Trivalent‐Intermediate Valent Cerium Ordering in CeRuSn – A Static Intermediate Valent Cerium Compound with a Superstructure of the CeCoAl Type |
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Authors: | Jan F Riecken Wilfried Hermes Bernard Chevalier Dr Rolf‐Dieter Hoffmann Falko M Schappacher Rainer Pöttgen Prof Dr |
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Institution: | 1. Münster, Institut für Anorganische und Analytische Chemie der Universit?t;2. Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), CNRS [UPR 9048], Université Bordeaux 1, Avenue du Docteur A. Schweitzer, F‐33608 Pessac Cedex, France;3. Münster, Institut für Anorganische und Analytische Chemie der Universit?tInstitut für Anorganische und Analytische Chemie, Universit?t Münster, Corrensstrasse 30, D‐48149 Münster, Germany |
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Abstract: | New equiatomic stannide CeRuSn was synthesized from the elements by arc‐melting. CeRuSn was investigated by X‐ray powder and single crystal diffraction: C2/m, a = 1156.1(4), b = 475.9(2) and c = 1023.3(4) pm, β = 102.89(3)°, wR2 = 0.0466, 1229 F2 values and 38 variables. CeRuSn adopts a superstructure of the monoclinic CeCoAl type through a doubling of the subcell c axis. In the superstructure two crystallographically independent cerium sites occur. Based on the interatomic distances the two sites can be assigned to trivalent Ce2 and intermediate valent Ce1. This trivalent‐intermediate valent cerium ordering is underlined by magnetic susceptibility measurements χm(T): below 150 K χm, measured with decreasing temperature, follows a Curie‐Weiss law χm = Cm/(T–θp) giving Cm = 0.38 emuK/mol as Curie constant per CeRuSn mol; a value showing that only half of the cerium atoms are trivalent in CeRuSn (Cm = 0.807 emuK/mol for one free Ce3+ ion). A remarkable feature of the CeRuSn structure are the short Ce1–Ru1 (233 pm) and Ce1–Ru2 (246 pm) distances. The crystal chemistry of CeRuSn is discussed on the basis of a group‐subgroup scheme. |
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Keywords: | Intermediate Valence Cerium Crystal Chemistry |
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