Yb3CoSn6 and Yb4Mn2Sn5: New polar intermetallics with 3D open-framework structures

摘要

Two new tertiary ytterbium transition metal stannides, namely, Yb3CoSn6 and Yb4Mn2Sn5, have been obtained by solid-state reactions of the corresponding pure elements in welded tantalum tubes at high temperature. Their crystal structures have been established by single-crystal X-ray diffraction studies. Yb3CoSn6 crystallizes in the orthorhombic space group Cmcm (no. 63) with cell parameters of a = 4.662(2), b = 15.964(6). c = 13.140(5) angstrom, V = 978.0(6) angstrom(3), and Z = 4. Its structure features a three-dimensional (3D) open-framework composed of unusual [CoSn3] layers interconnected by zigzag Sn chains, forming large tunnels along the c-axis which are Occupied by the ytterbium cations. Yb4Mn2Sn5 is monoclinic space group C2/m (no. 12) with cell parameters of a = 16 937(2). b = 4.5949(3), c = 7.6489(7) angstrom, 106.176(4), V = 571.70(8) angstrom(3), and Z = 2. It belongs to the Mg5Si6 structure type and its anionic Substructure is composed of parallel [Mn2Sn2] ladders interconnected by Unusual zigzag [Sn-3] chains, forming large tunnels along the c-axis. which are filled by the ytterbium cations. Band structure calculations based on density function theory methods were also made for both compounds. (C) 2008 Elsevier Inc. All rights reserved.