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1.
Nanotubular titanium dioxide thin films were prepared by anodization of titanium metal films evaporated on indium tin oxide (ITO) coated glass. A facile method to enhance the adhesion of the titanium film to the ITO glass was developed. An optimum thickness of 550 nm for the evaporated titanium was found to keep the film adhered to ITO during the anodization. The films were further modified by growing amorphous titania, alumina and tantala thin films conformally in the nanotubes by atomic layer deposition (ALD). The optical, electrical and physical properties of the different structures were compared. It was shown that even 5 nm thin layers can modify the properties of the nanotubular titanium dioxide films. 相似文献
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Large size anodic alumina film has not been used in the industry due to that the fabrication parameters are very difficult to control, but the fabrication of large size anodic alumina is exigent as a template in the fabrication of diverse nano-devices oriented to the industrialization. In this paper, large size (width length = 80 mm × 80 mm) porous ordered anodic alumina film was fabricated by using two-step anodization process as compared to the small size (diameter = 40 mm) anodic alumina film in the structures. Pore size and film thickness of anodic alumina film are strongly related to the size of the anodization film. The large size anodic alumina film has an ideally ordered pattern by applying low voltage. However, with the increase of voltage, the ordered pattern of the PAA films was gradually disrupted, especially in the 70 V due to the local thermal imbalance. 相似文献
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Effects of thin-film structural parameters on laser desorption/ionization from porous alumina 总被引:1,自引:0,他引:1
Nanoporous aluminum oxide layers, grown by anodization of aluminum thin films on glass and then sputter-coated with gold, were used to study the effects of the thin-film structural parameters on laser desorption/ionization (LDI) mass spectrometry (MS) of peptides. Variation of MS signal intensity was examined as a function of alumina pore depth, pore width, and gold layer thickness. Peptide molecular ion intensity was optimal with porous alumina formed from aluminum films of approximately 600-nm thickness; thinner or thicker films gave significantly lower signals. Signals decreased when pore sizes were increased beyond the as-formed width of approximately 100 nm. The MS signal also varied with the thickness of the sputtered gold layer with an optimum thickness being approximately 90 nm. The results of these studies provide values for empirical optimization of LDI MS performance as well as potential clues to the LDI mechanism. 相似文献
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高度有序多孔阳极氧化铝模板的制备 总被引:1,自引:0,他引:1
为了得到纳米孔排列高度有序的多孔阳极氧化铝模板,以0.3 mol·L-1的草酸为电解液研究了模板的制备工艺.采用场发射扫描电子显微镜(FE-SEM)对多孔氧化铝模板的表面形貌进行表征,X射线衍射分析高纯铝及氧化膜的结构.实验结果表明,铝基体不经过高温退火处理,同样能够得到高度有序的氧化铝膜,简化了多孔氧化铝膜的制备工艺.分别讨论了阳极氧化电压和电解液温度对多孔阳极氧化铝膜的形貌及孔径的影响,并对一步法和两步法制得的多孔氧化铝膜进行比较,结果表明,两步阳极氧化法制备的多孔氧化铝模板的有序性优于一步氧化法.XRD分析证实,多孔氧化铝膜由非晶态的Al2O3组成. 相似文献
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Kokonou M Nassiopoulou AG Giannakopoulos KP Boukos N Travlos A 《Journal of nanoscience and nanotechnology》2005,5(3):454-458
The formation of thin alumina films on a silicon substrate by anodization in a mild acid, specifically in 1% wt citric acid aqueous solution, is investigated by transmission electron microscopy (TEM). We present a comparative study between two cases of starting material: pure aluminum and an alloy of aluminum with 1% silicon. In both cases the thickness of the Al layer was less than 50 nm. It was observed that under exactly the same conditions, in the first case the anodization was stopping before anodizing the whole film and a remaining non-anodized Al layer was always present, while in the second case, the Al layer was fully anodized, resulting in an alumina matrix with a very high density of silicon nanocrystals of uniform sizes embedded in it. In both cases the alumina film was compact and amorphous. 相似文献
