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991.
High quality photonic crystal heterostructures with a thin titania planar defect layer between its two constitutional photonic crystals were fabricated and their structural and optical properties were analyzed. The results suggest that the thin planar defect layer is beneficial to separate the two constitutional photonic crystals from each other and to reduce the roughness of the interface. The quality of the resulting photonic crystal heterostructures is improved largely and the main features of the photonic band gaps of the two constitutional photonic crystals are inherited. The predominant optical quality of these heterostructures (e.g. deep double photonic band gaps and steep photonic band edges) may afford new flexibility and functionality for engineered photonic behavior in practical devices such as late-model light-operated switches. 相似文献
992.
B.Y. Man S.C. XuC. Yang M. LiuS.Z. Jiang Y.Y. MaC.S. Chen A.H. LiuX.G. Gao C.C. WangB. Hu 《Applied Surface Science》2011,257(15):6321-6325
Single-phase β-FeSi2 films on silicon (1 0 0) were fabricated by pulse laser deposition. The structure and crystal quality of the samples were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The field scanning electron microscopy showed that the film thickness increases with the increasing of the laser fluence. Moreover, atomic force microscopy observations revealed the changes of surface properties with different laser fluence. Based upon all experimental results, it is found that 7 J/cm2 is the most favorable for the formation of β-FeSi2 thin films. 相似文献
993.
Bioactive calcium phosphate coating formed on micro-arc oxidized magnesium by chemical deposition 总被引:3,自引:0,他引:3
In order to improve the bioactivity of the micro-arc oxidized magnesium, a calcium phosphate coating was formed on the surface of micro-arc oxidized magnesium using a chemical method. The microstructures of the substrate and the calcium phosphate coating before and after the simulated body fluids (SBF) incubation were characterized by X-ray diffraction, Fourier-transformed infrared spectroscopy and scanning electron microscopy. The results showed that the calcified coating was composed of calcium deficient hydroxyapatite (HA) and dicalcium phosphate dihydrate (DCPD). After SBF incubation, some new apatite formation on the calcified coating surface from SBF could be found. The corrosion behaviours of the samples in SBF were also investigated by potentiodynamic polarization curves and immersion tests. The results showed that calcium phosphate coating increased the corrosion potential, and decreased the hydrogen gas release. 相似文献
994.
Lihui SunHongwei Qin Feng GaoEnsi Cao Kai FanJifan Hu 《Applied Surface Science》2011,257(7):2633-2636
The adsorption of CO, NH3 and O2 gas molecules on Fe site of La0.875Sr0.125FeO3 (0 1 0) surface has been investigated based on the density functional theory (DFT) with the spin polarized generalized gradient approximation (GGA). The optimal adsorption orientations as well as the adsorption energies for these molecules adsorption on Fe site of La0.875Sr0.125FeO3 (0 1 0) surface are derived. Results show that adsorption configurations with C-down for CO, N-down for NH3 are stable. For the O2 molecule adsorption, the mode with an angle about 120° between the oxygen molecule and La0.875Sr0.125FeO3 (0 1 0) surface is stable. 相似文献
995.
Effect of stearic acid, zinc stearate coating on the properties of synthetic hydromagnesite 总被引:1,自引:0,他引:1
Synthetic hydromagnesite (SHM), used as flame retardant for polymers, may have similar or better flame retardancy effectiveness than aluminum tri-hydroxide (ATH) and magnesium di-hydroxide (MDH). Suitable surface modifiers are often employed to improve its dispersion and compatibility with polymer matrix. In this study, we chose stearic acid (SA) and zinc stearate (ZS) as the surface modifier, and investigated the properties of SHM modified with various surface modifier content using dry blending coating process. Scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG), particle size distribution, contact angle, oil absorption, bulk density, tapped density and Carr's index were employed to characterize the effect of surface modification. The results showed that the surface of SHM powders was changed from hydrophilic to lipophilic. The flowability of the surface modified powder was also improved. TG graphs showed that the surface modifier had no obvious influence on the degradation pathway of the SHM. 相似文献
996.
The possibilities of magnetism induced by intrinsic defects and nitrogen substitution in (5,5) single-wall SnO2 nanotube are investigated by ab initio calculations. The calculated results indicate that a stoichiometric SnO2 nanotube is nonmagnetic. The tin (Sn) vacancy can induce the magnetic moments rather than oxygen vacancy, which is originated from the polarization of O 2p electrons. A couple of tin vacancies can lead to the ferromagnetic coupling. A nitrogen substitution for oxygen also produces magnetic moments. When substituting two nitrogen atoms, the characteristics of exchange coupling depend upon the distance of two nitrogen atoms. The longer distance of two nitrogen atoms prefers the ferromagnetic coupling, whereas the short distance leads to the antiferromagnetic coupling. 相似文献
997.
文章研究了SOI衬底上SiGe npn异质结晶体管集电结耗尽电荷和电容.根据器件实际工作情况,基于课题组前面的工作,对耗尽电荷和电容模型进行扩展和优化.研究结果表明,耗尽电荷模型具有更好的光滑性;耗尽电容模型为纵向耗尽与横向耗尽电容的串联,考虑了不同电流流动面积,与常规器件相比,SOI器件全耗尽工作模式下表现出更小的集电结耗尽电容,因此更大的正向Early电压;在纵向工作模式到横向工作模式转变的电压偏置点,耗尽电荷和电容的变化趋势发生改变.SOI薄膜上纵向SiGe HBT集电结耗尽电荷和电容模型的建立和扩展为毫米波SOI BiCMOS工艺中双极器件核心参数如Early电压、特征频率等的设计提供了有价值的参考.
关键词:
耗尽电容
SiGe HBT
SOI 相似文献
998.
999.
Dissipation of a two-mode squeezed vacuum state in the single-mode amplitude damping channel 下载免费PDF全文
We explore how a two-mode squeezed vacuum state sechθ ea+b+ tanh θ |00> evolves when it undergoes a singlemode amplitude dissipative channel with rate of decay κ. We find that in this process not only the squeezing parameter decreases, tanh θ → e-κt tanh θ, but also the second-mode vacuum state evolves into a chaotic state exp{b+bln[1 - e-2κt tanh2 θ]}. The outcome state is no more a pure state, but an entangled mixed state. 相似文献
1000.