Nanorods and Nanowires

Initially, it is necessary to differentiate between nanorods and nanowires. The aspect ratio of a shape is defined as the length of the major axis divided by the width of the minor axis . Nanorods form a class of material that have a width of between 1 and 100 nm and an aspect ratio of greater than 1, but less than 20. Nanowires are similar materials but with an aspect ratio of greater than 20 [70]. Although this definition is by no means uniform in the literature, it is nevertheless a good guideline to use. 

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One-dimensional colloidal gold and silver nano-structures by Murphy et al. (2006). Recent advances in the synthesis of metallic nanorods and nanowires are reviewed. The increasing relevance of the bottom-up chemical synthesis is underlined. Physical properties and potential applications are described with emphasis on silver and gold. 

N. R. Jana, L. Gearheart, and C. J. Murphy, Wet chemical synthesis of silver nanorods and nanowires of controllable aspect ratio, Chem. Commun. 7, 617-618 (2001). 

H. Chen, K. Sun, Z. Tang, R.V. Law, J.F. Mansfield, A. Czajka-Jakubowska, B.H. Clarkson, Synthesis of fluorapatite nanorods and nanowires by direct precipitation from solution. Crystal Gro wth and Design 6 (2006) 1504-1508. 

Murphy CJ, Jana NR (2002) Controlling the aspect ratio of inorganic nanorods and nanowires. Adv Mater 14 80-82... 

Pinna, N., M. Willinger, K. Weiss, J. Urban, and R. Schlogl. 2003. Local structure of nanoscopic materials V2Os nanorods and nanowires. Nano Lett. 3 1131-1134. 

Several nanoparticles having a non-spherical shape have been synthesized, e.g., carbon nanotubes, nanofibers, nanorods, and nanowires which exhibit, similar to asbestos, a fibrous shape. 

Nanorods and nanowires of hep structure become available by thermolysis of the precursor [Co( -C8Hi3)( " -C8Hi2)] in oleic acid and oleylamine at 3 bar of H2 pressure.Variations in concentration and nature of stabilizing compounds result in changes of the aspect ratio of the nanorods. " ... 

Nanorods and nanowires are characterized by their long, linear shape. The a ct ratio defines the difference between a nanorod and a nanowire It is considered that nanorods have aspect ratios < 20, while nanowires have aspect ratios > 20 [40]. In the context of MEF, nanorods are of greater interest There are a number of reasons for... 

The aspect ratio can be varied between 1.5 and 4.5 by varying the Ag content, with higher aspect ratios up to 10 being achieved when a binary surfactant mixture was used [68]. Recently, single crystalline gold nanorods and nanowires with aspect ratios up to 70 have been obtained with cetyltripropylammonium bromide (CTPAB) and cetyltributylammonium bromide (CTBAB) solutions in the presence of AgNOs [51]. 

Figure 11.37 Left (a) TEM image of and (b) schematic diagrams of the Au decahedral core, (c to Q TEM images of Au Ag nanorods and nanowires prepared by addition of various amounts of AgNC to Au cores with microwave heating for 2 min. Right Schematic for growth of silver nanowires from Au decahedral core. Reprinted with permission from reference [97], (2006) American Chemical Society.

Vayssieres, L. (2003). Growth of arrayed nanorods and nanowires of ZnO fiom aqueous solutions. Adv. Mater. 15 464-466. 

For nanorods and nanowires, the plasmon band of the metal is split in two the... 

Seed-Mediated Growth Approach to the Synthesis of Inorganic Nanorods and Nanowires 287 9.2... 

The seeds are then added to a growth solution that consists of fresh metal salt, and a surfactant, cetyltrimethylammonium bromide, CTAB, that directs the growth of nanopartides into nanorods and nanowires. Growth is initiated by the addition... 

Murphy, C. and Jana, N. 2002. Controlling the Aspect Ratio of Inorganic Nanorods and Nanowires. Advanced Materials 14(1) 80—82. 

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