Structure-Property Relationships of the 10H Hexagonal-Type Perovskite BaMn0.4Fe0.6O2.73

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• 作者：Laura Miranda ; Khalid Boulahya ; Aurea Varela ; José ; M. Gonz&aacute ; lez-Calbet ; Marina Parras ; Marí ; a Hernando ; M. Teresa Fern&aacute ; ndez-Dí ; az ; Antonio Feteira ; Derek C. Sinclair
• 刊名：Chemistry of Materials
• 出版年：2007
• 出版时间：July 10, 2007
• 年：2007
• 卷：19
• 期：14
• 页码：3425 - 3432
• 全文大小：682K
• 年卷期：v.19,no.14(July 10, 2007)
• ISSN：1520-5002

文摘

The crystal structure of BaMn_0.4Fe_0.6O_2.73, a recently identified oxygen-deficient 10H-type hexagonalperovskite in the system BaMn_1-xFe_xO_3-y, has been established by a combination of electronmicrodiffraction and neutron diffraction. The structure (space group P6₃/mmc, a = 5.74435(5) Å, and c= 24.0331(3) Å) can be described by a stacking sequence (hch'ch)₂ along the c-axis with the aniondeficiency located exclusively in the h'-BaO₃-type layers. The anion distribution in the h'-BaO₃ layersdiffers significantly from that observed for 10H BaFeO_2.8 and results in a 70:30 random distribution ofcorner-sharing tetrahedral Fe₂O₇ dimers and face-sharing octahedral (Mn,Fe)₂O₉ dimers as opposed tothe exclusive Fe₂O₇ dimers in 10H BaFeO_2.8. The difference is attributed to the preference of Mn foroctahedral coordination. The compound is a "leaky" insulator at room temperature with a permittivity of~20. The conduction mechanism has low activation energy, ~0.3 eV, and is consistent with polaronichopping associated with the Fe and/or Mn ions.