低红外发射率TiO2/Ag/TiO2纳米多层膜研究

利用磁控溅射在玻璃衬底上制备了具有良好的光谱选择性透过率的TiO2/Ag/TiO2纳米多层膜.通过用X射线衍射、扫描电子显微镜、UV-VIS-NIR分光光度计、傅里叶红外光谱仪对样品进行表征,优化了薄膜的制备工艺,研究了多层膜的光学特性.结果表明,当Ag膜的厚度为12nm时,多层膜具有高的可见光透过率和优良的导电性能.样品在555nm波长处的透过率最高达93.5%,红外波段平均反射率为90%左右,8μm～14μm波段红外发射率ε＜0.2.Ag层厚度的增加使可见光高透过率波段变窄,透过率下降.内层及外层TiO2厚度的变化引起薄膜可见光透过峰的位置及强度发生变化,外层的影响高于内层.     

Ag掺杂TiO2纳米晶粉体的制备及性能表征

以钛酸丁酯、无水乙醇、硝酸银等为原料,通过溶胶-凝胶法制备了不同Ag掺杂含量的TiO2纳米晶粉体,用X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）检测分析了粉体的晶型转化、微观形貌和晶粒尺寸,用光致发光光谱（PL）表征材料的光电性能。结果表明,Ag掺杂后的TiO2纳米晶粉体的锐钛矿相比未掺杂Ag样品的含量有所增多,当Ag掺杂量为1%和3%时,锐钛矿的相对含量约为65%;随着Ag掺杂量的增加,锐钛矿晶粒尺寸逐渐减小;由TEM图像可知,Ag颗粒较为均匀地弥散在TiO2纳米晶粉体中;由PL荧光检测结果可知,Ag掺杂TiO2纳米晶粉体的荧光强度比未掺杂的TiO2纳米晶粉体的低。试验结果表明,Ag颗粒较为均匀地弥散在TiO2纳米晶粉体中,有利于在锐钛矿界（表）面形成Ti-O-Ag的键合,有效阻止锐钛矿向金红石的转变,同时抑制锐钛矿TiO2纳米晶粒的增长,Ag颗粒与TiO2纳米晶粉体接触形成肖特基势垒,加速光生电子由TiO2向Ag颗粒传输,减小光生电子与空穴的复合几率,从而提高TiO2纳米晶粉体的光电性能。     

表面等离子共振Ag／TiO2复合膜双光束光强归一化传感器

为了克服由于光源光强的波动而导致的表面等离子共振传感器的测量误差,提出一种双光束归一化光强的表面等离子共振检测方法,传感器的结构为金红石材料作成的棱镜作为耦合棱镜,在棱镜的底边采用射频溅射技术制作AS／TiO2复合膜,Ag膜和TiO2膜的厚度分别为50nm和100nm,在复合膜上设置待测气体的样品池。在He—Ne光入射激励下,复合膜的分界面发生表面等离子共振现象。实验结果表明：采用了双光束归一化光强检测方法,使系统的重复性、稳定性得到大大的提高,减少了测量误差。     

Ag负载TiO2纳米管阵列的制备及紫外探测性能研究

利用阳极氧化方法制备了高度有序的TiO2纳米管阵列,采用化学还原AgNO3在纳米管表面均匀沉积了Ag纳米颗粒以形成Ag/TiO2/Ti（MSM）结构的紫外探测器,并通过SEM和EDS对形成的TiO2-Ag纳米管进行形貌表征和成分分析。通过测试不同光照强度、不同偏压下的电压-电流（I-V）和电流-时间（I-t）曲线,研究了MSM结构在紫外光下的光电特性。实验发现,在偏压为1V、光照强度为1.04mW/cm2的375nm紫外光照射下,基于TiO2-Ag肖特基结的紫外探测器光电流可达46.9μA,响应度为0.21A/W,外量子效率（EQE）为70.8%。研究结果表明,Ag负载的TiO2纳米管阵列具有良好的紫外探测性能。     

Nematic Phases in 1,2,4‐Oxadiazole‐Based Bent‐Core Liquid Crystals: Is There a Ferroelectric Switching?

Four series of new 1,2,4‐oxadiazole derived bent‐core liquid crystals incorporating one or two cyclohexane rings are synthesized and investigated by optical polarizing microscopy, differential scanning calorimetry (DSC), X‐ray diffraction (XRD), electro‐optical, and dielectric investigations. All the compounds exhibit wide ranges of nematic phases composed of tilted smectic (SmC‐type) cybotactic clusters with strongly tilted aromatic cores (40–57°) and show a distinct peak in the current curves observed under a triangular wave field. Dielectric spectroscopy of aligned samples corroborates the previously proposed polar structure of the cybotactic clusters and the ferroelectric‐like polar switching of these nematic phases. Hence, it is shown that this is a general feature of the nematic phases of structurally different 3,5‐diphenyl‐1,2,4‐oxadiazole derivatives. In these uniaxial nematic phases there is appreciable local biaxiality and polar order in the cybotactic clusters. As a second point it is shown that electric field induced fan‐like textures, as often observed for the nematic phases of bent‐core liquid crystals, do not indicate the formation of a smectic phase, rather they represent special electro‐convection patterns due to hydrodynamic instabilities.     

