Solid State Phenomena Vols. 121-123

Abstract: Multi morphology of polyaniline (PANI), nanotubes, micrograins, solid and hollow spheres, were synthesized by aqueous oxidative polymerization of aniline in the presence of sodium hydroxide (NaOH), which was proposed as an alkali-guided method by the authors. By changing the molar ratio of aniline monomer to alkali, with a constant pH, the morphology can be controlled from nanotubes to micrograins, to solid spheres and to hollow spheres which were proved by SEM and TEM. The backbone structure was characterized by UV-VIS, FTIR and XRD.

Abstract: The constrained growth was observed during the formation process of the photonic crystals from the monodispersed PMMA colloidal microsphere and a controllable vertical deposition (CVD) technology was developed to prepare the photonic crystal based on these growth behaviors and the PMMA colloid particles with size of 345nm were assembled into the 3-D arrays. The transmittance spectrum of the typical sample exhibited an enlarged transmission mode. Their SEM observation revealed that the bulk structure of the crystalline array had a high periodical and long range order, the perfect order zone was above 20μm and the surface of the crystal was complete flat and had only two vacancies in the 3
5 μm order zone. The growth interface analysis indicated that the colloidal spheres sedimented subsequently and the drying front between the suspension and crystal moved at a constant velocity with time. The crystals developed by the continuous growth mechanism and the growing crystals had rough interface during the process of controllable vertical deposition.

Abstract: We dissolved 1-iodo-4-nitrobenzene in various solvents, including ethanol, benzene, toluene and dimethylacetamide, and prepared solution with different concentration from 10-2 M to 10-5 M. Epitaxial Au(111) film and graphite were used as substrates. Scanning tunneling microscope (STM) was used to observe structures of 1-iodo-4-nitrobenzene molecules on those substrates. Experimentally, we found that 1-iodo-4-nitrobenzene molecules constructed nanowires on graphite surface at room temperature in air. The mechanism of formation of nanowire is briefly discussed in this paper.

Abstract: BaF2 nanorods were synthesized by hydrothermal microemulsion method using sodium fluoride (NaF) and barium chloride (BaCl2) as the raw materials. The as-prepared products were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The results showed that the products were composed of BaF2 nanorods with diameters of 18-62 nm and lengths up to 1μm. A directed aggregation growth process mediated by the microemulsion droplet building blocks is proposed for the formation of BaF2 nanorods. Further work is in progress to evaluate the possibility of synthesizing other fluoride 1D nanostructures using a similar method.

Abstract: The surface morphology of the anodic aluminum oxide (AAO) prepared with different surface coating has been studied by AFM and SEM. Under optimized condition, highly ordered stripe patterns have been obtained. These regular patterns, including random stripes and regular stripes, show strong dependence on the crystal orientation of the aluminum substrate. This method can be developed into a novel nanoscale fabrication technique.

Abstract: The electrostatic layer-by-layer self-assembled multilayer films were successfully prepared from alternating deposition of K13[Nd(SiW9Mo2O39)2]·25H2O and a bipolar ferrocenyl derivative (Fc) on quartz, optical glass and indium-tin-oxide coated glass substrates. The films were investigated by UV−visible and X-ray photoelectron spectroscopies (XPS), and cyclic voltammetry. The UV−vis spectra demonstrated that the deposition of the films was uniform and reproducible. XPS revealed that the film was of chemical composition of [Nd(SiW9Mo2O39)2]13-:Fc = 1:6. The dependence of cyclic voltammograms of the film on the potential scan rates showed a redox couple with a formal potential Ef (Ef = (Epa+Epc)/2) of 0.36 V which is similar to that (0.31 V) for Fc aqueous solution, and the redox reaction for the film was surface confined.

Abstract: Ultra-small silver oxide was synthesized using the novel nanoporous nickel phosphate VSB-1 as the template by a simple method under mild experimental conditions. The UV-vis spectra of the as-synthesized silver oxide showed a large blue shift of ca. 200 nm comparing with that of the bulk Ag2O and which may come from the confinement of the pore size. The intensities of the XRD diffraction peaks of the host after assembly decreased along with the increase the concentration of AgNO3 solution used.

Abstract: Gold nanowires, 50 nm in diameter and 1-2 μm in length, were prepared by template synthesis and modified by bifunctional thiols then suspended in different solvents. The dispersibility of nanowires is found to be strongly affected by the selection of solvents. The functionalized gold nanowires can be selectively assembled onto patterned surface via electrostatic interactions. It is possible that this simple process can be carried out in fabrication of more complicated structures, which are potentially useful in many applications such as nanoelectronic, photonic and SERS.

Abstract: Alkaline hydrothermal process with using cetyl-trimenthylammonium bromide as template is typical method to prepare MCM-41 mesoporous material. Synthesis in acid media was seldom researched deeply. With cheap inorganic water glass, effect of different silicon sources on self-assembly in acid media was investigated. Not like typical MCM-41 mesoporous materials, it is found that results of analysis are a little different and morphology of mesoporous materials synthesized in acid media does not rely on silicon sources, regardless of organic or inorganic silicon source. It is also noticed that nanometer granule of mesoporous material can be directly made by simply adjusting water dosage, which open up a new way for preparing nanometer material by self-assembly.