) is a promising oxide-ion conductor for intermediate-temperature solid oxide fuel cells, but its practical application is limited by a first-order monoclinic-to-cubic (alpha to beta) phase transition. Here, we investigate the electronic structure of pristine La2Mo2O9 and the Gd/W co-doped composition La1.6Gd0.4Mo1.7W0.3O9 using spin-polarized density functional theory with an on-site Hubbard correction for the localized Gd-4f states. The projected density of states reveals that pristine La2Mo2O9 is an O-2p/Mo-4d charge-transfer oxide in which La contributes negligibly near the band edges. Gd/W co-doping introduces a strongly exchange-split Gd-4f manifold with a majority-minority separation of approximately 1011 eV, substantially redistributes the Mo-4d electronic states through a threefold increase in crystal-field splitting, and reduces the O-2p contribution near the valence-band maximum from 78% to 66%. These electronic signatures are consistent with the experimentally observed lattice contraction, MoO Raman-mode softening, and the non-monotonic evolution of oxide-ion conductivity across the co-doped series. In particular, the pronounced crystal-field splitting and localized Gd magnetism at the highest doping level provide a microscopic electronic explanation for the observed suppression of ionic conductivity. The present results establish an atomistic electronic-structure framework for understanding dopant-induced phase stabilization and oxide- ion transport in Gd/W co-doped LAMOX electrolytes, providing design principles for improved solid oxide fuel cell materials.
