密度泛函理论
兴奋剂
价
化学计量学
氧气
钙钛矿(结构)
空位缺陷
氧化还原
材料科学
化学
无机化学
分析化学(期刊)
结晶学
物理化学
计算化学
光电子学
有机化学
语言学
哲学
色谱法
作者
Dawei Zhang,Jiyun Park,Boyuan Xu,Cijie Liu,Wei Li,Xingbo Liu,Yue Qi,Jian Luo
出处
期刊:Dalton Transactions
[The Royal Society of Chemistry]
日期:2023-01-01
卷期号:52 (4): 1082-1088
被引量:2
摘要
Aliovalent doping of perovskite oxides can tune the oxygen vacancy formation energy. This work discovers normal vs. abnormal aliovalent doping effects on redox behaviors in medium-entropy compositionally complex perovskite oxides (CCPOs) (La1-xSrx)(Mn1/3Fe1/3Ti1/3)O3-δ (LS_MFT) vs. (La1-xSrx)(Mn1/3Fe1/3Cr1/3)O3-δ (LS_MFC). In the LS_MFC series, the oxygen non-stoichiometry range Δδ (= δred - δox) linearly depends on the Sr molar ratio x, while the LS_MFT series shows a V-shape dependence of Δδ on x. This unusual observation is investigated and explained based on the analysis of the energy loss near edge structure (ELNES) in STEM electron energy loss spectroscopy, along with density functional theory (DFT) calculations. In LS_MFC, Cr-L2,3, Mn-L2,3 and Fe-L2,3 peaks have a similar linear shift to higher energy with increasing x, which indicates higher oxidation states of Cr, Mn, and Fe with lower oxygen vacancy formation energies. In LS_MFT, the V-shape of the Δδ vs. x curve is caused by the stable Ti4+ state and a V-shape Mn/Fe valency dependence on x. This study suggests the possible existence of different (including unexpected) coupled aliovalent doping effects in CCPOs with multiple B-site redox active elements.
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