Insights into the structural transformations of aluminosilicate inorganic polymers: a comprehensive solid-state NMR study

0379050 - ÚMCH 2013 RIV US eng J - Journal Article
Brus, Jiří - Kobera, Libor - Urbanová, Martina - Koloušek, D. - Kotek, Jiří
Insights into the structural transformations of aluminosilicate inorganic polymers: a comprehensive solid-state NMR study.
Journal of Physical Chemistry C. Roč. 116, č. 27 (2012), s. 14627-14637. ISSN 1932-7447. E-ISSN 1932-7455
R&D Projects: GA ČR GAP108/10/1980; GA AV ČR IAA400400904
Institutional research plan: CEZ:AV0Z40500505
Institutional support: RVO:61389013
Keywords : inorganic polymers * phase transition * water
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 4.814, year: 2012

To clarify the problem of undesired crystallization of amorphous aluminosilicate inorganic polymers (AIPs), we used 27Al MQ/MAS spectroscopy that revealed a two-component character of the prepared AIPs. The prevailing fraction of [AlO4]− species (amorphous phase) is charge-balanced by Na+counterions and exhibits considerable distribution of 27Al chemical shifts induced by the variation of Al−O−Si valence angles. In contrast, the minor fraction of [AlO4]− tetrahedra, which can be attributed to the partially ordered domains, shows a broad distribution of quadrupolar parameters that result from variability in the chemical nature of counterions. The partially ordered domains of the phase-unstable AIPs contained a considerably larger amount of [AlO4]− species charge-balanced by H+. Therefore, we assume that the destabilization of AIPs is associated with the presence of bridging hydroxyl groups (Si−OH+−Al, Brønsted-acid sites) that induce breaking of Si−O−Al bonds.
Permanent Link: http://hdl.handle.net/11104/0210329