Advanced Materials Research Vols. 284-286

Abstract: Transparent conducting zirconium-doped zinc oxide (ZnO:Zr) and aluminium-doped zinc oxide (ZnO:Al) thin films were deposited on glass substrates by direct current (DC) magnetron sputtering at room temperature. The crystallinity of ZnO:Zr and ZnO:Al thin films increases as the target-to-substrate distance decreases, and the crystallinity of ZnO:Zr films is found to be always better than that of ZnO:Al films prepared under the same deposition conditions. As the target-to-substrate distance decreases, the resistivity of both film types decreases greatly while the optical transmittance does not change much with the variation of the distance. When target-to-substrate distance is 4.1 cm, the lowest resistivity of 6.0×10^-4 Ω·cm and 5.7×10^-4 Ω·cm was obtained for ZnO:Zr and ZnO:Al films, respectively. The figure of merit arrived at a maximum value of 3.98×10^-2 Ω for ZnO:Zr films lower than 5×10^-2 Ω for ZnO:Al films.

Abstract: This paper introduces electroless plating Ni-Cr-P/Ni-P composite coating technologies and techniques on the Nd-Fe-B permanent magnet surface. It has got a Ni-Cr-P/Ni-P composite coating successfully on the Nd-Fe-B substrate surface through rational processing plan. The coating surfaces are bright and have low Porosity, good binding between the electroless plating and Nd-Fe-B matrix. The experimental results show that the composite coating prepared by Ni-Cr-P electroless plating (15min) and Ni-P acidic electroless plating (45min) has amorphous structure, simple process and better anticorrosion property in both alkaline and acidic medium.

Abstract: (La_0.7Sr_0.3)MnO3 (LSMO) thin films were grown on Si (100) substrate by using pulsed laser deposition (PLD) process. Both structure and surface morphology of the films were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. From XRD, the results indicate that the films grown on Si (100) substrates have a single pseudocubic perovskite phase structure with a high (100) orientation. The XPS results show that La, Sr and Mn exist mainly in the forms of perovskite structure and a SrO layer was found on outermost surface. The films resistivity emeasured under room temperature is 6.4´10^-4 W×cm.

Abstract: Using a polyaryletherketone bearing carboxyl groups (PEK) as macromolecular ligand, Tb³⁺ and Ce³⁺ as central coordination ions, 1,10-phenanthroline (Phen) as the second ligand, a kind of novel terbium-cerium coordination polymer (PEK-Tb³⁺_0.5Ce³⁺_0.5-Phen) was prepared. The structure of PEK-Tb³⁺_0.5Ce³⁺_0.5-Phen was investigated by ICP, FTIR and XRD. The results showed that Tb³⁺ and Ce³⁺ ions coordinated to both the polymer ligand PEK and the second ligand Phen, and rare earth ions homogeneously distributed in the polymer matrix. The fluorescence measurement indicated that PEK-Tb³⁺_0.5Ce³⁺_0.5-Phen can exhibit the characteristic emission of Tb³⁺. Furthermore, the emission intensity of PEK-Tb³⁺_0.5Ce³⁺_0.5-Phen at 546 nm, corresponding to the green color, was higher than that of PEK-Tb³⁺-Phen.

Abstract: Electrical behaviors of light-emitting diodes (LEDs) prepared by wide-band GaN material were measured accurately using alternating-current (AC) small-signal together with an I-V plot. An abnormal negative capacitance (NC) was observed in all measurend LEDs, and at the same voltage the lower the frequency is, the more obvious NC is. Form the slopes of ln(I)-V plot and the relation between NC and voltage the ideality factor was approximately obtained.

Abstract: Fe/In₂O₃ magnetic granular films have been prepared by rf sputtering method. The results reveal that the nanometersized Fe particles uniformly dispersed in the amorphous matrix In₂O₃ for the as-deposited samples. At room temperature, the Fe_0.35/(In₂O₃)_0.65 film shows a superparamagnetic behavior. The average diameter of particles (d = 5 nm) estimated from the fitting values of the saturation magnetization of Fe particles M_Fe and magnetic moment m is fitted well with that observed by TEM. The spectra analyses indicate that the indirect photon transitions of granular Fe_x/ (In₂O₃)_1-x films substitute for the direct photon transition of In₂O₃ film in the absorption process. The band gaps of magnetic granular films decrease monotonously with the increase of volume fraction of Fe particles in the magnetic granular films, and the tail width of localized states becomes wider in concentration range of Fe studied.

Abstract: 1,3,4-oxadiazole (OXD) and its derivatives have excellent thermal stability and oxidation resistance and strong blue fluorescence emission. Six novel compounds have been designed and synthesized, and their structures were confirmed by ¹HNMR, FT-IR and MS. Their UV-Vis absorption and fluorescence spectroscopy data were studied. The UV-Vis absorption results showed that the maximum absorption wavelength appeared at 335-355 nm. and fluorescence spectroscopy results showed that they emit strong purple fluorescence in DMF solution. The electrochemical properties Show that electron affinity (EA) of these compounds show their electronic transmissions more transfer than commonly used electron transport material PBD (EA = 2.82eV).

Abstract: In this paper, the technique of alkali hydrogen peroxide extracting hemi-cellulose and the effects of pre-extraction on APMP pulping process of the Pink Sheets bamboo are investigated. The results show that the yields of pentosan and bamboo chip are optimal under the conditions of the dosage of hydrogen peroxide 1.5%, the reaction temperature 90°C, liquid ratio 1:8, holding time 4h. After pre-extracting the tensile index and folding strength decline, and the burst index is kept and the tear index increases slightly. But there is little loss to the brightness of APMP, and the refining energy is reduced largely after pre-extracted.

Abstract: In this paper, we report the synthesis of the bifunctional Fe₃O₄@SiO₂@Eu-polyoxometalates particles. The magnetite nanoparticles (Fe₃O₄) homogeneously coated with silica spheres prepared with the Stöber method. The so-obtained Fe₃O₄@SiO₂ core/shell particles were modified by 3-aminopropyltriethoxysilane and finally grafted with the luminescent Europium -polyoxometalates. The core-shell particles were characterized by scanning electron microscopy, transmission electron microscopy, FT-IR, UV, magnetism and luminescence spectroscopy. The results indicated that the core-shell particles show both interesting luminescence and magnetic properties.

Abstract: A lead free graphite conducting pastes were prepared by using graphite powder, lead free low-melting glass and terpineol ethyl cellulose solution. By analyzing the sheet resistance, Vickers hardness as well as the adhesion strength of the sintered film prepared by the pastes formulated with different composition, the composition of the paste with preferable properties was evaluated as in mass percent: organic vehicle 60, graphite powder 15~20, and low melting glass 20~25. The films, prepared by the pastes using the lead free glass with a glass transition temperature of 476°C, were perfectly flat and compact after fired at a peak temperature within the range from 520°C to 580°C. The sheet resistance of the fired film with glass content of 25wt% was 135Ω/mm² when the thickness of the film was 25±3μm, while the Vickers hardness and the binder force between the sintered film and the substrate were favorable. In addition, the rheological behaviors of the typical paste were characterized by using an ARES (RFS-III) rheometer. It is found that a weak flocculated network structure is formed in the paste for the high solid filler.