THE STRUCTURE OF ZEOLITE ZSM-23 (MTT) REFINED FROM SYNCHROTRON X-RAY-POWDER DATA

The structure of zeolite ZSM-23 (structure-type code MTT) loaded with NH4F [a(o) = 11.129 (1), b(o) = 5.025 (1) and c(o) = 21.519 (1) angstr om and beta = 89.85 (4)-degrees] was refined from high-resolution sync hrotron X-ray powder data. The Rietveld refinement converged in space group P12(1)1 (No. 4) to R(F) = 0.090 and R(wp) = 0.085, confirming th e proposed model of the silicate framework. The use of complementary m ethods (synchrotron X-ray powder diffraction, Si-29 magic-angle-spinni ng, nuclear-magnetic-resonance spectroscopy, and distance and angle le ast-squares refinements) was essential for the determination of the tr ue space-group symmetry, a prerequisite for the successful Rietveld st ructure refinement.