一种纳米孔洞阵列金膜制备方法

以多孔阳极氧化铝膜(anodic aluminum oxide,AAO)为模板,用磁控溅射的方法制备纳米孔洞阵列金膜,SEM结果表明,制备得到的纳米孔洞阵列金膜形貌与AAO模板形貌一致,孔洞阵列规则,孔径大小均匀。此方法适合于纳米孔洞阵列金膜的复制,为纳米线、量子点等纳米阵列材料的组装与合成提供新的条件。     

外加电场制备CdS纳米线阵列、纳米带和纳米管

在外加电场的条件下利用物理热蒸发法成功制备出CdS纳米线阵列、纳米带和纳米管，纳米线阵列沿平行于电场方向生长。借助SEM、EDX和TEM以及XRD，研究了外加电场对CdS纳米线生长的影响。结果表明：外加电场大大促进了CdS纳米线定向排列生长；但是，低温区获得的CdS纳米带和纳米管没有任何方向性。     

氧化铝模板制备镍纳米阵列

阳极氧化铝模板合成技术是近年发展起来的纳米结构材料组装的最重要的技术之一，是目前纳米材料研究中的一个热点。与其它方法相比，具有很多优点。目前，应用此模板已合成出多种金属纳米阵列。由镍制得的纳米阵列有许多优良的性质，具有广泛的应用价值和前詈。本文以纳米孔的多孔氧化铝膜作为模板，采用电化学沉积法在孔内合成出高度有序的镍纳米阵列体系。并对制备出的氧化铝模板及镍纳米阵列进行XRD，TEM及SEM表征。     

清华大学纳米科研有重大突破

全球范围内平均每年新增3000项纳米技术专利，纳米与化工的交叉领域也接连涌现出多项新技术和新产品，大力推动了化工等产业的发展。清华大学的李亚栋课题组在纳米合成及功能化应用方面取得了一系列的突破。该研究组在低维纳米材料钒氧化物纳米带、不同结构银纳米线、硫化铅三维纳米线阵列、稀土磷酸盐纳米线、溴氧铋纳米带、硒化镍微球、     

纳米-微米复合图形化衬底及其在半导体异质外延上的应用

报道了一种新型的纳米-微米复合的蓝宝石图形化衬底,采用dip-coating的方法在微米级SiO2半球阵列表面静电自组装一层SiO2纳米球,形成了适合纳米范围选择性生长的区域。研究发现,该复合结构的制备过程与后续外延的工艺兼容。经封装后,在复合图形衬底上制造的LED芯片,其所测试的光通量比未添加SiO2纳米颗粒的微米图形衬底制造的LED光通量提高57%左右,而光输出功率则提高了17.8%。研究表明,在传统的微米图形衬底上加入SiO2纳米颗粒阵列不仅能够提供纳米级区域外延生长的模板,有效减少外延层的线位错密度,而且能够进一步粗化衬底表面,增加有源层光线逸出的几率,从而有效地提高了光提取效率。     

PMMA-SnO2复合纳米微球的制备及作为润滑油添加剂的研究

采用原位种子乳液聚合法合成了PMMA—SnO2核壳结构复合纳米微球，并通过透射电镜(TEM)，红外光谱(IR)，热分析(TG—DTA)和X-射线粉末衍射(XRD)等测试手段对其结构及性能进行了表征。在四球试验机上对其摩擦学行为进行了考察，研究结果表明，PMMA—SnO2核壳结构复合纳米微球用作润滑油添加剂具有良好的抗磨性能，能显著提高基础油的失效负荷，并推测其抗磨机理是微球的滚动和成膜。     

具有缓冲层的ZnO光阳极染料敏化太阳电池研究

摘要：采用乳液聚合技术合成聚苯乙烯微球（polystyrenespheres,简称PS）,利用浸提法,在透明的导电玻璃（SnO2：F,简称FTO）基底上制备PS胶晶阵列模板;然后,继续采用浸提法,将ZnO溶胶灌注于PS阵列模板上,煅烧后,制得多孔结构的ZnO缓冲层。采用水热法合成ZnO纳米线,并将其分别涂覆于干净的FTO基底和具有ZnO缓冲层的FTO基底,制成光阳极。利用X射线衍射仪（XRD）和环境扫描电子显微镜（SEM）,对光阳极光电转换材料进行结构和形貌表征分析。     

