Infinite Linear Zinc Chains in AAu4Zn2 (A = Ca, Ce, Pr, Nd) with YbAl4Mo2 Type Structure

Abstract

AbstractThe intermetallic zinc compounds AAu4Zn2 (A = Ca, Ce, Pr, Nd) were obtained by induction melting of the elements in sealed tantalum tubes. The samples were studied by X‐ray diffraction on powders. The structures of the calcium and the cerium compound were refined from single crystal diffraction data: YbAl4Mo2 type, I4/mmm, a = 692.8(1), c = 527.6(1) pm, wR2 = 0.0304, 244 F2 values and 11 variables for CaAu4.08Zn1.92 and a = 699.6(1), c = 531.2(1) pm, wR2 = 0.1152, 186 F2 values and 10 variables for CeAu4Zn2. The 4d site of the calcium compound shows small mixed Zn/Au occupancy. The AAu4Zn2 structures consist of three‐dimensional gold networks (272–286 pm Au–Au in CeAu4Zn2), which are penetrated by linear infinite zinc chains (266 pm Zn–Zn in CeAu4Zn2) that extend along the c axis. The calcium or rare earth atoms fill Au12 cavities within the networks. Temperature dependent magnetic susceptibility measurements reveal Pauli paramagnetism for CaAu4Zn2 and Curie‐Weiss paramagnetism for the cerium, praseodymium, and neodymium compound, respectively. No magnetic ordering was evident down to 2.5 K. The static intermediate‐valent compound Ce2RuZn4 crystallizes with a superstructure of CeAu4Zn2 (klassengleiche subgroup P4/nmm) with a different but fully ordered substitution on the transition metal sites. This structural relationship is discussed on the basis of a group‐subgroup scheme.