Er2Au2Sn and other Ternary Rare Earth Metal Gold Stannides with Ordered Zr3Al2-Type Structure

Abstract

Abstract The ternary stannides RE2Au2Sn (RE = Y, Dy, Ho, Er, Tm, Lu) were prepared by arcmelting of the elemental components and subsequent annealing at 800 °C. The structure of Er2Au2Sn (single crystal, X-ray, P42/mnm, Z = 4, a = 778.2(2) pm, c = 739.6(3) pm, V = 0.4479 nm3 and R = 0.026) is described as the ternary ordered version of the Zr3Al2-type structure, a superstructure of the U3Si2-type. It consists of two-dimensionally infinite layers (Au2Sn)n which are separated by the erbium atoms. The structure is built up from slightly distorted [SnEr8) square prisms and [AuEr6] trigonal prisms which are condensed in all three directions. These fragments are derived from the well known AlB2 and CsCl-type structures.