Abstract: Polycrystalline tungsten oxide films with good electrochemical stability were prepared by dc reactive sputtering methods. The Raman spectra of the films show that W6+ is reduced to W⁵⁺ with Li⁺ and electrons co-intercalation. Intercalated electrons entere extended states of crystalline tungsten oxide and cause infrared reflectance. The emissivity of WO₃/ITO/Glass can be reversible modulated between 0.261-0.589.

Key words: dc reactive sputtering, polycrystalline tungsten oxide films, infrared reflectance