Synthesis of V-doped TiO₂ films by chemical bath deposition and the effect of post-annealing on their properties

详细信息	查看全文 | 推荐本文 |

• 作者：Denitsa Shopova-Gospodinova^a ; Lars P.H. Jeurgens^b ; Udo Welzel^b ; Luciana Pitta Bauermann^a ; Rudolf C. Hoffmann^a ; Joachim Bill^a ; ^{mwishopova@imw.uni-stuttgart.de}
• 关键词：Chemical bath deposition ; V4+-doped titanium dioxide ; Vanadium dioxide ; Band gap
• 刊名：Thin Solid Films
• 出版年：2012
• 期刊代码：78_00406090
• 类别：ph
• 出版时间：1 July, 2012
• 卷：520
• 期：18
• 页码：5928-5935
• 文件大小：1232 K

摘要

Amorphous composite films, composed of a Ti_{1 鈭?#xA0;x}V_xO₂ solid-solution phase and a V₂O₅ phase, were produced by chemical bath deposition and subsequently air-annealed at various temperatures up to 550 掳C. The microstructure and chemical composition of the as-prepared and annealed films were investigated by a combinatorial experimental approach using Scanning electron microscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy. Ultraviolet-Visible Spectrometry was applied to determine the optical band gap of the as-prepared and annealed films. It followed that the incorporation of vanadium in the as-deposited films reduces the optical band gap of TiO₂ from about 3.8 eV to 3.2 eV. Annealing of the films up to 350 掳C leads to slight increase of band gap, as attributed to a reduction of the defect density in the initially amorphous oxide films due to the gradual development of long-range order and a concurrent reduction of the V⁴⁺-dopant concentration in the Ti_{1 鈭?#xA0;x}V_xO₂ solid-solution phase. The films crystallized upon annealing in air at 550 掳C, which resulted in drastic changes of the phase constitution, optical absorbance and surface morphology. Due to the lower solubility of V⁴⁺ in crystalline TiO₂, V⁴⁺ segregates out of the crystallizing Ti_{1 鈭?#xA0;x}V_xO₂ solid-solution phase, forming crystalline V₂O₅ at the film surface.