FRACTAL MODEL OF AMORPHOUS AND SEMICRYSTALLINE NANO-SIZED ZIRCONIA AEROGELS

A small angle X-ray scattering (SAXS) study of fractal aggregates of n ano-sized ZrO2 aerogel powders was carried out. Two samples showing di fferent structural properties (one is semicrystalline and the other is completely amorphous) have similar fractal behaviour showing an infle xion point, h(f), located between the fractal linear and Pored linear part in the log J(h)-log h plot. In order to provide a quantitative in terpretation of the SAXS intensities, a best fit procedure was applied . A short-distance scaling factor in the structure factor which gradua lly makes the fractal behaviour develop through a transition r-region and a form factor characterized by a coherent and continuous merging o f Guinier's and Pored's regime are proposed. The best fit procedure en abled determination of fractal and microstructural parameters of the t wo systems.