Abstract: The wide band-gap semiconductor, ZnO, has been proposed as one of the good host for Er3+ ions. In this investigation S was doped into the Er-containing ZnO specimens through the heat treatment in a H2S gas atmosphere. After sulfurization, the photoluminescence (PL) peak centered at 675nm from the ZnO host became much weaker, and accordingly the absorption peaks of Er3+ at 526nm, 550nm, and 665 nm became weaker. Also, the PL intensity around 1.54µm decreased after
the sulfurization. However, when the sulfurized specimens were annealed at 1000oC in air, the PL intensity increased by about 3 times. The effects could be due to the modification of the local structure around the Er3+ ions in ZnO.
Abstract: In order to meet the demand on the miniaturization and manufacturing cost reduction of the multilayer ceramic capacitors we have developed a nano-BaTiO3-based non-reducible dielectric material through a soft chemical route. The particle size has been decreased down to the level of 30nm and the dielectric medium could be co-fired with Ni-electrodes under a N2+H2 reducing atmosphere. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and volume shrinkage have been employed to detect the sintering behavior and microstructure evolution including grain growth, pore formation and body densification. Dielectric measurements showed, after a sintering process at 1200°C for 2h, the dielectric constant was 8800, the dissipation factor was less than 2%, the insulation resistance was about 12~13exp Ω.cm, and the temperature coefficients of capacitance were less than 22% and -82% at -30°C and 85°C respectively. On the basis of the results it is anticipated that the material could be used for the Ni-MLCC with thin dielectric layers with a Y5V specification in the Electron Industries Association standard.
Abstract: Textured bismuth titanate ceramics were successfully produced by spark plasma sintering, using plate-like Bi4Ti3O12 particles prepared by a molten salt method. The microstructure and electric properties of the samples were investigated. The results show that the textured Bi4Ti3O12 ceramics electric property is anisotropic in different direction, and spark plasma sintering is an effective sintering technology to get textured dense Bi4Ti3O12 ceramics at a low temperature.
Abstract: The oriented 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMNT) polycrystals were prepared by the conventional ceramic technique and the templated grain growth method adding excess PbO in the matrix. Kinetics of the development of oriented structure was investigated systemically. In the presence of PbO liquid phase, the oriented PMNT polycrystals mainly grow by the dissolution-precipitation mechanism. The diffusion is determined by the sintering temperature and the PbO-excess content in the matrix. The thickness of oriented PMNT polycrystals displays a t1/3
dependence, which is characteristic of diffusion-controlled growth. For the thicker oriented structure, 20% excess PbO in the PMNT matrix and 1150oC for 10h are the proper experimental conditions. Moreover, the addition of PbO in the matrix hardly affects the final composition of ceramic matrix.
Abstract: A catalyst, as a kind of function material, plays important roles. In the paper
RuO2/g-Al2O3 and RuO2-TiO2/g-Al2O3 catalyst were prepared by the impregnation method. The structure o f two catalysts was studied with XRD, SEM and XPS. The addition of TiO2 promoted the dispersion of Ru particles, and made the amount of the chemisorbed oxygen increased on catalyst surface. The activity was investigated in WAO of phenol over RuO2/g-Al2O3 and RuO2-TiO2/g-Al2O3 catalysts. The results showed that two catalysts had good activity, and TiO2
effectively increased the activity of RuO2/g-Al2O3 catalyst in WAO of phenol. With
RuO2-TiO2/g-Al2O3 catalyst 96% phenol removal was observed at 150°C and 3MPa after 80min reaction in WAO of phenol.
Abstract: The use of lead zirconate titanate ceramics for high power application must have superior mechanical properties, the composition Pb0.98Sr0.02(Mn1/3Sb2/3)0.05Zro.48Ti0.47O3 + x wt% SiO2 (x = 0-1.0) have been studied for this purpose. The microstructures were observed to study the improvement of mechanical properties by SEM and TEM. The nano-scale secondary phase of SiO2
and PbSiO3 were observed on the grain boundary and the twinned ZrO2 was found surrounded by PMS-PZT perovskite phase. The mechanism to the occurrence of twinned ZrO2 and its content increased with increasing Si concentration are discussed in the paper. The occurrence of the nonferroelectric phase such as ZrO2, SiO2 and PbSiO3 on the grain boundary should be the main reason for great improvement of fracture strength.
Abstract: NiO-SDC(Ce0.8Sm0.2O1.9) cermet anodes for solid oxide fuel cells (SOFCs) were fabricated by sintering NiO-SDC composite particles derived from gel-casting. The influence of Ni content and sintering temperature on the electrode polarization using humidified CH4 as fuel was investigated in order to optimize the fabrication conditions. The lowest anodic polarization was obtained for an anode sintered at 1350 oC and consisting of equal volume of Ni and SDC. The anodic polarization at 600 oC was about 37mV at a current density of 300mA/cm2. Maximum power density of 352 mW/cm2 was achieved at 600oC for a single cell based on the optimized anode, inferring high catalytic activity of the gel-cast Ni-SDC anode. This high performance seems to be attributed to the microstructure in which Ni and SDC are uniformly distributed.
Abstract: Single perovskite phase PMN-PT powders had been synthesized using molten salts
method. The powders of PMN-PT synthesized by MSS had submicrometer particle size and high sinterability, which beneficial to an enhancement of the densification process and a decrease of the sintering temperatures. These advantages have an important bearing on the dielectric properties of these materials. The density of ceramics sintered at 1175°C was up to 98% of the theoretical density. These ceramics had excelled dielectric and piezoelectric properties.
Abstract: Composites consisting of silver and yttria-stabilized bismuth oxide (YSB) were
fabricated and investigated as cathodes for intermediate-temperature solid oxide fuel cells (SOFCs) with thin electrolyte films of yttria-stabilized zirconia (YSZ). The films were deposited using spin coating with YSZ suspension. Comparison of YSB-Ag and conventional La0.8Sr0.2MnO3 (LSM) based cathodes showed that the YSB-Ag composite has better electrochemical performance; Interfacial polarization resistance of YSB-Ag cathode is 0.13 Ωcm2 at 750oC. Power density of the single cell with YSB-Ag cathode was about 535 mW/cm2 at 750oC, while that with LSM-Sm0.2Ce0.8O1.9 cathode was only 329 mW/cm2.
Abstract: Tin doped tetra-pod shaped ZnO (T-ZnO) were fabricated by equilibrant airflow reaction method. The microstructure of tin doped T-ZnO was characterized by X-ray Diffraction analysis and Scanning Electron Microscope. The results demonstrated that most of tin acted as a catalyst during the ZnO crystal growth process and the others reacted with ZnO to generate Zn2SnO4. Tin had catalytic influences on the morphology of T-ZnO, which promoted predominant growth on the c axis of ZnO crystal at the addition of 15% in weight and advanced the growth on the a axis at higher weight proportion.