Direct Atomic Observation in Powdered 4H-Ba0.8Sr0.2Mn0.4Fe0.6O2.7

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• 作者：Mar铆a Hernando ; Laura Miranda ; Aurea Varela ; Khalid Boulahya ; Sorin Lazar ; Derek C. Sinclair ; Jos茅 M. Gonz谩lez-Calbet ; Marina Parras
• 刊名：Chemistry of Materials
• 出版年：2013
• 出版时间：February 26, 2013
• 年：2013
• 卷：25
• 期：4
• 页码：548-554
• 全文大小：434K
• 年卷期：v.25,no.4(February 26, 2013)
• ISSN：1520-5002

文摘

A new hexagonal polytype in the BaMn_1-xFe_xO_3-未 system has been stabilized. Powdered Ba_0.8Sr_0.2Mn^IV_0.4Fe^III_0.6O_2.70 crystallizes in the 4H hexagonal polytype (space group P6₃/mmc) according to X-ray diffraction. HAADF images and chemical maps with atomic resolution have been obtained by combining Cs-corrected electron microscopy and EELS spectroscopy. The structure is formed by dimers of face-sharing octahedra linked by corners. EELS data show a random distribution of the transition metals ions identified by Fe and Mn-L2,3 chemical maps. A systematic difference in contrast observed in the O鈥揔 signal mapping suggests that anion deficiency is randomly located along the hexagonal layers in agreement with ND data. The magnetic structure consists of ferromagnetic sheets with the magnetic moments aligned along the x-axis and coupled antiferromagnetically along the c-axis.

Keywords:

corrected aberration electron microscopy; energy electron loss spectroscopy; hexagonal perovskites