Ag/S/C共掺杂纳米TiO2的制备与光催化活性

采用溶胶-凝胶法制备了Ag/S/C共掺杂纳米TiO2,用于光催化降解气相乙醛.XRD分析结果表明掺杂纳米TiO2均为锐钛型晶相,BET测试表明它们具有较高的比表面积.UV-vis吸收表明S和C掺杂能明显降低TiO2的能隙宽度,而Ag 对此作用较小.Ag 掺杂能促进光生电子-空穴对的分离,从而提高光催化活性.Ag-S-C-TiO2-1催化剂的催化活性高于其它样品,在焙烧温度500℃,Ti∶Ag 摩尔比100∶1,Ti∶SCN-摩尔比1∶4时催化活性最强.Ag/S/C掺杂TiO2光催化活性除受前驱体影响外,还由于其晶相为锐钛型,并且比表面积高,能隙宽度低,因此有良好的光催化活性.     

表面活性剂对光催化还原法合成纳米Ag/TiO2影响的电镜观察

在透射电子显微镜下，通过对加入表面活性剂修饰纳米TiO2粒子前后以及在不同溶胶稳定态下光催化还原合成金属纳米银簇的观察发现：适量的表面活性剂能有效改善纳米TiO2在水中的分散度，提高颗粒的稳定性．过量的表面活性剂将导致胶束的形成；在稳定的溶胶状态下，金属纳米银簇能稳定负载在纳米TiO2上，在不稳定的溶胶状态或形成胶束情况下并不能观察到金属银簇的生成。     

The impurity photovoltaic (IPV) effect in wide‐bandgap semiconductors: an opportunity for very‐high‐efficiency solar cells?

Following recent progress in the study of limiting efficiencies of photovoltaic devices with multiple energy levels, we suggest using the impurity photovoltaic (IPV) effect in wide‐bandgap semiconductors as a means to achieve very‐high‐efficiency solar cells. We discuss the requirements for a high‐efficiency IPV device and review some of the material systems that could be used. As a case study, we investigate theoretically β‐SiC IPV solar cells with a model based on a modified Shockley–Read–Hall theory. The high‐efficiency potential is confirmed and the important issues for implementation are presented and discussed. Copyright © 2002 John Wiley &; Sons, Ltd.     

Do built‐in fields improve solar cell performance?

Intrinsic fields can be built into solar cells by varying the doping level and/or the cell bandgap with potential benefits long recognised. A counteracting effect is that varying the doping or bandgap from the optimum for a particular material system will result in poorer material quality. New solutions are described to the standard semiconductor transport and recombination equations that allow such effects to be incorporated and the impact of these fields on device current and voltage to be assessed. Clear boundaries are found between when built‐in fields are beneficial or deleterious. For the case of doping gradients, built‐in fields decrease both cell current and voltage if carrier lifetime decrease more quickly than as the inverse square of doping; decrease current but can increase voltage if the inverse variation is between linear and square; can improve both if less than linear but only significantly if lifetime varies less than the inverse square root of doping. In the case of a graded bandgap, an optimal field exists as a trade‐off between decreased absorption and increased carrier collection. Copyright © 2008 John Wiley & Sons, Ltd.     

纳米TiO2添加剂对TiO2压敏陶瓷性能的作用

为了改善TiO2压敏陶瓷材料的电学性能,通过添加少量的纳米TiO2,使其压敏电压有了明显的降低,非线性系数有了明显的提高,并对其原因进行了合理分析.结果表明,随着烧结温度的提高,总趋势是压敏电压下降,非线性系数提高.当添加5%纳米TiO2并在1400℃烧结时,样品显示出较好的压敏特性:VImA=4.66V/mm,α=4.73和εr=1.1 9×104.     

Hopping carrier transport in epitaxial V:TiO2 − x layers

The electrical conductivity of TiO₂ layers heavily doped with vanadium has been measured as a function of temperature in the range 77?C300 K. It is shown that, in the case of doping with vanadium, thin epitaxial layers exhibit 3D variable-range hopping conductivity according to Mott??s law. The conductivity parameters, i.e., the average hopping energy and distance and the density of states near the Fermi level, are calculated.     

