LaNiO3底电极上的BiFeO3薄膜的铁电性能

用溶胶一凝胶方法在LaNiO3底电极上制备了500℃退火的BiFeO3薄膜.研究了室温下薄膜的结构,介电与铁电性质和漏电流性质.XRD研究表明薄膜呈R3m结构,没有观察到不纯相.铁电性研究表明,薄膜具有大的剩余极化强度,在600 kV/cm的测试电场下,薄膜的剩余极化强度为20uC/cm2,矫顽场为440 kV/cm.介电性质研究表明,在整个测试频率范围内,薄膜具有小的介电损耗.而漏电流特性测试表明,通过工艺的改进,有效的限制了BiFeO3薄膜的漏电流.     

用于自组装巨磁阻材料的铁磁性纳米Co粒子的研制

采用化学液相法合成可控制尺寸的六方晶形Co纳米粒子 ,对其形状和大小进行了透射电镜及激光散射分析 ,确认Co纳米粒子为球形 ,平均粒径为 4 0 0nm。在正己烷中基本无团聚。本文着重探索了制备纳米级钴粒子的工艺流程 ,通过改变反应物浓度、反应温度、反应时间、分散剂的添加量和反应过程搅拌情况等 ,寻找到制备Co纳米粒子的最佳反应条件。并初步进行了自组装实验。     

基于自组装技术改性处理镁和铝金属的摩擦学特性研究

采用自组装技术对镁、铝金属表面进行改性处理,并对制备的试样进行紫外照射.利用接触角测量仪、原子力显微镜和UMT-2型微摩擦磨损试验机对制备的试样进行表征和摩擦学特性测试,分析了载荷、滑动速度以及紫外照射对试样摩擦学特性的影响.结果表明,经OTS自组装分子膜改性处理的镁、铝金属表面平整均匀,具有疏水特性和良好的摩擦学性能.Si3N4球与OTS自组装分子改性处理试样间的摩擦系数随载荷和滑动速度的增大而增大.紫外照射5min可有效地提高OTS自组装分子膜改性处理的效果,减小了有机杂质的粘着效应.改性处理的镁、铝金属表面在降低摩擦系数的同时,摩擦副的耐久性显著提高.     

纳米薄膜研究的进展

介绍了纳米材料研究的产生、现状以及这类材料的特性。着重介绍了几种具有不同用途的纳米薄膜的结构特性、制备方法和性能特点。     

NH3 sensing characteristics of nano-WO3 thin films deposited on porous silicon

The NH3 sensing characteristics of nano-tungsten trioxide (WO3) thin films deposited on porous silicon (PS) were investigated in the present study. Porous silicon layer was first prepared by electrochemical etching in an HF-based solution on a p(+)-type silicon substrate. Then, WO3 nano-films were deposited on the porous silicon layer by DC magnetron sputtering. Pt electrodes were deposited on the top surface of the WO3 films to obtain the WO3/PS gas sensor. The WO3 films deposited on PS were characterized by SEM, XRD and XPS. The NH3 sensing characteristics for WO3/PS gas sensor were tested at room temperature and 50 degrees C. The results showed that the NH3 sensing characteristics of WO3/PS were superior to WO3/Al2O3 at room temperature. The sensing mechanism of the nano-WO3 thin films based on PS was also discussed.     

镍基纳米Al2O3复合刷镀层的摩擦磨损性能研究

为评价复合刷镀层在油润滑条件下的抗沙粒磨损性能,在45钢基体上制备了镍基纳米Al2O3复合刷镀层(n-Al2O3/Ni).采用MM-200环块式摩擦磨损试验机对比评价了线接触条件下润滑油中沙粒含量对n-Al2O3/Ni复合刷镀层和快速镍刷镀层摩擦学性能的影响.实验结果表明,随着润滑油中沙粒含量的增加,两种刷镀层的磨损体积均逐渐增加,复合刷镀层的耐磨损性能是快速镍刷镀层的1.3～1.5倍.对复合刷镀层磨痕表面的SEM分析表明其磨损失效机理主要是磨粒磨损.     

氨化Si基Ga2O3/In制备GaN薄膜

研究了Ga2O3/In 膜反应自组装制备GaN薄膜,再将Ga2O3/In膜在高纯氨气气氛中氨化反应得到GaN薄膜,用X射线衍射(XRD),傅里叶红外吸收(FTIR),扫描电镜(SEM),原子力显微镜(AFM),透射电镜(TEM)对样品进行结构,形貌的分析.测试结果表明:用此方法得到了六方纤锌矿结构的GaN多晶膜,且900℃时成膜的质量最好.     

