IUCr journals

Elucidation of zeolite microstructure by synchrotron X-ray diffuse scattering

J. Appl. Cryst. (2004). 37, 187–192 [ doi:10.1107/S0021889803028048]

[Weissenberg image]Weissenberg image of diffuse structure within the sheet-like scattering distribution concentrated in the l = 5 plane of a natural mordenite single crystal.
Zeolite mordenite, an important industrial catalyst, has long been suspected of framework variability. A broad single-crystal X-ray diffuse-scattering survey now reveals columnar framework fault defects and a block-mosaic network of planar stacking faults, which, even at very low concentrations, may significantly alter mordenite’s fundamentally shape-selective properties. An experimental 3D diffuse-scattering distribution, mapped out using 20 keV synchrotron X-rays and a CCD camera, was compared with computer-simulated distributions that employed large-scale atomistic defect models. Isolated c-axis columns of 4MR rings are fault-shifted by c/2, while columnar faults also cooperate along the <110> directions to form planar antiphase boundaries.

B. J. Campbell, T. R. Welberry, R. W. Broach, H. Hong and A. K. Cheetham