疏水型SiO2光学增透膜的制备

以正硅酸乙酯（TEOS）为有机醇盐前驱体,采用溶胶-凝胶技术,通过酸/碱二步法控制实验条件,结合三甲基氯硅烷（TMCS）对胶粒表面的修饰过程,制备出结构可控的疏水型SiO2薄膜.采用椭偏仪、FTIR、接触角测试仪、SEM等对薄膜的折射率、红外特性、接触角以及表面形貌等进行了测量.研究结果表明,疏水型SiO2薄膜的折射率在1.33～1.18之间连续可调;SiO2胶粒表面的亲水性－OH中的H已部分被非活性－Si(CH3)3基团取代;接触角由表面未修饰膜的40°左右增加到表面修饰膜的120°左右.     

甲基三乙氧基硅烷修饰的Ti3+/SiO2复合薄膜的发光性能

采用溶胶-凝胶(Sol-Gel)法, 以正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)为先驱物, 盐酸为催化剂, 用二步水解法制备了Ti3+/SiO2薄膜和甲基三乙氧基硅烷修饰的Ti3+/SiO2复合薄膜. 采用红外光谱仪、X射线衍射仪、椭偏仪、荧光光谱仪等对膜层性质进行了分析. 结果表明, 掺杂Ti3+的SiO2薄膜分别在250 nm附近有一弱的激发峰, 294 nm附近有一强的激发峰, 在393 nm附近出现一强的发射峰. IR光谱发现, MTES修饰的Ti3+/SiO2复合薄膜的Si—OH的吸收峰强度比Ti3+/SiO2薄膜的略减小, Si—O—Si的吸收峰明显增强, 表明复合薄膜硅氧网络结构更规则, 有利于Ti3+的均匀分散. Ti3+/SiO2薄膜与复合薄膜的孔隙率分别为13.64%和6.66%, 表明MTES的加入使薄膜更致密. 在空气中陈放30 d后, Ti3+/SiO2薄膜已经检测不到荧光发射峰, 而MTES修饰的Ti3+/SiO2复合薄膜荧光强度只下降了18%. 在氮气中陈放30 d后, 普通薄膜与复合薄膜的荧光强度均仅下降了10%. 表明Ti3+的荧光猝灭的主要原因是由于Ti3+被氧化造成的. 溶胶中加入MTES后, 薄膜表面结构得到改善, 有效地防止了Ti3+的氧化, 荧光强度更稳定.     

C(膜)/Si(SiO2 )(纳米微粒)/C(膜)热处理的形态及结构分析

用直流辉光溅射+真空镀膜法制备了一种新型结构的硅基纳米发光材料- C(膜)/Si(SiO2)(纳米微粒)/C(膜)夹层膜,并对其进行了退火处理.用TEM、 SEM、 XRD和XPS对其进行了形态结构分析.TEM观察表明: Si(SiO2)纳米微粒基本呈球形,粒径在30 nm左右.SEM观察表明: 夹层膜样品总厚度约为50 μm,膜表面比较平整、致密.400℃退火后,样品表面变得凹凸不平,出现孔状结构; 650℃退火后,样品表面最平整、致密且颗粒均匀.XRD分析表明:制备出的夹层膜主要由SiO2和Si组成,在C原子的还原作用和氧气的氧化作用的共同作用下, SiO2和Si的含量随加热温度的升高而呈现交替变化: 400℃时, C的还原作用占主导地位, SiO2几乎全部被还原成了Si,此时Si含量最高; 400～650℃时,氧化作用占主导地位, Si又被氧化成SiO2, Si含量降低, SiO2含量逐渐上升,在650℃达到最高.XPS分析表明: 在加热过程中, C原子逐渐扩散进入Si(SiO2)微粒层,在650℃与Si反应生成了新的SiC.     

