Nanowire morphology, controlling

Bai, R., Shi, M., Ouyang, M., Cheng, Y, Zhou, H., Yang, L., Wang, M. Chen, H. (2009). Erbium bisphthalocyanine nanowires by electrophoretic deposition Morphology control and optical properties Thin Solid Films 517, 2099-2105. 

With this method, the tubes are generated along with simultaneous filling by the doped element. The major drawbacks are the inability to control the size of the filled material, which generally presents nanowire morphology, and the fact that... 

We found recently that the viscosity (//vac) of the colloidal thiolate precursor is a key parameter in controlling the shape of the nanoproducts in the solventless method [8]. Uniform nanowires, rods, or spheres could be made from the corresponding precursors that came from the solutions with different viscosities. The viscosity is a measure of the polymerization of the metal-thiolate complexes. Accordingly, the precursor with the highest viscosity produces nanowires (Fig. 20.5 a), and with decreases in the viscosity, the product morphology changes to rods (Fig. 20.5b) and then spheres (Fig. 20.5c). 

In general, the various synthesis strategies for nanocarbon hybrids can be categorized as ex situ and in situ techniques [3]. The ex situ ( building block ) approach involves the separate synthesis of the two components prior to their hybridization. One can rely on a plethora of scientific work to ensure good control of the component s dimensions (i.e. size, number of layers), morphology (i.e. spherical nanoparticles, nanowires) and functionalization. The components are then hybridized through covalent, noncovalent or electrostatic interactions. In contrast, the in situ approach is a one-step process that involves the synthesis of one of the components in the pres-... 

Tang et al., 1999) and correspond to broad distributions of wire diameters and lengths. Therefore, it would be important to devote future research efforts toward controlling the wire diameter, length, morphology, and assembly in such synthesis in order to utilize the nanowires derived effectively for potential electronic applications. 

Conductive polymers have received increasing interest in the last decade due to their potential applications. The synthesis of molecular conductors, for example, is a field of intensive research with the purpose of producing objects in the nanometer scale. Therefore, control of the morphology of conducting polymers is very challenging for the production of molecular wires (nanowires) or tubes. Appropriate templates for the confined polymerization of conductive polymers are required to give them a controlled shape and dimension. 

By using polymer-controlled growth in ethylenediamine at 170°C, very long CdS nanowires (100px40 nm) were synthesized (Fig. 9a) [36]. Cadmium sulfide with different morphologies, such as nanoparticles and nanorods (Fig. 9b) [39], peanut-like nanostructures [37] and hollow nanospheres [38] (Fig. 9c) were prepared via solvothermal routes. 

The size and shape of ceria NCs are proven fo appreciably change the chemical and physical properties hence, their control in synthesis is one chief objective for study, and various nanoparticles, nanocubes, nanooc-tahedra, nanowires, and nanotubes have been obtained for this purpose. Owing to the cubic fluorite structure, ceria tends to form isometric particles, which present sphere-like morphology and are usually intermediates between the shape of cubes and octahedra. The major exposed crystal surfaces for ceria NCs are low index ones, that is, 100, llOj, and 111, with considerable surface relaxation and reconstructions. Figure 1 shows some typical morphologies of ceria NCs. 

To maximize fluorophore excitation and increase the fluorescence quantum yield, the spectral properties of the metal nanoparticles need to be optimized. While spherical colloidal nanoparticles of noble metals have been well known for many years, it is only recently that there has been an explosion of reports on the preparation and properties of anisotropically-shaped materials. As will be discussed in the following sections, a wide range of morphologies can be produced, including triangular nanoplates (nanoprisms), cubes, octahedra, nanowires, nanorods and bi-pyramids. The last few years have also seen major developments in our understanding of the growth processes involved, so that now it is possible to prepare many types of shaped p>articles in a controlled fashion. 

One of the most important issues of nanomaterial growth is the control of the morphology. This can be done by varying different process parameters. The effect of the growth temperature on the structure of the Si nanowires has been studied systematically [32, 33]. 

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