Structural Changes of Sol–Gel‐Derived TiO 2 –SiO 2 Coatings in an Environment of High Temperature and High Humidity

Structural changes in sol–gel‐derived TiO 2 –SiO 2 coatings were found to proceed in an environment of high temperature and high humidity as follows: (1) dissociation of Si–O–Ti bonds in the coating by the attack of water vapor, (2) formation of Ti–O–Ti bonds, and (3) nucleation and growth of anatase TiO 2 . The coating obtained with the addition of poly(ethylene glycol), PEG, reacts with water vapor more easily than the coating obtained without PEG, since the former is more porous than the latter due to the decomposition of PEG during heat treatment.