Synthesis and Structure of Large AlPO4-5 Crystals

Large, high quality, perfect hexagonally shaped AlPO 4 -5 crystals have been crystallized using hydrothermal synthesis. The crystallization was carried out at 447 or 457 K with a crystallization time from one to four days and tripropylamine (TPA) molecules as template. The morphology of the crystals was observed with SEM. For the first time, the structure of the AlPO 4 -5 crystal together with TPA template molecules has been successfully refined in space group P6cc by single crystal X-ray diffraction. The parameters are a = b = 13.725(3) Å, c = 8.473(3) Å, and γ = 120.0 ∘ . The size of some crystals is up to 2.2 mm in c direction, or up to 0.31 mm in a or b direction. All observed angles and distances are within acceptable ranges: P–O = 1.50–1.54 Å, Al–O = 1.62–1.72 Å, O–P–O = 107–111 ∘ , O–Al–O = 103–113 ∘ and P–O–Al = 147–150 ∘ .