Longitudinal NMR relaxation of 27Al nuclei in zeolites

Application of27Al NMR techniques to structure determination in solids

“…The 27Al relaxation time increases markedly on dehydration from -1 ms to > 100 ms in zeolite A as the mofion of the sorbate molecules decrease. This reduces the modulation of Cq at the aluminium site which has been shown for zeolites to be the dominant relaxation mechanism [124]. The aluminium signal from the framework can be observed even in highly siliceous materials where (Si/A1)-1000.…”

Solid-state 33S MAS NMR of inorganic sulfates

“…This is attributed to the motion of the water molecules in the crystal lattice, which increases the T 1 relaxation efficiency. Haase et al [37][38][39] showed that relaxation of 27 Al nuclei in hydrated zeolites were overwhelmingly dominated by modulation of the time-dependent electric field gradient at the nuclear site due to motion of water molecules and hydrated cations in zeolite pores. There was no relationship observed between the quadrupole coupling constant and T 1 Õs in the anhydrous samples.…”

27Al NMR Studies of Aluminosilicate Glasses

“…If a noticeable resolution improvement is not observed, the stator is likely off its optimal position. The only exception when the stator may be perfectly positioned but the ST 3/2 sidebands remains broad is if the sample exhibits dynamics, sometimes relevant for 27 Al NMR on openframework materials (e.g., zeolites), where motions of physisorbed water molecules or remaining templating molecules may accelerate spin-spin (T 2 ) relaxation [152].…”