TiO2薄膜的光强度

TiO2n薄膜与SiO2n膜搭配,广泛用来制备可见光区和近红外区的增透膜,分光膜,多层介质激光反射镜。TiO2薄膜具有许多优点:坚硬,化学稳定性高,粘结性好,并且折射率高。但是,TiO2薄膜的使用却受到抗激光照射稳定性低的限制。在毫秒脉冲激光条件下,用真空热蒸发法交替蒸镀ZnS和MgF2n制得的多层膜,其强度往往比类似的TiO2n-SiO2n多层膜高出数量级。     

Thermal Conductivity Reduction in CoSb<Subscript>3</Subscript>–CeO<Subscript>2</Subscript> Nanocomposites

CoSb₃ + x% CeO₂ nanocomposites (x = 1, 3, 5) were synthesized by ball-milling and spark plasma sintering. Scanning electron microscopy showed that some CeO₂ nano-inclusions sit at the boundaries of CoSb₃ grains. These inclusions also reduce the sizes of the CoSb₃ grains and crystallites by inhibiting their growth during sintering. Hall-effect measurements show that the CeO₂ inclusions modify the charge-carrier concentration in CoSb₃. The variations of the electrical resistivity for the 1% and 3% CeO₂ samples can at least partially be attributed to these modifications of the carrier concentration. Nonetheless, the resistivity increase in the 5% CeO₂ sample can unambiguously be ascribed to the presence of the CeO₂ inclusions. Thermal conductivity is systematically reduced (by more than 15% at 300 K) upon CeO₂ addition. Phonon diffusion by the increased number of CoSb₃ grain boundaries is one of the mechanisms involved in this reduction.     

基于TiO2、掺铁TiO2纳米粒灭活HL60细胞研究

以不同时间培养添加有不同剂量TiO2、掺铁TiO2纳米粒的HL60细胞,研究TiO2、掺铁TiO2纳米颗粒对HL60白血病肿瘤细胞活性的影响,并对比分析细胞在接受可见光照射和不接受光辐照的情况下细胞的活性,探讨基于TiO2、掺铁TiO2纳米颗粒作为光敏剂PDT灭活肿瘤细胞的可能性.实验结果表明纳米颗粒对细胞的生长具有一定的抑制/毒性作用,培养时间越久、纳米浓度越大,抑制/毒性作用越明显;添加了纳米颗粒的PDT灭杀效率比不加纳米颗粒的PDT灭杀效率高,但交互效应不显著.     

TiO2薄膜的光触媒作用

本文介绍了ＴｉＯ２薄膜的光触媒机理和特性以及ＴｉＯ２薄膜的制造和应用。ＴｉＯ２作为光触媒应用于照明光源和灯具等处，它可以净化空气杀菌、去除表面的污垢，减少了照明系统的污染，提高照明效率。     

Glassy/Ceramic Li2TiO3/LixByOz Analogous “Solid Electrolyte Interphase” to Boost 4.5 V LiCoO2 in Sulfide-Based All-Solid-State Batteries

Sulfide-based all-solid-state lithium-ion batteries (ASSLIBs) are the widely recognized approach toward high safety owing to excellent ionic conductivity and nonflammable nature of solid-state electrolytes (SSEs). However, narrow potential window of SSEs brings about serious interfacial parasitic reactions, resulting in fast degradation of the battery. Herein, a glassy/ceramic analogous solid electrolyte interface (SEI) is constructed on LiCoO₂ (LCO) to enhance interfacial stability between LCO and the Li₁₀GeP₂S₁₂ (LGPS) SSEs. In which, ceramic Li₂TiO₃ guarantees good mechanical toughness of analogous SEI, while glassy LixByOz reinforces the coverage to avoid parasitic reactions. Analogous SEI endows ASSLIBs with excellent cycling and rate performance under an upper charge voltage of 4.3 V with 82.3% capacity retention after 300 cycles at 0.2 C. When pushing charge voltage to 4.5 V, analogous SEI also enables desirable performance with an initial capacity of 172.7 mAh g⁻¹ and long lifespan of 200 cycles at 0.2 C. Both experiments and theoretical computation reveal excellent stability between analogous SEI and LGPS, which endows ASSLIBs with small polarization and improved performance. This work provides an insight on glassy/ceramic analogous SEI strategy to boost the interfacial stability of ASSLIBs.     

集成Ti/TiO2敏感电极和液接式Ag/AgCl参比电极的pH微纳传感器

常见的pH传感器大多采用电位法进行检测,基于电位法进行检测的传感器由敏感电极和参比电极组成.在尺寸仅为5 mm×5 mm的传感器芯片上制备了钛电极、银电极和铂电阻丝.采用电化学氧化的方法对钛电极进行阳极氧化制成Ti/TiO2敏感电极.采用电化学氯化的方法对银电极进行阳极氯化,再将饱和KC1溶液(3 mol/L)注入参比...     

PANI/TiO2和PANI/TiO2/HCSA纳米复合材料的光电性能

采用原位聚合的方法制备了PANI/TiO2纳米复合材料,用樟脑磺酸掺杂PANI/TiO2(EB)得到纳米复合膜.使用红外光谱、紫外光谱、荧光光谱及透射电镜探讨了复合材料的光电性能.