Order distance estimation in porous glasses via transformed correlation function of small-angle scattering

A mesoporous two-phase system, consisting of colloidal silica in the cavities of the main silica frame work of a macroporous glass, was investigated by use of Small-Angle X-ray scattering. The transformed correlation function gamma (T)(r) was determined for this material for distances r > 40 nm. The application of the intrinsic properties of gamma (T)(r) yields estimations for two fundamental order distances L(1)=11 nm and L(2)=120 nm of the porous glass possessing a clear geometric interpretation: L(1), a short-order-range, is the mean chord length of the mesopores plus the mean chord length in the secondary particles. L(2), a long-order-range, is an estimation of the mean diameter of a macropore plus the mean free distance in the silica framework which separates two nearly parallel segments of two adjacent macropores.