Peculiarities of the coordination state of the aluminum atoms in aluminophosphate AlPO₄-5

It has been established that in pattern-free hydrated AlPO4-5 crystals the water molecules are coordinated by more than half of the aluminum-oxygen tetrahedra. The fraction of the tetrahedra with different coordination of the aluminum atoms changes in the order Ald>Alt>Alo, where Ald is the fraction of the aluminum atoms that coordinate one water molecule, A1o two water molecules, and Alt is the fraction of the tetrahedrally coordinated aluminum.