Microcrystallite supported

Extremely thin, self-supporting film electrodes have been successfully produced. For example, polypyrrole films of 120 nm thickness have been used successfully to grow microcrystallites, followed by removal of the film plus crystallites from the substrate for characterization of the crystallographic structure and orientation of the microcrystallites by transmission electron microscopy with selected area electron diffraction [23]. Thin-film electrodes have been applied to allow transmission of high-energy beams, including x-rays, for in situ... 

Fig. 13.28. TEM micrograph of 20 wt.% Pt-C electrocatalyst powder (Prototech). Vulcan XC-72 carbon support electrodes are now 0.2 mg cathode, 0.05 (for H2) anode. (Reprinted from M. A. Parthasarathy, S. Srinivasan, and A. J. Appleby, Electrode Kinetics of Oxygen Reduction at Carbon-Supported and Unsupported Platinum Microcrystallite/Nafion Interfaces, J. Electroanalytical Chem. 339 101-121, copyright 1992, p. 105, Fig. 2, with permission from Elsevier Science.)...

The dependence of the isomer shift (41) and recoil-free fraction (9, 42-48) on particle size has also been suggested, but such relationships may be somewhat tenuous. It is clear that caution must be exercised in the use of methods hitherto described in the interpretation and correlation of microcrystallite size. Recent work has suggested (12) that ferric oxide may react with the support when calcined at high temperatures, e.g. for 2 hr at 500°C. The presence and contribution... 

The linewidths of the Mossbauer spectra of supported iron oxide microcrystallites are larger than those recorded for iron in well-crystallized compounds and may suggest the superimposition of different quadrupole-split doublets arising from a number of ferric ions in a heterogeneity of sites. 

Ikon-57 Mossbauer Parameters for Quadrupole-Split Spectra of Supported Iron Oxide Microcrystallites Reduced in Hydrogen... 

The first and most studied Mossbauer nucleus, iron-57, displays specific catalytic behavior. Mossbauer investigations of supported microcrystallites of iron and its oxide have demonstrated the importance of the techniques in the investigation of surface structure and chemistry. The application to other nuclei that have important catalytic qualities indicates the potential importance of the study of supported microcrystallites by Mossbauer spectroscopy in future investigations of catalysts. Developments in experimental techniques enabling in situ investigations are enhancing the scope of the technique. 

We view the well established microporous and microfibrillar character of cellulose cotton fibers to support our fractal interpretation. The behavior of the SAXS scattering function is consistent with this fractal interpretation and does not conform to the usual Guinler and Porod methods of analysis. We hope the appoach used in this study is sufficiently provocative to stimulate the thinking of other researchers regarding the growth process of cotton cellulose, whether it be via aggregation of microcrystallites followed by some rearrangement or another process. 

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