Eine neue Verzerrungsvariante des CaBe₂Ge₂‐Typs – Die Kristallstrukturen von SrPd₂Bi₂, BaPd₂Bi₂ und BaAu₂Sb₂

Abstract

Abstract A New Distorted Variant of the CaBe 2 Ge 2 Type – Crystal Structures of SrPd 2 Bi 2 , BaPd 2 Bi 2 , and BaAu 2 Sb 2 SrPd 2 Bi 2 ( a = 4.886(1), b = 4.778(1), c = 10.679(1) Å, β = 91.80(1)°), BaPd 2 Bi 2 ( a = 4.919(1), b = 4.854(1), c = 10.783(1) Å, β = 91.30(1)°), and BaAu 2 Sb 2 ( a = 4.899(2), b = 4.783(2), c = 11.102(5) Å, β = 91.16(3)°) crystallize in a new monoclinic variant ( P 2 1 / m ; Z = 2) of the tetragonal CaBe 2 Ge 2 type of structure. The distortion can be described as a rotation of the coordination polyhedra around the alkaline earth metal atoms. Investigations of SrPd 2 Bi 2 at high temperatures by X‐ray methods indicate a phase transition in the range of 150°‐300 °C resulting in tetragonal symmetry. It is most likely that the high temperature form of SrPd 2 Bi 2 crystallizes with the undistorted CaBe 2 Ge 2 type of structure ( P 4/ nmm ). The compounds were prepared by heating mixtures of the elements at 900°‐1100 °C.