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We investigated the nanopattern transferring process by a template of anodic aluminum oxide and the formation of a nanoporous aluminum oxide layer on a Si solar cell by the anodization process of Al thin films. The anodization process provided a template to transfer the nanopattern onto the Si surface. The small-sized nanoporous alumina template was attached to be covered on the textured surface and played the role of etching mask in the F-based dry etching process. Furthermore, we deposited an Al thin film onto the Si surface and the subsequent anodization process was performed. The alumina formulated on the deposited Al thin film did not show the array of nanoporous structure and no nanopatterns were transferred onto the surface. The large-areal alumina deposited on the Si surface showed enhanced photo-absorption in the ultraviolet spectral region of 243 nm, but increased the photo-reflectance in the visible and infrared spectral regions when compared to the Si-bare sample. 相似文献
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Indium oxide/tin oxide multilayered films with a 2 nm pair thickness were deposited on glass substrates at temperatures lower
than 100° C by an ion-beam sputtering method. The structure, electrical properties and visible transmissivity were investigated
as a function of composition and the total thickness on as-deposited and annealed films. X-ray diffraction analysis showed
that the as-deposited 200 nm thick film (with 0.15 nm tin oxide layers) was partially crystalline and films thinner than 100
nm were amorphous or microcrystalline. The roomtemperature resistivity of as-prepared films increased with the increase of
an average tin oxide layer thickness from ∼0.05 to ∼0.3 nm (ideal monolayer thickness) under a constant total thickness ∼100
nm. We observed a decrease of the Hall mobility with the increase of the total film thickness from 10 to 200 nm in as-deposited
samples containing 0.15 nm tin oxide layers. 相似文献
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S.‐Z. Chu K. Wada S. Inoue M. Isogai A. Yasumori 《Advanced materials (Deerfield Beach, Fla.)》2005,17(17)
A simple, low‐cost approach to fabricating large‐area highly ordered nanoporous alumina films in sulfuric acid solutions through a single‐step high‐field anodization, without the assistance of any additional process, is reported on p. 2115 by Chu and co‐workers. The critical high anodizing potential in the adopted electrolyte system increases with the ageing of solutions after a long period of anodization. Correspondingly, the applicable current density for stable anodization rises significantly, thus leading to high‐speed film growth. Uniform porous anodic alumina films in sulfuric acid solutions under a high electric field of 40–70 V and 1600–2000 A m–2 are achieved. 相似文献
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Masahiro Kitada 《Journal of Materials Science》1991,26(15):4150-4154
Magnetic properties of permalloy/permalloy-oxide multilayer thin films are investigated. These thin films are prepared by
a repeat of sputter deposition of permalloy thin film, followed by oxidation of the film surface. The total thickness of the
permalloy thin films before oxidation is about 100 nm. The number of layers is one to twenty. The oxide layers are formed
by oxidation in dry air. The estimated oxide layer thickness is about 2 nm. The oxide NiFe2O4 is identified by RHEED. The film coercivity decreases linearly with increasing layer numbers. The saturation magnetization
and magnetoresistivity decrease as the number of layers increase. The coercivity decrease is due to grain growth suppression
and magnetic separation by oxide film of permalloy layer, and magnetoresistivity decrease is due to electrical resistivity
increase originating into electron scattering by the oxide layer. 相似文献
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Gowtham M Eude L Cojocaru CS Marquardt B Jeong HJ Legagneux P Song KK Pribat D 《Nanotechnology》2008,19(3):035303
Confined lateral alumina templates are fabricated with different pore sizes by changing the acid electrolyte and the anodization voltage. The control of the number of pore rows down to one dimension is also achieved, by controlling the thickness of the starting aluminum film as well as the anodization voltage. We observe that the mechanism of pore formation in the lateral regime is very similar to that in the classical vertical situation. 相似文献
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A piezoelectric laminated cylindrical shell with shear rotations effect under the electromechanical loads and four sides simply supported boundary condition was studied by using the two-dimensional generalized differential quadrature (GDQ) computational method. The typical hybrid composite shells with 3-layered cross-ply [90°/0°/90°] graphite–epoxy laminate and bounded PVDF layers are considered under the sinusoidal pressure loads and electric potentials on the shell. The governing partial differential equation with first-order shear deformation theory in terms of mid-surface displacements and shear rotations can be expressed in series equations by the GDQ formulation. Thus we obtain the GDQ numerical solutions of non-dimensional displacement and stresses at center position of laminated piezoelectric shells. Displacement is generally affected by the thickness of laminated piezoelectric shells under the action of mechanical load. Stresses are generally affected by the thickness and the length of laminated piezoelectric shells under the actions of mechanical load and electric potential. 相似文献
