Aluminium Alloys 2014 - ICAA14
Structural and Chemical Characterization of Metals, Alloys and Compounds II
Applied Electromagnetic Engineering for Magnetic, Superconducting, Multifunctional and Nano Materials
Solidification and Gravity VI
Nano-Scale Materials, Materials Processing and Genomic Engineering
Energy, Environment and Functional Materials
Multi-Functional Nanomaterials and their Emerging Applications
Silicon Carbide and Related Materials 2013
Mechanical Stress Evaluation by Neutrons and Synchrotron Radiation VII
20th Brazilian Conference on Materials Science and Engineering
Energy, Environment and Functional Materials
摘要: MoS2 is a candidate for new generation lithium ion battery anode. In this paper, two groups of materials, pure MoS2 and MoS2/graphite composite, were treated by mechanical alloying (MA). The results showed that MA treatment did not change the phase structure of MoS2, but MA will reduce the particle size of MoS2. For MoS2/graphite composite, MA makes graphite distributing homogeneous on the surface of MoS2. After MA, MoS2 keeps the character of 100% columbic efficiency during charging and discharging process. With the increase in cycle number, capacity of MoS2 decays. MA treatment on MoS2 accelerates the decay of capacity. The addition of graphite in MoS2 reduces the harmful effect of MA treatment on cycling property.
摘要: Currently, Al-Si alloy is one of the most widely studied aluminum alloy for the phase change thermal storage materials which can be used in solar thermal power generation. However, there still exist some problems to be solved on Al-Si alloy in the present researches. For instance, the latent heat of Al-20%Si alloy is lower than that of Al-12%Si alloy in some papers while the an opposite conclusion was draw in other papers. To solve this problem, five kinds of Al-Si alloy were designed in this investigation, and the mass fraction of silicon was 4%, 8%, 12%, 16% and 20% respectively. The latent heat value of these alloys was determined using an SII TG/DTA 6300 differential thermal analyzer. According to the phase diagram and photomicrographs as well as the measured values, the quantitative expression of the relationship between alloy composition and the latent heat of Al-Si alloy were obtained. And the two quantitative relational expressions (Y1=13.14x+372.05 for the hypoeutectic alloy and Y2=-4.72x+599.01 for the hypereutectic alloy) were validated through the determination of latent heat of Al-6%Si alloy and Al-14%Si alloy.
摘要: 4-Phenoxy-4', 4''-diaminotriphenylamine was synthesized from N, N-diarylation of 4-amino diphenyl ether and 4-fluoro nitrobenzene, and subsequent reduction of the resultant dinitro compound. The prepared triphenylamine and 4-methoxy-4', 4''-diaminotriphenylamine were dissolved in acetone respectively as the curing agents with epoxy resins to obtain a homogeneous mixture of the reactants. The cross-linked polymer film, which was well adhered to the ITO glass were cured by gradually increasing the temperature under N2 atmosphere. The cured epoxy resins films exhibited good thermal stability and electroactive properties. CV of the films revealed two pairs of reversible redox peaks, with coloration change from the colorless neutral state to the blue oxidized state.
摘要: With a wide band gap of 3.4 eV and a large exciton binding energy of 60 meV at room temperature, ZnO is attractive for blue and ultra-violet optoelectronic devices, and transparent conducting oxide films for photovoltaic applications. For a semiconductor to be useful, particularly in reference to optoelectronic devices, band gap engineering is of great importance in device development. Alloying of MgO and CdO with ZnO has been studied extensively in comparison to other ZnO alloys incorporating equivalent anions like ZnO1-xSx (ZnOS). In this work, high-quality ZnOS thin films were grown on glass substrates by pulsed laser deposition using a ZnS ceramic target with varying O2 partial pressures between 0 and 6 Pa. ZnOS alloys with a wurtzite structure were achieved and no evident phase separation was observed in the whole composition range as determined by X-ray diffraction. The optical transmission measurements show that the average transmittance in the visible range of the films is about 80%. The absorption edges of the films first shift towards low-energy side with increasing the oxygen partial pressure and then blueshift when the oxygen partial pressure is over 2 Pa. The bandgap energies of the ZnOS films were calculated to change from 3.06 to 3.72 eV, showing a nonlinear variation with a bowing behavior that was previously reported.
