A series of a-Si：H films are deposited by hot wire assisted microwave electron cyclotron resonant chemical vapour deposition （HW-MWECR-CVD）, subsequently exposed under simulated illumination for three hours. This p...
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A series of a-Si：H films are deposited by hot wire assisted microwave electron cyclotron resonant chemical vapour deposition （HW-MWECR-CVD）, subsequently exposed under simulated illumination for three hours. This paper studies the microstructure change during illumination by Fourier Transformation Infrared （FTIR） spectra. There are two typical transformation tendencies of microstructure after illumination. It proposes a model of light induced structural change based on the experimental results. It is found that all samples follow the same mechanism during illumination, and intrinsic structure of samples affect the total H content.
We have investigated infrared-to-visible upconversion luminescence of Er^3＋ in bismuth-lead-germanate glasses. The UV cutoff wavelength is shortened while its lifetime is increased almost linearly, with PbF2 substitu...
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We have investigated infrared-to-visible upconversion luminescence of Er^3＋ in bismuth-lead-germanate glasses. The UV cutoff wavelength is shortened while its lifetime is increased almost linearly, with PbF2 substituting for PbO in the bismuth-lead germanate glasses. Three emissions centred at around 529, 545 and 657 nm are clearly observed, which are identified as originating from the ^2H11/2→^4 I15/2,^4S3/2→^4 I15/2 and ^4 F9/2 →^4 I15/2 transitions, respectively. It is noted that all the upconversion emission intensities increase with PbF2 concentration increasing. The ratio between the intensities of red and green emissions increases with the increasing of PbF2 content. Energy transfer processes and nonradiative phonon-assisted decays account for the populations of the ^2 H11/2,^4 S3/2 and ^4F 9/2 levels. The quadratic dependence of fluorescence on excitation laser power confirms a two-photon process to contribute to the upconversion emissions.
Material of Retention on Leachability Cr (VI) was prepared with ground granulated blast-furnace slag (GGBFS) and ground electric steel furnace slag (GESFS). Then, the following two aspects were carried out: (1) invest...
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Material of Retention on Leachability Cr (VI) was prepared with ground granulated blast-furnace slag (GGBFS) and ground electric steel furnace slag (GESFS). Then, the following two aspects were carried out: (1) investigation into the reducing effect of GGBFS and GESFS on the leachability Cr (VI) in harden fly ash cement;(2) relation between the amount of Cr (VI) leached from hardened fly ash and Cr (VI) concentration in the pore solution of the hardened fly ash. The results indicated that the both slags possessed excellent reducibility on leachability Cr (VI). With the addition of the slags Cr (VI)-containing in hardened fly ashes, the concentration of Cr (VI) in the solution and the leaching of Cr (VI) from hardened fly ashes was reduced, and the effect was kept stable during the investigated term.
Based on Clausius-Mosotti equation and Debye relaxation theory, the dielectric model of yttria ceramics was developed according to the dielectric loss mechanism. The dielectric properties of yttria ceramics were predi...
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Based on Clausius-Mosotti equation and Debye relaxation theory, the dielectric model of yttria ceramics was developed according to the dielectric loss mechanism. The dielectric properties of yttria ceramics were predicted at high temperature. The temperature dependence and frequency dependence of dielectric constant and dielectric loss were discussed, respectively. As the result, the data calculated by theoretical dielectric model are in agreement with experimental data.
In this paper, we have studied the permittivities of E-glass fabric/epoxy composite laminates containing three different types of carbon-based nano conductive fillers such as carbon black (CB), carbon nano fiber (CNF)...
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In this paper, we have studied the permittivities of E-glass fabric/epoxy composite laminates containing three different types of carbon-based nano conductive fillers such as carbon black (CB), carbon nano fiber (CNF) and multi-wall carbon nano tube (MWNT). The measurements were performed for permittivities at the frequency band of 0.5 GHz ∼ 18.0 GHz using a vector network analyzer with a 7 mm coaxial air line. The experimental results show that the complex permittivities of the composites depend strongly on the natures and concentrations of the conductive fillers. The real and imaginary parts of the complex permittivities of the composites were proportional to the filler concentrations. But, depending on the types of fillers and frequency band, the increasing rates of the real and imaginary parts with respect to the filler concentrations were all different. At the frequency of 10 GHz, the rates in the CNF filled composite and the MWNT filled composite were much larger then those of the CB filled composite. Between the CNF filled composite and MWNT filled composite, however, the former showed a little higher increasing rates than the other. These different rates can have great effect on the thickness in designing the single layer microwave absorbers. The effect of the different rates was examined by using Cole-Cole plots;the plot is composed of a single layer absorber solution line and permittivity lines of these three types of composites.
