Nanocomposites HRTEM

Fig. 7.8 TEM images of the Si SiOx/C nanocomposite nanoparticles produced by hydrothermal carbonization of glucose and Si and further carbonization at 750 °C under N2. (a) Overview of the Si SiOx/C nanocomposites and a TEM image at higher magnification (in the inset) showing uniform spherical particles (b) HRTEM image clearly showing the core/shell structure (c), (d) HRTEM image displaying details of the silicon nanoparticles coated with SiOxand carbon.

Fig. 1.7 Representative EDS spectra of Na-montmoriUonite. Cu peaks arise from the TEM grid. Reprinted with permission from Yaron-Marcovich D, Chen Y, Nir S, Prost R (2005) High resolution electron microscopy (HRTEM) structural studies of organo-clay nanocomposites. Environ Sci Technol 39 1231-1239. Copyright 2005 American Chemical Society...

For appropriate comprehension of morphology and the concomitant structure-property correlations in nanocomposites, knowledge of the state and extent of nanofiller dispersion in the matrix is of paramount importance. Numerous methods have been reported in the literature in this regard, for instance, WAXD [6, 38], SAXS [8, 39], SANS [40], SEM, [6, 41], AFM [7, 42], HRTEM, STEM, EELS [43], SSNMR [44], EPRS [45], UV/vis/NIR, FTIR [46], Raman spectroscopy... 

Figure 7 shows the representative bright field HRTEM images of nanocomposites of NR and unmodified montmorillonite (NR/NA) prepared by different processing and curing techniques. It is apparent that the methodology followed to prepare the nanocomposites by latex blending facilitates the formation of exfoliated clay structure, even with unmodified nanoclays. It has been reported in the literature that hydration of montmorillonite clay leads to extensive delamination and breakdown of silicate layers [94, 95]. It has also been shown that NA disperses fully into the individual layers in its dilute aqueous dispersion (clay concentration <10%)... 

Fig. 7 Bright fiefd HRTEM images showing the deveiopment of morphoiogy in 4 phr NA-filled NR nanocomposites under different processing and curing conditions a latex-biended uncured NC (NLUNA) b prevuicanized NC (NLPNA) and c conventionaliy cured NC (NMNA). d X-ray diffractograms of NA and its nanocomposites...

The exact number of clay stacks having the above three categories of platelet stacking were measured by taking at least six different HRTEM images for each type of nanocomposite sample and the average distribution of the clay platelets were noted down (Fig. 38). This has been represented as the extent of exfoliation (B) in Table 9. It is apparent that as the level of exfoliation increases, the number of clay platelets per stack decreases and their effective surface area contribution increases. 

Detailed HRTEM characterization of the specimens showed that all metal-ceramic interfaces in the two different nanocomposites had thin ( 1 nm thick) amorphous films (see Fig. 11.5). In addition, occluded particles were found inside the alumina grains which also had thin amorphous films at their interfaces with alumina. Analytical microscopy showed the films to contain Ca, Si, and Al.41 Hamaker coefficients were calculated for metal-ceramic interfaces in the presence of a Si02-based film, which indicated that a stronger attractive force is expected for intergranular films at metal-alumina interfaces,... 

Figure 2. (a) Plane view TEM image (b) SAED pattern and (c) HRTEM plane view image of diamond/p-SiC nanocomposite film deposited using a TMS flow rate of 5 seem. 

Yu et al. [112] reported the fabrication of nanocomposites of onedimensional (ID) titanate nanotubes and rutile nanocrystals by hydrothermal treatment of bulky rutile Ti02 powders. It was performed in a lOM NaOH solution without using any templates and catalysts. The iimer and outer diameters of the nanotubes were approximately 5 and 8 nm, respectively (Table 2). TEM and HRTEM images of the products revealed that many rutile nanocrystals of 5-10 nm attached to the outer surface of the titanate nanotubes. Some rutile nanocrystals of about 5 nm also existed in the interior of the nanotubes. This generates an interesting composite structure that possesses both the surface properties of rutile nanocrystals and the morphology and mechanical properties of titanate nanotubes. 

Fig. 47 (A) TEM and (B) HRTEM images of Ag3P04/Bi2MoOe nanocomposite and (C) schematic diagram of the energy band structure of the Ag3P04/Bi2MoOe composite and the possible charge transfer process under visible light irradiation. Reproduced from Ref, 98 with permission from The Royal Society of Chemistry.

Figure 6.5. (a) TEM of crystalline gold colloid particles (the halo of organic molecules is invisible), (b) computer simulation of a dendrimer nanocomposite, (c) HRTEM of a gold nanocomposite particle containing 14 Au atoms. (D) Dendrimer template. CNDs are in the middle of the structural "spectrum", to the far left lie dendrimer compatibilized "hard" gold nanoparticles, and "soft" dendrimers are on the right. 

Figure 19.4 shows the HRTEM images of the hsv fibres and injection-moulded nanocomposites. Overall, the relative thickness and dispersion of the layered-silicates in the PP matrices are consistent with the XRD trend. For example, the highly delaminated silicate platelets observed in the PPEX matrix are manifested as a level plateau in its XRD spectmm an indication of full exfoliation. The observed smaller lateral dimension of layered-silicates in the hsv matrix relative to their corresponding Isv fibres would corroborate the more repressed XRD peaks seen for the hsv fibres. This further suggests the influence of extensional flow deformation on the exfoliation of layered-silicate. 

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