Advanced Materials Research Vols. 55-57

Abstract: The total leakage current in silicon p-n junction diodes compatible with 0.8 µm CMOS technology is investigated. The generation lifetime is a key parameter for the leakage current, which can be obtained from the current-voltage (I-V) and the capacitance-voltage (C-V) characteristics. As will be shown, the electrically active defect from ion implantation process generated in p-n junction can be extracted from the generation current density.

Abstract: This paper descript studying and preparation indium-tin oxide (ITO) thin film from method 90 wt.% In2O3 and 10 wt.% SnO2 formula target with 99.99% purity on glass slide by RF reactive sputtering method at room temperature. This paper, sputtering time 5, 15, 30 and 60 mins. Thin films ITO were measured crystallization, optical and electrical characteristic by an X-ray diffractometer (XRD), scan electron microscopy (SEM) , Four Point Probe and UV-VIS spectrophotometry. The results found that thin films which made from RF sputtering method had a high crystallization, order arrangement grain. Strong peak of XRD (400) and (441), low resistivity are 2.2 x 10-3, 4.4 x 10-3, 1 x 10-3 and 7 x 10-4 Ω-cm, transmittance are 82%, 84%, 87% and 89%, respectively. The overall experimental results identify that fabricated thin films ITO have good properties and is suitable for transparent electrode application. The ultimate goal is developing schottky photodetector.

Abstract: SnO2 nanoparticles were successfully synthesized with either the presence (PS) or absence (NPS) of the Broussonetia papyrifera (L.) Vent Pulp as the dispersant by the precipitation coupling with the thermal decomposition methods using tin tetrachloride pentahydrate (Sn4Cl.5H2O) and ammonium hydroxide (NH4OH) as the starting material and precipitant respectively. The pulp was soaked in SnCl4 solution and NH4OH was slowly added dropwise. The white gelable precipitate of Sn(OH)4 was obtained. Afterward, the white precipitate was filtered and washed until it was free from chloride. The white precipitate was then dried at 80°C for 24h and calcined for 1h at 600°C, 650°C, and 700°C respectively. The synthesized products were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET) measurement of specific surface area. The crystallite sizes of SnO2 nanoparticles with the presence and absence of the pulp were found to be ranging from 5-15 nm and 5-30 nm respectively. The specific surface areas (SSABET) were 62.53 m2/g and 26.60 m2/g for PS and NPS samples respectively. SnO2 nanoparticles were doped with palladium in the range from 0.25-1.00 mol% by the impregnation method. The photocatalytic activity of SnO2 and Pd-doped SnO2 nanoparticles were investigated for the degradation of sucrose and glucose under UVA-light irradiation. The results showed that the photocatalytic activity of Pd-doped SnO2 was higher than pure SnO2 and the best photocatalytic activity for the degradation of sucrose and glucose were obtained in the case of Pd-doped SnO2 nanoparticles with 0.5 mol % and 1.0 mol % Pd loading respectively.

Abstract: Configurational averaging technique is adopted via lattice statics approach to obtain the thermodynamic and structural properties of ZSM-5 containing various impurity content. Different Si:Al:Fe and Si:Al:P ratios within o-ZSM-5 and m-ZSM-5 frameworks have been studied. The results show that the third type of atom (Fe or P) incorporated to aluminosilicate ZSM-5 plays an important role on the structural stability of zeolite. It is indicated that the lattice enthalpy of aluminosilicate ZSM-5 is highered when doping with Fe, but it is lowered when doping with P. It is found that for o-ZSM-5 doped by Al/Fe and Al/P, the values of bond lengths, as well as and bond angles, are close to those for siliceous o-ZSM-5. However, for m-ZSM-5 doped by Al/Fe and Al/P, the values of are slightly longer whereas and are smaller compared with those for siliceous m-ZSM-5.

Abstract: PLA-based aliphatic aromatic copolyesters have been synthesized and characterized in order to incorporate the degradability of PLA and good mechanical properties of aromatic species. Synthesis of the copolymers was conducted by polycondensation of lactic acid with dimethyl terephthalate (DMT) and various diols using stannous(II) octoate as a catalyst. Three types of diols with different methylene lengths were employed, i.e., ethylene glycol (EG), propylene glycol (PG) and 1, 4-butanediol (BD). Effects of diols and comonomer molar ratio on the extent of polycondensation reaction and molecular weight of the resulting copolymers were investigated. Diacids and diol ratios of L-lactic acid (LLA), dimethyl terephthalate (DMT) and diol of 1/1/2, 1/2/4 and 2/1/2 were employed. Characterization of chemical structure, molecular weight and thermal and physical properties of the resulting copolymers were conducted by FTIR, NMR, and DSC.

