Materials Science Forum Vols. 663-665

Abstract: Zinc silicate-based (Zn2SiO4:Eu3+) long afterglow phosphors were fabricated by combustion synthesis and annealing method. The effects of different Zn sources, annealing temperature, Eu3+ additive on the properties of the combustion products have been studied. The results show that, the product is white with ZnO as zinc source while that from Zn(NO3)26H2O is slightly yellow. At higher annealing temperature, the sample is purer. Small amount of Eu2O3 additive did not change the phase composition. The fluorescence spectroscopy shows that, the emission peak of the sample with Eu3+ additive located at 620nm.

Abstract: A series of novel polystyrene derivatives with oligofluorene pendants were synthesized by Friedel-Crafts reaction. The structure and properties of the polymers and monomers were characterized using NMR, UV-vis spectroscopy, DSC, photoluminescence and electroluminescence spectroscopy. The content of fluorescent units in OPS (oligofluorene grafted polystyrene) was proportional to the dosage of oligofluorene monomers in a wide scope. All the materials were soluble in common organic solvents and easily spin-coated onto the indium-tin oxide(ITO)-coated glass substrates. The polymers showed good fluorescent properties with comparely wide photoluminescent spectra. This method could be an easy way to obtain non-conjugated fluorescent polymers for photoelectric devices by solution processing. The electroluminescent properties of these polymers were reported briefly in this paper.

Abstract: Fluorinated diamond-like carbon (F-DLC) thin films are deposited using radio frequency plasma enhanced chemical vapor deposition under various gas flow ratios. The surface morphology of the F-DLC thin films deposited at lower gas flow ratios is a compact and uniform structure, and it became rough with the increase of gas flow ratios. The relative atomic contents of fluorine and chemical bonding configurations of C-Fx (x=1, 2, 3) in the thin films increases with the increase of gas flow ratios. The optical band gap of the thin films presents a decrease of different degree with the increase of gas flow ratios.

Abstract: A series of 1, 10-phenanthroline terbium/ polyvinyl alcohol hybrid materials with different coupling agent contents were prepared by sol-gel method. The morphology and photophysical properties were investigated. FT-IR was applied to characterize the structure of the obtained hybrid material, SEM and fluorescence spectra were applied to characterize the performance of the hybrid material. The result shows that the phase separation processes and the fluorescence quenching were avoided and the optical performance of hybrid materials were improved effectively.

Abstract: The growth of polycrystalline curved surface diamond film using direct current plasma jet CVD (DCPJCVD) is measured by those techniques. The relationships between morphology, microstructure, and film quality are investigated by scanning electron microscopy (SEM) and Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), respectively. The results show that, after molybdenum substrate was polished by series of diamond powder, atom hydrogen etching, respectively, a much higher nucleation density can be achieved. Synthetic diamond film is compact, continuous and uniform, and diamond film grows with the columnar spreading from the nucleation surface to the growth surface, (111) faces were dominant in polycrystalline texture diamond film. Raman spectrum indicates that there is only diamond characteristic peak in diamond film, and high quality curved surface diamond film was prepared. IR transmittance of curved surface diamond film in the range of 750 - 4300 cm-1 reached about 60%. Meantime, the IR transmittance was almost the same in the central and fringe regions of the film. These properties indicate that curved surface diamond film has a promising application in infrared windows and dome.

Abstract: The germanium film and Ge/Si multilayer structure were fabricated by magnetron sputtering technique on silicon substrate at temperatures of 500°C. Raman scattering spectroscopy measurements reveal that the nanocrystalline Ge occurs in both kinds of samples. Furthermore, from the atomic force microscopy (AFM) results, it is found that the grain size as well as spatially ordering distribution of the nc-Ge can be modulated by the Ge/Si multilayer structure. The room temperature photoluminescence was also observed in the samples. However, compared with that from the nc-Ge film, the intensity of PL from the nc-Ge/a-Si multilayer film becomes weaker, which is attributed to its lower volume fraction of crystallized component.

Abstract: Barium yttrium fluorides ( BaYF5 ) co-doped with Er3+ and Yb3+ were synthesized by the chemical co-precipitation method and the structural and optical properties of solution-processed Er3+/Yb3+ co-doped BaYF5 were characterized. Intense visible emissions centered at around 523, 546 and 658 nm, originated from the transitions of 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 of Er3+, respectively, have been observed in samples upon excitation with a 980nm laser diode, and the involved mechanisms have been explained.

Abstract: Eu3+-doped La2Mo2O9 phosphor was fabricated by sold-state reaction method. The as-prepared samples were characterized by the application of X-ray diffraction (XRD), scanning electron microscopy (SEM), and emission spectra. The effect of the sintering temperature and doping amount of europium ion on the luminescent properties of La2Mo2O9:Eu3+ was investigated. The results show that the luminescent intensity will reach the strongest when the sintering temperature is equal to 1073 K. The Eu3+ doping amounts also have obvious effect on the luminescent properties.

Abstract: Silicon oxynitride films were deposited in very-high-frequency (40.68 MHz) plasma enhanced chemical vapor deposition (VHF-PECVD), and subsequently annealed between 400 and 1200°C in N2 ambient. The effect of annealing temperature on the PL characteristics of the samples was investigated. The experimental results reveal that a broad PL peak around 430 nm (2.88eV) appears in all of the samples. The maximum intensity of this broad PL peak was obtained in the sample annealed at 400°C. The PL characteristics of the annealed samples were discussed.

Abstract: For the upper atmospheric wind field measurement, the conversion relations between the unit of auroral (airglow) intensity Rayleigh and illumination, luminance, height of atmosphere, the photon number are derived. The auroral volume emission rate (VER) of O(1S)557.7nm and O(1D)630.0nm with height is presented. The VER peak values are 668R and 2630R respectively. The results can provide theory for light illumination and brightness of detecting upper atmosphere.