退火对TiO2薄膜形貌、结构及光学特性影响

利用射频磁控溅射技术在熔融石英基片上制备TiO<,2>薄膜,采用X射线衍射、扫描电子显微镜(SEM)、拉曼光谱以及透过谱研究了退火温度和退火气氛对TiO<,2>薄膜的结构、形貌和光学特性的影响.实验结果表明:在大气环境下退火,退火温度越.高,薄膜晶化越好,晶粒明显长大,温度高于700℃退火的薄膜,金红石相已明显形成.实验还发现,退火气氛对金红石相的形成是非常重要的,拉曼光谱反应出Ar气氛退火,抑制了金红石晶相的发育,薄膜仍以锐钛矿相为主.Ar气氛退火的薄膜在可见光范围内的透过率比大气退火的要低,并且由透过率曲线推知:金红石的光学带隙约为2.8 eV,比锐钛矿的光学带隙小0.2 eV.     

TiO2花状纳米结构的制备及光催化性能

用Ti片和H2O2在较低的温度下通过控制反应时间制备了不同形貌的纳米TiO2.在80℃下反应10 min得到了和Ti片黏附较好的多孔纳米结构,延长反应时间先后得到了类花状和类棒状纳米结构．在80℃下反应4 h得到的纳米结构样品为非晶态,而反应10 h制备出以锐钛矿相为主的结晶态纳米结构．通过300℃退火得到的几乎是纯锐钛矿相的纳米TiO2．用紫外光照射降解RhB溶液的方法研究了纳米TiO2的光催化性能．结果表明7 cm2的退火后的类花状纳米TiO2降解染料分子的光催化效率是仅用紫外光降解的29．8倍．     

掺铁TiO2纳米薄膜的制备及光催化性能研究

采用溶胶-凝胶提拉法制备了掺铁改性TiO2纳米材料镀膜玻璃,研究了掺铁、PEG用量、镀膜层数等因素对TiO2纳米膜透光率和光催化降解性的影响,并对相关机理进行了探讨。研究发现,掺铁能提升TiO2纳米膜的光催化活性,催化降解速率为不掺铁时的1．38倍;溶胶前驱体中PEG用量为0．1g（0．13wt％）时制取的薄膜具有最佳的光催化活性和较好的透光率,低于或超过这个值,催化降解效果都不理想;镀膜层数为2～5层时,均有较高的透光率,光催化活性依次递增,其中综合效果最佳的为2层镀膜。纳米TiO2镀膜玻璃是一种性能优异的新型自净节能环保材料,在高楼建筑、灯具制造、城市照明系统等领域具有潜在的广泛用途。     

TiO2纳米薄膜微观结构及光学性能研究

用sol-gel法制备了纳米TiO₂薄膜,用原子力显微镜(AFM)观察了薄膜的表面形貌,测量了薄膜的表面粗糙度(RMS)为2.832 nm;用红外光谱(IR)研究了TiO₂薄膜前驱体溶胶的组成; 探讨了TiO₂薄膜的焙烧温度、层数等制备条件对TiO2光催化活性的影响,结果发现在490℃,8层膜的TiO₂活性最高.     

纳米TiO_2薄膜的结构与光电特性

用射频磁控溅射方法制备出厚度大约15-225nm的TiO2薄膜。Raman光谱测量显示,TiO2薄膜主要是金红石结构(含少量板钛矿相)。紫外可见光吸收光谱表明,在纳米厚度(100nm)范围内,TiO2薄膜的带隙宽度随着薄膜厚度的变化而变化。室温下测量TiO2薄膜的电阻率发现,随着厚度的增加TiO2薄膜的电阻率先后在导体、半导体和绝缘体范围变化。     

载铈纳米TiO2粉体的制备及其反射光谱特性研究

采用金属离子组装技术对纳米TiO2进行了稀土元素铈的负载,借助X射线衍射和透射电子显微镜对载铈纳米TiO2粉体进行了表征,并用紫外-可见光漫反射光谱法对载铈前后纳米TiO2粉体的反射光谱特性进行了分析。结果发现：稀土元素铈负载后,纳米TiO2的反射光谱特性向可见光方向移动,红移到了500nm;并且在可见光区域的吸光率也发生了明显变化,提高了3倍。表明稀土元素铈的负载有利于提高纳米锐钛矿型TiO2对可见光和紫外光的吸收,从而大幅度提高其光催化活性。     

磁控溅射制备ZnO薄膜的结构及发光特性研究

采用射频反应磁控溅射法在玻璃衬底上制备出具有c轴高择优取向的ZnO薄膜,利用X射线衍射、扫描探针显微镜及荧光分光光度法研究了生长温度对ZnO薄膜微观结构及光致发光特性的影响。结果表明,合适的衬底温度有利于提高ZnO薄膜的结晶质量;在室温下测量样品的光致发光谱(PL),观察到波长位于400 nm左右的紫光、446 nm左右的蓝色发光峰及502 nm左右微弱的绿光峰,随衬底温度升高,样品的PL谱中紫光及蓝光强度逐渐增大,同时,绿光峰的强度也表现出一定程度的增强。经分析得出紫光应是激子发光所致,而锌填隙则是引起蓝光发射的主要原因,502 nm左右的绿光峰应该是氧的深能级缺陷造成的。此外,还测量了样品的吸收谱,并结合样品吸收谱的拟合结果对光致发光机理的分析作了进一步的验证。     