化学修饰的纳米钛酸钙的摩擦学特性研究

利用化学修饰法制备了纳米钛酸钙,并用TEM对其结构进行了表征.将制备的纳米钛酸钙油液加入到合成酯中,用四球摩擦磨损试验机考察了其作为润滑添加剂的摩擦学特性.结果表明:纳米钛酸钙在合成酯中具有较好的抗磨性能和良好的减摩性能,其减摩性能优于常用的极压抗磨剂.利用俄歇能谱AES测定表面膜的组成,发现纳米钛酸钙在摩擦表面的沉积及随后的剪切作用形成了具有抗磨减摩性能的摩擦膜.     

纳米二硫化钼的水热法可控制备及极压性能研究

为获得产率高、重复性好的纳米二硫化钼制备工艺,提出纳米级二硫化钼的水热法可控制备方法。以钼酸钠、硫代乙酰胺为前驱体,分别以聚乙二醇(PEG-20 000)、十六烷基三甲基氯化铵(CTAC)、无水乙醇为表面活性剂,利用水热法制备出球状和花状纳米二硫化钼粒子。通过X射线衍射仪、扫描电子显微镜对产物特性进行表征,通过四球摩擦磨损试验机考察2%纳米二硫化钼在N46润滑油中的极压性能测试。结果表明:酸性环境下,添加表面活性剂PEG-20 000和CTAC可得到球状结构的纳米二硫化钼颗粒,粒径均匀,粒径约为100 nm;而添加无水乙醇时可得到花状结构的纳米二硫化钼颗粒,在硫酸和盐酸环境下粒径分别为190和70 nm;在硫酸环境下,以聚乙二醇为表面活性剂时二硫化钼产率最高,可达78.82%;制备的纳米球状二硫化钼作为润滑油添加剂显著提高了润滑油的极压性能,与工业二硫化钼相比,最大无卡咬负荷最大可提高42%左右。     

基于皮秒激光烧蚀的氧化铟锡纳米颗粒制备系统

液相脉冲激光烧蚀法合成纳米颗粒是一种绿色环保的制备方法。基于该方法搭建了一套氧化铟锡(ITO)纳米颗粒制备系统,该系统采用皮秒激光作为光源辐照去离子水中的氧化铟锡固体靶材,最终合成出ITO纳米颗粒。随着入射脉冲能量的增加及激光辐照时间的增长,激光烧蚀效率明显增大,ITO产量增多。采用扫描电子显微镜(SEM)及X射线能谱仪(EDS)对制备的ITO纳米颗粒进行表征,所制备的纳米颗粒不含除铟(In)、锡(Sn)之外的杂质成分,纯度较高且72%的ITO纳米颗粒粒径大小在20～50 nm之间。     

CsPbBr3纳米片–萘之间的高效三线态能量传递

铯铅卤化物钙钛矿纳米晶是光伏和发光应用领域中理想化的三线态敏化材料,具有较高的荧光量子产率和量子限域效应。以三层厚度的CsPbBr₃纳米片（NPLs）为三线态给体,实现了从NPLs到1-萘甲酸（NCA）分子的高效三线态能量传递（TET）。CsPbBr₃ NPLs采用配体辅助再沉淀方法制备,其与NCA分子结合后,稳态荧光被大幅淬灭,荧光寿命从复合前的6.743 ns缩短到0.995 ns,TET效率达到85.3%。通过与大尺寸纳米立方体对比发现,对于CsPbBr₃-多环芳烃复合体系,量子限域效应是获得高效TET的关键。研究结果表明,CsPbBr₃ NPLs作为三线态敏化剂,可应用在基于TET的光子上转换、光催化氧化-还原反应和室温磷光等领域。     

