Synthesis and crystal structure of Ba3Si4C2

SiC powder prepared by the Na flux method at 1023 K for 24 h and Ba were used as starting materials for synthesis of tribarium tetrasilicide acetylenide, Ba3Si4C2. Single crystals of the compound were obtained by heating the starting materials with Na at 1123 K for 1 h and by cooling to 573 K at a cooling rate of −5.5 K/h. The single crystal X-ray diffraction peaks were indexed with tetragonal cell dimensions of a = 8.7693(4) and c = 12.3885(6) Å, space group I4/mcm (No.140). Ba3Si4C2 has the Ba3Ge4C2 type structure which can be described as a cluster-replacement derivative of perovskite (CaTiO3), and contains isolated anion groups of slightly compressed [Si4]4− tetrahedra and [C2]2− dumbbells. The electrical conductivity measured for a not well-sintered polycrystalline sample was 2.6 × 10−2–7 × 10−3 S cm−1 in the temperature range of 370–600 K and slightly increased with increasing temperature. The Seebeck coefficient showed negative values of around −200 to −300 μV K−1.