Abstract: Because of their respective advantages, the combination of good material properties of poly(ethylene terephthalate) (PET) and degradability of polylactic acid (PLA) is researched as degradable copolymer for packaging and agricultural applications. Poly(ethylene terephthalate-co-lactic acid) (PET-co-PLA) has been synthesized by employing polycondensation of mixtures of dimethyl terephthalate (DMT), lactic acid (LA) and ethylene glycol (EG), using tin(II) octoate as a catalyst. A chain-extending reagent, hexamethylene diisocyanate (HMDI), was then used in the subsequent step to increase the chain length of the copolymer and improve its mechanical properties for suitable applications. The chemical structure and molecular weight of the copolymers were investigated by FTIR, NMR, and DSC. NMR results indicated the incorporation of lactic acid and PET units in the copolymer chain. Additionally, blends of the resulting copolymer with commercially-available PLA were studied. The blend miscibility was examined by DSC and FTIR spectroscopy.

Abstract: The β″-alumina solid electrolyte proposed for the application in the electric vehicle battery system was prepared via a liquid phase sintering method. The main aim of the study is to reduce sintering temperature which is normally required as high as 1700oC. The MgO-stabilized Naβ″-alumina with the composition Na1-xMg2xAl5-xO8 where x = 0.125 was prepared. The mixture of Na2CO3, MgO and γ -Al2O3 were produced and well-mixed by wet ball milling method. Then, calcination was performed at 1200oC for 10 h. Calcined β″-alumina was then added with a sintering aid, CuO, at several concentrations prior to forming by a dry pressing technique. The green pellets were then sintered at different temperatures with constant dwell time for 4 h. Phase identification on calcined powders indicate that β″-alumina present as a mojor phase co-existed with tiny proportion of β′-alumina. Co-existence of these two phases is commonly found for this particular system. Phase checking for sintered samples with CuO additive show no phase change but concentration ratio of the β′-alumina seem to increase with increasing sintering temperature and mol% of the CuO. Sintering at 1550oC, the higher densification is clearly observed for ceramic with higher CuO content, i.e. 5 and 10 mol%. Layered-structure of the β″-alumina can be clearly seen from the SEM micrographs. The SEM results also show that higher CuO content promoted a higher grain development and produced less porosity. Dc conductivity values of the samples with CuO adding are reasonable high comparing to that of without CuO adding. This study has been show that β″-alumina produced by liquid phase sintering here is considerably appropriate to the application in the battery of electric vehicles.

Abstract: Solid Oxide Fuel Cells (SOFCs) have attracted a number of researchers due to their efficiency as alternative energy devices. Studies have been conducted to investigate different components of the SOFCs to improve the performances. Current collecting wires are the components which have affected the overall performance. Since SOFCs are normally operated in the temperature range of 700-1000 °C in dual atmospheres, the wiring material must be able to function at this condition. Currently, the material used to make the wires is platinum because of its high electrical conductivity, high melting point and oxidation resistant. However, platinum is expensive, especially for the practical operation of SOFCs. Silver could be an alternative choice due to its very high electrical conductivity. Nevertheless, the melting point of silver is rather low (900-960 °C). In our study, a modified silver current collecting wire has been used in the temperature range of 100-1000 °C. Their conductivity curves have demonstrated higher performances in comparison with the systems employing Pt and gold wires. In addition, the cost is reduced approximately 800-1000 times from that of the traditional material used.

Abstract: The dielectric constant values of a set of synthetic alpha alumina samples doped with Cr and Be were determined using parallel plate method. The voltage frequency was selected at 1 MHz. When Cr was doped to the sample, the dielectric constant was increased due to the increase in polarizations of the sample, whereas the Be-doped one showed the decrease in dielectric constant cf. the undoped synthetic alpha alumina (reference sample). Experiments on doping alpha alumina with both elements showed increasing in dielectric constant compared to the undoped reference sample, i.e., Cr has more influence to the dielectric constant value. Dielectric constants of a set of natural sapphires were also measured and compared to those obtained from the synthetic ones. The results of both natural and synthetic samples varied in the same direction. It suggests, however, that the geological origins of the samples are needed to be considered. This is due to the differences in physico-chemical conditions of their formations that would have influenced partitioning of trace elements as well as evolving of defects in natural samples. Increasing of the R1 and R2 photoluminescence wavelengths and decreasing of refractive indices of the doped samples cf. those of the reference sample were obtained from the experiments.