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Nanoscale materials nanotubes

Resasco, D.E., Carbon Nanotubes and Related Structures. In Nanoscale Materials in Chemistry, 2nd Ed., Klabunde K. J. Richards R. M. (eds.), John Wiley. Sons, Inc., Hoboken,... [Pg.451]

This review focuses on nanoparticles, namely objects that are roughly spherical. We use the commonly accepted definition for nanoscale objects of having a dimension below 100 nm, and so identify nanoparticles as objects with a diameter of 100 nm or smaller. The review does not focus on larger aspect ratio nanoscale materials such as nanotubes and nanorods, though they are mentioned in some cases. [Pg.170]

In recent years much effort has been spent on the development of experimental techniques to grow well defined nanoscale materials, due to their possible applications in nanometric electronic devices. Indeed the creation of nanowire field effect transistors [128-132], nano-sensors [133,134], atomic scale light emitting diodes and lasers [135,136], has been made possible by the development of new techniques, which allow one to control the growth processes of nanotubes, nanowires and quantum dots. Of particular importance, among the different atomic scale systems experimentally studied, are... [Pg.248]

An additional factor which may modify the lung toxicity and corresponding risk following exposures to engineered nanoparticulates is the electrostatic attraction/aggregation or agglomeration potential of some nanoscale materials, such as single wall carbon nanotubes (SWCNT). The dimensions of individual SWCNTs have been reported as Inm (diameter... [Pg.1768]

Both EDLCs and pseudocapacitors benefit from tailored, high surface area architectures because they each store charge on the surface by electrostatic or faradaic reactions, respectively. There are numerous examples in the hterature which show that materials possessing such features as nanodimensional crystallite size and mesoscale porosity exhibit significantly higher specific capacitance as compared to nonpotous materials or materials composed of micron-sized powders. The assembly of nanoscale materials is also important. One structure envisioned to be of interest is an array of vertically aligned carbon nanotubes where the spacing between the tubes is matched to the diameters of the solvated electrolyte ions (3). [Pg.523]

In the field of nanoscale materials, SIESTA has probably made its largest impact in the study of carbon nanotubes. This is a field which has captivated the attention of researchers for their unusual electronic and mechanical properties. Simulation and theory have played a major role, often providing predictions that have guided the way for experimental studies. Work done with SIESTA has spanned many aspects of nanotube science vibrational properties [239-241], electronic states [242-246] (including the effect of lattice distortions on the electronic states [247-250]), elastic and plastic properties [251-254], and interaction with other atomic and molecular species [255-259]. Boron nitride nanotubes have also received some attention [260, 261]. [Pg.157]

Determined by their molecular nature, most CP nanoscale materials are either amorphous or polyerystalline. In the latter case, the size of the ordered crystalline grain/island is typically less than 10 nm [106]. This limits the electron and hole delocalization length to a similar scale. Therefore, based on this argument, unless the cross-seetion of a CP nanowire is comparable to the delocalization length, electron and hole transport in such a nanowire should follow their behavior in a 3-D bulk material. As we have discussed in the previous section, many nanowires and nanotubes prepared so far are indeed larger than the characteristic electronic localization length, and it is, in general, valid to treat these nanowires and nanotubes with the already established electronic-transport theories and models for 3-D CP materials. [Pg.446]

Very recently, Yin et al. applied this expression in a transport study of individual PPY, PANI nanotubes, and PEDOT nanowires [99]. The authors also found that the temperature- and field-dependent I-V characteristics of these nanoscale materials can be fitted very well with the expression. [Pg.448]

Kim, C., Lee, Y. H. (2003). EDLC Application of Carbon Nanofibers/Carbon Nanotubes Electrode Prepared by Electmspinning, in 203rd Meeting, Symposium Nanotubes, Nanoscale Materials, and Molecular Devices, The Electrochemical Society Paris, France. [Pg.248]

Nanoscale materials do exhibit chemical and ph5 ical properties from different bulk materials. For example, carbon can be made to form tubular structures as shown in Figure 1.23 A. These tubes, called nanotubes, resemble a cylindrical roU of chicken wire. When nanotubes are perfectly formed, they conduct electricity like a metal. [Pg.19]

The term upconversion describes an effect [1] related to the emission of anti-Stokes fluorescence in the visible spectral range following excitation of certain (doped) luminophores in the near infrared (NIR). It mainly occurs with rare-earth doped solids, but also with doped transition-metal systems and combinations of both [2, 3], and relies on the sequential absorption of two or more NIR photons by the dopants. Following its discovery [1] it has been extensively studied for bulk materials both theoretically and in context with uses in solid-state lasers, infrared quantum counters, lighting or displays, and physical sensors, for example [4, 5]. Substantial efforts also have been made to prepare nanoscale materials that show more efficient upconversion emission. Meanwhile, numerous protocols are available for making nanoparticles, nanorods, nanoplates, and nanotubes. These include thermal decomposition, co-precipitation, solvothermal synthesis, combustion, and sol-gel processes [6], synthesis in liquid-solid-solutions [7, 8], and ionothermal synthesis [9]. Nanocrystal materials include oxides of zirconium and titanium, the fluorides, oxides, phosphates, oxysulfates, and oxyfluoiides of the trivalent lanthanides (Ln ), and similar compounds that may additionally contain alkaline earth ions. Wang and Liu [6] have recently reviewed the theory of upconversion and the common materials and methods used. [Pg.30]

In October 2008, EPA issued a federal register notice reiterating its position that it would not treat aU nanoscale materials as new chemical substances under TSCA (Environmental Protection Agency, 2008a). However, EPA also classified carbon nanotubes as new and distinct chemical... [Pg.119]

California has indicated that its data call in efforts for engineered nanoscale materials will not end with carbon nanotubes. Rather, it intends to issue a series of letters over the coming months, focusing on various types of engineered nanoscale materials of potential concern. [Pg.130]


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See also in sourсe #XX -- [ Pg.444 , Pg.467 , Pg.489 , Pg.1059 , Pg.1060 ]




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