Structural Ordering and Ferromagnetism in La4Mn4O11

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• 作者：M. L. Ruiz-Gonz&aacute ; lez ; R. Corté ; s-Gil ; J. M. Alonso ; A. Hernando ; M. Vallet-Regí ; J. M. Gonz&aacute ; lez-Calbet
• 刊名：Chemistry of Materials
• 出版年：2006
• 出版时间：November 28, 2006
• 年：2006
• 卷：18
• 期：24
• 页码：5756 - 5763
• 全文大小：903K
• 年卷期：v.18,no.24(November 28, 2006)
• ISSN：1520-5002

文摘

Electron diffraction and high-resolution electron microscopy of LaMnO_{3-mages/gifchars/delta.gif" BORDER=0 >} (0 mages/entities/le.gif"> mages/gifchars/delta.gif" BORDER=0 > mages/entities/le.gif"> 0.25), obtainedby topotactic reduction of LaMnO₃, shows that an ordered pathway of anionic vacancies is only obtainedfor mages/gifchars/delta.gif" BORDER=0 > = 0.25. La₄Mn₄O₁₁ is an eightfold superlattice of the perovskite-type structure due to the orderedintergrowth of three octahedral layers and one tetrahedral layer along the b axis, according to the sequence...OOOTOOOT'... The reduced sample exhibits ferromagnetic behavior with T_c mages/entities/ap.gif"> 50 K. The staircaseeffect, observed at low temperature, is discussed in terms of the magnetic ordering adopted in the octahedrallayers.