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There are two major families of fullerenes, with fairly distinct properties and applications: the closed buckyballs and the open-ended cylindrical carbon nanotubes. [27] However, hybrid structures exist between those two classes, such as carbon nanobuds — nanotubes capped by hemispherical meshes or larger "buckybuds".
Fullerene or C 60 is soccer-ball-shaped or I h with 12 pentagons and 20 hexagons. According to Euler's theorem these 12 pentagons are required for closure of the carbon network consisting of n hexagons and C 60 is the first stable fullerene because it is the smallest possible to obey this rule.
The system of carbon allotropes spans an astounding range of extremes, considering that they are all merely structural formations of the same element. Between diamond and graphite: Diamond crystallizes in the cubic system but graphite crystallizes in the hexagonal system. Diamond is clear and transparent, but graphite is black and opaque.
The predicted properties for SWCNTs were tantalising, but a path to synthesising them was lacking until 1993, when Iijima and Ichihashi at NEC, and Bethune and others at IBM independently discovered that co-vaporising carbon and transition metals such as iron and cobalt could specifically catalyse SWCNT formation. These discoveries triggered ...
These endohedral fullerenes are usually synthesized by doping in the metal atoms in an arc reactor or by laser evaporation. These methods gives low yields of endohedral fullerenes, and a better method involves the opening of the cage, packing in the atoms or molecules, and closing the opening using certain organic reactions. This method ...
Sources of incidental nanoparticles include vehicle engine exhausts, smelting, welding fumes, combustion processes from domestic solid fuel heating and cooking. For instance, the class of nanomaterials called fullerenes are generated by burning gas, biomass, and candle. [14] It can also be a byproduct of wear and corrosion products. [15]
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The iron compounds produced on the largest scale in industry are iron(II) sulfate (FeSO 4 ·7H 2 O) and iron(III) chloride (FeCl 3). The former is one of the most readily available sources of iron(II), but is less stable to aerial oxidation than Mohr's salt ((NH 4) 2 Fe(SO 4) 2 ·6H 2 O). Iron(II) compounds tend to be oxidized to iron(III ...