Advanced Materials Research Vol. 924

Abstract: Rheological and interfacial property of nanoAl with Hydroxyl-terminated polybutadiene (HTPB), glycidyl azide polymer (GAP) and poly (ethyleneoxide-co-tetrafuran)(PET) were investigated by means of RS-300 rheometer, DCAT21 dynamic contact angle measuring instrument, interface surface tension meter (Germany) and X-ray photoelectron spectroscopy (xps). Rheological properties of three binders and nanoAl/binder suspensions in the mixing ratio of 1:2 were discussed. Results show that Three kinds of binders exhibit pseudoplastic characteristics with the apparent viscosity of less than 3 Pa s,and have weak interaction between molecular chain segment of itself. Within 30~60°C, with temperature increasing, the apparent viscosity of nanoAl suspensions decreases, in which the nanoAl/HTPB and nanoAl/GAP belong to pseudoplastic fluid of sensitive to temperature, with flow activation energy of 38.05 kJ/mol and 52.07 kJ /mol, respectively, but nanoAl/PET belongs to a bingham fluid of sensitive to changes in the shear rate, with flow activation energy of only 1.506 kJ/mol. The contact angles of nanoAl,GAP,HTPB and PET were measured by means of dynamic contact angle/surface tension instrument. The calculated values of adhesion and spread coefficient of nanoAl with binders decrease in the order Wnano-Al/PET>Wnano-Al/GAP>Wnano-Al/HTPB and Snano-Al/PET>Snano-Al/GAP>Snano-Al/HTPB.The results indicate that the interactions of nanoAl with binders decrease in the order nanoAl/PET>nanoAl/GAP>nanoAl/HTPB,which is consistent with the trends of apparent viscosity of the suspensions . Binding energy of Oxygen in nanoAl/HTPB is 532.03 ev,which is bigger than that of nanoAl,and indicate a strong action between nanoAl and HTPB.

Abstract: The micrographs and optical properties of Al-doped ZnO (AZO) films deposited by radio frequency (RF) magnetron sputtering are presented in this paper. The AZO films termed as films I, II and III were sputtered on glass substrates heating at 300C, 400C and 500C, respectively. The micrographs, crystal structures and optical properties of AZO thin films were analyzed by using scanning electronic microscopy (SEM) images, X-ray diffraction (XRD) pattern, optical transmission and reflection spectra ranging from 350 to 1000 nm. As the substrate temperature increases to 500C, the film III exhibits a better flatness surface and a larger grain size of ~25nm with a stronger c-axis orientation. The film II has a high transmittance of greater than 92% in the visible light region. We also show that the films II and III have significant red-shift band gap ~3.00 and ~3.13eV, respectively, in comparison with that of the film I (3.31eV). This might be due to the increasing doped Al atoms which do not activate due to segregation at the grain boundaries.

Abstract: We propose a novel surface passivation of InP, to obtain the strong luminescence property and completely remove the surface state. InP is passivated by (NH4)₂S solution, then treated by rapid thermal annealing (RTA) at different temperatures. Compared with unannealing sample, the PL intensity is increased to 1.7 times. We adopt atomic layer deposition (ALD) of Al₂O₃ avoiding oxidizing gradually.

Abstract: Mg, Ni, Co, Cu and Fe nanoparticles with a particle size of 30-300 nm were synthesized by hydrogen plasma metal reaction method. Nanostructured Mg-based hydrogen storage materials (Mg-H, Mg-Ni-H, Mg-Co-H, Mg-Cu-H and Mg-Fe-H systems) were synthesized from these metal nanoparticles. In this work, the kinetic and thermodynamic properties of these nanostructured hydrogen storage materials were studied. It was found that nanostructure could significantly enhance the hydrogen absorption kinetics but the thermodynamics (desorption enthalpy and entropy) does not change with downsizing in the size range of 50 to 300 nm.

Abstract: The degradation of the performance of the polymer solar cell based on the blend structures system of poly (3-hexylthiophene) (P3HT) and [6,-phenyl C61-butyric acid methyl ester (PCBM) is investigated. This study uses UV-vis absorption spectra, photoluminescence (PL) spectra, charge-transport dark J-V curve chart to explicate the reason for the degradation of the performance of P3HT:PCBM photovoltaic cells. Solar cell performance is degraded primarily through loss in short-circuit current density (Jsc) and fill factor (FF), the reduction in the Jsc and FF of the device is most likely to be due to the formation of the charge transfer complex, deep traps and destruction of the-conjugated system in the degraded P3HT:PCBM device. The exposure to oxygen and photo-oxidation lead to the emergence of these factors of the device performance degradation. Keywords: Degradation; Performance; Solar cells; P3HT: PCBM

