Transmission electron microscopy aerogel

The contribution by Rouzaud et al. teaches to apply a modified version of high resolution Transmission Electron Microscopy (TEM) as an efficient technique of quantitative investigation of the mechanism of irreversible capacity loss in various carbon candidates for application in lithium-ion batteries. The authors introduce the Corridor model , which is interesting and is likely to stimulate active discussion within the lithium-ion battery community. Besides carbon fibers coated with polycarbon (a candidate anode material for lithium-ion technology), authors study carbon aerogels, a known material for supercapacitor application. Besides the capability to form an efficient double electric layer in these aerogels, authors... 

We will illustrate this method by studies led on powders of zirconia nanociystals. The diffraction pattern shown in Figure 6.9 was obtained with a zirconia aerogel as the sample, produced by drying a precursor gel of zirconia in supercritical conditions [SIL 96, SIL 97, LEC 98]. A qualitative illustration of this material s microstructure, obtained by transmission electron microscopy, is shown in Figure 6.10. 

Figure 6.10. Micrographs of a zirconium dioxide aerogel burned for 1 hour at 350°C, obtained by using transmission electron microscopy...

In other Pt-doped monolithic carbon aerogels, prepared by adding the Pt pre-cnrsor to the initial R/F mixture [41], the Pt particle size determined by H2 chemisorption was mnch higher than that determined by high-resolution transmission electron microscopy (HRTEM). This indicates that some Pt particles were encapsnlated by the carbon matrix and were consequently inaccessible to H2. This can be the main problem of this preparation method when the metal-doped carbon gel is to be used as catalyst, because part of the metal will not be accessible to the reactant molecules. 

Falqui A, Corrias A, Gass M, Mountjoy G (2009) A Transmission Electron Microscopy Study of Fe-Co Alloy Nanoparticles in Silica Aerogel Matrix Using HREM, EDX, and EELS. Micros Microan 15 114-124... 

Hu X, Littrel K, Ji S, Pickles DG, Risen WM Jr (2001) Characterization of Silica-polymer aerogel composites by small-angle neutron scattering and transmission electron microscopy, with, J. Non-Ciyst. SoUds, 288 184-190... 

Stroud R M, Long J W, Pietron J J et al (2004) A practical guide to transmission electron microscopy of aerogels. Journal of Non-Crystalline Solids 350 277-284... 

According to equation (11-8), the buckling constant if is proportional to the diameter of the filaments which constitute the aerogel and xerogel skeletons. In order to assess the existence of a relation between k( and a characteristic dimension of the gel structure, Pirard et al. (1998) observed various xerogel samples by transmission electron microscopy (TEM). The mean diameters of the gel particles were determined by direct measurements on the micrographs. However, the particles themselves may not provide an adequate comparison, as they are not a good indicator of the structure of the network and they cannot... 

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