Dispersion and purification of Mo6S3I6 nanowires in organic solvents

Sedimentation measurements have been performed on dispersions of Mo6S3I6 nanowires in a range of common solvents. By far the best solvents were N,N-dimethylformamide (DMF) and acetone. Stable dispersions of purified Mo6S3I6 nanowires in DMF, with concentrations as high as 0.06 g l(-1), could be produced. Detailed analysis of the sedimentation curves showed that the material consisted of three phases, two insoluble phases and one which could be stably dispersed. We associate the insoluble phases with pseudospherical impurities and insoluble nanowires. The sedimenting nanowires tend to be in the form of large diameter bundles, in contrast to the dispersed phase which consists of nanowires arranged in smaller bundles. The average diameters of the nanowire bundles stably suspended in DMF are 12 +/- 14 nm. The measured sedimentation time constants of the insoluble nanowires agree very well with theory allowing us to calculate the solid-fluid interaction parameter, beta, to be very close to 10(5) Pa. The material could be purified by controlled sedimentation hence the identification of the various phases was confirmed by x-ray photoelectron spectroscopy and scanning electron microscopy. (c) 2007 American Institute of Physics.