Wear-Resistant PTFE/SiO2 Nanoparticle Composite Films

Polytetrafluoroethylene (PTFE) is a polymer that is well known for its exceptional tribological properties and, as such, it is commonly used to reduce the coefficient of friction between surfaces. In recent years it has also been established that by incorporating nanoparticle fillers in PTFE, it is possible to extend the polymer's life by reducing its wear rate. Although much study has been placed on bulk PTFE, very little study has been focused on thin films. This article demonstrates that SiO ₂ nanoparticles can be used as a filler to significantly reduce the wear of PTFE thin films while also maintaining a low coefficient of friction. The wear resistance and coefficient of friction of PTFE/SiO ₂ composite films on stainless steel substrates were tested using a linear reciprocating tribometer and compared to pure PTFE films and bare stainless steel to evaluate the benefit of incorporating the SiO ₂ filler in the film. The composite films showed a significant improvement in wear resistance when compared to pure PTFE films. The coefficient of friction for the composite film remained low and stable during a 50 g normal load friction test for a duration of approximately 300 cycles, whereas that of PTFE showed an increasing trend at onset. In addition, of 1.7 and 3.3 wt% SiO ₂ concentrations in solution, 3.3 wt% SiO ₂ showed better performance, with a much higher wear resistance than that of 1.7% SiO ₂ after being subjected to a 1,000-cycle abrasive wear test.     

VO2/GaAs异质结的制备及其光电特性研究

采用直流磁控溅射和后退火氧化工艺在p型GaAs单晶衬底上成功制备了n-VO_2/pGaAs异质结,研究了不同退火温度和退火时间对VO_2/GaAs异质结性能的影响,并分析其结晶取向、化学组分、膜层质量以及光电特性。结果表明,在退火时间2 h和退火温度693 K下能得到相变性能最佳的VO_2薄膜,相变前后电阻变化约2个数量级。VO_2/GaAs异质结在308 K、318 K和328 K温度下具有较好的整流特性,对应温度下的阈值跳变电压分别为6.9 V、6.6 V和6.2 V,该结果为基于VO_2相变特性的异质结光电器件的设计与应用提供了可行性。     

High-temperature tribological properties of spark-plasma-sintered Al2O3 composites containing barite-type structure sulfates

Al₂O₃–50BaSO₄–20Ag, Al₂O₃–50BaSO₄–10SiO₂, Al₂O₃–50(mass%)SrSO₄, Al₂O₃–50PbSO₄–5SiO₂, Al₂O₃–50BaSO₄ and Al₂O₃–50BaCrO₄ composites (mass%) were prepared by spark plasma sintering and their microstructure and high-temperature tribological properties were evaluated. Al₂O₃–50BaSO₄–20Ag composites (mass%) showed the lowest friction coefficients at the temperature ranging from 473 to 1073 K. Thin Ag film was observed on the wear tracks of the composites above 473 K. In addition, the friction coefficients of Al₂O₃ composites containing SrSO₄ and PbSO₄ were as low as those of Al₂O₃–BaSO₄ and Al₂O₃–BaCrO₄ composites at the temperatures up to 1073 K. The thin films formed on the wear tracks of the Al₂O₃–SrSO₄ composites were composed of Al₂O₃ and SrSO₄ phases, while the films formed on the wear tracks of the Al₂O₃–PbSO₄–SiO₂ composites consisted of Al₂O₃, PbSO₄ and SiO₂ phases.     

The friction and wear properties of nanometre SiO2 filled polyetheretherketone

Nanometre SiO₂ filled-polyetheretherketone (PEEK) composite blocks with different filler proportions were prepared by compression moulding. Their friction and wear properties were investigated on a block-on-ring machine by running a plain carbon steel (AISI 1045 steel) ring against the composite block. The morphologies of the wear traces and the transfer film were observed by scanning electron microscopy (SEM). It was found that nanometre SiO₂ filled-PEEK exhibited considerably lower friction coefficient and wear rate in comparison with pure PEEK. The lowest wear rate was obtained with the composite containing 7.5 wt.% SiO₂. The SEM pictures of the wear traces indicated that with the frictional couple of carbon steel ring/composite block (fillec with 7.5 wt.% filler), a thin, uniform, and tenacious transfer film was formed on the ring surface. It was inferred that the transfer film contributed largely to the decreased friction coefficient and wear rate of the filled PEEK composites.     

