Precipitation, nanoparticles

To study the nucleation and growth of Au nanoclusters in silica within the above theoretical frame, we implanted fused silica slides with 190keV-energy Au ions, at room temperature and current densities lower than 2 pA/cm, to reduce sample heating [49,50]. The implantation conditions were chosen to have, after annealing, a subsurface buried layer of Au nanoparticle precipitation of about... 

Figure 2.2 Apparatus to quantify nanoparticle precipitation using UV-visible spectroscopy.

H.C. Schwarzer, W. Peukert, Experimental investigation into the influence of mixing on nanoparticle precipitation, Chem. Eng. Technol. 25 (2002) 657-661. 

Marchisio, D. L. 2009 On the use of bi-variate population balance equations for modelling barium titanate nanoparticle precipitation. Chemical Engineering Science 64, 697-708. 

The hydrothermal crystallization is the most popular technique in preparing ceria-based nanoparticles. Precipitation from aqueous solutions under elevated temperature and high pressure are involved in the process. Usually the hydrothermal crystallization is carried out as follows. An excess amount of precipitates is added to the cerium salt solutions. The precipitated gels are sealed in Teflon-lined autoclaves and hydrothermally treated at 423-573 K for several hours. The autoclaves are quenched and the crystalline powder products are washed and dried. Using the hydrothermal crystallization method, a number of ceria-based nanoparticles have been prepared as summarized in Table 3.2. The particle size clearly depends on the reaction temperature and the starting materials used. It is shown that by heating at low temperature and by using tetravalent cerium salt solutions smaller particles can be obtained. 

Schwarzer H, Schwertfirm F, Manhart M, Schmid H, Peukert W (2006) Predictive simulation of nanoparticle precipitation based on the population balance equation. Chem Eng Sci 61(1) 167-181... 

Schwarzer, H. C. Peukert, W. Tailoring particle size throngh nanoparticle precipitation, Chemical Engineering Conununications, Band 191 (2004) Heft 4, p. 580... 

FIGURE 24.8 SEM image of yttrium acetate nanoparticles precipitated from DMSO (15 mg/ml) at 120 bar and 313 K, with mean diameters of about 150 nm. (Reprinted from Reverchon, E., J. Supercrit. Fluids, 15, 1-21, 1999. With permission from Elsevier.)... 

This is a simple two-step process for the fabrication of nanoparticles. The first step is polymeric emulsification in an aqueous medium. The second step is solvent evaporation from the polymer and nanoparticle precipitation. Finally, the nanoparticles are collected by ultracentrifugation and washed with distilled water for the removal of excess stabilizer and lyophUization [23]. The various types of polymer used include poly(lactic-co-glycolic acid) (PLGA), poly-D,L-lactic acid (PLA), poly(E-caprolactone) (PCL), ethyl cellulose, poly(P-hydroxybutyrate), cellulose acetate phthalate, etc. 

N. Di Pasquale, Multiscale simulation of polymer nanoparticles precipitation for pharmaceutical applications, PhD Dissertation, Politecnico di Torino, Italy, 2012. Available at http //porto.polito.it/2506098 [DOI 10.6092/polito/porto/2506098]. 

H.-C. Schwarzer, and W. Peukert, Tailoring particle size through nanoparticle precipitation, Chemical Engineering Communications, 191 (4), 580-606, 2004. 

Nano-oxide particles precipitate from the ferritic matrix, maintaining crystalline coherency or partial coherency with a ferritic matrix. In general, the nucleation and growth of precipitates proceed, as both interfacial and strain energies become minimal. In the case of ODS steels, interfacial coherency or partial coherency could be maintained between thermodynamically stable nanoparticle precipitates and the ferritic matrix in order to decrease the free energy in the system from the extremely high-energy state induced by MA. 

Schwarzer, H.C. and Peukert, W. 2004. Tailoring particle size through nanoparticle precipitation, Chem. Eng. Commun., 191, 580-608. 

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