二氧化钛超薄膜的组装

近年来LB膜技术和超微粒子研究的发展，将两者有效地结合起来组装了与量子电子学、非线性光学、光电化学、化学生物传感器有关的纳米量级无机半导体材料［‘－‘j．其中TIO。纳米薄膜材料已在太阳能电池反射膜、压电铁电薄膜、电致显示器件［‘j、可逆光电池和超导薄膜［’］研究中都显示了广阔的应用前景．这类薄膜制备多采用化学气相沉积（CVD）技术和原子层外延．也有人把LB技术应用于纳米粒子的组装来制备TIO。超薄膜［”’j二本文利用烷氧基钛在水／空气界面上发生的溶胶一凝胶化反应制备TIO。基胶态粒子及其固态凝聚膜，将其与…     

Photovoltaic Properties of Titanium Dioxide Nanowires with Different Crystal Structures

Titanium dioxide(TiO₂) nanowires with different crystal structures were successfully synthesized, and their charge transfer properties were further investigated by surface photovoltage(SPV), transient photovoltage(TPV) and surface photocurrent(SPC) techniques. The results reveal that both the surface states and the charge transfer rate of different TiO₂ nanowires are highly dependent on their crystal structures.     

紫外光照处理对TiO2膜光伏性能的影响

近年来人们利用纳米晶TiO2电极取代普通的TiO2电极[1],使其太阳能电池的光电转换效率得到很大提高.纳米晶TiO2电极具有大量表面态,在化学上表现为Ti3+或Ti—OH,对于光生电荷的分离过程和迁移过程有重要影响.这些表面化学结构的变化可能会导致TiO2的光伏性能的变化.1997年Fujishima等[2]用紫外光照射TiO2膜使它具有超亲水的性质,结构分析表明,超亲水的原因在于光照使TiO2膜的表面形成Ti—OH[3].因此,在光照处理的同时可能会导致TiO2的光伏性的变化.本文对紫外光照处理TiO2膜的光伏性能进行了研究,并结合光诱导TiO2的亲水性变化对光伏性能变化的原因进行了讨论.     

二氧化钛纳米晶薄膜的吸收光谱和激发发射光谱

由TiO₂反胶束溶胶制备一系列TiO₂纳米晶薄膜，对膜的吸收光谱和激发发射光谱研究表明制备的膜存在有二种模式的跃迁，直接跃迁和间接跃迁。由于厚膜中存在较强的表面相互作用，厚膜的直接跃迁禁带宽与薄膜相比发生了红移。在不同陈化时间，浸渍相同次数制得的膜具有相同的直接跃迁禁带宽。除浸渍一次的膜不存在间接跃迁外，所有的膜具有相同的间接跃迁禁带宽。所有的膜具有几乎相同的发射光谱模式。     

低银量掺杂TiO2纳米片薄膜的制备及其抗菌性能研究

采用溶胶凝胶和溶剂热两步法,在玻璃基底上垂直生长Ag-TiO₂纳米片薄膜.采用SEM、TEM、XRD、XPS等对样品进行表征,研究了不同前躯体浓度对Ag-TiO₂纳米片生长的影响,并检测了Ag-TiO₂纳米片薄膜的抗菌性能.结果表明,所获得的低银量掺杂改性的二氧化钛纳米片薄膜在紫外灯照射和黑暗条件下,对大肠杆菌和金黄色葡萄球菌均具有优异的抗菌性能.     

Lithium Intercalation into Titanium Dioxide Films from a Propylene Carbonate Solution

Intercalation of lithium from an LiClO₄ propylene carbonate solution into thin-film TiO₂ (rutile) electrodes produced by thermal oxidation of a titanium substrate are studied using cyclic voltammetry and impedance measurements at 0.01 to 10⁵ Hz. An equivalent circuit adequately modeling the impedance spectra of TiO₂- and Li _x TiO₂ electrodes throughout the frequency range studied is proposed. The electrochemical characteristics of film electrodes, the reversibility of intercalation-deintercalation process, the effect of surface passivation on the lithium transfer rate, and the dependence of electric, kinetic, and diffusion parameters on the electrode potential (composition) are discussed. The diffusion coefficient of lithium in Li _x TiO₂ is 10^–12 cm²/s, as estimated by the impedance method.     

Pulsed TEA CO2 Laser Irradiation of Titanium in Nitrogen and Carbon Dioxide Gases

Surface changes created by interaction of transversely excited atmospheric carbon dioxide (TEA CO₂) laser with titanium target/implant in nitrogen and carbon dioxide gas were studied. TEA CO₂ laser operated at 10.6 μm, pulse length of 100 ns and fluence of ∼17 J/cm² which was sufficient for inducing surface modifications. Induced changes depend on the gas used. In both gases the grain structure was produced (central irradiated zone) but its forms were diverse, (N₂: irregular shape; CO₂: hill-like forms). Hydrodynamic features at peripheral zone, like resolidified droplets, were recorded only in CO₂ gas. Elemental analysis of the titanium target surface indicated that under a nitrogen atmosphere surface nitridation occurred. In addition, irradiation in both gases was followed by appearance of plasma in front of the target. The existence of plasma indicates relatively high temperatures created above the target surface offering a sterilizing effect.

