The effects of microstructure on optical and thermal properties of porous silica films

In this study, two types of silica coating glass, namely aerogel coating glass and mesoporous silica coating glass, were prepared by sol-gel method, and their microstructure, optical and thermal properties were investigated and compared. The results show that both coatings gained porous structure, with porosity of 88% and pore size ranged from 20-100 nm for aerogel, and porosity of 7.14% and pore size around 3 nm for mesoporous silica coating. With thickness close to that of aerogel, mesoporous silica coating which has better ordered pore arrangement and uniform pore size exhibits higher transmittance in visible light region and lower thermal conductivity than aerogel coating does, though its porosity is smaller.