New intermetallic zinc compounds with ordering variants of the KHg 2 and LT-SrZn5 type

Schwickert C., Pöttgen R.

Abstract

The intermetallic zinc compounds CaAuZn, SrPdZn, SrPtZn, SrAuZn, BaPd 1.57Zn3.43, and BaAu1.41Zn3.59 were synthesized from the elements in sealed niobium ampoules in an induction furnace. The equiatomic compounds crystallize with the orthorhombic TiNiSi-type structure, space group Pnma. Single-crystal X-ray data exhibited small degrees of Au=Zn mixing within the three-dimensional [AuZn] networks and resulted in the compositions CaAu1.02Zn0.98 and SrAu 1.03Zn0.97 for two investigated single crystals. BaPd 1.57Zn3.43 and BaAu1.41Zn3.59 adopt partially ordered versions of the LT-SrZn5 type, space group Pnma. Both structures were refined on the basis of X-ray single-crystal diffractometer data: a=1331.13(6), b=531.45(3), c=682.20(4) pm, wR=0.0245, 1138 F2 values, 39 variables for BaPd1.57Zn3.43 and a=1344.35(2), b=537.47(2), c=691.22(4) pm, wR=0.0441, 931 F2 values, 37 refined variables for BaAu1.41Zn3.59. The transition metal and zinc atoms form a complex three-dimensional network of (T, Zn)4 tetrahedra which are condensed via common corners and T/Zn-T/Zn bonds. Large cavities within these networks are filled by the barium atoms which have coordination number 19, i. e. Ba@ (T, Zn)17Ba2. © 2014 Verlag der Zeitschrift für Naturforschung, Tübingen.