具有超疏水表面的硅/二氧化硅层次结构薄膜

目前报道的硅基材料的超疏水表面主要是通过制备粗糙微观结构,并在其表面修饰表面能相对较低的有机物两个步骤来实现的,在户外等实际环境中应用时存在由于表面修饰有机物的降解而逐渐失去超疏水性的问题.本工作以液态金属锡作为生长衬底,通过化学气相沉积(CVD)法制备了一种具有超疏水性能的硅基薄膜结构.利用扫描电镜(SEM),透射电镜(TEM)以及X射线衍射(XRD)等手段对产物的表面形貌和组成结构进行分析发现,薄膜表面由竖直生长的硅/二氧化硅(Si/SiO2)核壳层次结构组成.采用Cassie理论模型对其超疏水性能的产生提出了可能的解释.发现构成薄膜表面的Si/SiO2层次结构单元的形貌是影响超疏水性能的重要因素.相对于以前报道的硅基材料的超疏水表面,这种新结构的超疏水性能不依赖于表面化学修饰,有望拓宽硅基材料的应用环境.     

Gd2CuO4薄膜与Si, SiO2/Si基底界面相互作用研究

采用XRD和俄歇电子能谱（AES）等技术研究了钙钛矿型Gd2CuO4薄膜与基底Si和SiO2/Si的界面相互作用,发现衬底对Gd2CuO4薄膜的晶化特性有很大影响,以单晶Si为基镀时,Gd2CuO4薄膜经600℃热处理1h即可形成钙钛矿型晶体结构,而以SiO2/Si为基底时,经700℃热处理1h能形成较完善的钙钛矿型晶体结构,Gd2CuO4薄膜的晶粒度随热处理温度的升高而增大,热处理时间对晶粒度则影响较小,AES深度剖析表明,形成的薄膜组成均匀,在界面上有一定程度的扩散,以Si为基底时,Gd2CuO4与基底Si相互扩散,以SiO2/Si为基底时则主要是薄膜中Gd,Cu向SiO2层中的扩散,AES线性分析表明,在薄膜与基底的界面上,各元素的俄歇电子动能发现位移,表明基底作用使界面上元素的化学环境发生了变化。     

纳米二氧化钒薄膜的制备及红外光学性能

采用双离子束溅射方法在Si3N4/SiO2/Si基底表面沉积氧化钒薄膜, 在氮气气氛下热处理获得二氧化钒薄膜. 利用X射线衍射(XRD)、扫描电子显微镜(SEM)和X射线光电子能谱(XPS)研究了热处理温度对氧化钒薄膜晶体结构、表面形貌和组分的影响, 利用傅里叶变换红外光谱(FT-IR)对二氧化钒薄膜的红外透射性能进行了测试分析. 结果表明, 所制备的氧化钒薄膜以非晶态V2O5和四方金红石结构VO2为主, 经400 ℃、2 h热处理后获得了(011)择优取向的单斜金红石结构纳米VO2薄膜, 提高热处理温度至450 ℃, 纳米结构VO2薄膜的晶粒尺寸减小. FT-IR结果显示,纳米VO2薄膜透射率对比因子超过0.99, 高温关闭状态下透射率接近0. 小晶粒尺寸纳米VO2薄膜更适合在热光开关器件领域应用.     

微结构与表面修饰对二氧化硅多孔薄膜疏水性能的影响

通过引入聚乙二醇(PEG)改性传统二氧化硅(SiO2)溶胶,得到了粒径分布较宽且粒径可控的溶胶。比较了六甲基二硅氮烷(HMDS)溶胶内修饰和薄膜表面修饰以及溶胶粒径对SiO2薄膜疏水性能的影响。采用动态光散射粒度仪定量测试了二氧化硅溶胶老化过程中粒度的变化,用原子力显微镜、接触角测试仪、红外光谱仪、紫外-可见-近红外分光光度计分别对薄膜的表面形貌、表观静态接触角、薄膜成分及透光率等进行了测量。结果表明:PEG的添加可有效增大溶胶粒度从而增大薄膜的粗糙度,提高薄膜的疏水性。表面修饰效果受修饰方式和SiO2粒径影响,粒径较小时有利于溶胶内修饰,粒径较大时有利于对薄膜修饰。经过表面修饰剂(HMDS)的气氛处理得到了接触角为152°的超疏水薄膜,而且相比溶胶内修饰可以减小薄膜透光率的损失。     

