The hydrogenated nanocrystalline silicon (nc-Si:H) thin films were produced by capacitively-coupled plasma enhanced chemical vapor deposition (PECVD) technique at low substrate temperatures (Ts ≈ 40–200 °C). Firstly, for particular growth parameters, the lowest stable Ts was determined to avoid temperature fluctuations during the film deposition. The influence of the Ts on the structural and optical properties of the films was investigated by the Fourier transform infrared (FTIR), UV–visible transmittance/reflectance and X-ray diffraction (XRD) spectroscopies. Also, the films deposited at the center of the PECVD electrode and those around the edge of the PECVD electrode were compared within each deposition cycle. The XRD and UV–visible reflectance analyses reveal the nanocrystalline phase for the films grown at the edge at all Ts and for the center films only at 200 °C. The crystallinity fraction and lateral dark conductivity decrease with lowered Ts. FTIR analyses were used to track the hydrogen content, void fraction and amorphous matrix volume fraction within the films. The optical constants obtained from the UV–visible transmittance spectroscopy were correlated well with the FTIR results. Finally, the optimal Ts was concluded for the application of the produced nc-Si:H in silicon-based thin film devices on plastic substrates. 相似文献
Carbon fiber (CF)‐based WO3/TiO2 composite catalysts (WO3/TiO2/CF) were successfully synthesized by solvothermal method. The catalysts were characterized by XPS, SEM, BET, XRD, FTIR, Raman and UV–Vis. The analyses confirmed the WO3/TiO2 nanoparticles with high crystallinity deposited on the carbon structure. The photocatalytic degradation of Orange II azo dye under UV and sunlight illumination with the synthesized catalyst was explored. The composite catalyst displayed high performance (85%) for Orange II degradation while that of for WO3/TiO2 was found as 76%. The effects of CF amount, solution pH, initial dye concentration and catalyst dose on photocatalytic performance were studied. It was found that the degradation efficiency increased from 68% to 90% with the increasing CF amount from 3 wt% to 5 wt%, while the further increase in CF amount (7–10 wt%) decreased the photodegradation due to the blocking the active sites of WO3/TiO2. The enhanced photocatalytic efficiency was mainly attributed to the electrical properties of the CF and reduced bandgap. 相似文献
Two algorithms for establishing a connection between correlations before and after ordinalization under a wide spectrum of nonnormal underlying bivariate distributions are developed by extending the iteratively found normal-based results via the power polynomials. These algorithms are designed to compute the polychoric correlation when the ordinal correlation is specified, and vice versa, along with the distributional properties of latent, continuous variables that are subsequently ordinalized through thresholds dictated by the marginal proportions. The method has broad applicability in the simulation and random number generation world where modeling the relationships between these correlation types is of interest. 相似文献
The mesoscopic morphologies of linear and graft fluorinated block copolymers of ABCBA and C:BA types, respectively, have been investigated by using dissipative particle dynamics method. Self-assembly in a selective solvent has been examined by the introduction of dimethylformamide as the choice of solvent. By comparing the solubility parameters calculated using atomistic simulations, fluorine-containing segments are found to be immiscible both with other segments of the polymer and with the solvent. Morphologies of the pure linear and graft copolymers were lamellar and cylindrical, respectively. Interfacial tension versus concentration curves have been used to explain the self-assembly behavior of copolymers in solution, as well as to predict the kinetic mechanisms responsible for this behavior. 相似文献
Static adsorption of serine alkaline protease (SAP) enzyme on hydrophobic polyether sulfone (PES) ultrafiltration membranes in different ionic environments was investigated. The amount of SAP adsorbed on membranes was the lowest at its isoelectric point (IEP) where the maximum adsorption was obtained below the IEP of the enzyme. The extent of SAP adsorption in the phosphate buffer solutions including different salts followed the order: (NH4)2HPO4 > KH2PO4 > Na2HPO4-NaH2PO4 (buffer) > CaCl2 > ((NH4)2HPO4 + H2PO4 + CaCl2), which was consistent with the Hofmeister series. The zeta potentials of membranes contacted with the ionic species were calculated by streaming potential measurements and found that the increase in ionic strength decreased the electrical double layer thickness leading to a decrease in adsorption. A model based on mass balance was developed to calculate the diffusion coefficient of SAP in PES membranes. Employing experimental data evaluated in a diffusion cell along with the data of adsorption isotherms, diffusion coefficients of SAP in PES membranes in the presence of different ionic species were calculated. To detect the structural changes occurred, membrane surfaces were analysed by Fourier transform infrared-attenuated total reflectance (FTIR-ATR) measurements. 相似文献
The influence of beam intensity on laser ablation quality and ablation size is experimentally studied on graphene-coated silicon/silicon dioxide substrates. With an amplified femtosecond-pulsed laser system, by systematically decreasing the average power, periodic stripes with decreasing widths are ablated. Histogram analyses of the untouched and ablated regions of scanning electron microscope images of the fabricated structures make it possible to quantify the ablation quality. These analyses reveal that submicron ablation can be achieved while maintaining 75 % ablation accuracy by adjusting the beam intensity around the ablation threshold. 相似文献