Effects of the annealing process on the structure and valence state of vanadium oxide thin films. (April 2018)

• Record Type: Journal Article
• Authors: Li, Yuanbao; Liu, Juncheng; Wang, Danping; Pan, Guangyou; Dang, Yuanyuan
• Is Part Of: Materials research bulletin. Volume 100(2018)
• Page Start: 220
• Page End: 225
• Publication Date: 2018-04
• Subjects: Vanadium oxide film -- Valence states -- Thermochromic properties -- Sol-gel; Materials -- Periodicals; Crystal growth -- Periodicals; Matériaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Crystal growth; Materials; Periodicals; 620.11
• DOI: 10.1016/j.materresbull.2017.12.028
• Languages: English
• ISSNs: 0025-5408

Abstract

Graphical abstract: Highlights: TGA-DSC was used to determine the annealing temperature generally. Pure VO2 (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 V2p3/2 core level of V 5+, V 4+, V 3+ were 12.75, 14.0 and 14.7 eV. The Tc of pure VO2 (M) was 64.3 °C, its hysteresis loop width was 12.1 °C. Abstract: V2 O5 was used to prepare vanadium oxide films via the sol-gel method. The " n " in V2 O5 ∙ n H2 O was determined to be approximately 1.67. After annealing at 390 °C for 4 h, a pure VO2 (M) phase was obtained and denoted sample Ⅴ. The crystallite sizes of VO2 (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 5+ 2p3/2, V 4+ 2p3/2, and V 3+ 2p3/2 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.