Volume fraction of random two-phase systems for a certain fixed order range from the SAS correlation function

Considering a certain, well-defined, fixed order range, the volume fraction is defined in terms of the first derivative of the small-angle scattering (SAS) correlation function (CF) γ(r) in the origin γ′(0) and the average mean chord length d̄lm. If d̄lm is unknown beforehand, this length parameter can be estimated from the behaviour of γ(r) in most practical cases. The method and its limits are studied for selected particle models (Boolean model, dead leaves model), for which analytic expressions for γ(r) are known. The applicability is exemplified for experimental cases, too.