Nonoxidic nanoparticles

The term nanoparticles usually refers to particles with a size up to 100 nm [1]. Nanoparticles exhibit completely new or improved properties based on specific characteristics such as size, distribution, and morphology if compared with larger particles of their bulk material. Nanoparticles can be made of a wide range of materials, the most common being metal oxide ceramics, metals, silicates, and nonoxide ceramics. Even though other materials (e.g., polymer nanoparticles) exist, the former count for those used in most current applications [1]. 

Such a reaction of Fe(CO)5 (at 293-363 K, PVP) without ultrasonic radiation proceeds very slowly and only after few days there, a material is formed with very low Fe content (2%, the isolated particles 2-5 nm in size). It is of interest that the sonochemical decomposition of Fe(CO)5 does not proceed in the presence of PVP if THF is used as the solvent, but the reaction is very effective when anisole is used as the solvent and PFO is used as the polymer matrix [93]. A black product formed contains up to 10% (in mass) of the spheric particles of nonoxidized Fe (mainly y-Fe, with little content of a-Fe) with 1-12 nm in size (the mean diameter is 3nm, as shown in Figure 3.7). It is likely that the big particles present the flocks of little ones ( 2-2.5nm). The sonochemical synthesis allows us to produce the functionalized amorphous nanoparticles of ferric oxide with 5-16 nm in diameter [94]. The ultrasonic irradiation in the PFO presence allows us to also produce the stabilized nanoparticles of copper, gold, and so on. In the literature the findings are not about the bimetallic particle formation in the ultrasonic fields by carbonyl metal reduction in the polymer matrices presence (as, for example, in the case of the carbon-supported Pt-Ru from PtRu5C(CO)i6 reduced clusters [95]). 

Several other synthesis methods such as hydrolysis [20], pyrolysis [21,22], hydrothermal [10,23], and free-drying [24] methods are often used to fabricate ceramic nanoparticles, including calcium phosphates and carbonates, metal oxides, as well as nonoxides such as metal sulfates. Due to space limitations, these methods are not expanded here but it is important to note that the versatility of these methods provides rich opportunities to manufacture, modify, and functionalize complex nanoparticles or other nanoarchitectures. 

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