title: Superconducting tantalum disulfide nanotapes; growth, structure and stoichiometry.
abstract: Superconducting tantalum disulfide nanowires have been synthesised by surface-assisted chemical vapour transport (SACVT) methods and their crystal structure, morphology and stoichiometry studied by powder X-ray diffraction (PXD), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and nanodiffraction. The evolution of morphology, stoichiometry and structure of materials grown by SACVT methods in the Ta-S system with reaction temperature was investigated systematically. High-aspect-ratio, superconducting disulfide nanowires are produced at intermediate reaction temperatures (650 degrees C). The superconducting wires are single crystalline, adopt the 2H polytypic structure (hexagonal space group P6(3)/mmc: a = 3.32(2) A, c = 12.159(2) A; c/a = 3.66) and grow in the <21_1_0> direction. The nanowires are of rectangular cross-section forming nanotapes composed of bundles of much smaller fibres that grow cooperatively. At lower reaction temperatures nanowires close to a composition of TaS(3) are produced whereas elevated temperatures yield platelets of 1T TaS(2).
authors.affiliation: WestCHEM, Department of Chemistry, University of Glasgow, Glasgow, UK.
authors.forename: Charles W
authors.initials: CW
authors.lastname: Dunnill
authors.forename: Ian
authors.initials: I
authors.lastname: MacLaren
authors.forename: Duncan H
authors.initials: DH
authors.lastname: Gregory
mesh_terms: D004220:Disulfides / Q000737:chemistry*; D006358:Hot Temperature; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D013635:Tantalum / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D004220:Disulfides; D013635:Tantalum