ZnO薄膜的制备和结构特性及应变

在SiO₂/Si衬底上面,利用射频磁控溅射方法,在不同的工艺条件下生长ZnO薄膜,然后进行热处理(600～1000℃退火).研究了氩氧比和退火温度对薄膜结晶性能的影响.薄膜的表面结构和晶体特性通过扫描电子显微镜(SEM)、X射线衍射(XRD)来进行表征.结果表明:所制备的薄膜为多晶纤锌矿结构,具有垂直于衬底的c轴(002)方向的择优取向性.热处理可使ZnO(002)衍射峰相对强度增强,半峰全宽(FWHM)变小,即退火使c轴生长的薄膜取向性增强.未经退火的ZnO薄膜存在张应力,经过热处理后应力发生改变,最后变成压应力,并且随着退火温度的升高,压应力逐渐增大.     

强悬浮性纳米TiO2的制备、表征及光催化活性研究（I）制备与表征

以热分解方法制备纳米TiO2，后续处理采用甲基硅油淬火改性和自然冷却，对改性前后的产物进行了XRD，TEM，FTIR等表征。结果表明，两种后续处理方法对所制备的纳米TiO2的物相、晶粒度、结晶度影响不大；但经硅油改性后的纳米TiO2的团聚程度降低。进一步的研究表明，经硅油改性后的纳米TiO2可长期悬浮于水的表面及浅层，这可能有利于直接用阳光有效光催化降解污水和光催化剂的回收再利用。     

Au/TiO_2薄膜的光催化与表面增强拉曼散射性能研究

采用浸渍提拉法将预先合成的TiO2溶胶均匀涂覆在玻璃表面制膜,并在膜表面负载上具有高表面增强拉曼散射(SERS)活性的Au纳米粒子,获得Au/TiO2多功能薄膜。通过X射线衍射(XRD)、扫描电镜(SEM)、紫外可见吸收光谱(UV-vis)、拉曼(Raman)等表征手段,考察了Au/TiO2薄膜的结构、形貌与性能。所得Au/TiO2薄膜在UV灯辐照下可有效地降解罗丹明B等染料分子,其中Au粒子有效抑制了薄膜表面光生电子-空穴的复合,增强了光生载流子的分离效率,提高了薄膜的光催化性能。同时拉曼实验表明,Au/TiO2薄膜也是一种优秀的SERS检测基底。更为重要的是,Au/TiO2薄膜可通过UV灯照射"清洗"掉薄膜表面吸附的上组SERS实验中的检测分子,实现基底的循环利用,有望解决传统SERS基底一次性使用的缺陷。     

Influence of terbium on structure and luminescence of nanocrystalline TiO2 thin films

In this work analysis of the structural and optical properties of TiO₂ thin films doped with terbium has been described. Samples were prepared by a high energy reactive magnetron sputtering process under low pressure of oxygen plasma. X-ray diffraction results have shown that different TiO₂ crystal forms have been produced, depending on the amount of Tb dopant. The undoped matrix had rutile structure with crystallites with a size of 8.7 nm, while incorporation of 0.4 at. % of Tb into the film during the sputtering process resulted in anatase structure with bigger crystallites (11.7 nm). Increasing the amount of terbium up to 2 at. % and 2.6 at. % gave rutile structure with crystallites with a size of 6.6 nm for both films. However, Raman spectroscopy has revealed that in the case of TiO₂:(2 at. % Tb), except for the rutile form, the presence of fine-crystalline anatase was observed. Moreover, the lack of Raman peaks shift attests to the lack of stress in the titania lattice of all of the TiO₂:Tb films. This fact indicates localization of Tb3+ ions on the surface of TiO₂ nanocrystals. In the case of optical investigation, results have shown that doping with terbium has a significant influence on the properties of TiO₂, but it does not decrease the high transparency of the matrix. The observed changes of the transmission characteristics were produced only due to modification of the TiO₂:Tb structure. Photoluminescence measurements have shown that emission of light from TiO₂:Tb films occurs when the amount of terbium is 2.6 at. %. Based on the obtained results a scheme of direct energy transfer from titanium dioxide matrix (with rutile structure) to Tb³⁺ ions has been proposed.     

Tuning circular Bragg phenomenon of TiO2 sculptured thin films with chiral structure

TiO2 chiral sculptured thin films （CSTFs） prepared using glancing angle deposition （GLAD） method based on electron beam evaporation are studied. The relationship between structural parameters and circular Bragg phenomenon （CBP） is investigated. Results demonstrate that, the central wavelength of Bragg regime red-shifts with the increasing pitch of helix, and peak value of selective transmittance will increase after adding more turns to the helix. After annealing, the central wavelength blue-shifts and the peak value rises. Tuning CBP by modulating the deposition parameters and annealing can optimize the performance of circularly polarized devices fabricated from CSTFs.     

