Silicalite-1 films with preferred orientation

Smooth and homogeneous monolayer Silicalite-1 seeds were deposited on silicon substrate surfaces via the Langmuir-Blodgett (LB) technique. The LB films were prepared by vertical dipping leaving part of the substrate uncoated. Neither substrate modification nor additives were required to produce densely packed monolayer seeds. The degree of coverage and packing of the seed layers were dependent on the target pressure used for film deposition. Dense Silicalite-1 films with controlled thickness in the range 100-650 nm were synthesized after secondary synthesis. The (0k0) reflections dominated in all the XRD patterns, suggesting that the prepared polycrystalline films were preferentially b-oriented perpendicular to the substrate surface. The degree of in-plane orientation was preserved with increasing film thickness. All secondary growth films were very smooth with a clear boundary between the seeded and non seeded substrate sections. The Silicalite-1 films were highly stable upon both ultrasonic treatment and calcination. (C) 2008 Elsevier Inc. All rights reserved.