溶胶-凝胶法制备纳米二氧化钛颗粒的研究

本文采用钛酸丁脂等原料,利用sol-gel方法制备了TiO2纳米颗粒.研究了不同实验顺序(滴入方式)和工艺参数对制备效果的影响.通过实验和对TiO2纳米粉末的TEM分析,获得了粒度(30-40nm)比较均匀的球型TiO2纳米颗粒.     

TiO2纳米薄膜的溶胶-凝胶工艺制备和表征

通过ｓｏｌ－ｇｅｌ工艺在普通钠钙玻璃表面制备了均匀透明的锐钛矿型ＴｉＯ２纳米薄膜,ＴｉＯ２薄膜的Ｘ射线衍射分析表明,当薄膜的厚度小于０．４６μ时,薄中未出现锐钛矿的衍射峰,随着镀膜次数或薄膜厚度的增加,薄膜中ＴｉＯ２纳米微晶的平均晶粒大小逐渐增大,ＴｉＯ２薄膜的透光率略有减小,其吸收阈值发生了明显的红移,ＸＰＳ实验结果表明：薄膜中除含有Ｔｉ、Ｏ元素外,还有一定量来自有机前驱物中未完全燃烧的碳和少量     

溶胶-凝胶法制备改性TiO2纳米薄膜及其防腐蚀性能

应用溶胶-凝胶法和浸渍提拉技术在316L不锈钢表面分别制备TiO2纳米膜和 B-Fe-Ce改性的TiO2纳米膜. 采用场发射扫描电子显微镜(FE-SEM)、原子力显微镜(AFM)、拉曼光谱法和能量分散谱(EDS)对薄膜进行表征,通过电化学阻抗谱(EIS)和动电位阳极极化曲线的测试考察薄膜的耐蚀性及对不锈钢的保护性能. 结果表明:两种纳米薄膜均含锐钛矿型的TiO2纳米颗粒,纯TiO2纳米膜与改性后的纳米膜中颗粒直径分别约为15和10 nm. TiO2/316L不锈钢和 B-Fe-Ce-TiO2/316L不锈钢膜电极浸泡在0.5 mo.lL-1 NaCl溶液后,后者的电化学反应电阻较大,动电位阳极极化曲线的稳定钝化区较宽,击穿电位更高,说明改性的纳米膜的耐蚀性及其保护性能更好.     

TiO2纳米薄膜的溶胶-凝胶工艺制备和表征

通过sol-gel工艺在普通钠钙玻璃表面制备了均匀透明的锐钛矿型TiO2纳米薄膜.TiO2薄膜的X射线衍射分析表明,当薄膜的厚度小于0.46μm时,薄膜中未出现锐钛矿的衍射峰.随着镀膜次数或薄膜厚度的增加,薄膜中TiO2纳米微晶的平均晶粒大小逐渐增大,TiO2薄膜的透光率略有减小,其吸收阈值发生了明显的红移.XPS实验结果表明：薄膜中除含有Ti、O元素外,还有一定量来自有机前驱物中未完全燃烧的碳和少量从玻璃表面扩散到薄膜中的Na和Ca元素.     

NMP中制备TiO2溶胶及其凝胶化

溶胶-凝胶过程;NMP中制备TiO2溶胶及其凝胶化     

溶胶-凝胶法制备TiO2/玻璃膜和光催化降解玫瑰红B的研究

溶胶-凝胶法制备TiO2/玻璃膜和光催化降解玫瑰红B的研究     

溶胶-凝胶法制备纳米二氧化硅微球

在不同醇介质中,以氨水作为催化剂,正硅酸乙酯为硅源,利用溶胶-凝胶法制备了单分散纳米SiO2微球,利用激光粒度仪得到了微球粒径,利用扫描电镜得到了SiO2形貌,用能谱仪进行了元素成分分析。研究表明,随着氨水用量提高,溶液中OH-浓度增大,SiO2微球粒径增大;随着水用量增加,SiO2粒径有所增大,当水量太多时,粒径反而有下降趋势;在不同介质中,随着烃基中碳数和粘度改变,SiO2粒径会呈现不同变化。     

