Nanoparticle Synthesis Techniques

The sol-gel method, a nanoparticle synthesis technique, has been shown to be very flexible in film deposition. Smooth amorphous films can be deposited, and crystallized... 

For future practical applications of nanoparticles, synthesis techniques play an important role for producing high-quality crystalline metal particles with different sizes. Narrow size helps to assemble nanostructures with higher order that are capable of... 

Fig. 4.13 Depiction of the two nanoparticle synthesis techniques used and the initial reactivity results for electrophilic catalysis, (a) In the top scheme, Pt ions are loaded onto a PAMAM den-drimer and reduced to form a dendrimer-encapsulated NP. Sonication deposits the NPs on the mesoporous silica, SBA-15, to generate the NP catalysts. In the bottom scheme, polyvinylpyrrolidone (PVP) encapsulates the NP. Deposition on SBA-15 follows to produce the catalyst. In both cases, the NPs are synthesized before loading onto SBA-15. (b) Hydroalkoxylation of 1 with Pt NPs. To obtain electrophilic activity from the Pt NPs, treatment with the mild oxidant PhlClj is required. Pt4o/G40H/SBA-15 NPs must be further reduced under H atmosphere at 100 °C for 24 h before reaction. This treatment generates catalytically active NPs that activate the jc-bond in 1, resulting in hydroalkoxylation to benzofuran 2. Yields were determined by comparing peaks in NMR against an internal standard. Reprinted with permission from ref. [100]. Copyright 2009 Nature Publishing Group...

Semiconductor nanoparticles have unique size-dependent photoelectrochemical properties. Demand for nanocrystalline semiconductors of uniform size and shape has stimulated research into different synthesis techniques some of which we consider here. 

The inverse-micelle approach may also offer a generalized scheme for the preparation of monodisperse metal-oxide nanoparticles. The reported materials are ferroelectric oxides and, thus, stray from our emphasis on optically active semiconductor NQDs. Nevertheless, the method demonstrates an intriguing and useful approach the combination of sol-gel techniques with inverse-micelle nanoparticle synthesis (with OTO erafe-temperature nucleation and growth). Monodisperse barium titanate, BaTiOs, nanocrystals, with diameters controlled in the range from 6-12nm, were prepared. In addition, proof-of-principle preparations were successfully conducted for Ti02 and PbTiOs. Single-source alkoxide precmsors are used to ensure proper stoichiometry in the preparation of complex oxides (e.g. bimetallic oxides) and are commercially available for a variety of systems. The... 

Decomposition of silver azide in vacuum [52], induced by an electron beam, yields ultrafine particles of silver, predominantly less than 100 nm in diameter, and in the form of well-defined hexagonal or trigonal crystals and polygonized spheres. This technique of nanoparticle synthesis is recommended as having advantages over other methods. 

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-... 

One of the main problems in modern nanotechnology is the preparation and stabilization of nanoparticles of different nature semiconductors, metals, organic compounds, etc. Nowadays there are a number of methods for nanoparticle synthesis [1]. Among them water-in-oil reverse micelles (RMs) are the successful technique for the controlled preparation of very small and monosized nanoparticles. Water-in-oil RMs are thermodynamically stable dispersion of nanosized water drops in organic solvent, stabilized by surfactants. RMs are formed spontaneously due to the surfactants, which diminish the interface tension down to ultralow values, and as a result the free energy decreases when the total oil-water interfacial area increases. Thermodynamically stable water-in-oil microemulsions can be produced at strictly defined conditions. It is possible to change the size of the water pool of RMs by variation of the ratio between water and surfactant concentrations. This allows changing the size of nanoparticles, which are stabilized in such microemulsions. 

Metal-containing polymers may be produced by various methods, such as chemical reactions of precursors— in particular, reactions of metal salts in polymer solutions, the treatment of polymers with metal vapors, or the polymerization of various metal-monomer systems [1-4], Depending on the metal nature and the polymer structure, these processes lead to organometallic units incorporated into polymer chains, metal-polymer complexes, or metal clusters and nanoparticles physically connected with polymer matrix. Of special interest are syntheses with the use of metal vapors. In this case, metal atoms or clusters are not protected by complexones or solvate envelopes and consequently have specific high reactivity. It should be noted that the apparatus and principles of metal vapor synthesis techniques are closely related to many industrial processes with participation of atomic and molecular species [5]—for example, manufacturing devices for microelectronic from different metals and metal containing precursors [6]. Vapor synthesis methods employ varying metals and... 

This review approaches the preparation of gold and silver nanoparticles by employing green synthesis techniques instead of chemical and physical methods. This smdy will provide valuable information for the preparation and characterization of silver and gold nanoparticles and its present and future prospects and prospective constraints of techniques in industry. In addition, we have particularly emphasized the role of silver and gold nanoparticles with other materials and their biomedical applications. 

These methods have been widely used for nanoparticle fabrication techniques. These methods have been widely utilized for nanoparticles fabrication techniques which was subjected for both vaporization and condensation techniques. This method can play a vital role in both physical and chemical methods of synthesis of nanoparticles. The synthesized nanoparticles are subjected to various characterization techniques to identify whether they are the same size, if they are the same size the preparation method is physical vapor condensation. But if they are different particle sizes then we can conclude it with physical vapor condensation (Ghorbani et al., 2011). 

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