原位法常压干燥制备疏水SiO2气凝胶及其热稳定性

在正硅酸乙酯(TEOS)酸碱两步催化的溶胶-凝胶过程中, 加入干燥控制化学添加剂(DCCA)N,N-二甲基甲酰胺(DMF)和三甲基氯硅烷(TMCS)的混合溶液, 进行原位疏水改性处理, 并结合常压干燥工艺制备了高比表面积的疏水SiO2气凝胶. 利用N2物理吸附, 全自动X射线衍射仪(XRD), 傅立叶变换红外光谱仪(FTIR), 扫描电子显微镜(SEM)等对样品的形貌结构进行了表征. 实验结果表明, 原位疏水改性比非原位疏水改性制备的SiO2气凝胶具有更大的比表面积, 可达979 m2·g-1, 气凝胶表面存在憎水性基团—CH3, 有良好的疏水性. 500 ℃热处理后, 气凝胶因失去大量的—CH3基团, 由憎水性转为亲水性; 800 ℃高温热处理后, 疏水SiO2气凝胶仍处于非晶态, 具有良好的热稳定性能.     

SiO2气凝胶的非超临界干燥法制备及其形成过程

通过对正硅酸乙酯的两步水解-缩聚反应速率的调控，使生成的醇凝胶具有比较完整的网络结构，配合乙醇溶剂替换和正硅酸乙酯乙醇溶液浸泡和陈化，改善和增强凝胶的结构和强度，在分级干燥下实现了SiO2气凝胶的非超临界干燥制备，并采用SEM、TEM、TG-DTA、XRD和吸附-脱附技术等手段对所得气凝胶样品进行表征.结果表明, 该气凝胶是由粒径约10 nm均匀球状纳米粒子构成的具有连续网络结构的低密度多孔材料，密度为200～400 kg•m－3，孔径分布在10～30 nm范围内，孔隙率约为91％，比表面高达625.65 m2•g－1.外观及微观构造与应用超临界干燥制得的气凝胶完全一致.调节反应体系中各组分的配比以及控制两步水解-缩聚过程中酸与碱的加入量可以获得不同密度的块状SiO2气凝胶.     

Ta2O5/Si薄膜界面结构及光催化活性

利用溶胶-凝胶法和旋转镀膜法在单晶Si(110)基底上制备了Ta2O5光催化剂薄膜. 薄膜颗粒的晶粒度和大小随着热处理温度的升高而增加. 利用扫描俄歇电子能谱(AES)的表面成分分析、深度剖析和线形分析技术研究了热处理温度对Ta2O5/Si 样品膜层和基底的界面化学状态和相互作用的影响规律. 研究表明, 在700 ℃以下热处理时, Ta2O5/Si薄膜界面处以扩散作用为主;在800 ℃高温热处理时,在界面扩散的同时也引发界面反应, 生成了SiO2物种, 界面扩散和界面反应会对薄膜和基底元素的化学价态发生影响. 在紫外光下降解水杨酸的光催化活性的研究表明, 在600 ℃下焙烧制备的Ta2O5/Si薄膜具有与TiO2/Si薄膜相当的光催化活性.     

低介电多孔薄膜的制备及形成机制研究

摘要利用硅烷偶联剂KH-570(γ-甲基丙烯酰氧基甲氧基硅烷)水解缩合生成的多面低聚倍半硅氧烷(POSS)溶胶为模板剂, 经热解制备低介电多孔薄膜材料. 使用FTIR对材料制备过程及形成机制进行动态研究, 通过 ²⁹Si NMR、 椭偏仪、 氮气吸脱附曲线和TEM等对材料的介电性质、 孔洞大小和分布情况进行表征. 制备的介电多孔薄膜材料孔洞分布均匀、 孔径约1 nm, 比表面积为384.1 m²/g, 介电常数为2.5的低.     

