共查询到20条相似文献,搜索用时 15 毫秒
1.
Hybrid nanocomposite films of silica (SiO2) in polyimide (PI) from 4,4′-(hexafluoroisopropylidene) diphthalic arhydride (6FDA), 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane (6FHP) and nonlinear optical (NLO) molecule have been successfully fabricated by an in situ sol-gel process. The silica content in the hybrid films was varied from 0 to 22.5 wt%. These nanocomposite films exhibit fair good optical transparency. Fourier transform infrared (FTIR) spectroscopy results confirm the formation of SiO2 particles in PI matrix. Scanning electron microscope (SEM) images show that the SiO2 phase is well dispersed in the polymer matrix. Their glass transition behavior and thermal stability were investigated by differential scanning calorimeter (DSC) and thermal gravimetric analysis (TG). 相似文献
2.
Markus Håkansson Johanna Suomi Mauri Nauma Jouko Kankare Jarkko U. Eskola 《Analytica chimica acta》2006,556(2):450-454
Double insulating barrier tunnel emission electrodes were fabricated by adding a new pure aluminum layer upon oxidized aluminum electrodes by vacuum evaporation and thermally oxidizing the new aluminum layer in air at room temperature. Resulting Al/Al2O3/Al/Al2O3 electrodes allow the use of various aluminum alloys in the electrode body necessary for hardness or shaping ability of the electrode while obtaining the luminescence properties of pure aluminum oxide. During electrical excitation of luminescent labels by cathodic hot electron injection into aqueous electrolyte solution, the background noise is mainly based on high-field-induced solid-state electroluminescence and F-center luminescence of the outer aluminum oxide film. The more defect states and/or impurity centers the outer oxide film contains, the higher is the background emission intensity. The present electrode fabrication method provides a considerable improvement in signal-to-noise ratio for time-resolved electrochemiluminescence (TR-ECL) measurements when the original native oxide film of the electrode body contains luminescence centers displaying long-lived luminescence. The excellent performance of the present electrodes is demonstrated by extremely low-level detection of Tb(III) chelates, luminol, Pt(II) coproporphyrin and Tb(III) labels in an immunometric immunoassay by time-resolved electrochemiluminescence. 相似文献
3.
Benbo Liu Bin Zhang Xumeng Wang Xuanying Chen Guangxin Gu 《Journal of Saudi Chemical Society》2019,23(7):856-863
A number of polyimide films incorporated with different amounts of octa(aminopropylsilsesquioxane) (POSS-NH2) were prepared from 1,2,4,5-Benzenetetracarboxylic anhydride, 4,4′-Oxydianiline and POSS-NH2. The structure and properties of the hybrid polyimide films were characterized and evaluated. It is found that, compared with pure polyimide without POSS-NH2, the thermal stabilities and electrical capabilities of hybrid polyimide films are improved. Meanwhile, the incorporation of POSS-NH2 also brings improvement in the flexibility of polyimide films. 相似文献
4.
Hoichang Yang Praveen Bhimaraj Lin Yang Richard W. Siegel Linda S. Schadler 《Journal of Polymer Science.Polymer Physics》2007,45(7):747-757
The crystal growth and morphology in 150‐nm‐thick PET nanocomposite thin films with alumina (Al2O3) nanoparticle fillers (38 nm size) were investigated for nanoparticle loadings from 0 to 5 wt %. Transmission electron microscopy of the films showed that at 1 wt % Al2O3, the nanoparticles were well dispersed in the film and the average size was close to the reported 38 nm. Above 2 wt % Al2O3, the nanoparticles started to agglomerate. The crystal growth and morphological evolution in the PET nanocomposite films kept at an isothermal temperature of 217 °C were monitored as a function of the holding time using in situ atomic force microscopy. It was found that the crystal nucleation and growth of PET was strongly dependent on the dispersed particles in the films. At 1 wt % Al2O3, the overall crystal growth rate of PET lamellae was slower than that of the PET homopolymer films. Above 2 wt % Al2O3, the crystal growth rate increased with nanoparticle loading because of heterogeneous nucleation. In addition, in these PET nanocomposite thin films, the Al2O3 nanoparticles induced preferentially oriented edge‐on lamellae with respect to the surface, which was not the case in unfilled PET as determined by grazing‐incidence X‐ray diffraction. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 747–757, 2007 相似文献
5.
