Preparation and characterization of titania thin films from aqueous solutions

Dip- or spin-coating and characterization of titania (TiO2) thin films from various aqueous solutions have been studied. The aqueous titanium solutions mainly used in this study were halogen- and chelate-free solutions with the concentrations up to 1.4 M derived from titanium isopropoxide (TIP) with...

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Bibliographic Details
Published in:Journal of sol-gel science and technology 2003, Vol.26 (1-3), p.799-802
Main Authors: OHYA, Tomokazu, NAKAYAMA, Aki, SHIBATA, Yukio, BAN, Takayuki, OHYA, Yutaka, TAKAHASHI, Yasutaka
Format: Article
Language:English
Subjects:
Alkanolamines
Alkylamines
Anatase
Aqueous solutions
Carbon
Chelates
Chelation
Chemistry
Citric acid
Crystallization
Elements and non-metal compounds (oxides, hydroxides, hydrides, sulfides, carbides, ...)
Exact sciences and technology
Film thickness
Immersion coating
Inorganic chemistry and origins of life
Lactic acid
Preparations and properties
Refractivity
Spin coating
Substrates
Sucrose
Thin films
Titanium
Titanium dioxide
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Summary:Dip- or spin-coating and characterization of titania (TiO2) thin films from various aqueous solutions have been studied. The aqueous titanium solutions mainly used in this study were halogen- and chelate-free solutions with the concentrations up to 1.4 M derived from titanium isopropoxide (TIP) with tetramethylammonium hydroxide (TMAOH) or some alkylamines, while aqueous and alcoholic solutions containing titanium atoms stabilized chelating ligands were examined for comparison. The TiO2 films prepared from the TIP-TMAOH solution were already crystallized at 350°C to anatase form and those formed at 600°C had high transparency and refractive indices of 2.40. No carbon residue in the film prepared at 400°C was detected by XPS. The pure anatase form was sustained up to 850°C. Interestingly, it was found that the (004) preferentially oriented anatase films were obtained from TIP-lactic acid (LA) system until 700°C. The solutions containing citric acid (CA) or alkanolamines yielded anatase and rutile form fired at the temperatures equal to or higher than 600°C. Carbon residue was detected in the film fired at 400°C. The film thickness monotonically decreased from the upper to the bottom ends of the substrate. However, it was found that the thickness uniformity was drastically improved by an addition of sucrose to the aqueous solutions. The effects of the solution composition and polyhydroxy compounds on the crystal modifications of formed films and the film uniformity are discussed.
ISSN:0928-0707
1573-4846
DOI:10.1023/a:1020783113661