Cellular patterns in organic-inorganic hybrid film

The formation of cellular patterns, known as "Benard cell", was investigated in organic-inorganic hybrid films under various conditions. The cells were observed in undoped-hybrid films, and its origin was attributed to the convection of TiO2 nanoparticles formed in the aging process of the sol. These cells showed the particular properties such as the difference between the center and its surrounding: the center showed a lower refractive index than that of the surrounding, a valley at the center with mountain-like surroundings, and a hydrophobic center and hydrophilic surrounding. How the cell patterns were formed depended on the conditions such as the atmospheric humidity and the gravity. It should be also noted that the cells on a silica glass substrate remained after 1000 degreesC heating.