Key Engineering Materials Vols. 336-338

Abstract: Preparation and performance of poly(acrylonitrile-methyl
methacrylate) based microporous gel electrolyte for Li-ion batteries were studied. The poly(acrylonitrile-methyl methacrylate (P(AMMA)) was synthesized by suspension polymerization, and poly(acrylonitrile-methyl methacrylate) microporous polymer membrane with 0.03~0.1mm was prepared by phase inversion technique. The gel electrolyte was obtained by putting the P(AMMA) microporous polymer membrane in a liquid electrolyte, which was a solution of 1.0 M LiPF6 dissolved in a 1:1 (v/v) mixture of ethylene carbonate (EC) and diethylene carbonate (DEC, and heated at 60°C for 2 hours. The microporous gel electrolyte gelled with 325 wt.% of liquid electrolyte vs. the dried membrane presented an ionic conductivity of 7.52 × 10-4 S/cm at 25°C. The coin test battery with the microporous gel electrolyte showed a good cycling performance. The discharge capacity retention was above 88% at 0.1C rate at the 50th cycle.

Abstract: To retain the optimum hydration level of the proton exchange membrane fuel cell (PEMFC) without humidification sub-system, a novel self-humidifying composite membrane was fabricated by the technology of Si[OCH2CH3]4 in situ sol-gel reaction in a commercial Nafion 112 membrane. The physico-chemical properties of the membrane were studied by means of AFM, SEM and AC impedance. These results showed that the nano-SiO2 reactant was uniformly distributed in the composite membrane. It was found that the proton conductivity increased observably by dispersing 3 wt % nano-SiO2 in the composite membrane at low water content, and the SiO2/Nafion composite membrane improved the self-humidifying performance of PEMFC.

Abstract: The Li/S polymer secondary batteries presents higher capacity, lower materials cost and much better performance in higher operation temperature. A nano-scale sulfur polymer composite cathode material has been developed for these batteries, and its cycle capacity is over 700mAh/g when the lithium metal is used as the anode; A nano-scale Cu/Sn alloy powder has been synthesized by a novel micro-emulsion process, its cycle capacity is over 300 mAh/g; The performance of PVdF gel electrolyte has been improved through the addition of the nanometer SiO2 synthesized in-situ. The advanced Li/S polymer secondary batteries will be a promising alternative for next generation energy storage system.

Abstract: Translucent AlN ceramics were fabricated using spark plasma sintering (SPS) technique with 3wt% CaF2 as sintering additive. The samples achieved 52.4% maximum transmittance in medium IR region after 10 min holding time by spark plasma sintering at 1800°C and 30 MPa pressure in N2. The results from XRD, SEM, TEM and EDX showed that the sintered bodies were densely compacted and highly pure with fine grain size and uniform microstructures. No secondary phases were observed at the grain boundaries and triple grain junctions, which guaranteed good optical property of the sintered bodies.

Abstract: Hybrid inorganic-organic materials based on alkoxysilyl-functionalized and poly (methyl methacrylate) were prepared by the in-situ sol-gel approach in the presence of tethaethoxysilance. Interaction between silica network and polymer was analyzed by FTIR, and its influence on phase behavior of hybrid was also investigated by SEM. Thermal analyses indicated that P(MMA-MSMA)-Si had higher value of Tg ,about 170°C, than that of pure PMMA. Meanwhile, the hybrid samples behave favorable optical transparency with small optical loss of around 2 dB.

Abstract: In order to achieve a large hyperpolarizability (β) value and thermal stability, a novel Y-type silicon precursor ICTES-DBPNPI was synthesized. By the sol-gel process, the new organic-inorganic materials having organic chromophore were prepared.

Abstract: Nanocrystalline Ag doped silica inverse opals were prepared by a sol-gel chemistry method via templating of polystyrene colloidal crystals. The ordered structures of colloidal crystal templates and inverse opals are characterized by scanning electron microscopy. Ag nanocrystals size is estimated as 20~30nm by Scherrer Formula from X-ray diffraction. The color and the stop band of the inverse opals are characterized by transmission spectrum. And five emission peaks of the nanocrystalline silver clusters are observed from fluorescence spectrum.

Abstract: Well-crystallized SrBi2Nb2O9 (SBN) thin films with good surface morphology were fabricated on quartz glass substrates by RF magnetron sputtering technique at a deposition temperature of 600°C under the O2/Ar(3:1) pressure of 2.4 Pa for 2 hour. The films exhibited bismuth-layered perovskite phase structure without pyrochlore phase and the ratio of Sr:Bi:Nb is about 1:1.92:1.98. The nonlinear optical properties of the films were determined by a single beam Z-scan technique at a wavelength of 532 nm with laser duration of 25 ps. The measured values of the real and imaginary parts of the third-order nonlinear optical susceptibility were 4.324×10-8esu and 1.278×10-8esu, respectively. The large nonlinear optical effect shows that the SrBi2Nb2O9 thin films have great potential application in designing nonlinear optical devices.

Abstract: The synthesis, infiltration into a polystyrene opal and luminescence spectroscopy of BaTiO3: Tm3+ were reported in this paper. A photonic band gap and blue up-conversion photoluminescence were achieved in the synthesized inverted opal, respectively demonstrated by reflection spectrum and emission spectrum excited by 650nm laser source at room temperature. Changes of the emission spectroscopy compared with the thulium doped barium titanate reference sample were observed and thus provided evidence for the light inhibition effect of the photonic structure.

Abstract: ZnO:Al thin films were deposited on sapphire(001) substrates by RF magnetron sputtering. Effects of the O2/Ar flow ratio in the sputtering process on the crystallinity, surface roughness, carrier concentration, carrier mobility, and optical properties of the films were investigated. AFM analysis results show that the surface roughness is lowest at the O2/Ar flow ratio of 0.5 and tends to increase owing to the increase of the grain size as the O2/Ar flow ratio increases further than 0.5. According to the Hall measurement results the resistivity increases as the O2/Ar flow ratio increases. The transmittance of the film tends to increase as the O2/Ar gas flow ratio increases up to 0.5 but it nearly does not change with continued increases in the O2/Ar flow ratio. Considering the effects of the the O2/Ar flow ratio on the surface roughness, electrical resistivity and transmittance properties of the ZnO:Al film the optimum O2/Ar flow ratio is 0.5 in the RF magnetron sputter deposition of the ZnO:Al film.