A series of Au/Fe2O3/Al2O3 catalysts were prepared by the homogeneous deposition-precipitation method. The catalytic activity of the catalyst samples for selective catalytic reduction of NO by propene under oxygen-rich atmosphere was evaluated. The results showed that 2%Au/10%Fe2O3/Al2O3 exhibited good low-temperature activity. The maximum of NO conversion reached 43% at 300 °C, while it was only 21% over the 2%Au/Al2O3 catalyst at the same temperature. The addition of 2% steam to the feed gas had little effect on the catalytic activity. X-ray diffraction results indicated that both Au and Fe2O3 particles were highly dispersed over Al2O3. H2-temperature-programmed reduction results indicated that there was strong interaction between Au and Fe2O3, which made the reduction of Fe2O3 easy. The synergistic effect between Au and Fe2O3 was probably responsible for the good catalytic performance of the Au/Fe2O3/Al2O3 catalyst at low temperature. 相似文献
6.
Zhenxun Huang Jianqing Zhao Yanchao Yuan Shijing Yan Shumei Liu Xingtao Zan 《先进技术聚合物》2013,24(6):600-608
In this study, amino derivative of pure silica zeolite nanocrystal (A‐PSZN) was dispersed into polyimide (PI) matrix to prepare PI/A‐PSZN hybrid films, and their thermal and mechanical properties, as well as hydrophobicity, were characterized scientifically. The test results show that PI/A‐PSZN hybrid films possess higher glass transition temperature, higher thermal stability and lower in‐plane coefficient of thermal expansion than pristine PI. The mechanical property data suggest that the incorporation of A‐PSZN results in an increase in Young's modulus and tensile strength of the hybrid films, but as its content exceeds the critical value (maybe 5 wt%), its enhancement effect on the hybrid's strength and toughness gets weaker. Furthermore, liquid dripping imaging analysis results indicate that the film's hydrophobicity is clearly improved by the introduction of A‐PSZN. As compared with PSZN, A‐PSZN exhibits better effect on enhancing the overall performance of pristine PI films. A comparison with other studies suggests that PI/A‐PSZN is a hybrid film with superior comprehensive properties. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
7.
Effect of sol-gel preparation method on particle morphology in pure and nanocomposite PZT thin films
Double-scale composite lead zirconate titanate Pb(Zr0.52Ti0.48)O3 (PZT) thin films of 360 nm thickness were prepared by a modified composite sol-gel method. PZT films were deposited from
both the pure sol and the composite suspension on Pt/Al2O3 substrates by the spin-coating method and were sintered at 650°C. The composite suspension formed after ultrasonic mixing
of the PZT nanopowder and PZT sol at the powder/sol mass concentration 0.5 g mL−1. PZT nanopowder (≈ 40–70 nm) was prepared using the conventional sol-gel method and calcination at 500°C. Pure PZT sol was
prepared by a modified sol-gel method using a propan-1-ol/propane-1,2-diol mixture as a stabilizing solution. X-ray diffraction
(XRD) analysis indicated that the thin films possess a single perovskite phase after their sintering at 650°C. The results
of scanning electron microscope (SEM), energy-dispersive X-ray (EDX), atomic force microscopy (AFM), and transmission electron
microscopy (TEM) analyses confirmed that the roughness of double-scale composite PZT films (≈ 17 nm) was significantly lower
than that of PZT films prepared from pure sol (≈ 40 nm). The composite film consisted of nanosized PZT powder uniformly dispersed
in the PZT matrix. In the surface micrograph of the film derived from sol, large round perovskite particles (≈ 100 nm) composed
of small spherical individual nanoparticles (≈ 60 nm) were observed. The composite PZT film had a higher crystallinity degree
and smoother surface morphology with necklace clusters of nanopowder particles in the sol-gel matrix compared to the pure
PZT film. Microstructure of the composite PZT film can be characterized by a bimodal particle size distribution containing
spherical perovskite particles from added PZT nanopowder and round perovskite particles from the sol-matrix, (≈ 30–50 nm and
≈ 100–120 nm), respectively. Effect of the PZT film preparation method on the morphology of pure and composite PZT thin films
deposited on Pt/Al2O3 substrates was evaluated. 相似文献
8.
