Synthesis and structure of ternary transition-metal silicides Zr 3Mn 4Si 6 and Hf 3Mn 4Si 6

Abstract

The isostructural ternary transition-metal silicides Zr 3Mn 4Si 6 and Hf 3Mn 4Si 6 can be prepared by direct reaction of the elemental components or by arc-melting. The single-crystal structure of Zr 3Mn 4Si 6 was determined by X-ray diffraction (Pearson symbol tP104, tetragonal, space group P4 2/ mbc, Z = 8 , a = 17.1325 ( 7 ) Å , c = 5.1058 ( 2 ) Å ). Zr 3Mn 4Si 6 is isostructural to Nb 3Fe 3CrSi 6 and contains an essentially ordered arrangement of the transition-metal atoms. Square antiprismatic clusters with Zr and Mn atoms at the corners and Si atoms at the center share opposite faces to form one-dimensional columns ∞ 1 [ Zr 6 / 2 Mn 2 / 2 Si ] extending along the c direction. These columns occupy channels that are outlined by a framework of edge- and face-sharing MnSi 6 octahedra. The extensive metal-metal interactions in the structure are complemented by Si–Si bonding in the form of dumbbells, linear chains, and zigzag chains.