Phase-controlled preparation of TiO₂ films and micro(nano)spheres by low-temperature chemical bath deposition

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• 作者：Mingsong Wang ; Qihui Li ; Haiyan Yu ; Seung Hyun Hur ; Eui Jung Kim
• 关键词：Thin films ; TiO2 ; Chemical bath deposition ; Crystalline phase
• 刊名：Journal of Alloys and Compounds
• 出版年：2013
• 出版时间：25 November, 2013
• 年：2013
• 卷：578
• 期：Complete
• 页码：419-424
• 全文大小：2752 K

文摘

TiO₂ films and micro(nano)spheres have been simultaneously prepared by means of low-temperature chemical bath deposition (CBD). The films and precipitates are found to be constructed of the same building blocks regardless of the bath conditions. Thin nanosheets of ca. 20 nm in thickness serve as the building blocks of rutile TiO₂ grown in an acidic bath. They aggregate to form spheres to reduce the surface energy of the precipitates, while in the films they grow into discrete crystallites on the seeded substrate. Fine control over the crystalline phase of TiO₂ is achieved by replacing some water with ethanol or the addition of NH₄F. A gradual transition from rutile to anatase is observed as the ethanol and NH₄F contents are increased. Moreover, the crystallite size of TiO₂ is significantly reduced and there exists monodisperse nanoparticles and aggregate microspheres in the products modified with ethanol and NH₄F, respectively. This size-dependent phase transition is consistent with previous theoretical and thermodynamic studies. The facile tune of the TiO₂ phase by low-temperature CBD method may be useful to improve the performance of TiO₂ for its various applications.