Determination of the specific surface of a granular porous material by the USAXS–SAXS intensity of a loosely packed powder sample

Developing an earlier suggestion by Spalla, Lyonnard & Testard [J. Appl. Cryst. (2003), 36, 338–347], it is shown that the porosity and the specific surface of a porous material can be determined by the small- and ultra-small-angle X-ray scattering (SAXS and USAXS, respectively) intensity of a sample made up of loosely packed and rather large grains of the material, provided the Porod plot of the intensity shows two plateaux within the range of the explored scattering vectors. To this end, it is necessary to consider the system geometrically as formed by three phases: the bulk matter, the macropores and the micropores.