Magnesium-rich intermetallics RE3RuMg7 (RE=Y, Nd, Dy, Ho) - Rows of condensed Ru@RE6/2 octahedra in magnesium matrices

Kersting M., Rodewald U.Ch., Schwickert C., Pöttgen R.

Zusammenfassung

The magnesium-rich intermetallic phases RE3RuMg7 (RE=Y, Nd, Dy, Ho) have been synthesized from the elements in sealed niobium ampoules and subsequently characterized by powder X-ray diffraction. The structure of the dysprosium compound was refined on the basis of single-crystal X-ray diffractometer data: Ti6Sn5 type, P6 3/mmc, a=1019.1(2), c=606.76(9) pm, wR2=0.0159, 439 F2 values, 19 variables. The Mg3 site shows a small degree of Mg3/Dy mixing, leading to the composition Dy3:03RuMg6:97 for the investigated crystal. The striking structural motifs in the Dy 3RuMg7 structure are rows of face-sharing Ru@Dy 6 octahedra and corner-sharing Mg2@Mg8Dy4 icosahedra. The rows of octahedra form a hexagonal rod-packing, and each rod is enrolled by six rows of the condensed icosahedra. Temperature-dependent magnetic susceptibility measurements of Dy3RuMg7 show Curie-Weiss behavior with an experimental magnetic moment of 10.66(1) μB per Dy atom. Antiferromagnetic ordering is detected at TN =27.5(5) K. The 5 K isotherm shows a metamagnetic transition at a critical field of H C =40 kOe. © 2013 Verlag der Zeitschrift für Naturforschung, Tübingen.