Average nanoparticles size

Thanks to the presence of silver nanoparticies, the final product also has anti-inflammatory activity and protects the skin against undesirable microorganism action. Silver nanoparticies can penetrate deep into the skin and remove it from any bacterial contamination, which inhibits the formation of acne (Yaoguang et al., 2011). Nanosilver has also been used in the production of toothpastes and oral care gels. Silver at a concentration of 0.004% (w/w) is an effective ingredient which prevents the growth of bacteria that cause unpleasant smells and dental cavities. The authors stipulate that the best biocidal activity is accomplished, if the average nanoparticle size is less than 15 nm (Holladay, 2013). 

Fig. 3 a TEM image and nanobeam electron diffraction pattern of the PPy nanoparticles prepared using deqdtrimethjdammonium bromide (DeTAB) (0.4 M) at 3°C. b Average change in nanoparticle size as a function of surfactant concentration. The average nanoparticle size was determined by TEM (50 particles counted) (reproduced with permission from [146])... 

Let us start with nanopowders. The measurements were carried out by XRD method. In Fig. 2.2, the lattice constants a and c, measured on tetragonal BaTiOs nanopowder, are shown at room temperature [17]. One can see that at average particle size about 50 nm c = a, so that the symmetry becomes cubic and ferroelectric phase transforms into paraelectric one at room temperature. To estimate the average nanoparticle size, where the ferroelectric phase becomes unstable and transforms into paraelectric one, the Scherrer formula has been used. This formula relates the particle size to the XRD lines half-width. The average particle size leading to the symmetry breaking is called critical size and constitutes the important characteristic of nanomaterials. It turns out, that the critical size measured on different samples can be essentially different. To illustrate this, on Fig. 2.3 we report the ratio c/a at room temperature for BaTiOs nanopowder obtained in Ref. [18]. It is seen that ratio c/a= 1 was obtained in the samples with average size 120 nm. The difference between the critical sizes in the papers [17] and [18] can be related to the... 

Figure 19.17 Magnetic susceptibility of (a) MnO sample (average nanoparticle size 37 nm) and (b) Mn304 sample (average nanoparticle size 25.4 nm).

It has been reported that the base condition is preferable in the preparation of Pt-nanoclusters-deposited carbon supports because the Pt precursor (HePtCle) has to be reduced by a reducing agent [43,44], which reduction process is best effected under base conditions (e.g., pH>10) in precursor-containing solutions. Furthermore, the Pt average nanoparticle size is smaller when the preparation condition has characteristics of a more base nature. By contrast, ACB shows the smallest surface BET area of all samples due to the high degree of aggregation. In this view, Pt deposition of carbon support is not easily available in the case of decreased ACB surface areas. 

Determination of average nanoparticle size by line width method... 

Figure 9.3 (a) Average Pd nanoparticle diameter size plotted versus temperature. An increase in synthesis temperature results in an increase in nanopaiticle size, up to 140 C (b) Average nanoparticle size plotted versus increase in reaction time at 95 °C for a reaction time up to 3 h the particles continue to grow, but after this time no further growth occurs. 

Hops biomass has the ability to reduce Au(III) ions to form Au(0) nanoparticles [65]. XAS techniques have been used to elucidate the average nanoparticle size and to determine the binding and reduction mechanisms of Au(III). These authors... 

The viability of the impact approach has been demonstrated in authentic seawater media. Figure 8.14a shows oxidative current-time transients of citrate-capped silver nanoparticles (13 2 nm in radius) dispersed in seawater measured at a carbon microelectrode of radius ca. 6 pm whilst Fig. 8.14b shows the size distribution of the nanoparticles in terms of the number of atoms making up each nanoparticle inferred from the charge passed during transients such as those in Fig. 8.14a. From the independently measured average nanoparticle size of 13 nm radius it can be estimated that a single silver nanoparticle of this size contains ca. 5.4 X 10 atoms. It is evident from Fig. 8.14 that the nanoparticles must be extensively aggregated in the seawater (on the timescale studied which was ca. 40 min from the addition of the nanoparticles) deconvolution of the distribution... 

CuNPs) in Fig. 7 shows the monodisperse and uniformly distributed spherical particles of 10+5 nm diameter. The solution containing nanoparticles of silver was found to be transparent and stable for 6 months with no significant change in the surface plasmon and average particle size. However, in the absence of starch, the nanoparticles formed were observed to be immediately aggregated into black precipitate. The hydroxyl groups of the starch polymer act as passivation contacts for the stabilization of the metallic nanoparticles in the aqueous solution. The method can be extended for synthesis of various other metallic and bimetallic particles as well. 

For instance, nanoparticles of silver chloride have been synthesized by mixing two mi-croemnlsions, one containing silver ions and the other containing chloride ions. It was shown that the average particle size, the polydispersity and the number of particles formed depend on the intermicellar exchange rate and/or the rigidity of the surfactant shell [228],... 

The durability of the catalytic system was investigated by employing it in five successive hydrogenations. Similar TOFs were observed due to the water solubihty of the protective agent which retains nanoparticles in aqueous phase. The comparative TEM studies show that (i) the average particle size was 2.2 0.2 nm (ii) the coimter anion of the surfactant does not allow a major influence on the size and (iii) nanoparticle suspensions have a similar size distribution after catalysis. 

XRD provides useful information on the crystal phase, lattice constant, and average particle size of nanoparticles. In the case of bimetallic nanoparticles, XRD is important... 

Recently we investigated ferromagnetic properties of CoPt bimetallic nanoparticles [232,233]. CoPt3 nanoparticles can be prepared by a two-step reduction using NaBH4 as a reductant. The bimetallic nanoparticles were characterized by thermogravimetry (TG) and differential thermal analysis (DTA), FT-IR, TEM) and XRD. Structural and spectroscopic studies showed that the bimetallic nanoparticles adopt an fee crystalline structure with an average particle size of 2.6 nm. SQUID studies revealed... 

All Pt nanoparticles were monodisperse and the size distribution was less than 10%. The average particle sizes... 

Pt/MWNT) [20,21], fine and homogeneous Pt nanoparticles deposited on MWNTs were obtained when pure EG was used as the solvent or less water (<5vol.%) was introduced. With the increase in water content, aggregation of the metal nanoparticles occurred, the average particle size increased and the particle size distribution became wider. 

By changing the ultrasound power, changes in the mesoporosity of ZnO nanoparticles (average pore sizes from 2.5 to 14.3 nm) have been observed. In addition to the changes in mesoporosity, changes in the morphology have also been noted [13]. Recently, Jia et al. [14] have used sonochemistry and prepared hollow ZnO microspheres with diameter 500 nm assembled by nanoparticles using carbon spheres as template. Such specific structure of hollow spheres has applications in nanoelectronics, nanophotonics and nanomedicine. 

Platinum-based nanoparticles (e.g., Pt [1-15], Pt-Re [10,15], and Pt-W [5,6,15]) supported on granular activated carbon (KOH-activation, BET specific surface area 3100 m2/g, pore volume 1.78 cm3/g, average particle size 13 pm, average pore size 2.0 nm, Kansai Netsukagaku Co. Ltd. [32]) were mainly used as the dehydrogenation catalysts in the present study. 

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