Incorporation of organic groups within the channel wall of spin-on mesostructured silica films by a vapor infiltration technique

Organically functionalized mesoporous silica films have been prepared by a novel synthetic procedure that involves spin-coating of mesostructured silica films and a vapor infiltration (VI) technique, using organosiloxanes, before the removal of surfactant. The VI-treated mesostructured films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and a field emission scanning electron microscope (FE-SEM). Nitrogen adsorption/desorption measurements were performed using films attached with a silicon substrate. The XRD and FE-SEM measurements show that the mesochannel wall, densified and modified with organosilyl groups by the VI treatment, hardly contracts under calcination. FE-SEM observations for the films' cross section support the view that organosiloxane vapor is not deposited on the surface of the film. These results show that organosiloxane molecules penetrate the film and are selectively incorporated into the silica wall. Thus, hydrophobic mesoporous silica films can be synthesized without a reduction in pore size, a result that cannot be attained by conventional grafting and co-condensation methods. The excellent high porosity and hydrophobicity of the mesostructured composite films may be of advantage for next-generation low-k dielectric films.     

LaNiO3衬底上Pb(ZrxTi1－x)O3铁电薄膜及梯度薄膜的制备和研究

报道了在镍酸镧 (LaNiO₃, 简称LNO)衬底上锆钛酸铅 [Pb(Zr_xTi_1－x)O₃, 简称PZT]铁电薄膜及其成分梯度薄膜的结构、介电性能、铁电性能以及热释电性能. 首先通过金属有机化合物热分解(MOD)法在Si(100)基片上制备出LaNiO₃, 薄膜, 再通过溶胶-凝胶(sol-gel)法, 在LNO/Si(100)衬底上制备出Pb(Zr_0.80Ti_0.20)O₃, [PZT(80/20)]和Pb(Zr_0.20Ti_0.80)O₃, [PZT(20/80)]铁电薄膜及其成分梯度薄膜. 经俄歇微探针能谱仪(AES)对制备的梯度薄膜进行了成分深度分析, 结果证实成分梯度的存在. 经XRD分析表明, 制备的梯度薄膜为四方结构和三方结构的复合结构, 但其晶面存在一定的结构畸变. 经介电频谱测试表明, 梯度薄膜的介电常数比每个单元的介电常数要大, 但介电损耗相近. 在10 kHz下, 梯度薄膜的介电常数和介电损耗分别为317和0.057. 经电滞回线的测试表明, 梯度薄膜的剩余极化强度比每个单元都大, 而矫顽场却明显较小. 梯度薄膜的剩余极化强度和矫顽场分别为29.96 μC•cm^-2 和54.12 kV•cm^－1. 经热释电性能测试表明, 室温下梯度薄膜的热释电系数为5.54×10-8 C•cm^－2•K^－1, 高于每个单元的热释电系数.     

Effects of alicyclic moiety incorporation on the properties of polyimide/silica hybrid films

Polyimide (PI)/silica hybrid films were prepared from tetraethyl orthosilicate (TEOS) using a sol‐gel process as well as pyromellitic dianhydride and 4,4‐oxydianiline. 1,4‐Cyclohexanedicarboxylic acid (1,4‐CHDA) was added as a coupling agent. The PI/silica hybrid films were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, differential scanning calorimetry and wide‐angle X‐ray diffraction. The thermal, tensile and dielectric properties of the hybrid films were measured. The results showed that the tensile and dielectric properties of the hybrid films improved with increasing silica concentration and 1,4‐CHDA content in the PI matrix. Covalent ester bonds were formed between SiOH groups of silica and carboxyl groups of 1,4‐CHDA. As a result, the silica particle size was reduced and dispersed homogeneously in the PI matrix, leading to increased tensile strength and tensile modulus of the typical hybrid film with 1,4‐CHDA (PI‐2), when compared with the PI/silica hybrid film without 1,4‐CHDA at the same silica contents. The presence of an alicyclic moiety containing silica in PI reduced the dielectric constant considerably to 2.83, which was lower than that of pristine PI. Copyright © 2016 John Wiley & Sons, Ltd.     

