High-pressure synthesis and structures of lanthanide germanides of LnGe5 (Ln = Ce, Pr, Nd, and Sm) isotypic with LaGe5
High-pressure synthesis and structures of lanthanide germanides of LnGe5 (Ln = Ce, Pr, Nd, and Sm) isotypic with LaGe5
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DOI：
10.1016/j.jssc.2009.05.018
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发表时间：
2009-08-01
影响因子：
3.3
通讯作者：
Yamanaka, Shoji
中科院分区：
文献类型：
--
作者：
Fukuoka, Hiroshi;Baba, Kazuya;Yamanaka, Shoji
采用高压（5-13 GPa）高温（500-1200 ℃）反应制备了一系列镧系五锗酸镧LnGe（5）（Ln = Ce，Pr，Nd和Sm）。CeGe 5在正交晶胞中结晶（S.G. Immmm（71）），其中a = 4.000（5）埃，B = 6.192（5）埃，c = 9.86（1）埃，以及V = 244.1（5）埃（3）。新的锗化物与LaGe_5是同型的，由Ge共价网络和隧道组成，其中Ln（3+）位于其中。该网络是由亚层，与边缘共享锗六元环，只有船构象。子层由稀有的八配位Ge原子连接。的化合物的细胞体积系统地减少从La到Sm的化合物，除了CeGe 5。由于镧系元素收缩。CeGe 5的晶格常数小于Pr化合物的晶格常数，因为它含有Ce 4+离子。CeGe_5在2K以上是顺磁性的。但不遵守居里-外斯定律。PrGe_5和NdGe_5是Curie-Weiss型顺磁体，韦斯温度分别为-3.3和-18.4K。SmGe_5在10.4K时发生反铁磁转变。(C)2009 Elsevier Inc. All rights reserved.
A series of lanthanide penta-germanides LnGe(5) (Ln = Ce, Pr, Nd and Sm) has been prepared by high-pressure (5-13 GPa) and high-temperature (500-1200 degrees C) reaction. CeGe5 crystallizes in an orthorhombic unit cell (S.G. Immm (71)) with a = 4.000(5)angstrom, b = 6.192(5)angstrom, c = 9.86(1)angstrom, and V = 244.1(5) angstrom(3). The new germanides are isotypic with LaGe5 Consisting of a Ge covalent network with tunnels where guest ions Ln(3+) are situated. The network is composed of sublayers; with edge-sharing Ge six-membered rings with only boat conformation. The sublayers are connected by rare eight-coordinated Ge atoms. The cell volume of the compounds systematically decreases from La to Sm compounds, except for CeGe5. owing to the lanthanide contraction. The lattice constants of CeGe5 are smaller than those of the Pr compound because it contains Ce4+ ions. CeGe5 is paramagnetic above 2 K. but does not obey the Curie-Weiss law. PrGe5 and NdGe5 are Curie-Weiss type paramagnets with Weiss temperatures of -3.3 and -18.4 K. SmGe5 shows an antiferromagnetic transition at 10.4 K. (C) 2009 Elsevier Inc. All rights reserved.