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On the Solid Solution Series Er 15 [(Fe 1– x Ru x ) 8 C 25 ]: Site Preference for Substitution in the Range 0 ≤ x ≤ 0.625?
Author(s) -
Davaasuren Bambar,
Dashjav Enkhtsetseg,
Doert Thomas,
Kreiner Guido,
Kniep Rüdiger
Publication year - 2011
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201100274
Subject(s) - intermetallic , crystallography , cluster (spacecraft) , materials science , chemical composition , solid solution , crystal structure , chemistry , metallurgy , organic chemistry , alloy , computer science , programming language
The solid solution series Er 15 [(Fe 1– x Ru x ) 8 C 25 ] was prepared by arc‐melting of pressed pellets of mixtures of the elements, followed by annealing at 1173 K and quenching. Powder X‐ray patterns reveal the presence of a limited solid solution phase within the composition range 0 ≤ x ≤ 0.75 (trigonal, P 321). Its crystal structure contains polyanionic slabs $\rm^2_\infty$ [Fe 1– x Ru x ) 8 (C 25 ) 45– ] stacked along [001] with Er 3+ ions in between. The substitutions concern a planar triangular cluster made up of six transition metal atoms and a trigonal planar complex of composition [(Fe 1– x Ru x )(C 2 ) 3 ]. The single crystal structure determination of Er 15 [Fe 4.93(1) Ru 3.07 C 25 ] clearly shows that the iron atoms forming the outer triangle of the planar cluster are not affected by substitution, resulting in the chemical composition Fe 3 (Fe 0.19(3) Ru 0.81 ) 3 for the intermetallic cluster unit. According to the chemical bonding analyses, the formation of Ru–Ru bonds seems to be the driving force for this preferential site occupation. The trigonal planar complex, again, is affected by substitution: [(Fe 0.68(4) Ru 0.32 )(C 2 ) 3 ]. Assuming complete substitution except for the outer triangle of the intermetallic cluster, the limiting chemical composition for the series results inEr 15 [(Fe 3 Ru 5 )C 25 ] ( x = 0.625). The difference to the experimental value ( x = 0.75) gives reason for further investigations. The end member Er 15 [Ru 15 C 25 ] was not observed.