Nanostructured ultra-low-κ porous fluoropolymer composite films via plasma co-polymerization of hydrophobic and hydrophilic monomers and subsequent hydrolysis treatment

A new approach to fabricate porous nanostructured fluoropolymer composite films with a low dielectric constant (κ) was put forward at the first time. Initially, a film (pp-HDFD-PEGMA film) composed of dense, uniform, and well-defined nanospheres was controllably deposited on hydrogen-terminated silicon substrates by simultaneous plasma polymerization and deposition of a fluorine-containing hydrophobic monomer, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro-1-decene (HDFD), and a hydrophilic monomer poly(ethylene glycol) methacrylate (PEGMA), using a pulsed plasma polymerization technique. Then, by hydrolysing the plasma co-deposited film in aqueous hydrochloric acid solution to effectively remove the soluble nanospheres or fragments which mainly derived from PEGMA, a nanoporous fluorocarbon film was achieved. Subsequently, a top poly(tetrafluoroethylene) layer was deposited via the magnetron sputtering process to cap and complete an encapsulated structure. The resulting bilayer composite film consisting of a layer of nanostructured fluorocarbon porous film and a layer of encapsulation fluorocarbon polymer has a κ value of 1.8. The morphology investigation of the plasma co-deposited film prior and after acid-treatment by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) confirmed the form of the nanospheres and nanoporous structure, while the chemical composition and structure analysis by X-ray photoelectron spectroscopy (XPS) revealed that after the acid-treatment, the porous nanostructured film are composed predominantly of mainly fluorocarbon polymer.     

Investigation of the effect of calcination temperature on HMDS-treated ordered mesoporous silica film

To reduce signal delay in ultra-large-scale integrated circuits, an intermetal dielectric with low dielectric constant is required. Ordered mesoporous silica film is appropriate for use as an intermetal dielectric due to its low dielectric constant and superior mechanical properties. To reduce the dielectric constant, an ordered mesoporous silica film prepared by a tetraethoxysilane/methyltriethoxysilane silica precursor and Brij-76 block copolymer was surface-modified by hexamethyldisilazane (HMDS) treatment. HMDS treatment substituted OH with Si(CH₃)₃ groups on the silica surface. After treatment, ordered mesoporous silica films were calcined at various calcination temperatures, and the calcination temperature to obtain optimal structural, electrical, and mechanical properties was determined to be approximately 300 °C.     

Chemical solution processing and characterization of Ba(Zr,Ti)O<Subscript>3</Subscript>/LaNiO<Subscript>3</Subscript> layered thin films

Ba(Zr,Ti)O₃/LaNiO₃ layered thin films have been synthesized by chemical solution deposition (CSD) using metal-organic precursor solutions. Ba(Zr,Ti)O₃ thin films with smooth surface morphology and excellent dielectric properties were prepared on Pt/TiO _x /SiO₂/Si substrates by controlling the Zr/Ti ratios in Ba(Zr,Ti)O₃. Chemically derived LaNiO₃ thin films crystallized into the perovskite single phase and their conductivity was sufficiently high as a thin-film electrode. Ba(Zr,Ti)O₃/LaNiO₃ layered thin films of single phase perovskite were fabricated on SiO₂/Si and fused silica substrates. The dielectric constant of a Ba(Zr_0.2Ti_0.8)O₃ thin film prepared at 700°C on a LaNiO₃/fused silica substrate was found to be approximately 830 with a dielectric loss of 5% at 1 kHz and room temperature. Although the Ba(Zr_0.2Ti_0.8)O₃ thin film on the LaNiO₃/fused silica substrate showed a smaller dielectric constant than the Ba(Zr_0.2Ti_0.8)O₃ thin film on Pt/TiO _x /SiO₂/Si, small temperature dependence of dielectric constant was achieved over a wide temperature range. Furthermore, the fabrication of the Ba(Zr,Ti)O₃/LaNiO₃ films in alternate thin layers similar to a multilayer capacitor structure was performed by the same solution deposition process.     

