La4Cu3MoO12: A Novel Cuprate with Unusual Magnetism

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• 作者：Douglas A. Vander Griend ; Sophie Boudin ; Vincent Caignaert ; Kenneth R. Poeppelmeier ; Yanguo Wang ; Vinayak P. Dravid ; Masaki Azuma ; Mikio Takano ; Zhongbo Hu ; and James D. Jorgensen
• 刊名：Journal of the American Chemical Society
• 出版年：1999
• 出版时间：May 26, 1999
• 年：1999
• 卷：121
• 期：20
• 页码：4787 - 4792
• 全文大小：147K
• 年卷期：v.121,no.20(May 26, 1999)
• ISSN：1520-5126

文摘

La₄Cu₃MoO₁₂ is a new (ABO₃)_n=4 cuprate with mixed B-cations in a ratio of 1:3. When synthesizedat ambient pressure, the structure is not perovskite as expected but rather a homeotype of YAlO₃, a rare-earthhexagonal phase. While the P6₃/mmc and Pmnm space groups can be used to model average structures whichappear in quenched samples; powder, electron, and neutron diffraction data all confirm that a slow-cooledsample crystallizes in the monoclinic space group, P112₁/m. The copper and molybdenum are coordinated byoxygen in corner-sharing trigonal bipyramids that are sandwiched between layers of lanthanum cations. In theB-cation layer, the copper cations order into a kagomé-like lattice of triangular clusters. The magnetism hasbeen measured from 2 to 800 K and is highly influenced by the geometric arrangement of the Cu^II cations. Anantiferromagnetic transition occurs at 5 K, but the sample does not reach a purely paramagnetic state until 460K.