2010 年 25 巻 2 号 p. 140-148
With the fabrication and processing of films produced by conventional liquid-phase deposition methods, the obtained film porosities are often limited due to the need of post-deposition heat treatment steps. This may lead to collapse of microstructures and detrimentally affect the open morphology of porous films. A novel alternative production method therefore is single-step, gas-phase aerosol deposition. This method has been shown to produce films with estimated porosities of up to 98 %, validated in numerical simulations. The key to synthesize highly porous films through this approach is the successful generation of nanoparticle aggregates, ensuring high specific surface area. Particle production is to be assisted by thermophoretic deposition for loose packings while maintaining a cooled substrate to hinder possible film sintering. Highly porous films have found challenging applications e.g. in gas sensing, and as a consequence, much work has focused on characterizing porous film properties and understanding the diffusion and gas transport through porous structures.