新戊基钛在MCM-41表面的接枝反应及产物性质

采用原位红外光谱法在真空系统中考察了MCM-41分子筛表面与四新戊基钛Ti(CH2CMe3)4的反应,发现这个反应可在室温下定量进行,得到表面新戊基钛(≡Si－O)2Ti(CH2CMe3)2. 这种表面新戊基钛很容易与CH3OH、H2O和O2进一步发生反应分别得到(≡Si－O)2Ti(OCH3)2、(≡Si－O)2Ti(OH)2和(≡Si－O)2Ti(OCH2CMe3)2等表面化合物.在氧气中焙烧由(≡Si－O)2Ti(CH2CMe3)2水解所得的(≡Si－O)2Ti(OH)2可制得表面含钛MCM-41介孔分子筛（Ti-MCM-41）.元素分析、低温N2吸附-脱附、紫外可见漫反射光谱、X射线粉末衍射和FTIR等表征结果表明,接枝反应和后续的处理不破坏分子筛的介孔结构; Ti-MCM-41的比表面积和孔直径较MCM-41略有降低; Ti原子在Ti-MCM-41表面以TiO4四面体配位状态分散,并对乙烯氧化有较明显的光催化活性.论文还通过对Ti-MCM-41与水热合成骨架含钛[Ti]-MCM-41结构和光催化活性的比较,对分子筛类材料光催化作用机制进行了分析探讨.     

Mass transport and electrode accessibility through periodic self-assembled nanoporous silica thin films

Ordered nanoporous silica films have attracted great interest for their potential use to template nanowires for photovoltaics and thermoelectrics. However, it is crucial to develop films such that an electrode under the nanoporous film is accessible to solution species via facile mass transport through well-defined pores. Here, we quantitatively measure the electrode accessibility and the effective species diffusivity for nearly all the known nanoporous silica film structures formed by evaporation-induced self-assembly upon dip-coating or spin-coating. Grazing-angle of incidence small-angle X-ray scattering was used to verify the nanoscale structure of the films and to ensure that all films were highly ordered and oriented. Electrochemical impedance spectroscopy (EIS) was then used to assess the transport properties. A model has been developed that separates the electrode/film kinetics and the film transport properties from the film/solution interface and bulk solution effects. Accounting for this, the accessible area of the nanoporous film coated FTO electrode (1-theta) is obtained from the high-frequency data, while the effective diffusivity of the ferrocene dimethanol (D(FDM)) redox couple is obtained from intermediate frequencies. It was found that the degree of order and orientation in the film, in addition to the symmetry/topology, is a dominant factor that determines these two key parameters. The EIS data show that the (211) oriented double gyroid, (110) oriented distorted body center cubic, and (211) distorted primitive cubic silica films have significant accessibility (larger than 26% of geometric area). However, the double-gyroid films showed the highest diffusivity by over an order of magnitude. Both the (10) oriented 2D hexagonal and (111) oriented rhombohedral films were found to be highly blocking with only small accessibility due to microporosity. The impedance data were also collected to study the stability of the nanoporous silica films in aqueous solutions as a function of pH. The distorted primitive silica film showed much faster degradation in pH 7 solution when compared to a blocking film such as the 2D hexagonal. However, silica films maintained their structure at pH 2 for at least 12 h.