Abstract: Aluminum nanopowders coated with oleic acid (nmAl+OA), perfluorotetradecanoic acid (nmAl+PA) and nickel acetylacetonate (nmAl+NA) were prepared. The combustion characteristics of hydroxyl terminated polybutadiene (HTPB) composite solid propellants containing different coated aluminum nanpowders were investigated. The result shows that the burning rate of the propellant sample containing nmAl+NA is the highest at different pressure, the maximum burning rate is up to 26.13 mm·s^-1 at 15 MPa. The burning rates of propellant samples containing nmAl+OA and nmAl+PA are almost the same at different pressures, and higher than the propellant samples containing untreated aluminum nanopowders only at the pressure range of 10 ~ 15 MPa. The flame brightness of different propellants under different pressure is not the same. The flame brightness is increased with the pressure increasing. The flame center zone brightness of the propellant containing nmAl+PA and nmAl+NA is brighter under 4 MPa, and the brightness of nmAl+NA is the brightest. The surface coating of aluminum nanopowder has little effect on the combustion flame temperature of solid propellant. The burning surface temperature increases with the pressure increasing.

Abstract: In this paper, the unitary structure characteristics and the super-hydrophobic properties of the lower surface of the lotus leaf and artificial biomimetic surfaces were investigated through scanning electron microscopy, field emission scanning electron microscopy, x-ray photoelectron spectroscopy and contact angle measurement. The measurement of wettability showed that artificial unitary structure surfaces modified with the lower surface energy material exhibit a super-hydrophobic property with a water contact angle of about 150°. The artificial structure characteristics and the super-hydrophobic properties are similar to those on the lower surface of the lotus leaf. The contribution mechanism of the unitary structure on the hydrophobic property was discussed for the surfaces of the lotus leaf and artificial biomimetic surfaces based on the Cassis-Baxter model.

Abstract: Nickel/carbon nanotubes (Ni/CNTs), Nickel/alumina (Ni/Al₂O₃), calcium-promoted Ni/CNTs and calcium-promoted Ni/Al₂O₃ were synthesized by impregnation method. Methanation of carbon dioxide was used as a probe to evaluate their catalytic performance. The features of these Ni-based catalysts were investigated via XRD, H₂-TPR, H₂-TPD and the N₂ adsorptiondesorption isotherms. H₂-TPR showed that nickel species on Ni/CNTs was reduced more easily with respect to that on Ni/Al₂O₃, and addition of Ca can increase the content of easily reducible Ni species for Ni/CNTs. XRD and H₂-TPD indicated that addition of Ca promoted dispersion for CNTs-supported catalyst. These finding ultimately enhanced catalytic activity and stability for Ni/CNTs catalyst modified with Ca.

Abstract: Quasi-classical trajectory dynamical calculations of the title reactions have been performed on an accurate NH₂ potential energy surface [Poveda LA, Varandas AJC, Phys Chem Chem Phys 7:2867,2005] over the collision energy range of 25-80 kcal mol^-1. The reaction cross sections, variation of internuclear distances of N-H_a, N-H_b and H_a-H_b, and the reaction rate constants are reported for various initial vibrational and rotational states of H₂ (v=0-3; j=0) molecules. The reaction cross section in the ground vibrational state of H₂ and the rate constant over the thermal distribution of initial vibrational states of H₂ are compared with other theoretical results and existing experimental results in the literature, showing good agreement.

Abstract: Theoretical studies on a series of binuclear transition metal pentazolides M₂(N₅)₄ (M=Co, Rh and Ir) predict Paddlewheel-type structures with very short metal-metal distances suggesting high-order metal-metal multiple bonds. Natural Bonding Orbital (NBO) analysis have indicated that the bonding between the metal atom and the five-membered ring is predominantly ionic for each M₂(N₅)₄ species, and a high-order metal-metal multiple bonding exists between the two metal atoms, in addition, the presence of the delocalized π orbital plays an important role in the stabilization of this metal-polynitrogen species. Nucleus independent chemical shift (NICS) values confirm that the planar N₅ exhibits aromaticity in these M₂(N₅)₄ species. The values of NICS(0.0), NICS(0.5) and NICS(1.0) for Co₂(N₅)₄ are larger than those of the other two M₂(N₅)₄ species (M=Rh and Ir), with the order of Co₂(N₅)₄>Rh₂(N₅)₄>Ir₂(N₅)₄. The dissociation energies into Mononuclear Fragments for M₂(N₅)₄ (M=Co, Rh and Ir) are predicted to be 82.9 (85.7), 139.9 (113.2), and 155.1 (149.7) kcal/mol, respectively. However, the dissociation energies for the loss of one pentazolato group from the M₂(N₅)₄ analysis have indicated that the Co₂(N₅)₄ is relatively higher at ~40 kcal/mol. Thermochemistry suggests Co₂(N₅)₄ to be a viable species.