Abstract:
In order to understand the structure of aluminum phosphates, prepared by the sol-gel method, 27AI and MAS
NMR spectroscopy has been employed. The evolution of
structure during the gel-glass-crystal transformation has
been followed as a function of both temperature and
compostion. Aluminum is octahedrally coordinated in the
xerogel and on heating it is partially converted into
tetrahedrally coordinated A1 in the gel glass. Phosphorous
is present in metaphosphate units. The structure of
crystalline AIPO4 is shown to consist of an ordered covalent
network involving [PO4/2 ]+ and [A104/2]- units.
