Thermochromic properties of vanadium oxide films prepared by dc reactive magnetron sputtering

A transparent vanadium oxide film has been one of the most studied electrochromic (EC) and Thermochromic (TC) materials. Vanadium oxide films were deposited at different substrate temperatures up to 400 °C and different ratios of the oxygen partial pressure (P O2 ). SEM, AFM and X-ray diffraction's results show detail structure data of the films. IR mode assignments of the films measured by IR reflection-absorbance in NGIA (near grazing incidence angle) are given. It is found that the film has V 2 O 5 and VO 2 combined structures. The films exhibit clear changes in transmittance when the environment temperature (T e ) is varied, especially in the 3600-4000 cm -1 range. Applying a T e that is higher than a critical temperature (T c ) to the samples, the as-RT (room temperature) deposited film with 9% P O2 has a transmittance variation of 30%, but the films that were deposited on a heated substrate of 400 °C have little variation. There is tendency of bigger variation in transmittance for the sample deposited at a larger P O2 , when it is applied by 200 °C Te.