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Z. Naturforsch. 2012, 67b, 594 – 604
doi:10.5560/ZNB.2012-0070
Solid Solutions RE16Rh11–xZx (RE=La, Ce, Pr, Nd, Sm; Z = Ga, Zn, Cd, In, Sn, Sb, Pb, Bi) – Centrosymmetric n = 2 Variants of Parthé's Homologous Series A5n+6B3n+5
Frank Tappe, Falko M. Schappacher, Thorsten Langer, Inga Schellenberg, and Rainer Pöttgen
Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, D-48149 Münster, Germany
Reprint requests to R. Pöttgen. E-mail: pottgen@uni-muenster.de
Received March 7, 2012 / published online July 6, 2012
Dedicated to Professor Wolfgang Beck on the occasion of his 80th birthday
Several samples of solid solutions RE16Rh11−xZx (RE = La, Ce, Pr, Nd, Sm; Z = Ga, Zn, Cd, In, Sn, Sb, Pb, Bi) were synthesized by high-frequency melting of the elements in sealed tantalum ampoules. The samples were characterized by powder X-ray diffraction, and the structures of eight compounds were refined on the basis of single-crystal X-ray diffractometer data. The compounds crystallize with a centrosymmetric variant (space group P4/mbm) of the Ca16Sb11 type (P4̅21m). The relation between both structure types is discussed on the basis of a group-subgroup scheme. Only for La16Rh8Sn3 we observed full rhodium-tin ordering. The striking structural motif is a chain of face-sharing square prisms (filled with tin) and anti-prisms (filled with rhodium). The La16Rh8Sn3 structure is closely related to the structure types W5Si3, Ca16Sb11, Y3Rh2, Sm26Co11Ga6, Pu31Pt20, and Yb36Sn23 and is the centrosymmetric n = 2 member of Parthé's A5n+6B3n+5 series. 119Sn Mössbauer spectra resolved the two crystallographically independent tin sites of La16Rh8Sn3, while a Pr16Rh9Sb2 sample shows only a singlet in its 121Sb Mössbauer spectrum.
Key words: Intermetallics, Rhodium, Solid Solutions
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