Advanced Materials Research Vol. 620

Abstract: Bismuth titanate was systematically prepared by a single step combustion synthesis. Based on TG-DTA, the corresponding phase was completely obtained below 300°C, resulting in highly exothermic peak at 236°C. The formation of a single crystalline structure of Bi-layered with different degree of crystallinity was strongly affected by hydrolysis temperature. Goodness-of-fit indicator, S for entire samples was in the range of 1.55 1.94, which is acceptable for Rietveld refinement analysis. All Raman peaks became more intense and sharp with higher hydrolysis temperature, suggesting that the strong interactions between Ti-O bonding in BIT structure. The presence of peaks at 838 and 628 cm^-1 in the IR spectrum can be ascribed to the stretching vibrations of Bi-O and Ti-O, respectively. Besides, the obtained powders are very fine with minimal grain growth, resulting in agglomerated powders.

Abstract: This manuscript is explained and discussed the properties of ceramic thick films, [Ba_0.3Sr_0.7ZrO_3, BSZ (0.7)] synthesized through sol-gel route. The gel decomposition was studied by thermogravinometry analysis (TGA). From thermal analysis, it had shown that BSZ (0.7) phase started formed at 800 °C and above. The crystal structure of this composite film studied exhibited highly polycrystalline materials by X-ray diffraction analysis. From high magnification observation of field emission scanning electron microscopy (FESEM), grain boundaries of BSZ (0.7) films are clearly defined meanwhile grains displayed are in flaky shape. The average diameters of the grains measured were 94.6 nm. However, grains boundaries of BSZ (0.0) films, are unclear and grains slightly look dendritic structure. Electrical characterizations of the films are carried out with impedance analyzer at 4 - 12 GHz respectively. Both of electrical permittivity and loss tangent observed are dependable with microstructural and structural of the films.

Abstract: In this work, we present the results of sulfur crosslinking and degradation in natural rubber (NR) studied by X-ray absorption near-edge structure spectroscopy (XANES). Sulfur K-edge XANES spectra has been collected and analyzed to provide the geometry and electronic environment of sulfur crosslinks during vulcanization and degradation processes by ozone aging. We found that reversion took place before the onset of oxidative process at the sulfur bridge. Parallel to the oxidative process, the production of cyclic sulfanes took places. This physico-chemical properties which were calculated from S K-edge XANES spectra were correlated with the mechanical of NR films by varying accelerator type. The accelerator zinc diethyldithiocarbamate (ZDEC) gave highest film strength when compared with other accelerators: N-cyclohexylbenzothiazole sulfenamide (CBS), 2,2' dibenzothiazyl disulfide (MBTS), and tetramethylthiuram disulfide (TMTD).

Abstract: The synthesis of alkylpolyglucosides involves condensation of decanol with dextrose in the presence of mesoporous silica sol-gel as a catalyst. In this study, mesoporous silica was produced using sol-gel technique by converting tetraethyl orthosilicate (TEOS) into silica. The mesoporous silica was characterized using BET surface area measurement and X-ray Photoelectron Spectroscopy surface analysis. The specific BET surface area was 794m²/g. From the XPS analysis, the Si2p binding energy is 103.7 eV while the O1s binding energy is 532.8eV indicating the formation of Si-O-Si bond which attributed to SiO₂. Mesoporous silica has been found efficient to be solid catalyst for synthesis alkylpolyglucosides and easy to be separated. The reaction was carried out 8 hours at 110°C-120°C under vacuum condition. The mass determination of alkylpoluglucosides has been achieved by ESI LC-MS/MS (ToF) positive-mode giving a mass peak at m/z = 343.21 corresponding to [M+⁺ of alkylmonoglucoside peak at retention time 11.0 min.

Abstract: Apossible evidence of Mg related emission in Mg doped GaN material is observed inoptical measurement, even without thermal annealing. Meanwhile, the electrical properties of the sample improve when Ni/Au contact layer was annealed up to 400°C, but degrade at further temperature. We propose that such behavior isrelated to degradation of surface morphology of metal contact at higher temperature.

Abstract: Mukah clay deposits are characterized and evaluated for their potential as industrial raw materials through chemical, mineralogical and fired body (900 to 1250^o C) physical properties determinations. Results show that the main oxides in the samples are SiO₂ and Al₂O₃, whereas the other oxides present only in small quantity. Kaolinite and quartz present as dominant mineral phases and the minor phases of muscovite, nacrite, illite also appeared in the samples. From the results of the fired properties, the significant development of densification of ceramic behaviour can be noticed at the firing temperature above 1000°C. Mukah clay demonstrated that it is most suitable to be used as raw materials for making pottery, general refractory, structural ceramics, wall and floor tiles.

Abstract: In this study, we report the fabrication of nanoporous aluminum oxide film from high purity aluminium foil via a two-step anodisation process controlled by a constant direct current potential ranging from 40 60 V from a DC power supply. The anodisation process was conducted at 20^˚C in an electrochemical cell with the Al foil acting as anode, Pt as cathode and an acidic bath as electrolyte. Porous aluminium oxide films of pore diameters ranging between 30 90 nm were successfully fabricated. The morphologies and phase compositions of the anodized porous alumina films were investigated using scanning electron microscopy (SEM) and x-ray diffraction (XRD) for characterizations.

Abstract: Dredging along Kuala Perlis Jetty results in huge amount of marine sediments which has thrown considerable challenge for disposal. This research was conducted to characterize dredged marine sediment which was collected at Kuala Perlis Jetty as potential raw material for brick production. Three different characterizations were performed namely XRF, XRD and FTIR. XRF analysis showed the presence of SiO₂ and Al₂O₃ as major quantities. Low concentration of heavy metals namely As, Cr, Cu, Pb, Ni and Zn presence in the sediment comply the US EPA guideline for brick production. XRD analysis indicated the presence of quartz as primary mineral while kaolinite and illite also present as secondary and ternary phases. FTIR analysis identified various form of minerals presence in the samples which strongly supported XRD results.

Abstract: Aluminium (Al) thin films on polyimide (PI) plastic substrates prepared via thermal evaporation technique and annealed in nitrogen (N₂) ambient at different temperatures (250 - 400°C, for 30 minutes) have been investigated. Structural properties of the as-evaporated film have been studied by high resolution X-ray diffraction (HR-XRD). The result illustrates crystalline nature of the Al thin film with a dominant Al (111) peak at 2θ = 38.4°. Atomic force microscope (AFM) shows increased surface roughness root mean square (RMS) with increased annealing temperature (with roughness of 11.96 nm at 400°C). Sheet resistance drops with increased temperature and records the lowest reading (64 mΩ/) at 400°C. Besides, increased annealing temperature also results in reduced surface reflectance (with minimum reflectance of 73% reflectance in the visible region at 400°C). The effects of the resulting Al back contact properties towards thin film silicon (Si) solar cells on PI substrates were subsequently discussed.

Abstract: EDXRF analysis provides several important advantages such as simultaneous determination of the elements present, analyses of wide concentration ranges, and fast analysis with no sample preparation. The paper relates a comparative quantitative analysis using regression and modified Fundamental Parameter Technique FPT methods in the determination of minor elements present in low alloy steel. Regression was developed by plotting calibration graphs using low alloy reference standards while the modified FPT method involves incorporation of pure metal spectrum to the existing equation to improve on the accuracy of the analysis. Discrepancy tests carried out for the two methods showed that the error ranges were 0.3-6.5% and 1.2-7.9% for regression and modified FPT analyses, respectively. This makes the FPT method more acceptable for quantitative analysis of elements present in low alloy steel.