Phase Change Kinetics of Vanadium Dioxide Thin Film Prepared by Sol–Gel Deposition

Abstract

VO 2 is an attractive material for sustainable smart window applications due to its unique near-infrared light modulation capabilities; however, its energy efficiency is affected by its phase transition behavior of different forms. In this work, we first obtained high-quality VO 2 films by a facile sol−gel method followed by dip-coating and then thoroughly investigated the phase transition kinetics of the VO 2 thin films using an in situ XRD technique. Two phase transition kinetic models have been established and compared. The first based on the JMAK theory shows that, upon heating, monoclinic VO 2 started to transfer to rutile VO 2 phase transition at about 70 °C with an activation energy of 392.4 kJ/mol, and upon cooling the critical temperature dropped dramatically to about 45 °C with an activation energy of 126.0 kJ/mol, which is more suitable than the second model based on Kissinger's theory. This study enriched the existing theoretical systems of VO 2 phase transition kinetics, bridged the gap in understanding the thin film kinetics, and provided support for wide thermochromic applications in the future.