Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2.
Inorg Chem. 2010 Mar 1;49(5):2325-33. doi: 10.1021/ic902231b.
The rare-earth iron arsenides RE(12)Fe(57.5)As(41) (RE = La, Ce) have been prepared by direct reactions of the elements in the presence of a Sn flux. Analysis of single-crystal X-ray diffraction data reveals that they adopt a new orthorhombic structure type (Pearson symbol oP236, space group Pmmn, Z = 2; a = 10.8881(9) A, b = 25.753(2) A, c = 12.5436(10) A for RE = La; a = 10.8376(8) A, b = 25.639(2) A, c = 12.4701(9) A for RE = Ce). In this metal-rich arsenide, the complex three-dimensional network (derived from 4 RE, 24 Fe, and 17 As sites) can be described as being built from unusual wavelike layers of connected As-centered trigonal prisms. Five of the Fe sites are partially occupied. The electronic structure of these compounds was probed through core-line X-ray photoelectron spectra. Magnetic susceptibility measurements indicated ferromagnetic ordering at T(C) = 125 and 95 K for the La and Ce compounds, respectively. Electrical resistivity measurements on single crystals of Ce(12)Fe(57.5)As(41) showed metallic behavior with a prominent transition that coincides closely with the ferromagnetic ordering temperature.
稀土铁砷化物 RE(12)Fe(57.5)As(41)（RE = La、Ce）是通过元素在 Sn 通量存在下的直接反应制备的。单晶 X 射线衍射数据分析表明，它们采用了一种新的正交结构类型（Pearson 符号 oP236、空间群 Pmmn、Z = 2；对于 RE = La，a = 10.8881(9) A、b = 25.753(2) A、c = 12.5436(10) A；对于 RE = Ce，a = 10.8376(8) A、b = 25.639(2) A、c = 12.4701(9) A）。在这个富金属砷化物中，复杂的三维网络（由 4 个 RE、24 个 Fe 和 17 个 As 位点组成）可以描述为由连接的以 As 为中心的三角棱柱的不寻常波浪状层组成。其中 5 个 Fe 位点部分占据。通过芯线 X 射线光电子能谱探测了这些化合物的电子结构。磁化率测量表明，La 和 Ce 化合物分别在 T(C) = 125 和 95 K 处表现出铁磁性有序。Ce(12)Fe(57.5)As(41)单晶的电阻率测量表明具有显著过渡的金属行为，该过渡与铁磁性有序温度密切吻合。
