Iron nanostructures

Ferrocene has also been incorporated in zeolite hosts [244, 255] and hydrocarbon loss on heating and oxidation to ferricinium cation were observed. Similarly, substituted ruthenocenes were also investigated [256, 257]. The ring opening polymerization of a [l]silaferrocenophane within the channels of mesoporous silica (MCM-41) gave precursors of magnetic iron nanostructures [257a,b]. 

Wei, Y.M., Fu, Y.C., Yan, J.W. et al. (2010) Growth and shape-ordering of iron nanostructures on Au single crystalline electrodes in an ionic hquid a paradigm of magnetostatic couphng. Journal of the American Chemical. Society, 132, 8152-8157. 

Syntheses and magnetic studies of iron nanorods and nanospheres have been reported using pentacarbonyliron. Spherical nanostructures formed by thermal decomposition of Fe(CO)s in the presence of stabilizing surfactant trioctyl-phosphine oxide (TOPO) at 340 °C were reported to give small spherical and rod-shape iron nanostructures. However, in the presence of both TOPO and trioctylphosphine (TOP) at 300 °C, FeP nanoparticles are obtained. Presumably, the coordination of the phosphorus of the TOP molecule direcdy to Fe activates it to loss of the organic substituents. 

Tavakoli, A., Sohrabi, M. and Kargari, A. (2007) A review of methods for synthesis of nanostructured metals with emphasis on iron compounds. Chemical Papers,... 

There is considerable interest in developing new types of magnetic materials, with a particular hope that ferroelectric solids and polymers can be constructed— materials having spontaneous electric polarization that can be reversed by an electric field. Such materials could lead to new low-cost memory devices for computers. The fine control of dispersed magnetic nanostructures will take the storage and tunability of magnetic media to new levels, and novel tunneling microscopy approaches allow measurement of microscopic hysteresis effects in iron nanowires. 

The nanostructured fossils seem now to be less likely from Martian nanobacteria and probably are artefacts of the mineral formation process. Ironically, however, the discovery of the nanofossils may have been responsible for the massive interest in astrobiology, causing NASA to found the subject almost overnight. 

It was also found that the presence of some metal ions and borates can effectively accelerate the hydrothermal carbonization of starch, which shortens the reaction time to some hours. Thus, iron ions and iron oxide nanoparticles were shown to effectively catalyze the hydrothermal carbonization of starch (< 200 °C) and also had a significant influence on the morphology of the formed carbon nanomaterials [10]. In the presence of Fe2+ ions, both hollow and massive carbon microspheres could be obtained. In contrast, the presence of Fe203 nanoparticles leads to very fine, rope-like carbon nanostructures, reminding one of disordered carbon nanotubes. 

Iron carbonyls have been also used to fabricate nanostructures of potential use in catalysis. In this context, the preparation at room temperature of nano-sized a-Fe single crystals over carbon micro-grid films has been reported. The particles were prepared by electron beam induced deposition using Fe(CO)s as precursor [77]. The use of a focused electron beam to induce metal deposition from carbonyl compounds opens a new route for the preparation of nano-sized metal particles. 

Fig. 10. Scanning electron micrograph of amorphous nanostructured iron powder produced from the ultrasonic irradiation of Fe(CO)5...

Originally, the effect of charge state of nanostructures on their catalytic activity was recognized from analysis of the experimental data on the catalytic properties of metallic nanoparticles immobilized in the matrix of a poly-paraxylylene polymer [13-15,24]. It was found that the dependence of the catalytic activity (and, in some cases, of the selectivity) of copper, palladium, and iron nanoparticles on the metal content of these structures has a maximum. This maximum exists not only for the specific (related to unit weight) activity, but also for the absolute activity. More specifically, for copper and... 

These results pave the way to functional nanoparticles where the size, shape, and iron oxide concentration can be controlled leading to tunable magnetic and optical properties of nanostructures on surfaces and interesting research in catalysis, molecular labeling, and detection, as well as controlled dmg delivery using external magnetic fields. 

Leis, J., Perkson, A., Arulepp, M., Nigu, P., and Svensson, G. Catalytic effect of metals of the iron subgroup on the chlorination of titanium carbide to form nanostructural carbon. Carbon 40, 2002 1559-1564. 

Nanostructured aluminum [74—78], iron [74] and aluminum-manganese alloys [74] have been prepared from a Lewis acid A1Q3/[BMIM]Q mixture (65 mol% AICI3, 35 mol% [BMIMJC1) whereas palladium alloys have been deposited from a Lewis basic system (45 mol% Aid , 55 mol% [BMIMJC1). The electrochemical cell and all parts which are in contact with the electrolyte have to be built from inert materials. As cathode material glassy carbon can be used. A constant ion concentration in the electrolyte can be realized by the use of a sacrificial anode consisting of the... 

Table 8.3 Saturation magnetization, relative remanence and coercivity for different crystallite sizes of nanostructured iron.

The magnetic moment m of the atoms in a nanostructure nearly exclusively originates from the electrons in the partially filled inner shells of transition or rare-earth metals. There are both spin (S) and orbital (L) contributions, but since L is much smaller than S in most iron-series transition-metal magnets, the magnetic moment is often equated with the spin polarization. The situation is similar to that encountered in bulk magnets, although both S and L may be modified at surfaces and interfaces (Ch. 2). As in infinite solids, nuclear moments are much smaller than electron moments and can be ignored safely for most applications. 

This book is devoted to the fabrication, characterization, experimental investigation, theoretical understanding, and utilization of advanced magnetic nanostructures. Focus is on various types of bottom-up and top-down artificial nanostructures, as contrasted to naturally occurring magnetic nanostructures, such as iron-oxide inclusions in magnetic rocks, and to structures such as perfect thin films. 

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