Crystal structure of new ternary disilicide of platinum and erbium

Abstract

Crystal structure of the ternary compound ErPtSi2 (diffractometer HZG-4a, CuK-radiation, structure type YIrGe2, Pearson symbol oI32, space group Immm, a=4.19395(6) Å, b=8.41465(13) Å, c=15.85404(19) Å, RB=0.0639, Rp=0.0424, and 2=1.11) was studied by X-ray powder diffraction method. Intermetallide ErPtSi2 is the first representative of YIrGe2 structure type in R–Pt–Si systems. Crystal structures of ternary compounds in the system Er–Pt–Si were analyzed and the structural relationships between them were established according to the systematics of the nearest coordination environment around the less electronegative Er atoms. Compounds, found in the system, were divided into two main types based on the nearest coordination environment, namely on the derivatives of hexagonal and pentagonal prisms with different amounts of additional atoms. These polyhedra exist both alone and in the combination with each other and with cubooctahedra in the structures of the different ternary silicides of erbium. Such a relatively small coordination environment of rare-earth metal atoms can be explained by the structural peculiarities of the ErPt3 binary compound. The coordination polyhedra of the smallest atoms are trigonal prisms with different amounts of additional atoms or cubooctahedra.