Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published December 27, 2000 | public
Journal Article

Spontaneous Formation of Periodically Patterned Deposits by Chemical Vapor Deposition

Abstract

Patterns of colloidal origin that are formed in ionic precipitation-diffusion systems and are known as Liesegang Rings (LR) have fascinated researchers since the beginning of the century and have been the subject of numerous theoretical, numerical, and experimental studies. The terms recurrent, rhythmic, or periodic precipitation are often used to describe the temporal pattern evolution in such systems. Pattern formation in the vapor phase reaction of NH_3 and HCl has also been reported since 1930. It has been suggested that any reaction giving an insoluble product is capable of LR pattern formation. However, the potential of such self-organized deposition for the fabrication of materials (other than NH_4Cl) from vapor precursors has not been demonstrated. Moreover, reproducible LR patterns are usually characterized by uneven spacing (Matalon-Packter law) and band thickness, although nearly periodic patterns have been reported as well. Here we propose, for the first time, a connection of LR phenomena, with the spontaneous (i.e., involving no external concentration, temperature, or other parameter forcing) formation of micrometer size periodic stripes of nanocrystalline titania deposited in mesoporous glass by counter diffusion chemical vapor deposition (CVD) using titanium chloride and water.

Additional Information

© 2000 American Chemical Society. Received June 22, 2000. M.T. acknowledges support from a NSF CAREER Award, a David and Lucile Packard Foundation Fellowship in Science and Engineering, and a Henry and Camille Dreyfus Teacher-Scholar Award. M.T. and D.G.V. thank Prof. H. K. Henisch for stimulating their interest in LR phenomena.

Additional details

Created:
August 19, 2023
Modified:
October 24, 2023