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41.
An analytical method for analyzing high-resolution transmission electron microscopy (HRTEM) images is presented. The method is composed of two major parts: digital image processing and lattice fringe characterization. The digital image processing is composed of the following operations: negative transformation, region of interest (ROI) selection, contrast enhancement, Gaussian lowpass filter, top-hat transformation (used to correct uneven illumination across an image), thresholding to obtain a binary image, morphological modification, clearing fringes on the ROI border, skeletonization, and removing short fringes that lack physical meaning. These operations are defined by equations with effects illustrated by images. The lattice fringe characterization generates statistics on fringe length, tortuosity, and separation based on the skeletons of the graphene layers. Fringe length and tortuosity are obtained automatically from the features of the skeletons, while fringe separation is obtained by analyzing manually selected fringe pairs. The algorithms are implemented within MATLAB, and demonstrated upon an exemplary HRTEM image of carbonaceous material. The image analysis algorithm permits quantitative HRTEM, here specifically addressing nanostructure of carbonaceous materials. 相似文献
42.
Jianhua Jiang Jiangwei Ren Aidang Shan Junliang Liu Hongwei Song 《Materials Science and Engineering: A》2009,520(1-2):80-89
The mechanical property and microstructure evolutions of Ni3Al intermetallic compound subjected to surface mechanical attrition treatment (SMAT) were investigated in relation to surface nanocrystalization. Grain size in topmost surface of SMATed Ni3Al alloy was refined to a minimum size of about 10 nm, and then increased with the enhancement of the depth from surface to matrix. The original ordered L12 phase transformed to Ni (Al) solid solution with a disordered face-centered cubic structure. The maximum nanohardness of the deformed Ni3Al alloy was near 12 GPa. The microstructure evolution including the variation of defects during the SMAT as well as post-annealing processes showed that the surface nanocrystallization of Ni3Al intermetallic compound was predominantly controlled by dislocations which divided the coarse grains. The different microstructures at each sublayer illustrated that the nanocrystallization process was decided by the accumulated energy resulted from plastic strain. 相似文献
43.
G. Siviero V. Bello G. Mattei P. Mazzoldi G. Battaglin N. Bazzanella R. Checchetto A. Miotello 《International Journal of Hydrogen Energy》2009
In this paper we present a study on the relation between the evolution, upon successive H2 cycling, of the crystalline order and the H2 sorption properties of Pd-capped textured Mg thin films grown on Si and glass substrates. 相似文献
44.
Wen-Yin Ko Wei-Hung Chen Ching-Yuan Cheng Kaun-Jiuh Lin 《Nanoscale research letters》2009,4(12):1481-1485
Cu particles with different architectures such as pyramid, cube, and multipod have been successfully fabricated on the surface
of Au films, which is the polycrystalline Au substrate with (111) domains, using the electrodeposition technique in the presence
of the surface-capping reagents of dodecylbenzene sulfonic acid and poly(vinylpyrrolidone). Further, the growth evolution
of pyramidal Cu nanoparticles was observed for the first time. We believe that our method might open new possibilities for
fabricating nanomaterials of non-noble transition metals with various novel architectures, which can then potentially be utilized
in applications such as biosensors, catalysis, photovoltaic cells, and electronic nanodevices. 相似文献
45.
Flavio L. Souza Kirian P. Lopes Edson R. Leite 《Solar Energy Materials & Solar Cells》2009,93(3):362-368
Doped and undoped hematite films for photoelectrochemical hydrogen production were prepared by spin-coating deposition solution (SCDS). To understand the influence of the Si-doping and identify the critical parameters of the proposed SCDS method an extensive characterization was conducted. The Si-doped hematite exhibited higher photocurrent response when compared with undoped films. We have shown that the crystallographic orientation degree of the films appears to be a dominant factor affecting the photocurrent. The performance of our hematite electrodes is well below the maximum theoretical efficiency and the conceivable explanation could be given by the high value of recombination phenomena (electron/hole pair). 相似文献
46.
CaRuO3-CaTiO3 ceramic composites were prepared by sintering for short times for potential applications in the areas of electronic ceramics. Scanning electron microscopy and energy dispersive X-ray analysis showed two separate phases, CaRuO3 and CaTiO3 in the composite. Conductivity data, measured by the four-probe method, showed that the composites have high electrical conductivity when x ≥ 0.19 in xCaRuO3-(1 − x)CaTiO3 composites. Furthermore, the nanoparticle of calcium ruthenate prepared by reverse micelle synthesis was used to be conductive agent for the composite. The result shows that the use of nano-sized calcium ruthenate enabled higher electrical conductivity to be maintained down to x = 0.09. 相似文献
47.
A newly developed route for the synthesis of hollow carbon nanospheres without introducing template under hydrothermal conditions
was reported. Hollow carbon nanospheres with the diameter of about 100 nm were synthesized using alginate as reagent only.
Many instruments were applied to characterize the morphologies and structures of carbon hollow nanospheres, such as XRD, TEM,
and Raman spectroscopy. The possible formation and growth mechanism of carbon hollow spheres were discussed on the basis of
the investigation of reaction influence factors, such as temperature, time, and content. The findings would be useful for
the synthesis of more materials with hollow structure and for the potential use in many aspects. The loading of SnO2 on the surface of carbon hollow spheres was processed, and its PL property was also characterized. 相似文献
48.
Nanostructured thin films of lead sulfide have been synthesized by a new electrochemical approach based on the underpotential deposition (UPD) of Pb and S from the saturated solution of PbS containing excess of PbS particles as a source of Pb2+ and S2− at various temperatures.We have demonstrated that this new electrochemical route is a simple method with several advantages, including better control of the growth conditions and a one-step process to obtain the nanostructures of PbS. Scanning probe microscopy studies indicate that the growth of PbS nanofilms follows a two-dimensional layer-by-layer growth kinetics at the beginning of electrodeposition but a three-dimensional growth dominates after the formation of the first few layers. The results of morphological and structural investigations reveal that PbS nanostructures grown by this method are single-crystalline in cubic structure and have a preferential orientation along the [2 0 0] direction. The optical absorption spectra of PbS nanostructures show the blue-shift with respect to those of the bulk counterpart, which are attributed as quantum-size effect. 相似文献
49.
The emerging discipline of biomolecular computation in the US 总被引:2,自引:0,他引:2
50.
C. Persson C.L. Dong L. Vayssieres T. Schmitt R. Ahuja C.L. Chang J.-H. Guo 《Microelectronics Journal》2006,37(8):686-689
The electronic structures of ZnO nanoparticles and microrod arrays are studied by O 1s X-ray absorption spectroscopy (XAS) and O Kα X-ray emission spectroscopy (XES). We show that the present LDA+USIC calculation approach is suitable to correct the LDA self-interaction error of the cation d-states. The atomic eigenstates of 3d in zinc and 2p in oxygen are energetically close, which induces strong Zn-3d-O-2p hybridization. This anomalous valence band cation-d-anion-p hybridization is affected when the localization of the Zn 3d-states is taken into account. Experimentally, the XES spectra show energy dependence in the spectral shape revealing selected excitations to the Zn 3d, 4s and 4p states, hybridized with O 2p states. Strong anisotropic effects are observed for the highly oriented ZnO rods, but not for the isotropic spherical nanoparticles. The nanostructured ZnO has primarily bulk XAS and XES properties. 相似文献