Ti₂Sn₃:  A Novel Binary Intermetallic Phase, Prepared by Chemical Transport at Intermediate Temperature

Ti2Sn3 was obtained by chemical transport using iodine as the transport agent in a sealed quartz ampule at 500 degrees C. Its crystal structure-a new type structure-was determined via single-crystal structure analysis to be orthorhombic, space group Cmca, a = 595.56(4), b = 1996.4(2), c = 702.81(5) pm, V = 835.6(1) x 10(6) pm(3), and Z = 8. The structure can be derived from a three-dimensional condensation of a single polyhedron, which comprises a Ti atom in the center, surrounded by seven Sn and four Ti atoms forming a tri-capped square antiprism. Supporting the results of the self-consistent band structure calculations, Ti2Sn3 is a metallic p-type conductor, exhibiting Pauli paramagnetism and a specific resistivity of 160 mu Omega cm at room temperature. Sn-119 Mossbauer spectroscopy revealed Ti2Sn3 to be a stannide with three chemically slightly different Sn atoms.