DOE OSTI2018
Highlights: • TGA-DSC was used to determine the annealing temperature generally. • Pure VO{sub 2} (M) film was obtained with some annealing process. • The film surface transits from layer to grains as the annealing temperature increases. • Spans of O1s and V2p{sub 3/2} core level of V{sup 5+}, V{sup 4+}, V{sup 3+} were 12.75, 14.0 and 14.7 eV. • The Tc of pure VO{sub 2} (M) was 64.3 °C, its hysteresis loop width was 12.1 °C. - Abstract: V{sub 2}O{sub 5} was used to prepare vanadium oxide films via the sol-gel method. The “n” in V{sub 2}O{sub 5}∙nH{sub 2}O was determined to be approximately 1.67. After annealing at 390 °C for 4 h, a pure VO{sub 2} (M) phase was obtained and denoted sample Ⅴ. The crystallite sizes of VO{sub 2} (M) in samples Ⅱ, Ⅲ, Ⅳ and Ⅴ were 42, 41, 35 and 24 nm, respectively. The surface morphology of sample Ⅰ was flat; however, many small, dense particles covered the surface of sample Ⅴ. Sample Ⅱ had a layered structure, and samples Ⅲ and Ⅳ consisted of compact grains. The binding energy (BE) differences between the O1s and the V{sup 5+}2p{sub 3/2}, V{sup 4+}2p{sub 3/2}, and V{sup 3+}2p{sub 3/2} core levels were 12.75, 14.0 and 14.7 eV, respectively. For the sample Ⅴ film, the maximum transmittance change at 2500 nm was 39%, the phase transition temperature (Tc) was 64.3 °C, and the hysteresis loop width was 12.1 °C.