Micro- and nanowires of iodine-containing Cu4Bi4S9

Cu4Bi4S9-related sulphosalts prepared by chemical vapour transport with iodine as transport agent showed nano- and microwire morphologies depending on the starting iodine content. Electron microprobe and transmission electron microscope (TEM) adopted energy dispersive X-ray analysis yielded the composition of Cu3.36Bi3.94I0.1S8.7 as rod-like, bundle-assembled microcrystals in the samples prepared with high concentration of transporting agent. In contrast, by decreasing the concentration of I2 in the synthesis, wires of Cu3.96Bi4.04I0.02S8.8 composition close to the stoichiometric Cu4Bi4S9 have been grown. Scanning electron microscope and TEM observations revealed that the wires have diameters ranging from 900 to 1500 nm, and lengths up to 10 μm, with occasional formation of nanowires that are on average ca. 10 nm in diameter and 100 nm long. Using X-ray powder diffraction data, the cell parameters of this material were determined with average values of a=3.1528(2) nm, b=1.1622(1) nm, c=0.3949(2) nm. High-resolution TEM studies confirmed defect free structure of Cu3.96Bi4.04I0.02S8.8 nanowires. The wire elongation appeared to be identical with direction parallel to the crystallographic c-axis in Cu4Bi4S9.