2024-03-28T12:00:16Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/739452022-11-17T02:08:08Zhdl_2115_20045hdl_2115_139External-Field Hot-Water Treatments of Sol-Gel Derived SiO2-TiO2 Coatings for Surface Nanostructure Control : A Review外部場温水処理によるゲルーゾルSiO2-TiO2系コーティング膜の表面ナノ構造制御 : 総説MATSUDA, Atsunori松田, 厚範SAKAI, Mototsugu逆井, 基次KOGURE, Toshihiro小暮, 敏博1000090244657TADANAGA, Kiyoharu忠永, 清治TATSUMISAGO, Masahiro辰巳砂, 昌弘open accessCreative Commons Attribution-NoDerivatives 4.0 InternationalExternal fieldSol-gel coatingHot-water treatmentTitaniaNanosheetNanocrystal573This review paper is focused on the area of titania nanocoatings prepared from sol-gel derived films by hot-water treatment under external reaction fields to design their functionality through the control of their surface morphology and crystallinity at low processing temperatures. First, the formation of titania nanocrystalline coatings at low temperatures by wet chemical procedures is briefly reviewed. Second, a concept of material design based on an external-field hot-water treatment for sol-gel derived films and the effects of the external fields on the formation of titania nanocrystals from the sol-gel derived films are discussed. Finally, promising characteristics of the resultant titania nanocrystal-dispersed coatings with unique morphology are described. External fileds of vibrations and electric voltages affect the nanostructure of titania crystallites formed on SiO2-TiO2 gel coatings during hot-water treatment. Without the external fields granular anatase nanocrystals of 30-50 nm in size are formed on the coatings during the hot-water treatment, whereas the shape of the precipitates becomes sheetlike by applying a vibration to the substrate during hot-water treatment. Similar changes in shape of the precipitates on the coatings are also observed, and ramiform (branchlike) crystallites are formed at the negative electrode by applying an electric field between the substrates. The sheetlike and ramiform crystallites are mainly composed of a hydrated titania, m(TiO2)•nH2O, with the lepidocrocite-like layered structure with a d-spacing of 0.6-0.8 nm. Titania nanosheets are characterized by a large surface-to-volume ratio, which gives rise to the excellent wettability for water and antifogging properties. Processing temperatures for the preparation of the coatings are lower than 100°C under atmospheric pressure, so that the coatings have a great potential for applications to various substrates including organic polymers with poor heat resistance.Ceramic Society of Japan日本セラミックス協会2006-01engjournal articleVoRhttp://hdl.handle.net/2115/73945https://doi.org/10.2109/jcersj.114.260914-54001348-6535AN10040326Journal of the Ceramic Society of Japan日本セラミックス協会学術論文誌11413252635https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/73945/1/JCS114.26-35.pdfapplication/pdf1.68 MB2006-01