Crystal Structure, Specific Heat, and119Sn Mössbauer Spectroscopy of CeRu4Sn6: A Ternary Stannide with Condensed, Distorted RuSn6Octahedra

Abstract

CeRu4Sn6was prepared from the elements by a reaction in an arc-melting furnace and subsequent annealing at 1123 K. It crystallizes with the tetragonal YRu4Sn6type structure of space groupI42m:a=688.1(1),c=975.2(2) pm,V=0.4617(1) nm3, wR2=0.0472, 554F2values, and 19 variables. The cerium atoms in CeRu4Sn6have coordination number 16 formed by 12 tin and 4 ruthenium atoms. These polyhedra are arranged in a tetragonal body-centered packing and are linked by common Sn1 atoms. The strongest bonding interactions are between ruthenium and tin atoms. The ruthenium atoms have 6 tin neighbors at distances from 256.9 to 276.8 pm in the form of a strongly distorted octahedron. Four of such octahedra are condensed via common edges and faces forming [Ru4Sn6] units. These groups are packed in a tetragonal body-centered arrangement. The cerium atoms occupy the space between the [Ru4Sn6] units. The [Ru4Sn6] substructure of CeRu4Sn6is discussed in comparison with the structures of Ru2Sn3, LaRuSn3, and Ru3Sn15O14which also contain condensed RuSn6octahedra or trigonal prisms as characteristic structural motifs. Despite the two different tin sites the119Sn Mössbauer spectroscopic measurements show only one signal atδ=1.99 mm/s subjected to quadrupole splitting. Heat capacity measurements indicate that CeRu4Sn6behaves like a heavy-fermion compound.