Synthesis of large silicon substituted AlPO4-11 single crystals

We report the effects of gel composition and crystallization conditions on the hydrothermal synthesis of large silicon substituted AlPO4-11 single crystals (SAPO-11). Perfect large SAPO-11 single crystals with a typical dimension of 40 × 80 × 180 μm3 were synthesized by optimizing the following synthesis conditions: crystallization temperature and duration, molar ratio SiO2/Al2O3, amount of the organic template dipropylamine (DPA) and HF. Single-crystal X-ray diffraction measurement showed that the as-synthesized SAPO-11 single crystals are of space group Icm2 symmetry with lattice constants a = 13.384 Å, b = 18.60 Å and c = 8.414 Å, and their unit cell volume is V = 2094 Å3.

Graphical abstractLarge-sized SAPO-11 single crystals (40 × 80 × 180 μm3) have been successfully synthesized by hydrothermal method. Single-crystal X-ray diffraction show that the crystal is of Icm2 space group symmetry.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Adding SiO2 into reaction system not only influences the average size and morphology of SAPO-11 crystals, but also product purity. ► The F- ions in the gel are favorable for the formation of large single crystals with low aspect ratio of brachy pinacoid (010) face. ► The high DPA content can bring the crystals an opal color and the surface of the lager SAPO-11 single crystals becomes rough. ► Crystallization temperature has a pronounced effect on the size and structure of crystals.