Masashi Miyakawa Hidenori Hiramatsu Masahiro Hirano 《Journal of solid state chemistry》2010,183(2):385-391
Epitaxial growth and electron doping of 12CaO·7Al2O3 (C12A7) and 12SrO·7Al2O3 (S12A7) are reported. The C12A7 films were prepared on Y3Al5O12 (YAG) single-crystal substrates by pulsed laser deposition at room temperature and subsequent thermal crystallization. X-ray diffraction patterns revealed the films were grown epitaxially with the orientation relationship of (001)[100] C12A7 || (001)[100] YAG. For S12A7, pseudo-homoepitaxial growth was attained on the C12A7 epitaxial layer. Upon electron doping, metallic conduction was achieved in the C12A7 film and the S12A7/C12A7 double-layered films. Analyses of optical absorption spectra for the S12A7/C12A7 films provided the densities of free electrons in each layer separately. Hall measurements exhibited larger electron mobility in the S12A7/C12A7 film than those in C12A7 and S12A7 films, suggesting free electrons may be accumulated at the S12A7/C12A7 interface due presumably to a discontinuity of the cage conduction bands. 相似文献
9.
溶剂极性对微波辐射老化制备前驱体及CuO/ZnO/Al2O3催化剂结构的影响 总被引:1,自引:1,他引:0
在制备CuO/ZnO/Al2O3催化剂的老化过程中,采用微波辐射老化技术,着重研究了溶剂极性对前躯体物相组成,烧后CuO/ZnO/Al2O3催化剂结构及其在浆态床合成甲醇工艺中催化性能的影响。通过XRD、DTG、H2-TPR,FTIR、HR-TEM和XPS对前驱体及催化剂表征表明,沉淀母液在微波辐射条件下进行老化,溶剂的极性对前躯体物相组成及催化剂结构影响显著。随着溶剂极性的增大,Zn2+/Cu2+取代Cu2(CO3)(OH)2/Zn5(CO3)2(OH)6中Cu2+/Zn2+的取代反应增强,使得前躯体中(Cu,Zn)5(CO3)2(OH)6和(Cu,Zn)2(CO3)(OH)2物相的含量增多,结晶度提高,导致烧后CuO/ZnO/Al2O3催化剂中CuO-ZnO协同作用增强,且CuO晶粒减小,表面Cu含量增加,催化剂活性和稳定性提高。水溶剂的极性最大,制备的催化剂活性和稳定性最好,甲醇的时空收率(STY)和平均失活率分别为320 mg.g-1.h-1和0.11%.d-1。 相似文献
10.
Zhiming Liu Jiming Hao Lixin Fu Tianle Zhu Junhua Li Xiangyu Cui 《Reaction Kinetics and Catalysis Letters》2003,80(1):45-52
SnO2/Al2O3 catalyst prepared by sol-gel method showed higher activity than those prepared by impregnation method, and their activity
was significantly improved by pre-treatment in the reaction gas. The increased activity is closely related to the agglomeration
of SnO2 species and the re-exposure of Al2O3, which was previously covered by dispersed SnO2 species.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
Barium titanate (BaTiO3) powders with particle sizes of 30~50 nm were prepared from barium stearate, titanium alkoxides and stearic acid by stearic acid-gel method. Dispersing the agglomerate of BaTiO3 nanoparticles into poly(amic acid) solution followed by curing led to the formation of polyimide hybrid films. The hybrid films were transparent and well distributed with BaTiO3 nanoparticles when the BaTiO3 content was less than 1 wt%. Highly loaded hybrid film containing 30 wt % BaTiO3 was tough, had a smooth surface and possessed much higher dielectric and piezoelectric constants than the parent polyimide. 相似文献
12.
Jiangfeng Xiang Caixian Chang Liangjie Yuan Jutang Sun 《Electrochemistry communications》2008,10(9):1360-1363
A facile method has been developed to synthesize Al2O3-coated LiNi0.8Co0.2O2 cathode materials. The sample was characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and energy dispersive analysis of X-rays (EDAX). Electrochemical tests show that the cycling stability of LiNi0.8Co0.2O2 at room temperature is effectively improved by Al2O3 coating. The differential scanning calorimetry (DSC) and high temperature (60 °C) cycling tests indicate that Al2O3 coating can also improve the thermal stability of LiNi0.8Co0.2O2, which is attributed to that the coating layer can protect the LiNi0.8Co0.2O2 particles from reacting with the electrolyte. 相似文献
13.
