Advanced Materials Research Vols. 287-290

Abstract: High purity low hydroxyl synthetic fused silica glass was prepared by electric melting synthetic crystallized silica powders which were made by the process of hydrolysis, dehydration and calcination of high purity silicon tetrachloride obtained from the by-product of polysilicon production. The structure morphology and hydroxyl content of synthetic silica powders were characterized by XRD and IR, respectively. The experimental results suggest that the silica powders dried at 120°C are amorphous, and the amorphous silica powders are gradually transformed to alpha-cristobalite after sintered in 1250°C, but the crystallization peaks are very strong and sharp until the temperature reaches at 1400°C. The hydroxyl content of silica powders can be effectively reduced by heat-treatment at high temperature.the crystallized silica powders calcined at 1500°C have much lower hydroxyl content than the amorphous silica powders. The hydroxyl group content in the silica glass products melted synthetic pre-crystallized silica powders is 7.3ppm, which meets the requirements for full-spectrum (wavelength from 190nm to 3200nm) transmittance.

Abstract: With zirconium oxychloride, aluminium sulphate and titanium oxysulphate as the basic raw materials, zirconia-aluminum titanate nano-composite powders were prepared with the liquid precipitation method. The nanocomposite powders were detected with XRD, TEM and TG-DTA.The results show that recovery ratio of zirconia and aluminum titanate precursosr is higher, with respective pH about 9.5, 5.5 and concentration of 0.1 mol dm^-3 in the system. About several nanometer zirconia and 100 nanometer size aluminum titanate can be obtained when the precursors are respectively roasted at 600°C and 1000°C.

Abstract: In this study, composite polymer electrolytes were prepared by addition of titanium oxide, TiO₂ nanofiller into polyvinylidene fluoride-co-hexafluoropropylene/polymethyl methacrylate-ammonium triflate (PVDF-HFP/PEMA-NH₄CF₃SO₃) complex. The effect of TiO₂ on conductivity of the complex was examined using impedance spectroscopy. The highest room temperature conductivity of 1.32 × 10^-3 S cm^-1 was shown by the system containing 5 wt % of TiO₂. This system was used for the fabrication of proton batteries with the configurations of (Zn + ZnSO₄.7H₂O + C + PTFE)/PVDF-HFP/PEMA-NH₄CF₃SO₃-(5wt%)TiO₂/(MnO2 + C + PTFE) and (Zn + ZnSO₄.7H₂O + C + PTFE)/PVDF-HFP/PEMA-NH₄CF₃SO₃-(5wt%)TiO₂/(MnO2 + PbO₂ + C + PTFE). The performance of the batteries indicated potential application of the electrolyte system in proton batteries.

Abstract: The volatilization behavior of Seleenium in coal / coal char was studied by determining the concentration of Se with AFS at H₂O(Ar) atmosphere in high-temperature tube furnace. The inhibition effects on the volatilization of Se with calcium-based material (CaO) and nano materials Fe₃O₄ as absorbents were studied during coal gasification. The results show that the volatilization rates of Se, rising with the temperature of gasification, can be effectively controlled with the absorbent of CaO. Because CaO can reacts with Se produce CaSeO₄, a more stable compoud. Nano-Fe₃O₄ can enhance the ability of CaO to inhibit the volatilization of selenium, it is because not only can promote more CaSeO₄, while also reducing the possibility of its decomposition.

Abstract: Because of the good photoelectric learning properties and chemical properties, CdTe nanocrystalline as an important Ⅱ-Ⅵ clan semiconductor materials has been used in LEDs, photonics, in aspects of materials and biomarker and so on. W/O microemulsion method has the peculiarity of tester simpleness, easy manipulation, room temperature react etc. In this paper CdTe nanoparticles was synthesized in CTAB/cyclohexane/isobutanol/water quatemary microemulsion system in alkaline condition and nitrogen. The morphology of the final products were characterized by X-ray power diffraction, transmission electron microscopy. according to the means, this paper researches the effect of surfactant contentration to morphology. The result is that the different morphology can be obtained through the different CTAB concentration. Finally, according to TEM chart, this paper infers the formation mechanism of the CdTe.

Abstract: Opto-eletrical stabilization/tracking device has the need to improve its accuracy due to the wide use in the field of observation, measurement equipment on the mobile correspondingly. The paper analyzes error sources of stabilization and tracking based on system working principle, and expatiates the effect of some error items including disturbance moment, assembling error of gyro etc. Furthermore, according as the probability theory, the paper expresses the comprehensive accuracy and obtains the evaluation method of device accuracy. Finally, it gives the example of evaluation on the direct stabilization/tracking device.

Abstract: The mechanical properties, swelling, solubility, and optical properties of composite films with poly(vinyl alcohol) (PVA) and gelatin were studied. With increasing the PVA content in the composite films, the tensile strength (TS) and elongation at break (EB) of the films increase. The swelling and solubility are different with different gelatin/PVA ratios, with the lowest at 1:5.

Abstract: To improve the solar energy conversion of GaN for photocatalytic, the band gap of GaN should be tailored to match with visible light absorption, we calculated that Cr/C codoping effectively narrows the band gap of GaN by using first-principles calculations. Cr/C codoping can split the band gap with the formation of an intermediate band. Positive defect pair binding energy indicates that the defect pairs are stable with respect to the isolate impurity in the sample. The band gap narrowing can be optimized to shift light absorption into the peak of the visible spectral region , which enable maximal utilization of sunlight and thus offer immense potential for applications in solar energy conversion.

Abstract: The electron transport behavior of a short graphene nanoribbon sandwiched between two gold(111) electrodes is investigated using density functional theory calculations and nonequilibrium Green’s function technique. The calculated current-voltage characteristic of the graphene nanoribbon junction shows an obvious negative differential resistance (NDR) phenomenon. The mechanism of this NDR behavior of graphene nanoribbon is discussed in terms of the evolution of the molecular energy levels, the spatial distribution of frontier molecular orbitals, and the electron transmission spectra under various applied biases. It is found that the changes of the spatial distribution of molecular orbitals near Fermi level with the applied bias lead to such NDR behavior.

Abstract: The calcination process of titanium silicalite zeolite TS-1, which was prepared by hydrothermal method, was investigated using TG-DTA, XRD, FT-IR and SEM. With TG-DTA analysis, it has been observed that the crystal form was not changed after calcination under 1073K and the amount of template removal from zeolite channels was not affected by heating rate. The photographs of SEM showed that calcined TS-1 crystal morphology was integrated under 823K, but ruptured at 923K. Analyzing FT-IR with XRD results, the calcination process changed the cell parameter and unit cell volume, and increased the crystallinity of zeolite TS-1.