     

Nanocrystallite Titanium Dioxide Films Made by the Sol-Gel Method Using Reverse Micelles

Reverse micelles have been made by dissolving Triton X-100 in cyclohexane and adding water. Titanium isopropoxide was then introduced in the solution under vigorous stirring yielding a clear sol. If left at ambient temperature the sol gels in a time of a few hours. Gelation has been studied by fluorescence probing. When a glass slide was dipped in the sol at an early stage of gelation, a thin, photometrically uniform film formed, containing both TiO₂ and surfactant. The organic substances could then be burned out at 400–450°C. Heating secured total TiO₂ formation and permanent attachment to the glass substrate. The ensuing film was studied by electron and AFM microscopy. The film possessed a mesoporous structure characterized by uniformity and particle size monodispersity. It also possessed a high capacity for adsorption of a variety of inorganic particle and ionic species.     

The Low Temperature Processing of Titanium Dioxide Films by the Addition of Trimesic Acid

Sol-gel deposited titanium dioxide films are used for a wide range of applications. One of the drawbacks to these films is that they must be heated in excess of 400^∘C in order to obtain durability. We have found that the processing temperature required to prepare sol-gel derived titanium dioxide films can be significantly reduced by the addition of small amounts of trimesic acid. The addition of this material provides a low energy pathway for the growth of titanium dioxide particles. Titanium dioxide films prepared with trimesic acid show significantly enhanced physical properties with respect to cracking and peeling. Scanning Electron Microscopy and X-Ray Diffraction analyses of films are presented.     

100 cm2 Organic Photovoltaic Cells with 23% Efficiency under Indoor Illumination

Chinese Journal of Polymer Science - The application of organic photovoltaic (OPV) cells to drive off-grid microelectronic devices under indoor light has attracted broad attention. As organic...     

TiO2中孔分子筛的合成与X射线衍射分析

利用X射线粉末衍射（XRPD）对以十六烷基三甲基溴化铵（CTAB）为阳离子模板剂合成的中孔TiO2分子筛进行表征；XRPD研究表明分子筛的结构受到Ti与CTAB的物质的量之比和陈化时间的影响；当Ti与CTAB的物质的量之比为3，陈化时间为12h，可以形成孔径为4.5nm的六角相中孔结构；有机-无机片段自组装过程显示TiO2中孔分子筛的合成按照协同作用机理（CFM）进行；后处理研究表明300℃烧结导致分子筛孔径分布变宽，孔径变大，进一步提高烧结温度将完全破坏中孔结构；而以溶剂萃取法处理样品不能保持中孔结构。     

防晒美白化妆品中TiO_2纳米颗粒的定性定量分析

建立了分析不同种类、性状及形态的化妆品中TiO2纳米颗粒的样品制备技术和定性定量方法。实验使用乙酸乙酯、乙醇对化妆品逐步溶解、离心,去除大部分有机成分,通过透射电子显微镜(TEM)、X射线光电子能谱(XPS)、X射线粉末衍射(XRD)对纳米颗粒的形貌、元素化学态及结构进行定性表征,用电感耦合等离子体发射光谱(ICP-OES)对化妆品中的纳米颗粒进行定量测定。所建立的方法简单快捷,可用于一般化妆品中纳米TiO2的检测。     

纳米二氧化钛粒子分散性能的研究

以四氯化钛为原料，采用溶胶-凝胶法技术合成路线，获得了平均粒径为63nm的二氧化钛粉末。采用分散技术，不仅可以改善粒子的分散性能，而且对粒子的生长也起到一定的抑制作用。研究表明：(1)采用SDS作为分散剂时，其极性基团和非极性基团分别与水和纳米TiO2粒子相结合，从而阻隔了TiO2粒子的团聚，起到分散作用。(2)以稀土元素La作为分散剂，其独特的轨道结构，不仅扩大了能量吸收的范围，更重要的是它与TiO2形成的络合物，使其成为相对独立的小团体，而它本身很小的固溶度使其难于形成合金化组元，结果被释放出来，从而形成更小的纳米TiO2粒子，起到分散纳米TiO2粒子的作用，并同时抑制纳米TiO2粒子的生长。     

Lithium Incorporation into Titanium Dioxide Films from a Propylene Carbonate Solution: A Photoelectrochemical Study

Photoelectrochemical behavior of thin-film TiO₂ electrodes produced by chemical and electrochemical oxidation of a titanium substrate is studied at potentials corresponding to the domain of active incorporation/extraction of lithium in an LiClO₄ solution in propylene carbonate (1.0 V <; E <; 2.5 V vs. Li/Li⁺) and the inert domain (2.6 V <; E <; 3.6 V). Spectral and current–voltage characteristics are obtained for the photocurrent of TiO₂- and Li _x TiO₂-electrodes, which show n-semiconductor properties, in particular, generate an anodic (hole) photocurrent under illumination. The disappearance of the anodic photocurrent and the onset of a small cathodic photocurrent correlate with the beginning of active incorporation of lithium into the source oxide. The photosensitivity of intercalate Li _x TiO₂ in the studied domain of spectrum is low and decreases with increasing lithium concentration. A photoeffect is discovered in the long-wave domain of spectrum beyond the limits of intrinsic absorption of a solid. The photocurrent is described by a characteristic exponential spectral curve.     