溶胶凝胶法制备纳米LiCoO2

纳米微粒;放电初容量;循环稳定性;溶胶凝胶法制备纳米LiCoO2     

溶胶-凝胶自蔓燃法制备铁掺杂纳米TiO2光催化剂

为了研究溶胶-凝胶自蔓燃法（SHS）制备的铁掺杂纳米TiO2的光催化活性,以TiCl4为原料制备了Fe3+掺杂TiO2光催化剂,分别在低压汞灯、中压汞灯和太阳光照射下进行了亚甲基蓝降解实验。 XRD和SEM显示,以TiCl4为前驱体,n(Ti)∶n(柠檬酸)∶n(NH4NO3)=1∶3∶5,经250 ℃自蔓燃和500 ℃热处理后,TiO2呈疏松、多孔的灰白色锐钛型粉体,粒径约为20 nm;在不同光源作用下,掺铁摩尔分数为0.02%的TiO2催化活性均最大;亚甲基蓝溶液在掺铁分数为0.02%的TiO2作用下,经太阳光照90 min后降解率达到了96.1%,为纯TiO2的1.78倍。     

Biological activity of functionalized SiO2 thin films prepared by sol-gel method

In this work we investigated the biological properties of sol-gel films in aqueous medium. Functionalized silica films were prepared by the sol-gel process, from organically modified silicon alkoxides with amino or thiol groups. Covalent binding of proteins with different orientations according to the hydrophilic or hydrophobic character of the surface was studied. This binding occurred via a covalent coupling agent providing a very stable linkage. No denaturation was detected and a good detection of the antigen was observed. Immunoassays have demonstrated the biological activity of grafted antibodies.     

Anatase TiO2 porous thin films prepared by sol-gel method using CTAB surfactant

Anatase TiO₂ porous thin films were prepared on glass substrates by sol-gel method with Cetyltrimethylammonium Bromide (CTAB) as a pore-forming agent, Tetrabutylorthotitanate as Ti precursor, ethanol as solvent and diethanolamine as chelating agent respectively. IR, TG-DSC, XRD and SEM analyzed the chemical and physical changes during sol-gel process and characteristics of the films. Effects of the amount of CTAB, alkane and water on morphology of the films were discussed and the principle of forming porous structure was proposed. It was shown that the diameter of pores was changed in the range of 30–400 nm.     

Understanding and improving the deposition conditions of SiO2 thin films obtained by ultrasonic sol-gel procedure

Sol-gel deposition of an ultrasonically atomized aerosol has been proven to be a convenient thin film deposition method. Flexibility of the ultrasonic process allows the use of a large range of source solutions. In this paper we describe and discuss the deposition conditions of SiO₂ films. The chemical parameters are contemplated and we discuss the influence of ultrasonic waves on the reliability of our process. Source solutions and SiO₂ film properties are studied by viscosimetry, Fourier Transform IR spectroscopy and spectroscopic ellipsometry.     

Direct crystallization of perovskite phase in PMN-PT thin films prepared by polyvinylpyrrolidone modified sol-gel processing and their properties

A modified sol-gel processing has been developed by using polyvinylpyrrolidone (PVP) as modifier and lead nitrate as lead source to synthesize (1−x)Pb(Mg_1/3,Nb_2/3)O₃-xPbTiO₃ (PMN-PT) thin films with x=0.23-0.43. With PVP additions, perovskite phase could directly crystallize from amorphous films at the temperature as low as 430 °C via bypassing the metastable phase-pyrochlore and crystallinity was significantly enhanced. The PVP addictives have been optimized with molecular weight <630 K and the ratio of PVP monomer/PMN-PT at 0.25-1.0. XPS analysis indicates that the chemical states of the elements in the well-crystallized PMN-PT films are close to the literature data for the PMN-PT single crystals and the films possess highly desired electrical and optical properties.     

Electrochemically induced sol-gel deposition of zirconia thin films

A novel electrochemical method for deposition of ZrO(2) thin films is described. The films, 50-600 nm thick, were obtained by applying moderate positive or negative potentials (+2.5 V to -1.5 V versus SHE) on conducting surfaces immersed in a 2-propanol solution of zirconium tetra-n-propoxide [Zr(OPr)(4)] in the presence of minute quantities of water (water/monomer molar ratios in the range of 10(-5) to 10(-1)), which was the limiting reagent. Oxidative electrochemical formation of solvated H(+) and reductive formation of OH(-) catalyze the hydrolysis and condensation of the metal alkoxide precursor. The magnitude of the applied potential and its duration provide a convenient way of controlling the film thickness. The films consist of an amorphous phase, as revealed by XRD measurements. The effects of different parameters, such as the applied potential and its duration, the amount of added water and the current-time characteristics, were studied. A mechanism for the electrodeposition of the zirconia films which is in accordance with our findings is proposed.     

