Materials Science Forum Vols. 663-665

Abstract: Carbon fibers (CNFs) were surfacial metallized by electroless deposited with copper, and their field emission properties were investigated by diode test. The results indicated that the field emission properties of CNFs were affected by the thicknesses of copper. After CNFs were surfacial metallized, the volume resistivity of CNFs was decreased and field emission property was increased, respectively; increase the thin-film thickness, there appeared an optimal film thickness value for properties of field electron emission. It was found that CNFs owned the best field emission properties after electroless depositing for 15 min, with copper metal thickness as 2.1 µm and the volume resistivity down to 2.3510-4 Ω•cm. The field emission tests showed when applied voltage was 562 V, CNFs appeared bright dots, and the high luminance achieved 1388 cd/m2 under applied voltage 1013 V. Further more theoretical analyses, copper coating on CNFs surface is attributed to good electric conductivity, the low work function and the lower attenuation of electron scattering in thin-film.

Abstract: Based on X-ray diffraction results, the gallery height of modified Mg3Al-LDH was expanded to 9.6Å from the original 4.8Å, indicating that the H3PW12O40 was indeed inserted into the hydroxide layers. Moreover, the results of FT-IR spectra proved the Keggin structure of PW11O397- species. The resulting material showed a high activity of degradation of methyl orange in the presence of H2O2 and UV light irradiation.

Abstract: By means of the transfer matrix method, transmission spectra and dispersion relationships of photonic crystals (AB) m (CD) n (AB) m (CD) n (AB) m are investigated herein. The number and highness of transmission peaks are found to relate closely with the repeating periodicity n, and (CD)n medium of positive- or negative- refractive index as well. The results may be helpful for designing optical filters of desired properties.

Abstract: The electronic and optical properties of hexagonal wurtzite AlN doped with Zn and Mg are studied based on the density functional theory. The density of states, dielectric function and absorption spectra are calculated using plane-wave ultrasoft pseudo-potential and the generalized gradient approximation (GGA). The absorption peaks are found during 0-13 eV and 43-48 eV in Mg doped AlN, while in Zn doped AlN, only during 0-15eV. The absorption peak about 43-48 eV found in Mg doped AlN is due to the transition of the deep 2p energy level in Mg to conduction band. The first peak of the dielectric imaginary part is related to the transition of the doped atoms. The peak of the dielectric imaginary part and absorption peak appears about 8 eV is due to the transition of N 2p to Al 3p state. Results show that the electronic and the optical properties of hexagonal wurtzite AlN are directly related to the electronic structure of the impurities in the crystal.

Abstract: Performing an event-based continuous kinetic Monte Carlo (KMC) simulation, all the important kinetic behaviors take place during the growth of the semiconductor material in the molecular beam epitaxy (MBE) system such as deposition, diffusion, desorption, and nucleation are considered, we investigate the effects of the growth conditions which are important to form semiconductor quantum dot (QD) in MBE system. The simulation results provide a detailed characterization of the atomic kinetic effects. The KMC simulation is also used to explore the effects of anisotropy effects to the epitaxy growth of QD. We find that the flux plays an important role in determining the size of the QD. The agreement between our simulation and experiment indicates that this KMC simulation is useful to study the growth mode and the atomic kinetics during the growth of the semiconductor QDs in MBE system.

Abstract: With the effective screen-printing technique and high-temperature sintering process, the suspersion gate structure was developed. The silver slurry was printed on the gate substrate to form the gate electrode. Using carbon nanotube as cold field emitter, the triode field emission display (FED) panel was fabricated, and the detailed manufacture process was also presented. The anode back plane, the cathode back plane and spacer combined to device room, in which the suspension gate structure would be included. The distance between the gate electrode and carbon nanotube cathode could be reduced, which could decrease the device manufacture cost because of the small gate voltage. The modulation of emitted electron by the gate voltage would be confirmed, and the field emission characteristics was measured. The sealed FED panel with simple fabrication process and designed structure possessed better field emission uniformity, high display brightness and field emission perofrmance.

Abstract: The effect of anionic surfactants on the chemiluminescence (CL) properties of CPPO- H2O2-Rhodamine B system was researched, and the maximum fluorescent intensity of every system was found at the critical micelle concentration (CMC) of corresponding surfactant. The reduced vibration of Rhodamine B molecules induced by the combination of micelle was offered to explain the positive effect of anionic surfactants. Moreover, the structure of anionic surfactant was found to be relative to the enhanced fluorescent intensity, and the hydrophobic group’s structure and stereospecific blockade were considered as two main factors to the sensitization ability of anionic surfactant on CL.

Abstract: Ternary rare earth luminescence complexes composed of Tb (III)-phthalic acid (H2L)-1,10-phenanthroline (phen) were synthesized using precipitation method. The elemental analysis, plasma atomic emission spectra, infrared spectra were measured the composition of obtained samples and the chemical composition deduced is TbL3/2(phen)0.5. XRD patterns show that the obtained coordination compound is new crystal different from that of two ligands. SEM results indicate that the coordination compound is a floral crystal with the size about 1-2 µm and has better dispersity. The TG-DTA result showed that the luminescence complex has good stability below 478 oC. Photoluminescence analysis indicated that the coordination compound emits Tb3+ characteristic green luminescence under ultraviolet excitation.

Abstract: ZnO thin films with a strong c-axis orientation have been successfully deposited on quartz glass substrates at room temperature by radio frequency (rf) magnetron sputtering technology. X-ray diffraction, Rutherford backscattering, and prism coupling method were used to investigate the structure and optical properties of ZnO thin films. X-ray diffraction results shown lower sputtering pressure is propitious to increasing the crystallinity, and enhancing the c-axis orientation of the films. Rutherford backscattering analysis revealed that the films were stoichiometric ZnO, and as the sputtering pressure decreasing, the deposition rate were increased from 0.758 3nm/min to 2.892 nm min for sputtering pressure in the range from 1.0Pa to 0.5Pa. Under the lower sputtering pressure (0.5Pa) condition, the results obtained by prism coupling method investigation confirmed that the effective refractive index of ZnO films (no=1.8456，ne=1.8276) at a wavelength of 633nm is more close to Crystal Refractive index.

Abstract: Using carbon nanotube as field emitter, the diode-structure field emission display device was fabricated with conventional sintering techniques. With the precise photolithography process, the indium tin oxide film coated on the anode faceplate surface was etched to form the bar anode electrode. Using the screen-priinting technology, the insulation slurry was prepared on the bar anode electrode surface to form the anode separate layer. So the discrete anode sub-pixels layer structure was developed. For the vacuum-selaed FED device, the typical field emission characteristics were measured and the displayed dot matrix image was also presented. The fabricated FED device with discrete anode sub-pixel layer possessed higher dispaly image brightness, good image disnlay performance and better field emission characteristics.