Summary Al2O3-TiO2 supported Pd-Ru bimetallic catalysts were prepared and characterized by X-ray photoelectron spectroscopy and X-ray diffraction (XRD) techniques. The catalytic system was evaluated in the partial hydrogenation of palm oil. Based on these results, it was deduced that core-shell model particles, with Ru cores, would be most likely formed in the bimetallic catalysts. As a result, the dispersing effect of ruthenium on palladium and the charge transfer from ruthenium to palladium may be closely related to the excellent catalytic performance. Besides, the highly dispersed TiO2 on γ-alumina support seems to be crucial for inhibiting the formation of trans fatty acid. 相似文献
14.
L. Deutschmann H. Suhr D. Krug U. Straub 《Fresenius' Journal of Analytical Chemistry》1991,341(5-6):339-342
Summary Improved methods for Al2O3 metallization by Cu are described. Good adhesion between Cu and Al2O3 substrate depends on the formation of chemical bonds between the substrate and the metallic layer. The temperature needed for the formation of a CuAl2O4 spinel interface is reduced from 1050°C to 900°C by the addition of various oxides. The adhesion between the CuAl2O4 interface and deposited Cu is stronger then the tensile strength of pure Cu. Plasma techniques for the formation of a Cu containing interface are also described. Bombardment of a Cu film with Xe+ ions in a rf-glow discharge implants Cu atoms into the substrate to a depth of 5 nm, as determined by SIMS depth profiling. Methods for reduction of the CuAl2O4 surface for subsequent metallization are also presented. 相似文献
15.
Nengqin Jia Qin Zhou Ling Liu Manming Yan Zhiyu Jiang 《Journal of Electroanalytical Chemistry》2005,580(2):213-221
Horseradish peroxidase (HRP) was immobilized into a new type of sol–gel-derived nano-sized tin oxide/gelatin composite film (SnO2 composite film) using a sol–gel film/enzyme/sol–gel film “sandwich” configuration. Direct electrochemistry and electrocatalysis of HRP incorporated into the composite films were investigated. HRP/SnO2 composite film exhibited a pair of stable and quasi-reversible cyclic voltammetric peaks for the HRP Fe(III)/HRP Fe(II) redox couple with a formal potential of about −0.25 V (vs. SCE) in a pH 6.0 phosphate buffer solution. The electron transfer between the enzyme and the underlying electrode was greatly enhanced in the microenvironment with nano-SnO2 particles and nanoporous structures. Morphologies and microstructures of the composite films and HRP/composite films were characterized with TEM, AFM. Electrochemical impedance spectroscopy (EIS) was also used to feature the HRP incorporated into composite films. FTIR and UV–Vis spectroscopy demonstrated that HRP in the composite film could retain its native secondary structure. With the advantages of organic–inorganic hybrid materials, the HRP/SnO2 composite film modified electrode displayed good stability and electrocatalytic activity to the reduction of H2O2, The apparent Michaelis-Menten constant was estimated to be 0.345 mM, indicating a high affinity of HRP entrapped into the composite film toward H2O2. 相似文献
16.
Environmentally acceptable lead-free ferroelectric KNbO3 (KN) or NaNbO3 (NN) and K0.5Na0.5NbO3 (KNN) thin films were prepared using a modified sol-gel method by mixing potassium acetate or sodium acetate or both with the Nb-tartrate complex, deposited on the Pt/Al2O3 and Pt/SiO2/Si substrates by a spin-coating method and sintered at 650°C. X-ray diffraction (XRD) analysis indicated that the NN and KNN films on the Pt/SiO2/Si substrate possessed a single perovskite phase, while NN and KNN films on the Pt/Al2O3 substrate contained a small amount of secondary pyrochlore phase, as did KN films on both substrates. Scanning electron microscopic (SEM) and atomic force microscopic (AFM) analyses confirmed that roughness R q of the thin KNN/Pt/SiO2/Si film (?? 7.4 nm) was significantly lower than that of the KNN/Pt/Al2O3 film (?? 15 nm). The heterogeneous microstructure composed of small spherical and larger needle-like or cuboidal particles were observed in the KN and NN films on both substrates. The homogeneous microstructure of the KNN thin film on the Pt/SiO2/Si substrate was smoother and contained finer spherical particles (?? 50 nm) than on Pt/Al2O3 substrates (?? 100 nm). The effect of different substrates on the surface morphology of thin films was confirmed. 相似文献
17.
