POLYANILINE ELECTROLYTIC CAPACITOR

Aluminum solid electrolytic capacitors with polyaniline doped with inorganic and organic acids as counterelectrode were fabricated, their properties were studied.

Correlation between Discharging Property and Coatings Microstructure during Plasma Electrolytic Oxidation

The voltage-current properties during plasma electrolytic discharge were determined by measuring the current density and cell voltage as functions of processing time and then by mathematical transformation. Correlation between discharge I-V property and the coatings microstructure on aluminum alloy during plasma electrolfic oxidation was determined by comparing the voltage-current properties at different process stages with SEM results of the corresponding coatings. The results show that the uniform passive film corresponds to a I-V property with one critical voltage, and a compound of porous layer and shred ceramic particles corresponds to a I-Vproperty with two critical voltages. The growth regularity of PEO cermet coatings was also studied.

Amorphous Coatings Deposited on Aluminum Alloy by Plasma Electrolytic Oxidation

Amorphous [Al-Si-O] coatings were deposited on aluminum alloy by plasma electrolytic oxidation (PEO). The process parameters, composition, micrograph, and mechanical property of PEO amorphous coatings were investigated. It is found that the growth rate of PEO coatings reaches 4.44 mu m/min if the current density is 0.9 mA/mm(2). XRD results show that the PEO coatings are amorphous in the current density range of 0.3-0.9 mA/mm(2). EDS results show that the coatings are composed of O, Si and At elements. SEM results show that the coatings are porous. Nano indentation results show that the hardness of the coatings is about 3 - 4 times of that of the substrate, while the elastic modulus is about the same with the substrate. Furthermore, a formation mechanism of amorphous PEO coatings was proposed.

Structure and mechanical properties of ceramic coatings fabricated by plasma electrolytic oxidation on aluminized steel

Ceramic coatings were formed by plasma electrolytic oxidation (PEO) on aluminized steel. Characteristics of the average anodic voltages versus treatment time were observed during the PEO process. The micrographs, compositions and mechanical properties of ceramic coatings were investigated. The results show that the anodic voltage profile for processing of aluminized steel is similar to that for processing bulk Al alloy during early PEO stages and that the thickness of ceramic coating increases approximately linearly with the Al layer consumption. Once the Al layer is completely transformed, the FeAl intermetallic layer begins to participate in the PEO process. At this point, the anodic voltage of aluminized steel descends, and the thickness of ceramic coating grows more slowly. At the same time, some micro-cracks are observed at the Al2O3/FeAl interface. The final ceramic coating mainly consists of gamma-Al2O3, mullite, and alpha-Al2O3 phases. PEO ceramic coatings have excellent elastic recovery and high load supporting performance. Nanohardness of ceramic coating reaches about 19.6 GPa. (c) 2007 Elsevier B. V. All rights reserved.

Thermal stability and spectroscopic properties of Er3+-doped niobium tellurite glasses for broadband amplifiers

Three Er3+-doped tellurite glasses with compositions of 70TeO(2)-30ZnO, 70TeO(2)-20ZnO-10Nb(2)O(5) and 70TeO(2)-20ZnO-5BaO-5Nb(2)O(5) have been investigated for developing fiber and planar broadband amplifiers and lasers. The optical spectroscopic properties and thermal stability of Er3+-doped tellurite glasses have been discussed. The results show that the incorporation of Nb2O5 increases the thermal stability of Er3+-doped tellurite glasses significantly, Er3+-doped niobium tellurite glasses 70TeO(2)-20ZnO-10Nb(2)O(5) and 70TeO(2)-20ZnO-5BaO-5Nb(2)O(5) exhibit the good thermal stability (DeltaT > 150degreesC), the large emission cross-section (>10 x 10(-21) cm(2)) and broad full width at half maximum (similar to65 nm), will be preferable for broadband Er3+-doped fiber amplifiers. (C) 2004 Elsevier B.V. All rights reserved.

Three-photon-excited upconversion luminescence of niobium ions doped silicate glass by a femtosecond laser irradiation

We report on the bluish green upconversion luminescence of niobium ions doped silicate glass by a femtosecond laser irradiation. The dependence of the fluorescence intensity on the pump power density of laser indicates that the conversion of infrared irradiation to visible emission is dominated by three-photon excitation process. We suggest that the charge transfer from O-2-to Nb5+ can efficiently contribute to the bluish green emission. The results indicate that transition metal ions without d electrons play an important role in fields of optics when embedded into silicate glass matrix. (C) 2008 Optical Society of America.

