Nanoparticle synthesis thermal decomposition

Zhou et al. reported the synthesis of flower-like ceria NPs by thermal decomposition of (NH4)2Ce(N03)g in OA/OM solvents at 230-300 °C. The small ceria nanoparticles form, assemble, and fuse mainly via (111) faces by oriented attachment. Monitoring by in situ electrical resistance measurements shows that the conductive species are diminished when the flower-like nanostructures form (Zhou et al., 2008a Figure 6). Ceria nanoflowers and nanocubes are also obtained in octadecylamine, with higher temperature for nanoflower and lower temperature for nanocubes. The obtained colloidal nanoparticles can be self-assembled into nanospheres assisted by SDS surfactants (Wang et al., 2008a). 

An interesting approach to synthesize metal alloy nanocrystals is the use of simultaneous salt reduction and thermal decomposition processes. Sun et al. [18] reported on the synthesis of iron-platinum (FePt) nanoparticles through the reduction of platinum acetylacetonate by a diol, and decomposition of iron pentacarbonyl (Fe(CO)5) in the presence of a surfactant mixture (oleic acid and oleyl amine). On the basis of a similar approach, Chen and Nikles [217] synthesized ternary alloy nanoparticles (FC cCo3,Ptioo x-y), using a simultaneous reduction of acetylacetonate and platinum acetylacetonate and thermal decomposition of Fe(CO)5 and obtaining an average particle diameter of 3.5 nm and narrow particle size distribution. 

Metal nanoparticles can be prepared in a myriad of ways, e.g., by pulse radiolysis [110], vapor synthesis techniques [111], thermal decomposition of organometallic compounds [112], sonochemical techniques [113,114], electrochemical reduction [115,116], and various chemical reduction techniques. Some of the most frequently used reducing agents include alcohols [117,118], citrate [119,120], H2 [121], borohydrides [122], and, more recently, superhydride [123]. The chosen experimental conditions determine the size, size distribution, shape, and stability of the particles. Because naked metal particles tend to aggregate readily in solution, stabilizing the nanoparticles is the key factor for a successful synthesis. Sometimes the solvent can act as a stabilizer, but usually polymers and surfac-... 

Thermal decomposition has been used for the synthesis of nanoparticles of Pd, Pt, Au, and Ag on CNTs. In the process, CNTs are dispersed in either water or acetone by the addition of a metal salt. A subsequent evaporation of the solvent is carried out at a temperature of approximately 100°C. As a final step, both decomposition and a reduction of the mixture are conducted at temperatures between 300°C and 700°C under an H2 atmosphere. Using this method, nanoparticles with sizes between 8 and 20 nm were obtained on the surface of the nanotubes (Xue et al. 2001). 

Other procedures for the synthesis of CNTs use a gas phase for introducing the catalyst, in which both the catalyst and the hydrocarbon gas are fed into a furnace, followed by a catalytic reaction in the gas phase. The method is suitable for large-scale synthesis, because nanotubes are free from catalytic supports and the reaction can be operated continuously. A high-pressure carbon monoxide reaction method, in which the CO gas reacts with iron pentacarbonyl to form SWNTs, has been developed [38]. SWNTs have been synthesized from a mixture of benzene and ferrocene in a hydrogen gas flow [55]. In both methods, catalyst nanoparticles are formed through thermal decomposition of organometallic compounds, such as iron pentacarbonyl and ferrocene. 

During the last few years, different synthetic procedures have been reported for the synthesis of magnetic nanoparticles. These methods include co-precipitation, thermal decomposition and/or reduction, microemulsion synthesis, and hydrothermal synthesis. Despite poor shape control and quite polydisperse particles, co-precipitation is probably the simplest synthetic route. By contrast, thermal decomposition is experimentally more demanding but affords the best results in... 

Since most of magnetic materials are metal or metal oxides, the raw material is straightforward and can be easily found. However, the technology difficulties remain in the purity section. As mentioned above, the different chemical properties are based on the structure and the concentration of the alloys, so the synthesis process has to be controlled very carefiilly. Furthermore, when it comes to the nanoscale, many of the classic physics laws are not applicable and quantum physics is required. The synthesis of ferrofluid consists of synthetic procedures. Basically, it is the thermal decomposition of metal organic compounds or the thermal decomposition of monometallic metal organic compounds. Figure 1.1 shows examples of magnetic nanoparticles for one simple structure and for metal alloy compounds. 

Wang RC, Tsai CC. Efficient synthesis of ZnO nanoparticles, nanowaUs and nanowires by thermal decomposition of zinc acetate at a low temperature. Appl Phys A 2008 94(2) 241-5. 

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