Dy_0.64{Dy₅[Fe₂C₉]}: A complex carbide with a composite structure

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• 作者：Bambar Davaasuren^a ; Enkhtsetseg Dashjav^a ; ^{dashjav@cpfs.mpg.de} ; Rü ; diger Kniep^a ; Guido Kreiner^a ; ^{kreiner@cpfs.mpg.de} ; Walter Schnelle^a ; Lev Akselrud^b ; Sander van Smaalen^c ; Alexander Wö ; lfel^c
• 关键词：Ternary carbides ; Rare-earth metals ; Transition metals ; Crystal structure
• 刊名：Journal of Solid State Chemistry
• 出版年：2012
• 期刊代码：130_00224596
• 类别：ch
• 出版时间：June, 2012
• 卷：190
• 期：Complete
• 页码：73-79
• 文件大小：655 K

摘要

The ternary carbide Dy_5.64[Fe₂C₉] has been prepared by high temperature synthesis from the elements. The compound forms as a composite structure with two partial structures, {Dy₅[Fe₂C₉]} and {Dy_0.64} crystallizing in space groups Pnam and Pbam, respectively. The lattice parameters a=2934.63(9) pm and b=1263.63(5) pm for the two partial structures are identical, whereas the c lattice parameters for {Dy₅[Fe₂C₉]} (c_H=504.14(3) pm) and {Dy_0.64} (c_G=1056.01(5) pm) are different. This gives rise to a modulated structure in the (3+1)D superspace group Pnam(00g) with q=c_H/c_G=0.4775. The refinement converged to R(F) values below 0.055 for each partial structure using harmonic and Crenel functions. The compound is a bad metallic conductor and represents a new structure type composed of Dy³⁺ species embedded in a matrix of discrete planar FeC(C₂)₂ units and edge-sharing Fe(C₂)₄ tetrahedra forming infinite chains Fe(C₂)_4/2 running along the c axis.