Sol–gel synthesis and characterization of silica film with two opposite structures: Nano-porous and protuberant

Porous silicon films are currently under intense investigation for optical, thermal and electronic applications. In this work, the silica films have been prepared by an acid one-step and acid-base two-step catalytic sol–gel process using a CTAB template. The effects of the catalysis on the structure of films were investigated. The chemical and physical changes during sol–gel process were analysed using DSC-TGA and FTIR. The structure and morphology of films were characterized by XRD and AFM. The experimental results show that the films fabricated from the different catalyzed sols have two opposite structures: nano-porous and protuberant surface. The porous silica film (mean pore size 10 nm) is about 500 nm thick. The height of particles on the protuberant film ranges from a dozen to decades. The discovery of two opposite structures of silica films is a help to development of some films with different application properties dependant on their structures.