离子束辅助沉积铂碳混合膜及其抑制栅电子发射性能

采用离子束辅助沉积技术,在硅、钼衬底上分别制备铂碳混合膜.XRD的分析结果表明,当铂碳混合膜中铂的组份较多时,有较强的铂(111)面衍射峰和较弱的铂(200)面衍射峰,铂的组份呈(111)择优取向.Raman谱的分析结果表明,碳基本上呈非晶状态.模拟二极管的实验表明,在纯钼阳极上镀覆铂碳混合膜,其抑制热电子发射的性能明显优于纯钼阳极.     

Surface modification of multi-walled carbon nanotubes using 3-aminopropyltriethoxysilane

Multi-walled carbon nanotubes (MWCNTs) were functionalized via oxidation with a mixture of concentrated sulfuric acid and nitric acid. Thus functionalized nanotubes (f-MWCNTs) were silanized using a coupling agent, 3-Aminopropyltriethoxysilane (3-APTES). The f-MWCNTs and the reaction product of f-MWCNTs and 3-APTES (APTES–MWCNTs) were characterized by Fourier Transform Infrared Spectroscopy, Energy Dispersion Spectroscopy, Scanning Electron Microscopy, and Transmission Electron Microscopy. The results indicate the attachment of silane molecules on the surface of the functionalized MWCNTs. This silanization method allows for the improvement of the chemical compatibility of MWCNTs with specific polymers for application in nanotube-based polymer matrix composites.     

Imaging nanometer scale optical heterogeneities in phospholipid monolayers deposited on metal island films

Near-field scanning optical microscopy was applied to study the distribution of fluorescently labeled phospholipid monolayers deposited on the surface of gold island films by the Langmuir-Blodgett technique. Nanometer scale (approximately 50 nm) optical heterogeneities were observed in near-field fluorescence images of the monolayer deposited at 10 mN/m surface pressure. At higher surface pressure (30 mN/m) the heterogeneities became less pronounced. Overlaying of the near-field transmission and fluorescence images from the same area of the sample shows local transmission of gold island film is at a minimum where the fluorescence of the lipid monolayer is at a maximum. It was concluded that coverage of the metal island film by the Langmuir-Blodgett phospholipid monolayer is incomplete, and lipid molecules are preferentially localized in crevices of the film.     

Tribological characteristics of thin films and applications of thin film technology for friction and wear reduction

Thin film deposition technologies based on chemical and physical vapor deposition are now well established to improve the wear resistance of cutting tools. Although severe tribological conditions occur here, coated tools perform exceptionally well. Despite this, the growth in use of thin film deposition technology is slow in the general mechanical industry. In part, this is due to lack of data on the tribological characteristics of bodies coated with thin films.In this paper, tribological test data gathered in a systematic program of sliding and rolling contact tests are presented to demonstrate the usefulness of thin film coatings for wear protection and friction reduction. Samples coated by reactive magnetron sputtering were tested in sliding and rolling contact tests at low and high speeds and at varying contact stresses. These results are presented and used to identify the primary consideration guiding the choice of coating materials, coating properties, film thickness needed etc. A newly developed film-to-substrate adhesion strength test is also briefly described and the results obtained are cited. It is shown that film material selection and coating process selection have a reasonable physical basis.     

Fabrication of YbAl3 film via annealing amorphous Yb-Al film deposited by RF magnetron sputtering

YbAl₃ single-phase bulk alloy was synthesized by melting at 1258 K using raw Yb and Al metals in the ratio of 1:2.2. A sputtering YbAl₃ target was prepared using the precursor YbAl₃ bulk alloy with the spark plasma sintering process. An amorphous Yb-Al film was fabricated by RF magnetron sputtering using the YbAl₃ target, and a single-phase crystalline YbAl₃ film was fabricated by annealing the amorphous Yb-Al film at temperatures higher than 923 K in Ar atmosphere.     

纳米二氧化钛薄膜的制备及光致发光研究

采用溶胶-凝胶法制备纳米二氧化钛(TiO2)薄膜,扫描电镜观察薄膜比较均匀,成膜性好,通过X射线电子能谱(EDS)分析了薄膜成分.X射线衍射(XRD)分析表明纳米TiO2薄膜呈现锐钛矿和金红石晶型.光致发光(PL)谱结果表明,荧光峰对应着不同的发光中心,且相对体相TiO2的理论值有明显的蓝移,有很好的荧光特性.     

