Low-Temperature Synthesis of Vanadium Dioxide Thin Films by Sol-Gel Dip Coating Method

Abstract

The vanadium dioxide (VO2) thin films were synthesized by sol-gel dipping on a glass slide substrate at low temperature of 500°C in a vacuum tube furnace at a pressure of 2 × 10−3 mbar by 2-step calcination without an intermediate gas purging. Synthesis conditions, including temperature, vacuum pressure, and calcination steps in the vacuum tube furnace, were investigated to find the optimum condition that promoted the formation of VO2 phase. It was found that the 2nd calcination step was very important in realizing the monoclinic vanadium dioxide (VO2 (M)). The results of the valence electron analysis revealed the outstanding phase of VO2 and a small amount of V2O5 and V2O3 phases. The small crystallites of the VO2 were homogeneously distributed on the surface, and the grain was of an irregular shape of ∼220−380 nm in size. The film’s thickness was in a range of 69−74 nm. The film exhibited a metal-to-insulator transformation temperature of ∼68oC and good thermochromic property. Visible optical transmittance remained at ∼40−50% when the sample’s temperature changed from 25 to 80°C for a near infrared (NIR) region.

Perspective Chapter: Sol-Gel Science and Technology in Context of Nanomaterials – Recent Advances

“…Metal oxides, nitrides, and carbides are just a few examples of ceramic materials that are commonly prepared using sol-gel techniques [12][13][14][15][16][17]. This method has a number of benefits over traditional processing technologies [18][19][20][21], including low reaction temperatures [5,[22][23][24][25][26][27], precise composition control [28,29], high levels of purity [30][31][32], and the capacity to create processes for large-area applications [33][34][35][36][37][38][39][40][41]. The key steps of the reaction are the hydrolysis and condensation of an inorganic or metal-organic precursor, which produces a sol that, following a series of chemical reactions and/or mild thermal treatments, transforms into a gel, which is then calcined to produce the end product.…”

Fabrication of vanadium dioxide thin films and application of its thermochromic and photochromic nature in self-cleaning: A review

“…These made them more suitable for energy saving and smart window uses. Studies on the influence of hydrogenation, 9 optical phase transition properties, [10][11][12] effect on deposition temperatures, 13,14 and thermal properties of VO 2 thin films [15][16][17] have also been carried out While VO 2 has attracted significant interest as a diverse inorganic material for energy-saving and innovative appliance applications, the experimental construction of pure thermochromic VO 2 is very difficult. It is still complicated to prepare a stable thermochromic VO 2 structure free of impurities in bulk quantities due to their low redox stability, multivalent character, and many oxidation states.…”

“…These made them more suitable for energy saving and smart window uses. Studies on the influence of hydrogenation, 9 optical phase transition properties, 10–12 effect on deposition temperatures, 13,14 and thermal properties of VO 2 thin films 15–17 have also been carried out…”