Phosphorus Nanotubes

The now well-known carbon nanotubes are derived from bending flat graphite layers (graphenes) into a cylindrical shape. In a similar way, it may prove possible to bend the puckered sheets of rhombohedral black P into cylinders, although some alteration of the P/P/P bond angles would probably be necessary. The feasibility of reduction of these angles to 90 is demonstrated in the transition of rhombohedral to cubic black P. 

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Viewed from above the layer, the structure clearly resembles a graphenelike layer, although it is puckered in a similar way as in the silicide, silane, and phosphorus cases. Thus, the question arises as to whether siloxenes may form stable tubular structures as predicted for hypothetical silicides, silanes, and black phosphorus nanotubes. The experimentally synthesized siloxene consists of hexagonal puckered layers, in which the Si-Si bond distance is 2.34 A, the Si-H bond length is 1.54 A, and the Si-O bond length is 1.60 A. The Si-0-H bond angle is 115°. 

As mentioned in the introduction, the tubular materials are fascinating new structures with a considerable potential for various applications. Most of the nanotubes investigated to date have been carbon-based nanotubes. In this chapter, we have discussed the properties of various nanotubes with a silicon or germanium backbone structure. Most of these nanotubes are still hypothetical, "made" only in the computer. We proposed the stability of phosphorus nanotubes, and about a year later Li et al. reported the successful synthesis of nanotubes from bismuth, which is isoelectronic with phosphorus. The stability of NbS2 nanotubes was also proposed in 2000, and these were synthesized by Nath and Rao in 2001... 

Phosphorus nanotubes (or nanorods), although not yet properly characterised, will constitute yet another polymorphic form of the element. Several types are present in the structures of complexes such as (CuI)3Pi2 and (Cul)3P]2, which may serve as starting points for their synthesis [39]. 

Carbon monoxide off-gas, from phosphorus manufacture, 19 12 Carbon nanostructures, 27 46-58 Carbon Nanotechnologies, Inc., 2 718, 719 Carbon-nanotube fibers, 23 385-386 Carbon nanotubes (CNTs), 2 655, 693, 694, 719-722 20 434 27 47 8 ... 

B. G. Sumpter, V. Meunier, J.-C. Charlier.D. J. Smith, H. Terrones, M. Terrones, Heterodoped nanotubes theory, synthesis, and characterization of phosphorus nitrogen doped multiwaiied carbon nanotubes, ACS Nano, vol. 2, pp. 441-448, 2008. 

Research on modeling of endohedral fullerenes within single-walled carbon nanotubes (SWNTs) has received increased attention towards the understanding of their electronic and structural properties [304-307]. However, very recently particular emphasis was given to the endohedral fullerenes N C60 [308-313] and P C60 [314] due to the electron spin on the nitrogen or phosphorus site, respectively. Having an extremely long decoherence time the unpaired electron spin could be used as a qubit within a quantum computer. 

Multi-walled carbon nanotubes can be functionalized with PBI via a Friedel-Crafts acylation reaction in a phosphorus pentoxide/methanesulfonic acid medium [23]. The composites have been used as reinforced fillers in 100% acidified poly(hydroxyamino-ether) to prepare mixed composites. The acid-base interaction between the PBI chains attached on multi-walled carbon nanotubes plays a crucial role with regard to good dispersion and effective reinforcement. 

There is at present much interest in large cage (cluster) molecules based on carbon [62]. The best known of these is the established Cgo molecule (fullerene) which has exceptional stability and has the highly symmetrical truncated icosahedral structure depicted in Figure 4.7. Derivatives of C o, and carbon nanotubes, currently attract much interest because of their exceptional electrical, mechanical and structural properties. Phosphorus analogues may exist (P is used as a co-catalyst for growing of carbon nanotubes [63,64]). 

Nanostructured materials, obtainable as fine powders, thin films or in bulk forms, often exhibit properties dramatically different from those of the same materials in larger more ordinary forms. The latter are often unknown in the case of cavity structures which are characteristic of the material itself. Nanostructures of other kinds, for example, nanotubes, nanowires or nanocrystals can be formed with metal phosphides (Chapter 8) and phosphorus nitrides (Chapter 4.5). 

Fullerene cages (C ) and carbon nanotubes (C are currently of interest as possible biomaterials, biosensors and drug dehvery agents. Analogous cage and tube structures based on phosphorus, if they can be made, may well be of greater use in these and other fields of bioscience activity (Chapter 4.1). 

Liu Z, Peng F, Wang H, Yu H, Tan J, Zhu L (2011) Novel phosphorus-doped multiwalled nanotubes with high electrocatalytic activity for O2 reduction in alpine medium. Catal Commun 16(l) 35-38... 

Studies involving phosphmis compounds adsorbed on activated carbons Measurements on coals and related matmals Studies of phosphorus occurrence in soil matter, peat, and related materials Studies of surface properties of porous carbons, coals, carbon nanotubes, and other carbon materials using NMR measurements on adsorbed xenon... 

Additives used in final products Fillers aluminum hydroxide, calcium carbonate, clay, carbon nanotubes, magnesium hydroxide, montmorillonite, red phosphorus, quartz, silica, wood fiber, zinc oxide, zinc powder Plasticizers EVAC is used as plasticizer in PVC and PLA therefore it seldom requires plasticization Antistatics 2-methyl-3-propyl benzothiazolium iodide, alkylether triethyl ammonium sulfate, organic amide Antiblocking tty amide, laponite, silica Release methylstyryl silicone oil Slip eru-camide, oleamide, stearamide Thermal stabilizer BHT ... 

The results of the bioactivity of carbon nanotubes after 14 days of incubation in SBF are shown in Fig.3A. New, flake-like materials which may be precursors for apatite appeared on the surfaces of MWCNTs. The EDS analysis confirms the presence of an apatite-like structure on the surface of MWCNT (Fig. 3B), throughout the presence of calcium (Ca) and phosphorus (P) in the sample. 

Moreover, the calcium to phosphorus ratio (T ) is 1.48, which indicates the presence of calcium phosphate on carbon nanotubes. 

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