AlPO₄-18 Seed Layers and Films by Secondary Growth

AlPO 4 -18 layers were prepared on Si wafers via spin-coating or the Langmuir−Blodgett (LB) method using nanosized crystals. Multilayers were deposited by spin-coating, whereas the seeds assembled by the LB technique were monolayers. The seeded layers were not stable upon secondary growth under microwave radiation, and no films were formed on the supports. Dense AlPO 4 -18 films could be obtained by secondary growth after stabilization of the seed layers by adding prehydrolyzed tetraethylorthosilicate (TEOS) to the colloidal AlPO 4 -18 suspension prior to support seeding. The stabilized seed layers and the grown AlPO 4 -18 films were stable. The structure and the morphology of the films grown using the two types of seeded supports were similar, independent of the method used for seeding. The AlPO 4 -18 nanocrystals used for seeding showed very high water capacity with low temperatures of water removal when heated. The layers and films prepared are of potential interest for sensing, heat pump, and cooling machines applications.