Fabrication of porous thick films using room-temperature aerosol deposition

Abstract

A novel technique for the rapid room-temperature deposition of porous ceramic, glass, or metal thick films using the aerosol deposition (AD) method is presented. The process is based on the co-deposition of the desired film material and a second water-soluble constituent, resulting in a ceramic-ceramic composite. Following the subsequent removal of water-soluble end member, a network of pores is retained. To demonstrate the process, porous BaTiO3 thick films were fabricated through co-deposition with NaCl. Microstructural images show the clear development of a porous structure, which was found to enhance the dielectric properties over dense thick films, possibly related to the lower extent of internal residual stress. This simple but highly effective porous structure fabrication can be applied to any film and substrate material stable in water and is promising for the application of AD-processed films in gas sensors, solid oxide fuel cells, and humidity sensors.