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31.
A novel fishing rod-shaped GaN nanorod is successfully fabricated through a new method by using the two-step growth technology. This growth method is applicable to continuous synthesis and is able to produce a large number of single-crystalline GaN nanorods with a relatively high purity and at a low cost. X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy are used to characterize the as- synthesized nanorods. The results show that most of the nanorods consist of a main rod and a top curved thread. It is single-crystal GaN with hexagonal wurtzite structure. The representative photoluminescence spectrum at room temperature exhibits a strong UV light emission band centered at 370.8nm. Furthermore, a possible two-stage growth mechanism of the fishing rod-shaped GaN nanorod is also briefly discussed. 相似文献
32.
Study on the chemical composition features of Longquan celadon excavated from the Chuzhou site of Huai'an City in Jiangsu Province by EDXRF 总被引:1,自引:0,他引:1
A mass of Longquan celadon shards were excavated from the Chuzhou site of Huai'an City in Jiangsu Province, China. These celadon shards were fired during the period of the Late Yuan Dynasty to the Tianshun era of the Ming Dynasty, as identified by archaeologists at Nanjing Museum. In order to research the chemical composition features of this ancient celadon porcelain, energy dispersive X-ray fluorescence (EDXRF) for non-destructive analysis was used to determine the chemical composition of the porcelain body and glaze in these shards. The results indicate that Ti and Fe in the body of Longquan celadon are characteristic elements which can distinguish porcelain produced during the Late Yuan Dynasty from those produced in the Ming Dynasties. The results of the principal component analysis (PCA) show that different body and glaze raw materials were used for the production of porcelain in different periods and the raw materials of the body and glaze are also different for various vessel shapes. The chemical compositions in the porcelain body of civilian ware are slightly different. The imperial and civilian Longquan celadon porcelains produced during the Hongwu era to the Tianshun era of the Ming Dynasty are distinguishable by the MnO, Fe2O3, Rb2O and SrO content in their porcelain glaze. 相似文献
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36.
Sha-Sha Wang Guang-Bao Xu Xiang-Qian Liang Yu-Liang Wu 《International Journal of Theoretical Physics》2018,57(12):3716-3726
Based on four-qubit symmetric W state, the delayed measurement, decoy photos method, block transmission technique and the dense coding method, a multi-party quantum key agreement protocol is proposed. By utilizing the delayed measurement and decoy photos method, the fairness and security of the protocol are ensured. That is, the final generation key can be got fairly by m participants and the outside eavesdropper (includes Trojan-horse attacks, Measure-resend attack, Intercept-resend attack and Entangle-measure attack) and the dishonest participants attacks can be resisted in this protocol. By utilizing block transmission technique and the dense coding method, the efficiency of the protocol is improved. The efficiency analysis shows that the proposed protocol is more efficient than other multi-party QKA protocols. 相似文献
37.
We report the structural and optical properties of nonpolar m-plane GaN and GaN-based LEDs grown by MOCVD on a 7-LiAlO2 (100) substrate. The TMGa, TMIn and NH3 are used as sources of Ga, In and N, respectively. The structural and surface properties of the epilayers are characterized by x-ray diffraction, polarized Raman scattering and atomic force microscopy (AFM). The films have a very smooth surface with rms roughness as low as 2nm for an area of 10×10μm^2 by AFM scan area. The XRD spectra show that the materials grown on 7-LiAl02 (100) have (1 - 100) m-plane orientation. The EL spectra of the m-plane InGaN/GaN multiple quantum wells LEDs are shown. This demonstrates that our nonpolar LED structure grown on the 7-LiAlO2 substrate is indeed free of internal electric field. The current voltage characteristics of these LEDs show the rectifying behaviour with a turn on voltage of 1-3 V. 相似文献
38.
Hao-Jie Song Xiang-Qian Shen Xian-Feng Meng 《Journal of Dispersion Science and Technology》2013,34(11):1465-1468
The present work investigates the enhancement of water repellency on engineering materials surfaces using nanoscale roughness inherent in multi-walled carbon nanotubes (MWCNTs) together with a hydrophobic polystyrene coating via a simple spraying-based technique. The coatings show both a high contact angle and a small sliding angle for water droplets. The different surfaces obtained exhibit contact angles from 125° up to 153° depending on the preparation conditions. The observations of the topology by scanning electron microscopy reveal that the nanostructure created by the MWCNTs and the microstructure induced by the deposition of polystyrene particles forming a two-level structure that conceptually mimics the lotus leaf surface are necessary to create stable superhydrophobic surfaces. 相似文献
39.
Monte Carlo Hamiltonian:Inverse Potential 总被引:2,自引:0,他引:2
The Monte Carlo Hamiltonian method developed recently
allows to investigate the ground
state and low-lying excited states of a quantum system, using Monte
Carlo (MC) algorithm
with importance sampling. However, conventional MC algorithm
has some difficulties
when applied to inverse potentials. We propose to use effective potential and
extrapolation method to solve the problem. We present examples from the hydrogen
system. 相似文献
40.
Hao-Jie Song Xiang-Qian Shen Hai-Yan Ji Xiao-Jing Jing 《Applied Physics A: Materials Science & Processing》2010,99(3):685-689
A simple and economical route based on a K2CO3 mediated process was developed to synthesize three-dimensional (3D) flower-like Fe3O4 micro/nanoflakes on the surface of iron plates by a direct in-situ hydrothermal synthesis method. The prepared micro/nanoflakes were characterized by X-ray diffraction and scanning electron microscopy. It was found that the width of the nanoflakes ranges from 50 to 100 nm, and the length of the flakes is about 3 μm. The morphology of Fe3O4 nanostructures can be tuned from simple isolated nanoflakes to the ordered 3D flower-like shape by increasing the reaction temperature. The wettability of the surface with 3D flower-like micro/nanoflakes was changed from hydrophilicity to superhydrophobicity by chemical modification with vinyl tirethoxy-silane. The static contact angles for water on both of the modified surfaces were larger than 150°, which was closely related to the chemical modification and hierarchical structure. Furthermore, the surfaces retained good superhydrophobic stability in long-term storage as well, which should be critical to the application of iron materials in engineering. 相似文献