Hydrothermal synthesis and thermochromism effects in Eu-doped VO 2 polycrystalline materials

M phase Eu-doped VO 2 powders were prepared by a hydrothermal method followed by post annealing. The semiconductor–metal transition (MIT) properties of the produced samples were studied by Raman spectroscopy, infrared transmittance and resistance measurements. The results indicated that a low dose of Eu doping in VO 2 induces an enhanced switching ability of its infrared transmittance as the MIT occurs, and the ∆T r is 48% at 1000 cm −1 when the dose of Eu doping is 6%. Moreover, a low dose of Eu doping in VO 2 results a better crystal quality. While a high dose of Eu doping induces enhanced tensile stress in VO 2 , resulting in the formation of the M 2 phase of VO 2 at room temperature. These results suggested that Eu is a particularly effective dopant in the synthesis of high-quality M phase VO 2 . Thus, Eu doping in VO 2 is a distinctive strategy for realizing M phase VO 2 materials that have extensive applications in the construction of smart window coatings. Possible mechanisms of Eu doping in VO 2 are discussed.