3D-TEM measurements

D-TEM was introduced into rubber technology field in 2004 by the authors of this chapter [4]. In a recent review of 3D-TEM applied in materials science field [5], only two papers were cited on polymeric samples—one on block copolymers [6] and the other on rubbery composites with conventional and in situ silica [4]. Starting from the latter, 3D-TEM measurements have been carried out on rubbery nano-composites [7-16], and this recent and very important topic is described in this review. 

Another problem is that no method has been established yet for evaluating the exact resolution in 3D-TEM measurements. 

FIGURE 19.2 Procedure for three-dimensional-transmission electron microscopic (3D-TEM) observation, composed of TEM measurements and computerized tomography to reconstruct a 3D image. (From Kohjiya, S., Kato, A., Shimanuki, J., Hasegawa, T., and Ikeda, Y., Polymer, 46, 4440, 2005. With permission.)... 

While the principal stumbling block remains the development of more realistic models, improvements in experimental techniques are also needed. In the measurements of structure by diffraction or TEM, higher resolution and accuracy are desirable to provide a clearer picture of the atomic and surface structure. In the case of TEM measurements, the development of methods to obtain 3D structures, as opposed to the 2D thin-film structures currently possible, would provide a major advance. In the surface chemistry studies, further resolution of both the location and species of surface groups is needed. 

A 3D-TEM study on a series of Y zeolites reveals the mesopores (generated by steaming and/or acid leaching) with great clarity. Both the diameters and shapes of the visualised pores correspond very well with nitrogen physisorption measurements of the entire sample. Also cimorphous alumina in the mesopores and on the external surface can be visualised, which is in agreement with results obtained by XPS on these samples. From these results a more detailed model for the formation of mesopores in zeolite Y is proposed. 

D reconstruction (Fig. 13b) shows that most of the particles are in fact located at the outer domains of the investigated MOF-5 specimens with a maximum penetration of 20 mn, and only some particles are located in the core of the MOF-5 crystallites. This is in contrast to the results from the tomographical TEM measurements of Pd MOF-5 (Fig. 11), where a more or less uniform particle distribution was observed. Obviously, the preparation technique has a great impact on the particles distribution. The photolytically synthesized Pd MOF-5 shows a more uniform particle distribution than the material Ru MOF-5, which was obtained by thermally activated hydrogenolysis over a long period of time. In the case of Ru MOF-5,... 

In the classical contact mode (Fig. 6a) AFM measures the hard-sphere repulsion forces between the tip and the sample. As a raster-scan drags the tip over the sample surface, the detector measures the vertical deflection of the cantilever, which indicates the local sample height. A feedback loop adjusts the position of the cantilever above the surface as it is scanned and monitors the changes in the surface height, generating a 3D image—a decisive advantage of AFM over TEM [3]. 

That the optical properties of such 2D/3D colloid arrays will depend on particle packing densities has been demonstrated by Dusemund et al., who measured the reflectivity of gold colloid films as a function of colloid volume fraction [47]. Although the films were not ordered they showed a clear shift in surface plasmon position with increasing particle volume fraction. The only compromise was that the volume fraction could not be directly determined on the samples from which spectra were taken, but had to be measured on separately prepared TEM grids. Several groups have found that clustered quantum dots exhibit red-shifted fluorescence, a question recently reviewed by Weller [48]. 

EDX Energy-dispersive X-ray spectroscopy TEM Transmission Electron Microsoopry XRD X-ray Diffraction Nl Nanoindentations NIT Nano-Impact Test IT Impact Test ITMFS Impact Test with Modulated Force Signal BC Ball Cratering Test WLS White light scanning 3D measurements NT Inclined Impact Test S Scratch test NS Nano-scratch test RC Rockwell C OIF DiFfusion test OX Oxidation test TRM TRiboMeter... 

Since a conventional TEM produces a projected three-dimensional (3D) image on a two-dimensional (2D) plane, quantitative information on the filler dispersion can be attained by using AIA techniques. 97,99,102,115,125,127,134 this way, it is possible to recognize, select, measure and compare size and shape of the complex structures dispersed in the matrix through the use of descriptors based on geometrical parameters, such as area, perimeter, diameter and morphometric parameters, such as shape ratio and roundness (Figure 23.3). However, TEM image analysis of filler microdispersions is more difficult to... 

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