INTERACTION BETWEEN HYDROGEN AND CNTs
Current theoretical studies of simple physical adsorption on pure carbon nanotubes predict a maximum of 14 wt under low temperature and ideal conditions. The real adsorption process is likely to be more complicated, and the theoretical simulations have the potential for further refinement. In particular, as more quantitative and microscopically in-depth experimental results become available, the model parameters and assumptions will become more realistic. Only some of the experimental results...
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barrier. In Figure 12, it is shown that this decrease is rather slow for zt gt L 2 for instance, a donor placed 150 A away from a GaAs-Ga0 7AsAl03As quantum well L 94.8 A still binds a state by 0.5RJ which is 2.5 meV 70 . Figure 11. Dependence of the on-edge hydrogenic donor binding energy in GaAs-Ga1-xAlxAs quantum wells versus the GaAs slab thickness L. m 0.067m0. k 13.1. V0 212 meV curve 1 318 meV curve 2 424 meV curve 3 and infinite curve 4 . Reprinted with permission from 205 , J. L. Marin...
Silicon Oxide Nitride and Carbide
Because of the covalent character of the chemical bonds, the nonoxide amorphous and nanocrystalline refractory ceramics exhibit a very high 3000 C melting point, low mobility of atoms, low plasticity, and high hardness at temperatures up to 2000 C. Therefore these materials can substitute for metals, alloys, and intermetallics in many high-temperature engineering, chemical, and electronic applications. The synthesis of silicon-containing ceramics oxide, carbide, nitride, etc. is an active...
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60 61 62 61 63 63 150 149 149 32 32 83 83 Note represents data unavailable. material to adsorb and desorb hydrogen over a narrower range of pressure may be used in storage systems without wide pressure excursions. High hydrogen-storage capacities on a total sample weight basis were subsequently demonstrated on SWNTs with a large mean diameter of about 1.8 nm produced at high yield by a semicontinuous arc-discharge method 42 . In this study, a sulfur promoter FeS was added, and H2 rather than...
Heterometal Chalcogenides
Ternary chalcopyrite materials such as copper indium dis-elenide CuInSe2 , copper indium disulfide CuInS2 , and copper gallium diselenide CuGaSe2 are potential solar cell materials, given that their direct bandgaps are nearly optimal for the absorption of the solar spectrum. High-quality thin films of solar-cell materials with high specific power W kg-1 are required to fabricate efficient devices. Nanocrystalline films are an attractive alternative to single-crystalline devices that are...
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Figure 12. Schematic illustrating micellar microemulsion nanoparticle synthesis. Reprinted with permission from 4 , G. G. Wallace and P. C. Innis, J. Nanosci. Nanotech. 2, 441 2002 . 2002, American Scientific Publishers. by extended polymer synthesis in the presence of self-assembled polystyrene cores that are selectively removed by toluene. Selvan et al. 96, 97 utilized a block copolymer micelle of in toluene exposed to tetrachloroauric acid which was selectively adsorbed by the micelle...
Microemulsion Technique
Microemulsions are transparent, isotropic dispersions of oil and water two immiscible liquids stabilized by the presence of carefully adjusted emulsifier s surfactant molecules that can be cationic, anionic, or neutral , which are located at the interfaces between oil and water domains 339 Scheme 10 . This systems are clear and thermodynamically stable, and they are prized for their stability and small particle size. The use of microemulsion technique in the synthesis of nano-particles is based...
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Figure 26. Single-source approach for preparing semiconductor nanocrystallites in TOPO. Reprinted with permission from 22 , T. Trindade et al., Chem. Mater. 13, 3843 2001 . 2001, American Chemical Society. Figure 26. Single-source approach for preparing semiconductor nanocrystallites in TOPO. Reprinted with permission from 22 , T. Trindade et al., Chem. Mater. 13, 3843 2001 . 2001, American Chemical Society. The importance of using small molecular clusters as syn-thons to extended solid-state...