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The change in polystyrene (PS) layer thickness, which has been simultaneously determined during post-yield deformation, shows
that crazing is the basic mechanism of toughening in all laminated films, and that shear deformation supplements the contribution
of crazing especially for samples with high polyethylene (PE) volume fractions. Crazes formed in PS layers in the laminated
films are slender and regular compared with the short and lenticular crazes formed in bulk PS film. When PE volume fraction
increased, craze advance speed decreased because of the reduction of the stress concentration effect at craze tips. The life-time
of the first mature craze to be formed at a given strain rate increased with PE volume fraction because the PE supporting
the mature crazes could effectively inhibit craze rupture and blunt out the propagating crack by absorbing the stored elastic
energy in the PS layer that would have been dissipated as fracture surface energy. 相似文献
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《Materials Letters》2007,61(11-12):2385-2388
NiTi was galvanostatically anodized in acetic acid to increase the oxide film thickness for improving corrosion resistance. The galvanostatic anodization behavior of NiTi in acetic acid differed markedly from that of Ti. In particular, the anode potential reached was much lower for NiTi, and thus only thin oxide films could be obtained. With a suitable choice of anodizing conditions, the anodic oxide film formed had a thickness of 20–25 nm, as determined by profilometric measurement. Atomic force microscopy (AFM) revealed that the surface roughness was increased after anodization. Analysis by X-ray photoelectron spectroscopy (XPS) showed a low Ni/Ti ratio of 0.04 at the anodic oxide surface versus a value of 0.30 for bare NiTi. Electrochemical impedance measurements of the anodized sample in Hanks' solution at 37 °C recorded a 9-fold increase in polarization resistance, and cyclic polarization tests also recorded a matching reduction in the passive current density. These observations indicate that anodization of NiTi can serve as a simple low-temperature method to enhance the corrosion resistance of NiTi when used as an implant material. 相似文献
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The free vibration of laminated shallow shells containing piezoelectric layers is investigated in this article. A finite-element formulation based on the transverse shear deformation theory has been used to determine the natural frequencies, mode shapes, and modal voltages of laminated composite shell structures containing piezoelectric layers. Comparisons of degenerate cases with published results show excellent agreement. The effect of electromechanical coupling on the predicted natural frequencies is discussed. Results are presented for different geometries, laminate configurations, and boundary conditions. The effects of shell shallowness and piezoelectric layer thickness are also studied. Higher natural frequencies are obtained when the full electromechanical coupling is considered. It is also found that the natural frequencies increase considerably with the shell curvature, particularly for thin piezoelectric layers. 相似文献
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Nanoporous anodic aluminium oxide has traditionally been made in one of two ways: mild anodization or hard anodization. The first method produces self-ordered pore structures, but it is slow and only works for a narrow range of processing conditions; the second method, which is widely used in the aluminium industry, is faster, but it produces films with disordered pore structures. Here we report a novel approach termed "pulse anodization" that combines the advantages of the mild and hard anodization processes. By designing the pulse sequences it is possible to control both the composition and pore structure of the anodic aluminium oxide films while maintaining high throughput. We use pulse anodization to delaminate a single as-prepared anodic film into a stack of well-defined nanoporous alumina membrane sheets, and also to fabricate novel three-dimensional nanostructures. 相似文献