Advanced Materials Research Vols. 284-286

Abstract: It’s the first time to have a research on the electro-optical properties of GH-LCD more systemic. At the beginning of the paper, the electro-optical characteristic curves have been analyzed for the different cell thickness, such as 6μm, 9μm and 11μm. The result shows that GH-LCD and TN-LCD have the similar electro-optical property, and the dichroic dye contained in the GH-LCD is the key to control the color switch. Viewing angle property in the range of ±30° was tested in the horizontal direction. The visibility of the left angle is wider than the right angel, and the contrast of the left angle is better. Then, the case that the orthogonal orientation of liquid crystal cell thickness is 11μm will be discussed in the paper. When the cell thickness is 11μm and there’s no polarizer, the electro-optical characteristic curves was measured and compared. Research shows that the polarizer can filter out polarized light to enhance contrast. The electro-optical curve with polarizer has been measured when a certain percentage of the chiral agent was added into guest-host liquid crystal (negative). When the voltage gets to 15V, there is a state of phase change that the display color immediately turns from black to milky white. Compared with liquid crystal without being added chiral material, the contrast reduces obviously, but response time becomes lower than before. The research on electro-optical properties maybe makes the GH-LCD to be applied to the naked eye 3D display.

Abstract: A new unsymmetrical photochromic diarylethene bearing a pyrrole and a thiophene aryl unit 1-(5-cyan-1,2-dimethylpyrrole)-2-(5-aldehyde-2-butylthiophene) perfluorocyclopentene(1a) has been synthesized. Its properties, including photochromism and kinetics were investigated in detail. It underwent reversible cyclization and cycloreversion reactions upon alternating with UV and visible light both in solution and in PMMA film. The results showed that this compound exhibited reversible photochromism, changing from colorless to blue upon irradiation with UV light, in which absorption maximum were observed at 649 nm and 583 nm in solution and PMMA amorphous film, respectively. This new photochromic system also exhibited remarkable reaction kinetics in hexane solution.

Abstract: Hamiltonian system used in dynamics is introduced to formulate the transversely isotropic magnetoelectroelastic solids plane problem in rectangular domain and symplectic dual equation is derived corresponding to the generalized variational principle of the magnetoelectroelastic solids. The equation is expressed with displacements, electric potential and magnetic potential, as well as their duality variables--lengthways stress, electric displacement and magnetic induction in the symplectic geometry space. Since the x-coordinate is treated as time variable so that z becomes the independent coordinate in the Hamiltonian matrix operator. The symplectic dual approach enables the separation of variables to work and all the Saint Venant solutions in the symmetric deformation are obtained directly via the zero eigenvalue solutions and all their Jordan normal form of the corresponding Hamiltonian operator matrix and the boundary condition. An example is presented to illustrate the proposed approach.

Abstract: The feasibility of three-dimensional optical bit memory is demonstrated by using the change of fluorescence and refractive index in Sm(DBM)₃Phen-doped and un-doped Poly(methyl methacrylate). After a femtosecond pulsed laser irradiation, a refractive-index bit and a fluorescent bit can be formed at the same position inside the bulk sample. Multilayer patterns recorded by tightly focusing the pulsed laser beam were read out by a reflection-type fluorescent confocal microscope, which can detect the reflection signal and also the fluorescent signal of the stored bits. The signal-to-noise ratio via the two retrieval modes was compared as a function of recording depth. The stored bits were retrieved with a high signal-to-noise ratio in the absence of any crosstalk and the detection of the fluorescent signal enables retrieval of the stored bits with a higher S/N ratio.

Abstract: Crystal structure and magnetic properties of the double perovskite compounds Sr₂(Fe_1-xV_x)MoO₆ (0 ≤ x ≤ 0.1) have been investigated in this work. Rietveld refinement of the crystal structure shows that the cation ordering decrease monotonously with the V content. Magnetic measurement shows that saturation magnetization of the compounds decrease with increasing x due to the reduced degree of ordering. Analysis of saturation magnetization based on the ferrimagnetic model (FIM) indicates that the V atoms in Sr₂(Fe_1-xV_x)MoO₆ selectively occupy the Mo sites instead of Fe sites.

Abstract: Mn³⁺ ions doped in YAG:Ce phosphors as a co-activator and host lattice element by co-precipitation method, which have enlarged the emission spectral of pure YAG:Ce phosphor in the emission spectral, caused by ⁵T₂-⁵E and ⁵T₂-¹T2 transition. Respectively, the manganese co-doped yttrium aluminum garnet doped cerium blended with YAG:Ce phosphor would show an improved white light emission.

Abstract: Co_2-xCu_xO_y (x=0.0, 0.2, 0.4) Samples were prepared by solid-state reaction method and the effect of Cu substitution on the thermoelectric properties was investigated. The presence of Cu element improved the grain size and electrical conductivity, but Seebeck coefficients were reduced by Cu substitution. It was found Cu substitution is an effective way to improve the thermoelectric performance system at high temperature.

Abstract: Mn-ferrite powders were prepared by mechanochemical treatments using MnO₂ and Fe₂O₃ as raw materials. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM) were employed to evaluated the morphologies and structures of samples. The results indicated that the starting mixture became amorphous stage after ball-milled for 40h, and single phase MnFe₂O₄ could be obtained after annealed at 1200°C for 2h. In comparison with the traditional firing method , the mechanochemical method benefited achieving the higher saturation magnetization, which indicated that the samples had a better magnetic properties.

Abstract: Polyaniline (PANI) was deposited on the glassy carbon electrode in organic electrolyte. The deposition mechanism and properties of resulted PANI were characterized with Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Electrochemical Impedance Spectroscopy (EIS). The results show that: the polymerization of PANI can carry in a relatively high potential (2.4V), and the electrochemical deposition mechanism of PANI at high potential in organic electrolyte is different from that in inorganic system due to the low conductivity and diffusion coefficient of organic electrolyte. The electro-conductivity of PANI is good in the range of 0.2~0.8V which is wider than that reported in inorganic electrolyte.

Abstract: A active Cl-doping for photoluminescent ZnS powder has been carried out by thermal decomposed AlCl₃·6H₂O in a quartz tube. Room temperature photoluminescence of the Cl-doped ZnS powder has been investigated using a photoluminescence spectrometer with 365 nm excitation wave length. A strong blue photoluminescence with maximum peak about 450 nm and green photoluminescence with maximum peak about 500 nm can be observed if the doping temperature in range of 800 ~ 900 °C and 1100 ~1200 °C, respectively. The structural characterizations of the Cl-doped ZnS powders were performed with X-ray diffraction (XRD) and the mechanism of photoluminescence was preliminarily discussed.