THE INFLUENCE OF NAX ZEOLITE PARTICLE-SIZE ON CRYSTALLINITY MEASURED BY THE XRD METHOD

The degree of crystallinity of NaX zeolite samples, previously determined by X-ray diffraction (DCXRD), was measured by a series of methods (i.r. spectroscopy, specific area, and ion-exchange measurements). For NaX zeolite samples, crystallized with various amounts of added "seed" SASS, it was found that 1. (a) There were no significant changes in the position, number, and half-width of the diffraction lines. 2. (b) Only slight changes in the shape of the i.r. spectra, chemical composition, specific area, and ion-exchange capacity occurred. 3. (c) There was only a slight decrease in the intensity of the diffraction peaks caused by the increase of SASS up to 20%. 4. (d) With the addition of more than 20% SASS, there was a sharp decrease in the intensity of the diffraction lines, and on the basis of this a sudden decrease in DCXRD a decrease of the mean particle size, as well as a decrease in the fraction of particles of dimensions less than 1 μm. The decrease in degree of crystallinity DCXRD is explained by the mosaic structure of zeolites and extinction effects that lead to a decrease in the intensity of the diffraction lines due to the decrease in the dimensions of mosaic blocks and increase in the angle of disorder. © 1990.