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991.
Robert Piech 《Electroanalysis》2010,22(16):1851-1856
A new adsorptive stripping voltammetric method for the determination of trace scandium(III) based on the adsorption of scandium(III)‐mordant blue 9 complex on the cyclic renewable mercury film silver based electrode (Hg(Ag)FE) is presented. The effects of various factors such as: preconcentration potential and time, pulse height, step potential and supporting electrolyte composition are optimized. The calibration graph is linear from 2 nM (0.09 μg L?1) to 90 nM (4 μg L?1) for a preconcentration time of 45 s, with correlation coefficient of 0.9995. For a Hg(Ag)FE with a surface area of 7.9 mm2 the detection limit for a preconcentration time of 90 s is as low as 5 ng L?1. The repeatability of the method at a concentration level of the analyte as low as 0.2 μg L?1, expressed as RSD is 1.9 % (n=5). The proposed method was successfully applied and validated by studying the certified reference material (CRM 320 – river sediment) and natural samples with simultaneous recovery of Sc(III) from spiked water and sediment samples. 相似文献
992.
F. J. Garcia‐Garcia E. V. Koroleva G. E. Thompson G. C. Smith 《Surface and interface analysis : SIA》2010,42(4):258-263
Nitric acid is commonly used for surface treatments of aluminium alloys. It is used to clean the surfaces after alkaline etching; it has application in chemical polishing and is also used for electrograining. The majority of these treatments undergo the application of anodic polarisation that results in formation of anodic oxide film. However, little is known about the behaviour of aluminium containing magnesium or titanium in solid solution under such conditions. To reveal the effects of magnesium and titanium alloying additions on anodic film formation in nitric acid, Al‐1800 ppm Mg and Al‐800 ppm Ti alloys were investigated. It was found that porous alumina film developed on the surfaces with reduced efficiency of 40%, due to the reactive nature of nitric acid to alumina. The presence of magnesium and titanium in aluminium had little influence on the efficiency of film growth, as confirmed by the relatively similar thicknesses of oxide formed on binary alloys and aluminium. However, incorporation of magnesium ions into the alumina film led to development of a high‐population density of localised voids near the alloy/film interface. An increased titanium content was found in the film regions close to the alloy/film interface, indicating its oxidation. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
993.
994.
995.
将双极性半导体钝化膜空间电荷电容等效为钝化膜/溶液界面处电容和内层钝化膜/外层钝化膜界面处的np结电容的串联, 根据前期研究建立的半导体富集态、耗尽态以及反型态空间电荷电容的统一计算公式, 给出了双极性钝化膜Mott-Schottky(M-S)曲线的非线性拟合方法. 并将这一方法应用于镍基合金G3高温高压H2S/CO2腐蚀后的钝化膜半导体特征研究. M-S曲线非线性拟合结果显示, 温度升高外层p型半导体钝化膜多数载流子浓度明显增高, 而内层n型半导体钝化膜的多数载流子浓度基本未变. 通过非线性拟合, 证明本文所给出的M-S曲线非线性拟合方法能够同时给出钝化膜内外层多个半导体性质参数,为揭示钝化膜形成及破坏机制提供更多信息. 结合X射线光电子能谱(XPS)分析, 讨论了钝化膜结构变化机制及np结在抑制腐蚀过程中的作用. 相似文献
996.
Cordierite porous ceramics Z, X, and K were prepared using three mixtures of clay minerals: Z from kaolinite, talc, and aluminum
hydroxide, X from kaolinite, talc, vermiculite, and aluminum hydroxide, and K from kaolinite, talc, and magnesium oxide. Ceramics
were different in porosity, specific surface area, cordierite polymorphs, and secondary crystalline phases. Vermiculite influenced
textural architecture of calcined cordierite ceramics X and predestinated crystallization of the high-temperature hexagonal
α-cordierite with secondary minerals enstatite, spinel and corundum. Ceramics Z contained low-temperature orthorhombic β-cordierite,
enstatite, and corundum, K was diphase of β-cordierite and forsterite. Total pore area (TPA) and specific surface area (SSA)
of X, in spite of the higher porosity and the pore size distribution in the range of 300–1000 nm, were smaller in comparison
with TPA and SSA of Z. Ceramics K retained high porosity, two maxima at 300–1000 nm and 50–200 nm in the pores size distribution,
and the highest TPA and SSA compared to those observed in ceramics Z and X.
