Coated silicas and small-angle X-ray intensity behaviour

Abstract

Porod plots of the small-angle X-ray intensities scattered by porous silicas that have undergone different coating processes show deviations from the predicted constant asymptotic behaviour. The deviations are ascribed to the effect of the coating film. We propose a constant-electron-density model for these films. The theoretical scattering function calculated from the model permits an estimate of the film thickness, electron density and average number of coating molecules per unit area of the support.

Nanostructured CeO2 thin films: A SAXS study of the interface between grains and pores

“…The contribution to scattering of this presumed interfacial layer is also exhibited in the range of relatively small h-values, which is already reported in the literature for the case of coated voids in a supporting layer [7]. By detecting the pore/grain coverage, SAXS measurements contribute to novel characterizations of the nature of interfaces in nanostructured metal oxide films.…”

“…The SAXS curve of one of the samples follows the Porod's law and that corresponds to the determined behavior of the above mentioned nanostructured Thin Solid Films 515 (2007) 5624 -5626 www.elsevier.com/locate/tsf TiO 2 films, derived by various methods. The scattering of the other CeO 2 sample shows a specific deviation from the Porod's law, which is usually ascribed to a diffuse interface [5,6] or to an adsorbate coverage of interfaces [7].…”

Diffuse Interfaces and Small-Angle Scattering Intensity Behaviour

“…On the other hand, these considerations show the density profile cannot be uniquely determined by analyzing only the tails of the SAS intensities.t In contrast, when one deals with the t With further assumptions, of course, it is possible to say more. For instance, by depicting the interface region as a third phase characterized by an average electron density n3, Benedetti & Ciccariello (1994) have shown that it is possible to get reliable estimates of the third phase's thickness and of n3 when D and 2a obey the constraints D > 80 A and 2a=S> 10/k. SAS intensity observed throughout the explored h range, then Dmin can be less than 50 A and the z value can be larger than 1/4.…”

The vertex contribution to the Kirste–Porod term

“…In fact, the analysis of the deviations (from a constant behaviour), observed in the Porod plots of the intensities scattered by some demixing glass samples as well as by some coated porous silica samples, yielded quite interesting and consistent information on the microscopic texture of the samples (Benedetti, CiccarieUo & Fagherazzi, 1988;Benedetti & Ciccariello, 1994). facets, asymptotically, are always given by…”