A nanofabrication method for the production of ultra-dense planar metallic nanowire arrays scalable to wafer-size is presented. The method is based on an efficient template deposition process to grow diverse metallic nanowire arrays with extreme regularity in only two steps. First, III–V semiconductor substrates are irradiated by a low-energy ion beam at an elevated temperature, forming a highly ordered nanogroove pattern by a “reverse epitaxy” process due to self-assembly of surface vacancies. Second, diverse metallic nanowire arrays (Au, Fe, Ni, Co, FeAl alloy) are fabricated on these III–V templates by deposition at a glancing incidence angle. This method allows for the fabrication of metallic nanowire arrays with periodicities down to 45 nm scaled up to wafer-size fabrication. As typical noble and magnetic metals, the Au and Fe nanowire arrays produced here exhibited large anisotropic optical and magnetic properties, respectively. The excitation of localized surface plasmon resonances (LSPRs) of the Au nanowire arrays resulted in a high electric field enhancement, which was used to detect phthalocyanine (CoPc) in surface-enhanced Raman scattering (SERS). Furthermore, the Fe nanowire arrays showed a very high in-plane magnetic anisotropy of approximately 412 mT, which may be the largest in-plane magnetic anisotropy field yet reported that is solely induced via shape anisotropy within the plane of a thin film.
Nano Research - Porous Fe3O4/carbon microspheres (PFCMs) were successfully fabricated via a facile electrospray method and subsequent heat treatment, using ferrous acetylacetonate, carbon nanotubes... 相似文献
Structural optimization with frequency constraints is highly nonlinear dynamic optimization problems. Genetic algorithm (GA)
has greater advantage in global optimization for nonlinear problem than optimality criteria and mathematical programming methods,
but it needs more computational time and numerous eigenvalue reanalysis. To speed up the design process, an adaptive eigenvalue
reanalysis method for GA-based structural optimization is presented. This reanalysis technique is derived primarily on the
Kirsch’s combined approximations method, which is also highly accurate for case of repeated eigenvalues problem. The required
number of basis vectors at every generation is adaptively determined and the rules for selecting initial number of basis vectors
are given. Numerical examples of truss design are presented to validate the reanalysis-based frequency optimization. The results
demonstrate that the adaptive eigenvalue reanalysis affects very slightly the accuracy of the optimal solutions and significantly
reduces the computational time involved in the design process of large-scale structures. 相似文献
X-ray imaging and microscopy techniques have been developed in worldwide due to their capabilities of large penetration power and high spatial resolution. Fresnel zone plates is considered to be one of the most convenient optic devices for X-ray imaging and microscopy system. The zone plates with aspect ratio of 7 and 13 have been fabricated by e-beam lithography combined with X-ray lithography in this paper. Firstly, the X-ray lithography mask of zone plates with outermost zone width of 100 nm was fabricated by e-beam lithography and gold electroplating techniques. Secondly, the zone plates with gold profile thickness of 700 and 1,300 nm were replicated by X-ray lithography and gold electroplating techniques. X-ray imaging and microscopy techniques were introduced to characterize the high-aspect-ratio zone plates’ inner structures. At the X-ray energy of 7.5 keV, the first-order focusing efficiency of zone plates with gold profile thickness of 700 nm is about 8.63%. 相似文献
Micro-/nanopositioning stage with remote-center-of-motion (RCM) plays a key role in precision out-of-plane aligning since it can eliminate harmful lateral displacement generated at the output platform. This paper presents the design, modeling and test of a novel large-range flexure-based micropositioning stage with RCM characteristic. The stage is composed of an outer RCM guiding mechanism and a inner output-stiffness enhanced lever amplifier (OELA). The outer RCM guiding mechanism is constructed by a symmetric double parallelogram mechanism which can guide the stage to perform a RCM movement with high rotational precision. The inner OELA is designed to amplify the output displacement of the adopted piezoelectric stack actuator (PSA). Compared with conventional lever amplifier, the proposed OELA possesses twice the output stiffness, which makes it more appropriate for actuating the outer mechanism and therefore, a large rotational range can be obtained. Based on the pseudo-rigid-body-model (PRBM) method, the analytical models predicting kinematics, statics, and dynamics of the RCM stage have been established. Besides, the dimensional optimization is conducted in order to maximize the first resonance frequency of the stage. After that, finite element analysis is carried out to validate the established models and the prototype of the stage is fabricated for performance tests. The experimental results show that the developed RCM stage has a rotational range of 6.96 mrad while the maximum center shift of the RCM point is as low as \(9.2\,{\upmu } \text {m}\), which validate the effectiveness of the proposed scheme. 相似文献