Molten Salt Synthesis of an Open-Frame Aluminum Phosphate Ba3Al2P4O16 with a Rare-Pyramidal AlO5 Group.

A new open-frame aluminophosphate, Ba3Al2P4O16, was synthesized by a high-temperature flux method. Ba3Al2P4O16 features discrete [Al4P8O32]∞12- chains with rare square-pyramidal AlO5 groups adopted. Especially, this pyramidal AlO5 group acts as an ideal "plane builder" or "vacancy inducer" to construct open-frame structures compared with an ordinary trigonal-bipyramidal AlO5 group.