Ruthenium-doped sol-gel derived silica films: Oxygen sensitivity of optical decay times

Sol-gel silica thin films, produced by a dip-coating process, were impregnated with the complexes Ru(bpy) ₃ ²⁺ and Ru(Ph₂phen) ₃ ²⁺ . For each complex ruthenium fluorescence was quenched in the presence of oxygen. Intensity and decay time Stern-Volmer plots were produced for both complexes. The optical decay times were analysed in terms of one quenched and one unquenched component, the latter arising from the fraction of complex molecules which are inaccessible to oxygen. All the data were consistent with the predominance of dynamic quenching in these systems. The feasibility of an oxygen sensor based on decay times was discussed.     

The morphological,optical and electrical properties of SnO2:F thin films prepared by spray pyrolysis

Combining the spray pyrolysis and the sol–gel techniques gives the possibility to produce Fluorine doped Tin oxide (SnO₂:F) thin films. Transparent conducting SnO₂:F thin films have been deposited on glass substrates by the spray pyrolysis technique. This technique for the fabrication of SnO₂:F filmsby combining sol–gel process and the spray pyrolysis technique ispresented in this paper. The Sol–gel precursors have been successfully prepared using SnCl₂·5H₂O and (Ac)F₃. The structural, electrical, and optical properties of these films were investigated. The high resolution transmission electron microscopy (HRTEM) and selected area diffraction (SAD) patterns of SnO₂:F films show that the gel films lead to a tetragonal structure. The X‐ray diffraction pattern of the films deposited at substrate temperature 530° , the orientation of the films was predominantly [110]. In addition, the surface chemical components were also examined by X‐ray photoelectron spectroscopy (XPS) showing the SnO₂:F deposited with the atomic concentration ratios Sn/F 1.82:1. The minimum sheet resistance was 50 Ω and average transmission in the visible wavelength range of 300 to 800 nm was 87.25%. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis of TiO2 thin film by a modified sol-gel method and properties of the prepared films for photocatalyst

PTA (peroxo titanic acid) gel was prepared by a modified sol-gel method from peroxo titanic acid using TiCl₄/ethanol/water solution as the starting material at room temperature. Physicochemical properties of heat-treated gel were characterized by IR, XRD, TG-DTA and SEM. Optimal preparing conditions were chosen to prepare anatase film for the photocatalytic degradation of methyl orange. The dip-coating technique was used to synthesis the supported anatase film on quartz glass. Photocatalytic efficiency for the degradation of methyl orange under UV irradiation was also examined. It was found that the degradation efficiency of the anatase film synthesized in this paper is higher than commercial titania P25.     

Effect of post-metallization annealing on the ferroelectric properties of sol-gel derived PZT thin films

A series of monolithic Pt-PZT-Pt capacitors was prepared based on sol-gel derived PZT 53/47 films fired to 700 C. After deposition of top Pt electrodes, the capacitors were subjected to post-metallization annealing (PMA) temperatures of 100 C to 700 C. Dielectric and ferroelectric (FE) characterizations were performed. Increasing the PMA temperature produced lower values of spontaneous and remanent polarizations, dielectric constant and leakage currents. The observations are correlated with a proposed FE capacitor model.     

Investigation of thin surface films by microprobe analysis

The electron microprobe has been applied to study thin films on metallic substrates. The intensities of the characteristic X-rays emitted by thin films of various elements and thicknesses on sublayers of different materials were measured. Two different theoretical approaches (Bishop and Poole, as well as Yakowitz and Newbury) were applied to interpet the X-ray intensities and to determine the film thickness from the intensity measurements. The effect of backscattering from the substrate, resulting in an increase of the intensity of characteristic X-rays of the film, is being described on the basis of a theory given by Hutchins. The corresponding equation for the backscattering factor has been modified to take into account the transmission of the electrons through the film, depending on the mass thickness of the film and the electron energy. The results obtained from theory and experiment are in good agreement for the different experimental parameters applied, except for very thick layers of high atomic numbers measured at low energies where the absorption of electrons in the film plays a dominant role.