氧气分压对TiO2薄膜结构、磁性及输运性质的影响

采用脉冲激光沉积技术在LaAlO_3(100)基片上制备了TiO_2薄膜,研究了氧气分压对薄膜结构、磁性与输运性质的影响.结构测量表明,TiO_2薄膜的结构与沉积过程中的氧气分压有关,氧气分压的增大有利于薄膜向锐钛矿相转变.磁性测量表明,在较高的氧气分压下制备的TiO_2薄膜表现为顺磁性,在较低氧气分压下制备的TiO_2薄膜表现出明显的室温铁磁性,其铁磁性与氧空位有密切关系.输运测量进一步表明,TiO_2薄膜表现为半导体导电特性,在具有铁磁性的薄膜中还观察到了低温磁电阻效应.     

Cr和C共掺TiO_2的电子结构和光学性质的研究

利用第一性原理计算,研究了Cr与C共掺锐钛矿型TiO_2的能带的结构,态密度和光学性质.我们构建了两种不等价的Cr与C紧邻共掺体系:CrC_1-TiO_2和CrC_2-TiO_2.CrC_1-TiO_2体系在价带上方出现了主要由C-2p轨道和Cr-3d轨道耦合成的子带.同时,由于姜-泰勒变形效应,Cr-3d轨道的t_(2g)轨道进一步分裂的成Cr-3d_(yz)轨道在导带底形成附加带,有效带隙较纯TiO_2相比变窄了0.84eV.CrC_2-TiO_2体系带隙中有深带隙态存在,由于深间隙态的存在,价带顶到深带隙的能量宽度为0.84eV,电子从价带顶转移到导带底的所需要的能量将大大减小.最后,我们对纯TiO_2和Cr与C紧邻共掺TiO_2的光学特性进行了计算.结果显示Cr与C共掺TiO_2的光学吸收谱都有很好的可见光区域分布,大大提高了太阳光的利用率.     

电场热处理条件下TiO2薄膜的晶化行为研究

利用溶胶-凝胶法和电场热处理工艺在玻璃表面制备出一层TiO2薄膜,采用DTA,Raman光谱,XRD和AFM等测试手段分析了TiO2薄膜在电场热处理过程中的晶化行为.然后在理论上分析了外电场对TiO2薄膜热处理过程的影响,提出了通过引入外电场促进TiO2薄膜从无定形到锐钛矿的相转变的方法.通过甲基橙水溶液的光催化降解实验表明:在520℃电场热处理条件下的TiO2薄膜的光催化效率高于未引入电场热处理的TiO2薄膜.     

Recombination in nanophase TiO2 films

Recombination and transport parameters were determined in Schottky diodes made of thin TiO₂ solgel films with particle size around 50 nm. Effective recombination times are typically in the range, 10 s<<1 ms, depending on injection level. The lifetimes are found to decrease at higher current levels, indicating bimolecular recombination kinetics due to a progressive increase in trap occupation. The mobility-lifetime product is estimated to be 5×10^–11 cm²/V and is independent of current level.     

Optical and morphological properties of N-doped TiO2 thin films

Nitrogen doped titanium dioxide (TiO₂) thin films were deposited by RF magnetron sputtering onto various substrates. The films were prepared in plasma of argon, oxygen, and nitrogen, with varying the nitrogen content, from 0% up to 70%. The resulting TiOx–Ny films were found to consist of cubic TiN osbornite and tetragonal TiO₂ rutile phases. Using optical spectroscopy with large spectral range from 350 to 1000 nm, the band gap width was determined and a narrowing of the optical gap from 2.76 to 2.32 eV was observed as a function of the N-content. It was found that the optical properties of the TiOx–Ny layers are influenced by the surface morphology, roughness, surface energy and phase content. The chemical composition, the crystalline structure, the surface morphology and the surface energy were thoroughly studied by the Rutherford backscattering spectrometry (RBS), grazing-angle XRD, atomic force microscopy (AFM) and contact angle measurements (wettability), respectively.     

Co离子注入TiO2薄膜的显微结构和磁性研究

利用直流磁控溅射技术在玻璃衬底上沉积了TiO₂薄膜,并对其进行了Co离子注入,最后在真空中500 ℃退火50 min,得到系列薄膜样品. 利用剥离-分散方法制备了薄膜的透射电镜样品,并用扫描电镜(SEM)、X射线能量散射谱(EDX)和高分辨透射电镜(HRTEM)对样品做了近似原位观察,研究了薄膜样品中不同Co离子注入深度的成分分布和显微结构. 结果表明,薄膜呈锐钛矿结构,Co元素主要分布在薄膜表层,Co离子的注入使TiO₂薄膜的晶粒被部分破坏,并形成CoO,而5 关键词： 2薄膜')" href="#">Co注入TiO₂薄膜 电镜原位观察 室温铁磁性