L. Zhang C. H. Ma J. Wang S. G. Li Y. Li B. X. Wang 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(13):2435-2445
In this work, the Er3+:Y3Al5O12 as up-conversion luminescence agent was mixed with TiO2 and the corresponding Er3+:Y3Al5O12/TiO2 composite films were prepared on the one-sided surface of treated sheet glass through sol-gel dip-coating method. The prepared Er3+:Y3Al5O12/TiO2 composite films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Their photocatalytic activities were examined through the degradation of some organic dyes under visible-light irradiation. The degradation process of organic dyes was monitored by UV-Vis spectrophotometer. Furthermore, some main influence factors on the visible-light photocatalytic activity of Er3+:Y3Al5O12/TiO2 composite film such as heat-treatment temperature and heat-treatment time were studied. The results indicate that three layer Er3+:Y3Al5O12/TiO2 composite films with one Er3+:Y3Al5O12/TiO2 composite film (as first layer close to sheet glass) and two pure TiO2 film (as second and third layers) display a higher visible-light photocatalytic activity during photocatalytic degradation of Azo Fuchsine. In addition, the results showed that the visible-light photocatalytic activity of Er3+:Y3Al5O12/TiO2 composite film related to the layer number and layer sequence on the sheet glass. Perhaps, the research results may offer some meaningful references for developing solar energy continuous flow wastewater treatment reactor. 相似文献
18.
使用Al2O3和N3染料制备了一种交替组装的结构, 该结构能够提高染料敏化太阳能电池(DSCs)的开路电压(Voc), 短路电流(Jsc)和转换效率(η). 为了研究(染料/Al2O3)交替组装结构的作用机理, 使用电化学阻抗谱技术分析了电池的界面电阻. 分析结果表明, 随着交替组装结构中(染料/Al2O3)单元的增加, 光阳极/染料/电解质界面的电阻降低, 电池性能随之提高. 基于电化学阻抗谱分析结果, 建立了一系列的等效电路模型, 从理论上解释了(染料/Al2O3)交替组装结构的作用机理. 相似文献
19.
High dielectric constant is highly desirable in capacitors and memory devices. In this work, oleic acid (OA)‐capped BaTiO3 nanocrystals were synthesized by a two‐phase approach. Polyimide (PI)/BaTiO3‐nanocrystal composite thin films with high dielectric constant have been successfully fabricated. The morphologies and dielectric properties of the hybrid films were exploited. The results showed that BaTiO3 nanocrystals can be uniformly dispersed in the PI thin films owing to the surface modification of OA‐capped BaTiO3 nanocrystals. It was found that the dielectric constant of composite film varies with the volume fraction of BaTiO3 nanocrystals and sintering temperatures and reaches a maximum value of 44.1, which is around 13 times higher than that of pristine PI thin film (3.2). These results demonstrated that PI/BaTiO3‐nanocrystal composite films have considerable application potential in microelectronic fields. 相似文献
20.
Qing-Yuan Bi Li-Qiong Xing Qiang Zhou Meng-Fei Luo 《Journal of fluorine chemistry》2009,130(6):528-533
A series of La-doped Al2O3 catalysts were prepared and tested for the vapor phase hydrofluorination of C2H2 to vinyl fluoride (CH2CHF, VF). It was found that the La-doped catalyst gave a stable catalytic performance and a higher selectivity to the desired VF and a lower selectivity to coke deposition compared with the pure Al2O3 catalyst. The enhancement in VF selectivity on the La-doped catalyst was due to the elimination of acidic sites on the Al2O3 surface by the addition of La2O3, evidenced by NH3-TPD results, which could also explain the declined selectivity to coke deposition on the catalyst. Raman result indicated there were two different vibration forms of CH distortion and CC expansion for the coke deposition. 相似文献