Advanced Materials Research Vols. 760-762

Abstract: Ferroelectric BiFeO₃ (BFO) thin films were prepared on Pt (111)/Ti/SiO₂/Si substrates by pulsed-laser deposition under various oxygen partial pressures (P_O2). The effects of P_O2 on the phase, orientation, surface morphology, and ferroelectric properties of the films were investigated, particularly in regard to relationships between structure and properties. It was found that the crystallographic orientation and surface morphology of the BFO thin films strongly depended on P_O2. Films prepared at P_O2=10 Pa had a high degree of (111) orientation and densely packed grains. A maximum of twice the remanent polarization for the BFO thin film was 68 μC/cm².

Abstract: In order to reduce the weight of the elevating mechanism, which is a component of an unmanned airborne electro-optical platform, and improve its rigidity and strength, Carbon Fiber Reinforced Polymer (CFRP) is utilized to fabricate three supporting plates of the elevating mechanism. Finite element analysis has been conducted to compare the new material CFRP with the current material: aluminum alloy. Due to excellent mechanical properties such as lower density as well as higher rigidity and strength, the new material decreases the weight of the elevating mechanism by 4.4kg, reduces the maximum deformation by 61%, and increases the natural frequency by 51%, when compared with aluminum alloy. Furthermore, the high reliability of the CFRP based elevating mechanism has been verified by vibration test and practical flight test. Because its the first time to apply carbon fiber composites on elevating mechanism of an airborne electro-optical platform, this paper not only achieves good results but also makes effective exploration for the application of new aviation materials.

Abstract: The absorption and emission spectra of 1,8-naphthalimide derivatives have been calculated by time-dependent density functional theory. Their lowest singlet transition states can be described as the promotion of electrons from the HOMO to the LUMO. Substituents on naphthalimic ring seldom extend the conjugation of the central naphthalimic system.

Abstract: Multi-component doped photopolymer with phenanthrenequinone photosensitizers is prepared and its photosensivity characteristic is investigated experimentally. SiO₂ nanoparticles and ZnMA organometallic components are dispersed into the P(MMA-co-MAA) matrix to enhance the photosensitivity of sample. Experimental results indicate the photopolymerization time constants under consecutive exposure and the time constants of dark enhancement under darkness are evidently reduced at least one order of magnitude.

Abstract: A facile solution method for the synthesis of single-crystal copper indium gallium diselenide (CIGS) nanotubes was developed by using anodic aluminum oxide (AAO) as morphology directing template and triethylenetetramine as both reducing agent and effective chelating agent. The crystal structure, morphology, elemental composition of the as-obtained CIGS nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The as-obtained CIGS nanotubes have a diameter about 200 nm and a thickness of 30 nm. The proposed synthesis strategy developed in this work may be used as a general process for other metal chalcogenides nanotubes and may have a bright application prospects in high efficiency, yet low cost photovoltaic areas in the future.

Abstract: Two kinds of nanoscale particles (TiO₂ and ZrO₂) are dispersed uniformly in PVDF (polyvinylidene fluoride) solution. The pure PVDF film, hybrid TiO₂ or ZrO₂:PVDF (the weight ratio of 5:5, 4:6 and 3:7, respectively) films are fabricated by spin-coating. THz time-domain spectroscopy system (THz-TDS) has been used to get the transmission spectra of the samples in THz band, from which the optical constants of the samples are extracted. The reflection spectra of the distributed bragg reflectors (DBRs) with structure of Si substrate/[HL]ⁿH (H indicates TiO₂:PVDF or ZrO₂:PVDF, and L indicates pure PVDF, n=1, 2 and 3) are simulated based on transfer matrix method. The results show that from 600μm to 800μm, the reflectances of the two reflectors are both increased with the number of dielectric layers, and when n=3, the reflectivity of two reflectors at resonance wavelength are almost reaching 95%.

Abstract: Europium complexes exhibited intense red fluorescence with a narrow spectral bandwidth. But non-uniform blending or dispersion of complex resulted in phase separation, decomposition and inefficient energy transfer to reduce emission efficiency. The complexes were covalently attached to the main chain of polymers, which improved film quality and solubility. Eu (TTA)₂(AA)(TPPO)₂ as europium complex monomer (ECM) was prepared by Eu³⁺ coordinating with triphenylphosphine oxide (TPPO), acrylic acid (AA) and 2-thenoyltrifluoroacetone (TTA). Fluorescent Polymer marked as p1-30 (molar ratio for ECM/N-vinylcarbazole (NVK), 1/30) was synthesized. The emissions of ECM and p1-30 peaked at ca. 610 nm. The highest occupied molecular orbit (HOMO) and the lowest unoccupied molecular orbit (LUMO) energy levels were-5.36 and-1.99 eV. The organic light-emitting devices (OLED) A ITO/PEDOT: PSS/PBD: p1-30/AlQ₃/ LiF/Al and B ITO/PEDOT: PSS/PBD: p1-30/BCP/AlQ₃/LiF/Al were fabricated. A 4 nm thickness of BCP as a hole-block layer was introduced in Device B to block the movement of holes partly and to reduce the emission from AlQ₃. Devices A and B mainly emitted white emission and exhibited luminance of 420 and 315 cd/m² with Commission International de LEclairage (CIE) coordinates of (0.317, 0.392) and (0.336, 0.380), respectively. The emission from carbazole moieties was suppressed, electroluminescent (EL) spectra revealed that effective intramolecular energy transfer from carbazole unit to europium complex occurred.

Abstract: Fundamentals of two-photon photopolymerization have been introduced and a 3D femtosecond laser micro-nanofabrication system has been built. In this paper, 3D CAD data model based on femtosecond laser micro-nanofabrication system have been also discussed. The 3D various sphere-rod photonic crystal structure mimicking real atom structures in electronic crystals have been fabricated.

Abstract: PtAu bimetallic nanoparticles (NPs) were successfully synthesized on single-stranded DNA functionalized graphene nanomaterials (ss-DNA/GR) via a simple chemical reduction method. The nanocomposites (PtAu/ss-DNA/GR) were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDS) and electrochemical techniques. Then a sensitive dopamine (DA) sensor was fabricated based on PtAu/ss-DNA/GR nanocomposites modified glassy carbon electrode (GCE). The results of electrochemical experiments demonstrated that the sensor exhibited excellent electrocatalytic activity to the oxidation of DA. The sensor displayed wide linear detection range from 8.0×10^-8 to 1.0×10^-5 M and 1.0×10^-5 to 5.0×10^-5 M and a low detection limit of 1.0×10^-8 M (S/N = 3). In addition, the sensor also showed high selectivity, good reproducibility and stability for DA detection. Thus, it is considered to be an ideal candidate for practical application.

Abstract: nanoTiO2 photocatalyst powders were prepared through the sol-gel method and with supercritical fluid drying (SCFD). The SEMXRD and particle size distribution technique were used to characterize the hyperfine TiO2 particles.The reaction of photo-catalysis for methylene blue is in conformity with the first order kinetic law in appearance within the concentration range between 5mg/L and 15 mg/L. As the initial concentration methylene blue in water increase, the appearance rate constant of the reaction decreases while the half-life period of the reaction increases.