The degradation of the electrochromism of amorphous
WO3
and
WO3‐TiO2
films prepared by electron‐beam deposition have been studied. The lifetime of the
WO3‐TiO2
films is five times longer than that of the
WO3
films. SIMS and XPS analyses have revealed that lithium accumulates as OLi in the
WO3
films, but that it cannot accumulate in the
WO3‐TiO2
film. O1s electron energy loss spectroscopy (EELS) spectra have indicated that the change of the electronic structure for the
WO3‐TiO2
film by coloration is smaller than that for the
WO3
film. The increase of plasmon energy has been obtained in low loss EELS spectrum and the increase of the bond length in the
WO3‐TiO2
film has been measured by Raman spectrum. From these results, the number of the defect bonds as a trapping site of lithium is reduced and the bond length of W‐O decreases in the
WO3‐TiO2
films. We conclude that lithium cannot accumulate in the structure of the
WO3‐TiO2
film and that the structure gives a prolonged lifetime to the electrochromism.