A high-performance Si-based MOS electrooptic phase modulator with a shunt-capacitor configuration

A novel Si-based metal-oxide-semiconductor (MOS) electrooptic phase modulator including two shunt oxide layer capacitors integrated on a silicon-on-insulator (SOI) waveguide is simulated and analyzed. The refractive index near the two gate oxide layers is modified by the free carrier dispersion effect induced by applying a positive bias on the electrodes. The theoretical calculation of free carrier distribution coupled with optical guided mode propagation characteristics has been carried out. The influence of the structure parameters such as the width and the doping level of the active region are analyzed. A half-wave voltage V-pi = 4 V is demonstrated with an 8-mm active region length and a 4-mu m width of an inner rib under an accumulation mode. When decreasing the inner rib width to 1 mu m, the phase modulation efficiency is even higher, and the rise and fall times reach 50 and 40 ps, respectively, with a 1.0 x 10(17) cm(-3) doping level in the active region.

On the design and simulation of high speed electro-optic modulator based on SOI waveguide MOS dual capacitor structure

zhangdi于2010-03-29批量导入

A High-Performance Silicon Electro-Optic Phase Modulator with a Triple MOS Capacitor

We propose and analyze a novel Si-based electro-optic modulator with an improved metal-oxide-semiconductor (MOS) capacitor configuration integrated into silicon-on-insulator (SOI).Three gate-oxide layers embedded in the silicon waveguide constitute a triple MOS capacitor structure,which boosts the modulation efficiency compared with a single MOS capacitor.The simulation results demonstrate that the VπLπ product is 2.4V·cm.The rise time and fall time of the proposed device are calculated to be 80 and 40ps from the transient response curve,respectively,indicating a bandwidth of 8GHz.The phase shift efficiency and bandwidth can be enhanced by rib width scaling.

Design and simulation of charge sensitive preamplifier with CMOS FET implemented as feedback capacitor C-fp

In this paper, to design a new preamplifier for optimum performances with charged-particle or heavy-ion detectors, the CMOS FET is implemented as a feedback capacitor C-fp, so that the entire system should be built only with MOSFET. This work is a revolution design because to realize an ASIC for a preamplifier circuit, the capacitor will also be included. We succeed after a simulation to maintain a rise time less than 3 ns, the output resistance less than 94 Omega and the linearity almost good.

Preliminary study of a niobium quarter-wave prototype cavity for a heavy-ion superconducting linac

Superconducting quarter-wave resonators, due to their compactness and their convenient shape for tuning and coupling, are very attractive for low-beta beam acceleration. In this paper, two types of cavities with different geometry have been numerically simulated: the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz, beta=0.06 beams; then the relative electromagnetic parameters and geometric sizes have been compared. It is found that the second type, whose structural design is optimized with the conical stem and shaping drift-tube, can support the better accelerating performance. At the end of the paper, some structural deformation effects on frequency shifts and appropriate solutions have been discussed.

Electrolytic Deposition and Diffusion of Lithium onto Magnesium-9 Wt Pct Yttrium Bulk Alloy in Low-Temperature Molten Salt of Lithium Chloride and Potassium Chloride

The electrolytic deposition and diffusion of lithium onto bulk magnesium-9 wt pct yttrium alloy cathode in molten salt of 47 wt pct lithium chloride and 53 wt pct potassium chloride at 693 K were investigated. Results show that magnesium-yttrium-lithium ternary alloys are formed on the surface of the cathodes, and a penetration depth of 642 mu m is acquired after 2 hours of electrolysis at the cathodic current density of 0.06 A center dot cm(-2). The diffusion of lithium results in a great amount of precipitates in the lithium containing layer. These precipitates are the compound of Mg41Y5, which arrange along the grain boundaries and hinder the diffusion of lithium, and solid solution of yttrium in magnesium. The grain boundaries and the twins of the magnesium-9 wt pct yttrium substrate also have negative effects on the diffusion of lithium.

SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF THE DAWSON-TYPE TUNGSTOPHOSPHATE HETEROPOLY COMPLEXES SUBSTITUTED BY NIOBIUM

Eight new complexes alpha(2)-M(7-m)H(m)[P2W17NbO62]. H2O and alpha-1, 2, 3-M(g-m)H(m) [P2W15Nb3O62]. XH(2)O(M=K, TMA, TEA, TBA) were synthesized and characterized by IR and UV spectroscopy, polarography, XPS and XRD methods. P-31 and W-183 NMR studies show that the niobium atoms in the anions are on the polar sites. The crystal of alpha-1, 2, 3-K7H2 [P2W15Nb3O62]. 30H(2)O is hexagonal, its cell parameters: a=1.9836(4), b=1.9836(9), c=1.5498(6)nm, alpha=beta=90 degrees, gamma=120 degrees.