摘要: Molybdenum (Mo) doped vanadium dioxide (VO2) (V1-xMoxO2) thermochromic thin films with different Mo concentrations on borosilicate glasses were successfully synthesized via a facile and economic solution-based deposition method. The influences of substitutional doping with Mo dopants on the crystal structure and film morphology of VO2 were evaluated. All of the films were confirmed to be pure monoclinic crystalline phase of VO2 and no molybdenum oxides formed, suggesting the formation of a homogeneously dispersed solid-solution. The particle sizes and root-mean-square (RMS) roughness level obviously decreased upon Mo doping. V1-xMoxO2 films exhibited low metal-semiconductor transition (MST) temperature (Tc) and retained the excellent switching property at near-infrared region simultaneously. The rate of change of Tc with Mo doping reached as high as ~10°C/at.%. The reduced Tc may be attributed to the disruption of homo-polar V4+-V4+ bonding after the incorporation of Mo atoms in VO2 octahedron configuration. V1-xMoxO2 thin films exhibited narrower hysteresis loop width compared to undoped VO2, which show the promise for promoting practical implementation of VO2-based thermochromic fenestration.
摘要: Cu2ZnSnS4 thin films were fabricated by one-step RF magnetron sputtering of a single quaternary Cu2ZnSnS4 (CZTS) chalcogenide target on Mo/soda lime glass substrate, followed by post sulfurization using S vapor obtained from elemental S powders. The films were thermally annealed in Ar atmosphere to improve the crytallinity. The sulfurization temperature was fixed at 550°C. Both as-deposited and post-sulfured samples are close to the stoichiometric composition, meanwhile without any second phase was detected by XRD. As-deposited film has a compact columnar grain characteristic. Although crystallinity was improved with increasing annealing time, this characteristic disappeared after post-sulfured.
摘要: The p-n junction photocatalysts, p-CuO (at. 0-25%)/n-ZnO nanocomposite were prepared through hydrothermal method without using any organic solvent or surfactant. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-Ray spectroscopy, and UV-vis spectroscopy. The results demonstrated that the CuO/ZnO nanocomposite presented a two-dimensional morphology composed of sheet-like ZnO nanostructures adorned with CuO nanoparticles. The photocatalytic activity of CuO/ZnO with different Cu/Zn molar rations and pure ZnO synthesized by the identical synthetic route were evaluated by degrading methylene blue (MB) dye under UV-visible light irradiation. The CuO/ZnO with Cu/Zn molar ratio of 4% exhibits the highest photocatalytic activity compared that of the other photocatalysts under the identical conditions. It is mainly attributed to the increased charge separation rate in the nanocomposite and the extended photo-responding range.
摘要: Negative-charged PS microspheres were prepared through emulsifier-free emulsion polymerization method. High-quality PS colloidal crystals were obtained via the horizontal deposition method. Hierarchically ordered macroporous CeO2 sheets were fabricated on fluorine-doped tin oxide (FTO) substrates using PS colloidal crystals as template by a continuous infiltration process. The structure and morphology of the products were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and nitrogen adsorption-desorption. The characterized results showed that macroporous CeO2 sheets replicated well three-dimensionally (3D) ordered structure derived from PS colloidal crystals template and possessed a relatively large specific surface area. Moreover, the synthesized hierarchical CeO2 sheets showed the highest photocatalytic activity under solar irradiation and also exhibited remarkable ability to remove methylene blue, suggesting they are promising catalyst for wastewater treatment.
摘要: Hematite is one of the most promising photoanodes for water splitting, but its photoelectrochemical (PEC) efficiency is still low. This work proved that the PEC efficiency of hematite can be improved by Ce doping. The Ce doped hematite was successfully prepared by co-sputtering CeO2 and Fe2O3, and followed by thermal oxidation treatment. The results of J-V test showed that the photocurrent of 5 at.% Ce doped α-Fe2O3 film can reached 1.35mA/cm2 in 1 M NaOH (pH=13.6) at 1.23V vs. NHE, which is nearly 15 times higher than the undoped one. The enhancement of PEC efficiency was proved by the enhancement of absorbance of visible light, as well as increased carrier density after Ce doping.