Effects of friction on topography and vice versa

Experimental results of friction and topography measurements are presented which demonstrate the mutual modification of friction and contact topography. The effect of topographical ‘landmarks’ on friction was tested by Al₂O₃-balls sliding over Ti-ridges on Ti-surface and by Si₃N₄-balls sliding over grooves in SiO₂-surfaces. However, experiments of 100Cr6-balls sliding against 100Cr6-substrates in ultrahigh vacuum, Al₂O₃-balls sliding on DLC coated 100Cr6 and Si₃N₄-balls sliding on SiO₂-surfaces reveal that the formation of triboreaction layers and moreover the creation of wear particles can screen the effect of the topographical ‘landmarks’ completely. Wear particles and their exact behaviour in the contact area can affect friction in a stochastical and hence unpredictable way. Most modern friction theories have difficulties in coping with this problem.     

A Novel Sweating-Lubricating Epoxy Composite Coating Filled with Ionic Liquid-Incorporated Hollow Silica Microspheres

Ionic liquids (ILs) are promising high-performance lubricants with remarkable lubrication and antiwear capabilities in tribology. In this article, first solid-state (at room temperature) IL-incorporated SiO₂ hollow microspheres (IL-SiO₂) were synthesized at high temperature, and then a novel epoxy (EP) composite coating filled with IL-SiO₂ hollow microspheres (IL-SiO₂/EP) was successfully fabricated. The effects of IL- SiO₂ on the mechanical and tribological properties of the IL-SiO₂/EP coating were investigated. It was found the IL-SiO₂/EP coating possessed low friction and high wear resistance. When the IL ratio in the silica hollow microspheres was 58%, the flexural strength and hardness of the IL-SiO₂/EP coating surpassed those of the SiO₂/EP coating and pure EP coating. When the IL-SiO₂ content was 15?wt% in the composite, the friction coefficient and wear rate of the IL-SiO₂/EP coating were both minimized and were 46.2 and 81.6% lower than those of the SiO₂/EP coating, respectively. It was indicated that the addition of ILs overcame the heat and electron accumulation of SiO₂/EP coating in the friction process. The solid-state ILs were melted by friction heat and load into the lubricating liquid and released from the hollow silica microspheres to the worn surfaces, which was similar to sweating by the human body. In addition, the liquid-state ILs combined with the debris of EP through chemical bonding to form an internal continuous and steady lubricating protective film, which could directly protect the worn surfaces from abrasion. This IL-SiO₂/EP composite coating can be used to design and fabricate new sweating-lubricating functional coatings.     

Characterization of nanoscale recording mark on Ge2Sb2Te5 film

We have fabricated nanoscale recording marks on Ge₂Sb₂Te₅ (GST) films with conductive atomic force microscope (AFM). GST films were deposited on glass or polyimide film with thickness of 150–200 nm by the rf–sputtering method. Through current–voltage (I–V) spectroscopy, good cantilevers for fabrication and characterization of nanoscale marks on GST were selected. A fresh and highly conductive tip showed voltage-switching characteristic in the I–V curve, where the threshold voltage was 1.6 V. Nanoscale dot and wire arrays of crystalline phases were successfully obtained by varying sample bias voltage from −10 to 10 V. With highly conductive tips, nanowires having full-width at half-maximum of 20 nm could be fabricated, whereas nanowires could not be fabricated with bias voltage below −2 V. The width of the nanoscale mark was increased by repetition of AFM lithography even with same applied voltage and lithography speed. For a thicker nanowire, the width measured in current-image (C-image) was observed to be 2 times of that measured in topography-image (T-image). This result supports that current sensing provides an image of phase-changed GST area with higher resolution than topography sensing.     

HfO2薄膜的离子束刻蚀特性研究

实验研究了HfO₂薄膜特性以及掩模材料AZ1350以Ar为工作气体下的离子束的刻蚀特性.给出了离子能量、离子束流密度和离子束入射角等因素与刻蚀速率的关系曲线,用最小二乘法拟合了上述因素与刻蚀斜率的函数关系方程;分析了光刻胶和基片在刻蚀过程中随刻蚀深度的变化对图形转移精度的影响,用AFM的Tapping模式测量了刻蚀前后HfO₂薄膜表面质量的变化.结果表明刻蚀速率与离子能量的平方根,及速流密度成正比,并随离子束入射角变化而变化;与刻蚀前相比,刻蚀工艺降低了因HfO₂薄膜刻蚀深度的增加引起图形转移精度下降,因此提高刻蚀选择比是获得高分辨率图形的前提.研究结果已应用到了在HfO₂/SiO₂多层膜衍射光栅的制作中.