ISSUES OF MEASURING THE PRIMARY CRYSTALLITES SIZE IN POWDER, AIR SUSCEPTIBLE MATERIALS

Analysis of time stability of the profile of(1 1 1)Cu diffraction line in an activated carrier catalyst CHEROX 46-00 has been used in testin g the quality of a cuvette for XRD analysis of samples containing a co mponent unstable in air. It was found that the described type of cuvet te can provide a distorted information about the size of primary cryst allites of analyzed phase if the time stability of sample is not known . New method for protecting the active component of sample in the cuve tte against air oxygen was worked out and experimentally tested. The m ethod provides a high time stability of this type of samples for XRD a nalysis. It consists in the surface protection of an unstable solid ph ase with a laminar liquid film of a suitable non-reactive sorbate (e.g ., 2-ethylhexanol) and in the analysis of sample in a pasty form. The efficiency of sample stabilization is a function of the content of dis persing liquid in the analyzed paste. (C) 1997 Elsevier Science B.V.