Growth of oriented molecular sieve thin films from aligned seed layers

Oriented aluminum phosphate five (AlPO4-5) molecular sieve thin films were grown onto glass surfaces seeded with aligned AlPO4-5 crystals. The novel aligned seed layer was formed by depositing rod-shaped seed crystals from a colloidal suspension under an electric field. Alignment of the seed layer promotes adhesion of the seed crystals to the underlying substrate and enhances surface nucleation and growth to allow secondary crystallization of oriented thin films. There was no correlation between the crystal orientation of the seed layer and the orientation of the secondary crystals grown in the thin film. The orientation of the secondary crystals could be varied from parallel to perpendicular to the underlying seed layer depending on the synthesis conditions. The technique presented here offers a novel method for growing oriented molecular sieve membranes that are useful for separations and catalysis.