Presented at the 8th Conference on Solid State Chemistry, 6-11 July 2008, Bratislava, Slovak Republic. 相似文献
997.
Novel strategy in enhancing stability and corrosion resistance for hydrophobic functional films on copper surfaces 总被引:2,自引:0,他引:2
Shougang Chen Yan Chen Yanhua Lei Yansheng Yin 《Electrochemistry communications》2009,11(8):1675-1679
A rod-like 1-dodecanethiol film assisted with the preferential adhesion of polydopamine was prepared on the non-etching copper surfaces by a simple dip-coating method. The formation and surface structure of the film were characterized by water contact angle measurement, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Once the 1-dodecanethiol film formed on the polydopamine-coated copper surface, the hydrophilic surface changed to hydrophobic. The corrosion behavior of the functional films was evaluated by the electrochemical impedance spectroscopy (EIS). The excellent corrosion resistance property could be ascribed to the compact film structure and good seawater stability for modified copper surface, especially in limiting the infiltration of Cl−. 相似文献
998.
Yinpo Qiao Xiaopeng Zhao 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,340(1-3):33-39
Carbonaceous materials with different hierarchical porous structures for electrorheological (ER) dispersed phase have been synthesized by carbonization of as-prepared starch/silica precurser at different temperatures. The N2 adsorption isotherms show that Cmeso-700 and Cmeso-500 particles have the BET surface areas of 1028 and 603 m2 g−1, respectively. They both have the mesoporous pores with size of about 4.6 nm and the microporous pores (1.1 and 1.5 nm, respectively). The BET surface areas and C/O atomic ratio of porous carbon materials can be increased with the carbonization temperatures. The rheological measurements indicate that the Cmeso-700 and Cmeso-500 ERF have the better ER effect resulted from their hierarchical porous structures. The shear stress of Cmeso-700 ERF is 900 Pa at 1000 s−1 under 3 kV mm−1, which is almost 4.5 times larger than that of Cmicro-350 ERF. The mesoporous carbon ERFs also show the better sedimentation stability than microporous carbon ERFs. The different ER effect of carbonaceous particles may derive from their different dielectric polarization property induced by the hierarchical porous structures. 相似文献
999.
Wei Chen Dongchen Qi Xingyu Gao Andrew Thye Shen Wee 《Progress in Surface Science》2009,84(9-10):279-321
Surface transfer doping relies on charge separation at interfaces, and represents a valuable tool for the controlled and nondestructive doping of nanostructured materials or organic semiconductors at the nanometer-scale. It cannot be easily achieved by the conventional implantation process with energetic ions. Surface transfer doping can effectively dope semiconductors and nanostructures at relatively low cost, thereby facilitating the development of organic and nanoelectronics. The aim of this review is to highlight recent advances of surface transfer doping of semiconductors. Special focus is given to the effective doping of diamond, epitaxial graphene thermally grown on SiC, and organic semiconductors. The doping mechanism of various semiconductors and their possible applications in nanoelectronic devices will be discussed, including the interfacial charge transfer and the energy level alignment mechanisms. 相似文献
1000.
The surface modification of Ag/Ag2CO3 with Fe(III) ions has been achieved through simply photoreduction‐impregnation method. The obtained products were characterized by means of X‐ray diffraction (XRD), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), and UV‐vis absorption spectroscopy. Under visible‐light irradiation (γ>420 nm), the Fe(III)/Ag/Ag2CO3 sample displays a higher photocatalytic activity and stability than pure Ag2CO3 and Ag/Ag2CO3 samples for the degradation of methyl orange (MO). The improved photocatalytic activity and stability of this ternary system could be ascribed to the synergetic effect between Ag nanoparticles and Fe(III) nanocluster. The metallic Ag nanoparticles cause an obviously enhanced visible‐light absorption to produce more photogenerated charges, while the Fe(III) works as an active site for the following oxygen reduction to reduce the recombination rate of photogenerated electrons and holes. 相似文献