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101.
102.
Nana A. Kyeremateng Dr. Virginie Hornebecq Hervé Martinez Prof. Philippe Knauth Prof. Thierry Djenizian 《Chemphyschem》2012,13(16):3707-3713
Highly‐ordered Fe‐doped TiO2 nanotubes (TiO2nts) were fabricated by anodization of co‐sputtered Ti–Fe thin films in a glycerol electrolyte containing NH4F. The as‐sputtered Ti–Fe thin films correspond to a solid solution of Ti and Fe according to X‐ray diffraction. The Fe‐doped TiO2nts were studied in terms of composition, morphology and structure. The characterization included scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, UV/Vis spectroscopy, X‐ray photoelectron spectroscopy and Mott–Schottky analysis. As a result of the Fe doping, an indirect bandgap of 3.0 eV was estimated using Tauc’s plot, and this substantial red‐shift extends its photoresponse to visible light. From the Mott–Schottky analysis, the flat‐band potential (Efb) and the charge carrier concentration (ND) were determined to be ?0.95 V vs Ag/AgCl and 5.0 ×1019 cm?3 respectively for the Fe‐doped TiO2nts, whilst for the undoped TiO2nts, Efb of ?0.85 V vs Ag/AgCl and ND of 6.5×1019 cm?3 were obtained. 相似文献
103.
The influence of interfacial barrier engineering on the resistance switching of In2O3:SnO2/TiO2/In2O3:SnO2 device 下载免费PDF全文
The I-V characteristics of In2O3:SnO2/TiO2/In2O3:SnO2 junctions with different interracial barriers are inves- tigated by comparing experiments. A two-step resistance switching process is found for samples with two interfacial barriers produced by specific thermal treatment on the interfaces. The nonsynchronous occurrence of conducting filament formation through the oxide bulk and the reduction in the interracial barrier due to the migration of oxygen vacancies under the electric field is supposed to explain the two-step resistive switching process. The unique switching properties of the device, based on interracial barrier engineering, could be exploited for novel applications in nonvolatile memory devices. 相似文献
104.
《Optimization》2012,61(4):543-553
A model of optimal control for discrete systems and the historical development of the discrete maximum principle are considered. The paper deals with local optimality conditions of the first order, e.g. with a local maximum-principle and a quasi-maximum principle. Furthermore, optimality conditions of higher order, e. g. an optimality condition for singular controls are given. 相似文献
105.
以价廉的Ni板代替常用的Pt片为阴极,纯钛为阳极,采用电化学阳极氧化法在NH4F-H3PO4体系中制备出TiO2纳米管阵列.详细研究了制备参数(溶液酸度、氟离子浓度、外加电压和氧化时间)对所获纳米管阵列形貌的影响.采用场发射扫描电镜(FE-SEM)和X射线衍射(XRD)对样品的形貌和晶相结构进行了表征.在最优化的条件下,可以获得形貌规整、表面干净、有序的TiO2纳米管阵列.纳米管阵列的平均管径为60 nm.管长约530 nm.采用阳极氧化法制备的纳米管阵列是非晶态的.经400℃热处理2 h后,可以转变为锐钛矿相.实验结果还发现,经过热处理后,纳米管阵列变得更为有序,管径扩大至约95 nm. 相似文献
106.
阳极氧化钛纳米管(anodic titania nanotubes,ATNTs)阵列膜具有制备简便、比表面积大和有序度高等优点因而备受人们关注,已广泛应用于太阳能电池、传感器、光催化和超级电容器等领域。但与类似的多孔阳极氧化铝相比,在可控制备即微观形貌控制方面仍相差甚远。迄今,ATNTs的综述文章多侧重于ATNTs的形成机理、改性及应用方面,而本文则聚焦于近十年来ATNTs制备技术成果,试图揭示其在管长、管径和规整度等方面的可控制备规律。首先介绍了在乙二醇(EG)电解液中制备ATNTs的常规阳极氧化条件,以及得到的ATNTs的典型形貌特征。然后评述了非EG电解液体系中,ATNTs的生长规律和形貌特征。在此基础上,综述了如何通过改变阳极氧化工艺参数,如电解液温度、F-浓度、氧化电压和时间等来实现对ATNTs管径及规整性的调控,并讨论了制备超长纳米管膜的难点和方法,以及获得ATNTs自支撑膜的各种工艺。最后指出了目前ATNTs可控制备存在的不足及今后的发展方向。 相似文献
107.
Lanhao Zhao Xin Bai Wei Zhang Tongchun Li J.J.R. Williams 《International Journal of Computational Fluid Dynamics》2016,30(1):1-6
Local scour has been identified as the main factor that causes failures of structures in offshore engineering. Numerous research efforts have been devoted to local scour around offshore pipelines in the past. In this paper, a finite element numerical model is established for simulating local scour below offshore pipelines in steady currents. The flow is simulated by solving the unsteady Reynolds-averaged Navier–Stokes equations with a standard k ? ? turbulent model closure. A sand slide scheme is proposed for the scour calculation, and bed load is considered in the proposed scour model. To account for changes in bed level, the moving mesh method is adopted to capture the water–sediment interface (bed), and the change of bed level is calculated by solving Exner–Polya equation. All the equations are discretised within the two-step Taylor–Galerkin algorithm in this paper. It is found that the sand slide model works well for the simulation of the scour, and the numerical results are shown to be in good agreement with the available experimental data. 相似文献
108.
为了降低含氟电解液对环境的不良影响和有用资源的浪费,本文以不同使用次数(n≤15)的含氟溶液作为电解液,采用阳极氧化法制备了一系列TiO2纳米管阵列(TiO2NT).然后借助SEM、恒流充/放电、循环稳定性及循环伏安(CV)技术研究了含氟电解液的使用次数(n≤15)对所制备纳米管阵列电极的形貌及脱/嵌锂离子性能的影响.结果表明:含氟电解液的使用次数(n≤15)对TiO2NT形貌的负面影响不明显;作为锂离子电池负极活性材料时,电化学脱/嵌锂性能也没有出现大幅降低. 相似文献
109.
We report a two‐step anodizing approach for the fabrication of large‐scale open‐ended TiO2 nanotube arrays (TNAs) on a conductive Au layer. In this method, a deposited Ti/Au bilayer film is initially anodized under a high potential to form and shape the TNAs. A following low potential is then in situ applied at a suitable time to slowly eliminate the remaining barrier layer at the bottom of the TNAs without further treatment. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
110.
Merve İzmir Yiğithan Tufan Güher Tan Batur Ercan 《Surface and interface analysis : SIA》2019,51(9):954-963
Despite the widespread use of Ti6Al4V in orthopaedics, the bioinert nature of this alloy limits its biological fixation with the bone tissue. To enhance its bone fixation, two different types of Ti6Al4V foams were fabricated, and their surfaces were modified zto possess nanofeatures. To prepare the foams, spherical- or irregular-shaped Ti6Al4V particles were used to form the backbones of the foams, while magnesium or carbamide powders were used as space holder agents. Once Ti6Al4V foams were fabricated, oxide-based nanotubular arrays having 40 nm diameter were formed on the interconnected pore surfaces via anodization. Results showed successful growth of nanotubular oxide arrays independent of the pore surface morphology, chemistry, and porosity content. Nanotubular surfaces induced formation of calcium phosphate minerals independent of the Ti6Al4V particle type and the space holder agent. Thus, anodized nanotubular Ti6Al4V foams could potentially induce enhanced integration of Ti6Al4V-based porous implants with the bone tissue. 相似文献