ABSTRACT
Bi2Te3 based alloy nanosheet (NS)/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite films were prepared separately by spin coating and drop casting techniques. The drop cast composite film containing 4.10 wt % Bi2Te3 based alloy NSs showed electrical conductivity as high as 1295.21 S/cm, which is higher than that (753.8 S/cm) of a dimethyl sulfoxide doped PEDOT:PSS film prepared under the same condition and that (850-1250 S/cm) of the Bi2Te3 based alloy bulk material. The composite film also showed a very high power factor value, â¼32.26 µWm(-1) K(-2). With the content of Bi2Te3 based alloy NSs increasing from 0 to 4.10 wt %, the electrical conductivity and Seebeck coefficient of the composite films increase simultaneously.
ABSTRACT
PbTe nanocrystals were prepared by a modified molten composite-hydroxides method at 180 degrees C for different times, using Pb(NO3)2 and TeO2 as starting materials and KBH4 as a reductant. The nanocrystal structure and morphologies of the synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high resolution TEM (HRTEM), respectively. The results showed that the reaction time has a significant influence on the size and shape of the as-prepared PbTe nanocrystals. As the reaction time increased, the as-prepared products were eventually transformed from nanomaterials (nanocubes, nanorods, and nanosheets) to microcrystals with different morphologies (microcubes, mciroprisms, and microplates). The formation mechanism of the PbTe was proposed, and a one-dimensional oriented attachment growth process combined with two-dimensional oriented attachment growth process was suggested for the growth of nanorods and nanosheets.
ABSTRACT
SiCN nanowires are synthesized by pyrolysis of hexamethyldisilazane (HMDSN) using ferrocene as a catalyst precursor at 1200 degrees C in a flowing argon atmosphere on the surface of mullite substrate, polycrystalline alumina wafer and quartz tube. In oxygen-contained argon atmosphere, SiCN/SiO2 nanocables are synthesized. The as-synthesized products are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high-resolution electron microscopy equipped with energy dispersive X-ray spectroscopy. The lengths of the nanowires and nanocables are in the millimeter range. The diameter of the SiCN nanowires grown on mullite substrate and alumina wafer ranges from about 10-70 nm, while that of the nanowires grown on quartz tube surface is in the range of around 7-10 nm. The diameters of the SiCN/SiO2 nanocables are relatively large. A vapor-liquid-solid growth mechanism of the nanostructures is proposed. The electrical resistivity of a single SiCN/SiO2 nanocable is reported for the first time.
ABSTRACT
SiC nanowires are prepared by pyrolysis of hexamethyldisilane (HMDS), at 1200 degrees C in a flowing Ar atmosphere. The length of the nanowires is in millimeter scale. Transmission electron microscopy observations indicate that the diameters of the SiC nanowires are in the range of about 8 to 120 nm, and that most of the nanowires have numerous stacking faults. The formation mechanism of the nanowires is proposed.
Subject(s)
Carbon Compounds, Inorganic/chemistry , Nanostructures/chemistry , Nanotechnology/methods , Nanowires/chemistry , Silicon Compounds/chemistry , Argon/chemistry , Electron Probe Microanalysis , Equipment Design , Hot Temperature , Microscopy, Electron, Scanning , Microscopy, Electron, Transmission , Nanostructures/ultrastructure , Silanes/chemistryABSTRACT
Ultra long SiC core and SiO2 shell nanocables have been prepared by pyrolysis of poly(dimethyl siloxane) at 1050 degrees C in flowing Argon. The longest nanocable can be up to at least 6 mm. Transmission electron microscopy observations indicate that the diameter of the cores varies from about 3 to 18 nm, and the thickness of the outer sheaths varies from about 6 to 45 nm and that the cores are crystalline and the sheaths are amorphous. The growth of the nanocables may be governed by a chemical vapor solid process. The nanocables exhibit good photoluminescence property.
