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Z. Naturforsch. 2014,
69b, 121 – 124
doi:10.5560/ZNB.2014-3300
Sr2Au6Al3 and Eu2Au6Al3 – First Representatives of the Sr2Au6Zn3 Type with Aluminum Triangles
Institut für Anorganische und Analytische Chemie and NRW Graduate School of Chemistry, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany
Reprint requests to R. Pöttgen. E-mail:
pottgen@uni-muenster.de
Received November 18, 2013 / published online December 30, 2013
The aluminides Sr2Au6Al3 and Eu2Au6Al3 were synthesized by melting the elements in sealed tantalum tubes in a muffle or induction furnace. The samples were characterized by powder and single-crystal X-ray diffraction: Sr2Au6Zn3 type, R3̅c, a = 845.1(1), c = 2177.2(3) pm, wR2 = 0.0263, 520 F2 values, 20 variables for Sr2Au6.18(1)Al2.82(1), and a = 838.0(1), c = 2177.1(7) pm, wR2 = 0.0276, 510 F2 values, 19 variables for
Eu2Au6Al3. The gold atoms build up diamond-related networks of slightly distorted tetrahedra in the stacking sequence of the 6R polytype (289–296 pm Au–Au in Eu2Au6Al3). The voids left by this network are filled in an ordered manner by strontium (europium) atoms and the rare motif of Al3 triangles (286 pm Al–Al in Eu2Au6Al3). The Al3 triangles in Sr2Au6.18(1)Al2.82(1) show a small degree of Al/Au mixing.
Key words: Aluminum, Crystal Structure, Stuffed Diamond Network, Gold, Europium, Strontium