不同厚度对分子束外延生长GaSb薄膜的影响

采用分子束外延(MBE)在GaAs衬底上生长GaSb薄膜,为了减小因晶格失配度较大所引起的位错密度,采用低温GaSb作为缓冲层.通过X射线双晶衍射仪和原子力显微镜分析得出,当低温GaSb缓冲层的厚度为20nm时,GaSb外延层中的位错密度最小,晶体质量最好.此外,缓冲层和外延层的厚度共同对GaSb薄膜晶体质量和表面形貌产生影响.     

Effect of hot-press treatment on electrochemically deposited antimony telluride film

Antimony telluride thin film electrochemically deposited in a triethanol based alkaline electrolyte features amorphous structure, high electrical resistance, as well as fine morphology, minor impurity incorporation and anti-corrosivity. To further improve film thermoelectric performance, this film was subjected to hot-uniaxial-press (HUP) treatment at 170-250 °C. HUP treated films revealed crystallized structures, and exhibited 2-3 orders of magnitude improvement of electrical conductance. The [TeO₃²⁻]/[SbO₂⁻] of the deposition electrolyte was utilized to fine tune film composition and thermal electrical performance. Ni diffusion from the substrate into the film was also studied, and it can be reduced by using lower temperature and shorter time of HUP treatment. Film Seebeck coefficient and power factor reached 138 μV/K and 337 μW/K²?m, respectively, at elaborated deposition and HUP conditions.     

Electrokinetic and adsorption properties of sepiolite modified by 3-aminopropyltriethoxysilane

Surface modification of clay minerals has become increasingly important for improving the practical applications of clays such as fillers and adsorbents. An investigation was carried out on the surface modification of sepiolite with aminopropylsilyl groups in 3-aminopropyltriethoxysilane (3-APT). The zeta potential of the modified sepiolite suspensions was measured as a function of initial electrolyte concentration and equilibrium pH using a Zeta Meter 3.0 for modified sepiolite. The utility of the 3-APT-modified sepiolite was investigated as an adsorbent for removal of various heavy metal ions such as Fe, Mn, Co, Zn, Cu, Cd and Ni from aqueous solutions. The effects of various factors on the adsorption, such as pH, ionic strength and temperature of the solution were studied. The results showed that the amount adsorbed increases with solution pH in the pH range of 1.5 and 7.0; indicated that the modified sepiolite adsorbed Fe and Mn ions more than other metal ions such as Co, Zn, Cu, Cd and Ni. It was found that the temperature had an important effect on metal ion adsorption by the modified sepiolite. The adsorption isotherm has been determined and data have been analyzed according to the Langmuir and Freundlich models.     

Tracking the fate of γ-aminopropyltriethoxysilane from the sol state to the dried film state

In this work, ²⁹Si nuclear magnetic resonance and Fourier-transformed infrared spectroscopy were combined to study the hydrolysis and polycondensation of γ-aminopropyltriethoxysilane (γ-APS), both in the liquid sol state and in the film state. γ-APS sols were prepared in methanol or ethanol solvent in the pH range from 5.7 to 11 and deposited. The aim of the present study was to get the most complete picture in regard to the chemical events and time scale of these events. Transesterification reactions between γ-APS and methanol result in faster kinetics in methanol compared to ethanol. γ-APS films were deposited on aluminium and dried at ambient conditions (23 °C, 55% relative humidity). The silane films reached a chemical equilibrium in a couple of minutes (natural pH of 11) to 1 h (pH 7) depending on the pH of the silane solution. From a practical perspective, the results obtained here might give some clues to define an optimized schedule for the application of γ-APS coupling agent to metals.     

3-氨丙基三乙氧基硅烷对多壁碳纳米管的化学修饰研究

先用混酸体系(浓硫酸/浓硝酸体积比为3:1)对多壁碳纳米管进行了氧化处理,再利用氧化处理后多壁碳纳米管表面生成的羟基与3-氨丙基三乙氧基硅烷偶联剂(KH550)进行反应,制备了表面有机修饰的多壁碳纳米管。对比了未经改性的原始多壁碳纳米管、混酸处理过的多壁碳纳米管以及经过表面有机修饰的多壁碳纳米管在水中的分散性能。采用红外光谱、透射电镜、拉曼光谱等对化学修饰前后的各种多壁碳纳米管进行了表征和分析。结果表明,硅烷偶联剂KH550已成功地接到多壁碳纳米管上。硅烷化后的多壁碳纳米管保持碳纳米管的结构不变,在水中基本呈现分散状态并可稳定放置20天以上。     

Numerical calculation of pulsed laser deposited film profiles

Pulsed laser deposition (PLD) is a straightforward method for production of the widest variety of materials, especially multicomponent oxides, in the form of thin film. One of the particular advantages of this technique, the possibility of control of film composition, is ensured by applying (reactive) atmospheres of pressures up to tenths of millibars.