Advanced Materials Research Vols. 634-638

Abstract: The levitation between high temperature superconductors (HTSs) and permanent magnets (PMs) has been applied to the flywheel energy storage systems and magnetic bearing systems for the last nearly twenty years. The interaction forces acting on the levitating body are calculated by the modified frozen-image method. The magnetic dipoles are equivalent to Amperian current loops. The current intensity in loops changes linearly when the PM moves. Under the zero field cooling condition, the expression of vertical force is obtained when the PM traverses vertically, and when the PM traverses horizontally, the expressions of vertical and horizontal forces are obtained. Those expressions of vertical and horizontal forces are gained by calculating the forces between current loops and using superposition theorem of vector. The calculations agree well with the previous experimental data, which means that the deductions of the expressions are reliable.

Abstract: A new technique is presented for modeling submicron MOSFET devices and predicting the MOSFET device behaviors by using fuzzy theory and artificial neural network (ANN). The power of ANNs used as a realization of I-V characterizations is demonstrated on the submicron MOS transistors. The prediction results are compared with experimental data of the actual devices and obtained a good agreement under different bias situations.

Abstract: A non-Maxwellian hot-carrier generation current model for simulation of charge injection and erasing in the 0.35um flash EEPROM device is presented in this paper. Unlike the conventional model, which is based on the local electric fields in the device, and it accounts for non-local effects resulting from the large variations in electric field in a submicron flash EEPROM. Good agreements between the measured and calculated results in the charge writing and the Fower-Nordheim erasing operations.

Abstract: The series of Bi-Sr-Co-O thermoelectric materials Bi₂Sr₂Co₂O_y (BC-2202), Bi₂SrCaCo₂O_y (BC-2112), Bi₂Sr₂CaCo₂O_y (BC-2212) were prepared by conventional solid-reaction process. The crystal structure of Bi-Sr-Co-O compound were analyzed by XRD and TEM. The results show that the diffraction peak shift to the high angle, the interlayer spacing decrease with the Ca doping, however, the diffracion peaks of BC-2212 weak with the sintering temperature increased. The reason for that is some Ca can not enter the lattice while the Ca improved by whole mole.

Abstract: Eu2+-doped Ca2MgSiO5 phosphors were prepared by sol-gel method. The effects of using surfactants (hexadecyl trimethyl ammonium bromide (CTAB) and triethanolamine) during the sol process were investigated on the phosphor particle size distribution. The use of surfactants did not change the crystal form of the Ca2MgSiO5:Eu2+ phosphor, but the particle size distribution and the luminescence properties were improved.

Abstract: Al films were prepared on quartz substrates by thermal evaporation. The effects of annealing in air on structure and optical and electrical properties have been studied. It is found that the annealing in air will affect on structure and morphology of the films, which results in the difference in the optical and electrical properties. The as-deposited film is amorphous, the films annealed at 200 and 400oC are polycrystalline. After annealed at 600oC, the film was oxidized and changed to porous γ-Al2O3. The film annealed at 200 oC has the maximum reflectance and at 400 oC has the minimum resistivity in all samples. While for the film annealed at 600 oC, the resistivity is close to be infinite, the reflectance is the minimum at wavelength ranging from 400 to 800 nm in all the samples.

Abstract: A novel ligand with double sulfinyl groups, bis(benzylsulfinyl)methane L, was synthesized by a new method. Its novel ternary complex, has been synthesized [using L as the first ligand, and dipyridyl L' as the second ligand]. In order to study the effect of the second ligand on the fluorescence properties of rare-earth sulfoxide complex, a novel binary europium complex has been synthesized. Photoluminescent measurement showed that the first ligand L could efficiently transfer the energy to Eu (III) ions in the complex. Furthermore, the detailed luminescence analyses on the rare earth complexes indicated that the ternary Eu (III) complex manifested stronger fluorescence intensities, longer lifetimes, and higher fluorescence quantum efficiencies than the binary Eu (III) materials. The fluorescence emission intensities and fluorescence lifetimes of the ternary complex enhanced more obviously than the binary complex.

Abstract: A novel ligand, phenyl-naphthoylmethyl sulfoxide, was synthesized. Its novel ternary complex and a novel binary complex had been synthesized (salicylic acid as the second ligand), and characterized by elemental analysis, molar conductivity, coordination titration analysis, FTIR and TG-DSC. The fluorescence spectra, fluorescence lifetime and phosphorescence spectra were also discussed.

Abstract: CdZnTe bulk crystals were grown by temperature gradient solution growth (TGSG) method with the lower starting growth temperature of 1223K, temperature gradient of 20-30 K/cm and a crucible dropping rate varied from 1 to 0.6 mm/h. Optical microscope, IR microscope, I-V characteristics and FTIR transmission spectroscopy were employed to analyze the growth interfaces, Te inclusions, resistivity and IR transmittance respectively. The results indicate that a smooth and uniform growth interface has been achieved. The density of Te inclusions is about 7.9-9.5×10³ cm^-2, while the resistivity is higher than 6.87×10⁹ Ωcm and the IR transmittance is about 55-60%.

Abstract: Microcrystalline cellulose (MCC)/cadmium sulfide (CdS) nanocomposites were prepared by using ultrasound wave irradiation. The as-prepared samples were characterized using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), atomic absorption spectrometry (AAS), transmission electron microscopy (TEM). The photocatalytic behavior of MCC/CdS nanocomposites was evaluated using the degradation of a methyl orange (MeO) aqueous solution under ultraviolet (UV) light irradiation. Results showed that CdS nanoparticles were evenly distributed on the surface of MCC with little aggregation; the amount of Cd attached to the MCC was 23.75 % (w/w, Cd/composites). The MeO degradation rate was much higher when the MCC/CdS nanocomposites were irradiated with UV light than when CdS powder alone was irradiated. In dark conditions, the MCC/CdS nanocomposites showed almost no photocatalytic activity. In addition, the amount of MCC/CdS nanocomposites added to MeO solution and the initial pH of the MeO solution were also important factors influencing the photocatalytic activity. The results show that MCC/CdS nanocomposites are promising materials with excellent performance in photocatalytic applications.