In this paper, by taking into account the coupling of the ionization of ablation gas and atmosphere, an electrons density distribution model is built. Using this model, the transmission properties of different polariz...
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In this paper, by taking into account the coupling of the ionization of ablation gas and atmosphere, an electrons density distribution model is built. Using this model, the transmission properties of different polarization radar wave through sheath are evaluated on the basis of the transmission matrix theory. Then, we discuss the effects of the electrons density, the added magnetic field, and the radar wave frequency on the transmission properties. As a result of this investigation, greater transmission power could be gained in order to efficiently shorten communication blackout, by reducing the electrons density or choosing proper added magnetic field and the frequency of the radar wave according to the different polarization form of the radar wave.
First-principles calculations were performed to study the electronic structure and magnetic interactions of MnGa−MnI dimer formed by the neighboring substitutional MnGa and interstitial MnI ions in the zinc-blende str...
First-principles calculations were performed to study the electronic structure and magnetic interactions of MnGa−MnI dimer formed by the neighboring substitutional MnGa and interstitial MnI ions in the zinc-blende structured (Ga,Mn)N dilute magnetic semiconductor. On the basis of the formation energy calculations, we show that the clustering of MnGa and MnI in (Ga,Mn)N is energetically favored. The MnGa and MnI ions in the MnGa−MnI dimer are antiferromagnetically coupled, but this cannot strikingly reduce the magnetic moments induced by MnGa due to the strong localization character of MnI gap states. It is found that MnGa−MnI dimer in zinc-blende structured (Ga,Mn)N possesses unique electronic and magnetic properties, as compared with their counterparts in wurtzite structured (Ga,Mn)N or zinc-blende structured (Ga,Mn)As. The present study can provide some insight into understanding the rather scattered magnetic moment per Mn ion observed experimentally.
Mortar specimens of alkali-activated carbonatite-slag cementitious materials (AACSCM) were prepared, in which finely ground zirconite, being inactive under the reaction condition of this experiment, was also used to r...
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Mortar specimens of alkali-activated carbonatite-slag cementitious materials (AACSCM) were prepared, in which finely ground zirconite, being inactive under the reaction condition of this experiment, was also used to replace ground carbonatite or ground granulated blast-furnace slag (GGBFS) by iso-volume, so as to investigate the contribution of each material to the strength of AACSCM. According to the test results of mortar strength and the composition of pore solution of pastes, the effect of GGBFS on the strength improvement of alkali-activated cementitious material (AACCM) was discussed. The results indicated that, at the late stage of reaction, there did exist a synergistic effect between GGBFS and ground carbonatite under the activation of alkaline. The mechanism lied in: During the late period of reaction, the amount of Ca2+, Mg2+ provided by GGBFS to the reaction system was much decreased, while much more Al3+ were retained. The shortage of Ca2+, Mg2+ in the system was compensated by the dissolution of ground carbonated, leading the reaction be continued, and Al3+ were consumed simultaneously in the reaction, which promoted the dissolution of GGBFS in return. With the repeat of this process the reaction degree of AACSCM was much improved.
We propose an optical model of a cylindrical lens for fiber coupling based on the method of coupling an angle-ended fiber to the front facet of a chip that is used in high-speed optical receivers. We also study the ef...
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We propose an optical model of a cylindrical lens for fiber coupling based on the method of coupling an angle-ended fiber to the front facet of a chip that is used in high-speed optical receivers. We also study the effect of the packing process on coupling efficiency with the optical model and software simulation. The simulation results show that the optical coupling efficiency is determined by fiber position, the lens design of the photodiode chips, and the shape of the light source.
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