阳极氧化TiN薄膜制备N掺杂纳米TiO2薄膜及其可见光活性

室温下通过电泳沉积(EPD)的方法在Ti片表面制备TiN薄膜,然后对TiN薄膜进行阳极氧化得到N掺杂多不孔纳米结构的TiOz薄膜.利用x射线衍射(XRD),X射线光电子能谱(XPS),扫描电子显微镜(SEM)及光电化学方法对得到的薄膜进行表征.XRD测试结果表明,经过阳极氧化并在350℃空气气氛中退火1 h的薄膜中存在锐钛矿晶犁的TiO2.xPs的结果表明,样品中的N元素取代部分O,且N的摩尔分数为O.95%.SEM显示,经阳极氧化后薄膜表面出现多孔纳米结构.光电化学测试结果显示,阳极氧化提高了N掺杂TiO2薄膜在可见光下的光电响应.经阳极氧化并热处理的薄膜在0 V电位及可见光照射下光电流密度为2.325μ.cm2,而单纯热处理的薄膜在相同条件下光电流密度仅为0.475μA·cm-2.阳极氧化得到纳米多孔结构提高了 N 掺杂纳米 Ti02 薄膜的表面积,从而对可见光的响应增大.     

Rheological Behavior of Titanium Dioxide Suspensions

The rheological properties of titanium dioxide dispersed in water are measured over a wide range of powder concentrations, temperatures, and pH values. The value of intrinsic viscosity of titanium dioxide measured with an Ubbelohde capillary viscometer is 3.55, which is useful for determining the shape and aggregation property of the particles. The yield stress and steady shear viscosity of titanium dioxide with broad and narrow particle size distributions were measured over a wide range of solid volume fractions on a Brabender rheometer. It is observed that the rheological properties of the suspensions are quite different due to the difference in particle size distributions. Quemada, Casson, and Zhou's models were used to fit the experimental data and useful parameters were obtained. Calculated data are also in good agreement with the experimental data. As expected, the shear viscosity and yield stress decrease with increasing temperature. But when the temperature is around 50 degrees C, yield stress increases with increasing temperature while shear viscosity exhibits a complex behavior. The phenomena are very interesting and special. The Peclet number was used to analyze the shear thickening behavior. Models were also used to describe the shear viscosity under different temperatures and the master plots of the reduced variables eta/eta(infinity) vs t(c)gamma; at different temperatures are superimposed, which means the agreement is fair and the models are suitable to describe the rheological properties of titanium dioxide suspensions. pH effects were investigated on a Rheometrics RFS-II rheometer and it was found that pH can change the surface charge of the particles, which also affects the rheological behavior. The pH at which maximum shear viscosity and yield stress occur is in concordance with the isoelectric point. Copyright 2001 Academic Press.     

二氧化钛系列光催化剂的拉曼光谱

采用溶胶-凝胶法制备了TiO₂粉体和薄膜光催化剂.使用FT-Raman光谱和激光共聚焦拉曼光谱研究了粉体和薄膜的拉曼光谱,探讨了热处理条件、Fe³⁺掺杂和以硅胶为载体的薄膜化所引起的TiO₂结构变化.结果表明,TiO₂在350℃存在由无定形向锐钛矿相的转变,600℃下存在锐钛矿相向金红石相的转变,750℃下完全转变为金红石相;掺杂会引起TiO₂的晶格畸变,导致拉曼谱峰宽化;以硅胶为载体的TiO₂负载薄膜的部分拉曼谱峰与粉体相比,有一定的位移和宽化.     

UV Absorptance of Titanium Dioxide Thin Films by Plasma Enhanced Deposition from Mixtures of Oxygen and Titanium-Tetrakis-Isopropoxide

A low pressure radio frequency discharge was used to deposit films by mixtures of oxygen and titanium (IV) isopropoxide (TTIP) at powers of 200 W on films of polyethylene-terephthalat and samples of quartz glass. In the non-thermal plasma, films of rather pure TiO₂ could be deposited as revealed by X-ray photo-electron spectroscopy. Besides the film growth rate and the chemical composition, the spectral behaviour of the spectral transmittance of visually transparent films was determined in the range from 200 to 500 nm. Furthermore, the absorptance of films has been derived at characteristic spectral positions of the transmission spectra of the films. Accordingly, cut-off wavelength was found to increase with deposition time from 5 to 10 min as well as with the concentration of TTIP in a range below 1.7%. At 310 nm, the spectral absorption coefficient (extinction coefficient × concentration) was 12 μm⁻¹. While keeping other parameters constant, this coefficient decreased by 4 μm⁻¹ due to an increase of the concentration of TTIP from 1.7% to 8%. Simultaneously, the surface roughness increased as revealed by profilometry. Thus, since the chemical structure of films was found to change only marginally, a decrease of the film density is likely to cause the observed dependence of the absorption coefficient with increasing precursor concentration.