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Updated: Aug 25, 2026

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
One- and two-dimensional solid-state magic angle spinning NMR studies on the hydration process of layered sodium
Xuanjun Ai1, Feng Deng, Jinxiang Dong
1State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, The Chinese Academy of Sciences, Wuhan 430071, PR China.
Abstract:
Three different kinds of silanols, which include isolated silanol, silanol I (with the hydroxyl proton bonded to an oxygen atom in the adjacent layer) and silanol II (with the hydroxyl proton bonded to the non-bridging oxygen at the same silicon atom), are generated during the hydration process of SKS-6 (delta-Na2Si2O5). 1H-1H nuclear Overhauser enhancement spectroscopy reveals that the proton of silanol I has an effective chemical exchange or spin diffusion with the proton of hydrogen-bonded water, while the proton of silanol II is likely far away from the other proton-containing species. 29Si magic angle spinning, 1H-->29Si CP/MAS NMR and 1H-29Si phase-modulated Lee-Goldburg decoupled correlation experiments demonstrate that the local environments of the silicon sites in the final hydrated sample are mainly composed of Q2 [(SiO)2Si(OH)O(-)Na+], Q3 [(SiO)3Si(OH) and (SiO)3SiO(-)Na+] and Q4 [Si(OSi)4] groups.
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