Magnetic particles oleic acid

Solution phase chemical synthesis is a convenient way for making surfactant coated magnetic nanoparticles, as described in various reviews [12-18]. Monodisperse Co nanoparticles with standard deviation less than 10% are synthesized by decomposition of Co2(CO)8 [19-22] or Co(rj3-C8Hi3X n4-C8Hi2) [23] and reduction of cobalt salt [24,25] in the presence of oleic acid and trialkylphosphine, or trialkylphosphine oxide, or alkylamine. Monodisperse iron nanoparticles are normally prepared from decomposition of Fe(CO)5 [26-28]. However, metallic iron-based particles from this decomposition procedure are difficult to characterize due to the chemical instability. A recent synthesis using decomposition of Fe[NSiMe3)2]2 offers a promising approach to monodisperse Fe nanocrystals [29]. 

In this paper, we report an intriguing finding that binary surfactants helped self -assembly of magnetic particles into spherical aggregates. The self-assembly of magnetic nanometals occurs in a solvothermal reaction through the mortar of trioctylphosphine oxide (TOPO) and oleic acid. 

The magnetite particles were covered with oleic acid and were filtered, followed by dispersing in an organic liquid to form a stable dispersion of magnetic particles. Urea and urotropin, which on decomposition cause a controlled release of OFI ions, have been employed to precipitate magnetite. - ... 

More exotic magnetic phases could also be produced by similar procedures. For example, MnPt nanoparticles were obtained through decomposition of Mn2(CO)io and Pt(acac)2 in the presence of oleic acid and oleyl amine. The 3 nm particles adopt a crystalline fee structure and display a ferromagnetic behavior up to room temperature." ... 

Recently, the so-called polyol process [210] has been used successfully to process magnetic nanoparticles with a very narrow particle size distribution [211,212]. This process is based on the reduction of metallic salt in solution, at a high temperature (100 ethylene glycol), resulting in nanometric particles. In this process, surfactants such as oleic acid are used to control particle growth and stabilize the nanoparticles. 

Magnetic fluids can be used as a high-density solution for the sink-and-float separation of solids in suspension. This separation technique for non-ferrous metals is based on the anomalous viscosity increase of a magnetic suspension as a function of applied field. The magnetic fluid consists typically of magnetite particles with an average diameter of 100 A in water, with 15-25 wt% of ferrite. To prevent particle aggregation, a surfactant such as kerosene and oleic acid, or a polymer is usually... 

A method for the production of stable iron colloids in solution has been developed." Sonication of Fe(CO)5 in the presence of a polyvinylpyrrolidone (PVP) stabilizer yielded an iron colloid with a particle size ranging from 3 to 8nm, while sonication in oleic acid yielded colloids with a uniform size of 8nm. Heating of the resulting colloids yielded bcc-Fe. The colloids were superparamagnetic, with a saturation magnetization of 101 emug , compared to a saturation magnetization of 123 emu g for a typical iron-based ferrofluid. 

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