Advanced Materials Research Vols. 774-776

Abstract: VO₂ thin films with thickness from 100 nm down to 2 nm were prepare on C-plane sapphire (0001) substrates by magnetron sputtering and remarkable thickness-dependent structural and optical properties were found. Below 10 nm the films are nonconductive, and their phase transition temperatures are reduced to be much lower than those of the continuous, thick films. Structural defects are believed to be the main reason for this temperature reduction.

Abstract: Machinable ceramic was widely attended for it could extend application range of ceramic. As a kind of common ceramic, ZrO₂ ceramic was used widely, but it was difficult to be machined. CePO₄ powder was added into ZrO₂ powder to prepare composite powder. In this paper, two dispersion methods were used to prepared composite powder: mechanical mixed method and flocculation of multiphase suspension were used. Composite powder that prepared by mechanical mixed method sintered at 1450°C, 1550°C and 1600°C respectively. SEM was used to study microstructure of samples. Result of SEM showed that microstructure of sample that sintered at 1550°C was better than others, and there was no obviously default was found in it. Effect of mechanical mixed method was better than flocculation of multiphase suspension in this paper.

Abstract: Numerical simulations have been performed to investigate the effect of the temperature on the electronic transport through a small group of molecular assembly system (MAS). The model involves two 1,4-dithiolbenzene (DTB) molecular units stacked in one dimension (1D). The currentvoltage (I-V) and the conductance voltage (G-V) analysis are presented under the influence of the temperature associated with the π-orbital coupling interactions controlled by the intermolecular spacing d. The MAS with reduced d affects significantly the conductance which results in reducing the conductance gap and the saturation voltage V_sat. In addition, the present results show that the temperature rise effect plays an important role in determining the current flow in the saturation region. In this region, it is important to note that V_sat increases linearly when T goes from 50 to 325 K_.. To conclude, V_sat can be controlled either by changing the temperature or modifying its intermolecular spacing conformation.

Abstract: The CaO:xDy³⁺, yNa⁺ phosphors, were synthesized by high solidstate method, and the starting materials are CaCO₃Na₂CO₃ and Dy₂O₃. The effects of the Dy³⁺,Na⁺doping concentration on luminescent properties were studied by TG/DSC,XRD and PL spectra.The results indicated that when the sinter temperature of precursors over 950 °C,the main phase of the phosphor is CaO, and when x=0.02,y=0.15 we obtained the best luminescent properties of CaO:xDy³⁺, yNa⁺phosphors;Na⁺effectively enhances the luminescent properties of phosphors;The maximum emission wavelength is about 480 nm (blue),corresponding to ⁴F_{9 /2}⁶H_{15 /2} of Dy³⁺; There are a series of spectral lines in the 240-420 nm range of excitation spectrum,and the strong excitation peak located at 360 and 375 nm.

Abstract: Ternary NaFeS₂ nanorods were synthesized by solvothermal technique from Fe₂O₃ and Na₂S₂O₃·H₂O in ethylenediamine (en) solvent. The phase, morphology, microstructure and magnetic property of the nanorods were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscope and vibrating sample magnetometer. The possible growth mechanism of NaFeS₂ nanorods was discussed.

Abstract: Based on the bioaccumulation characteristics of fat cell, an innovative agent, biomimetic fat cell (BFC) has been prepared by interfacial polymerization to remove residual hydrophobic organic contaminants (HOCs) from aqueous solution. BFC exhibited efficient lindane removal from aqueous solution, and 95 % lindane was removed by 20 mg/L BFC at 4.6, 9.3, 19.2, 27.6 and 38.2 μg/L initial concentrations. Removal rate experiments indicated that external film diffusion and intra-particle diffusion accounted for removal rate controlling together. Removal equilibrium fit Freudlich model well with high correlation coefficients. The thermodynamic parameters demonstrated that the removal was favored at low temperature and exothermic in nature.

Abstract: Peach samples were pre-treated with microwave at 90, 270, 450, 720 and 900 W for 30, 60, 90 and 120 s, and juice browning was investigated during processing and storage. Polyphenol oxidase activity and ammonia nitrogen content decreased with microwave power enhancement or treatment time. The acidity of the peach samples initially decreased and then increased with prolonged treatment. The peach samples treated at 270 W preserved more polyphenol. The peach samples pre-treated at 270 W for 90 s or 450 W for 30 s demonstrated a reduction in peach juice browning. After 45 d of storage at room temperature, the juice colour value of the peach samples treated at 270 W for 90 s or 450 W for 30 s was 143.3% or 131.8% higher than that of the control samples, respectively. Microwave pre-treatment is a reasonable processing method for the effective prevention of peach juice browning.

Abstract: In this paper it is investigated the ageing dynamics of Al-4.2Cu-1.5Mg alloy aged at 170°C for different time. Vickers hardness and transmission electron microscopy were employed to test the hardness and microstructures of the aged alloy. It was found that there are two peaks in the curve. The first peak is attributed to the cluster hardening and the second peak is ascribed to the contribution of GPB zones.

Abstract: To provide polypropylene (PP) with better excellent mechanical properties, nanoCaCO₃ particles are incorporated into PP matrix by melt blending in this work. To improve the mophology between PP and nanoCaCO₃, maleic-anhydride grafted PP (PP-g-MAH) was added as a compatibiliser. The results showed that PP-g-MAH indeed enhanced the interfacial adhesion of PP /nanoCaCO₃ composites, which is demonstrated by the measurement of scanning electron microscope (SEM). The results of tensile tests revealed that the inclusion of nanoCaCO₃ slightly increased modulus and decreased tensile strength and significantly increased the elongation at break. At high fraction of nanoCaCO₃, the elongation at break was declined. The nanosized feature, shape and dispersion conditions of nanoCaCO₃, played important roles in determining the performances of PP/nanoCaCO₃ composites.

Abstract: Triethynylborazine-polyhydromethylsiloxane copolymers (TEB-PHMSs) were prepared through hydrosilylation reaction between -C≡CH attached to boron and ≡Si-H. The structures of TEB-PHMSs were characterized by Fourier transform Infrared (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopy. Their cure behavior were examined by Differential Scanning Calorimeter (DSC) and FT-IR, and then thermostability and ceramization of cured TEB-PHMS were investigated by Thermogravimetric analysis (TGA), pyrolysis-GC-MS, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The results indicated that TEB-PHMSs could be cured and converted into an outstanding thermostable SiBCN ceramics.