Key Engineering Materials Vols. 675-676

Abstract: [(K_0.5Na_0.5 )_0.935Li_0.065]NbO₃–Mn ceramics (Mn = 0, 1.50 and 3 mol %) (KNNL–Mn) were synthesized and measured dielectric properties. Which the K₂CO₃, Na₂CO₃, Li₂CO₃, Nb₂O₅ and MnO₂ (0, 1.5, 3 mol%) were mixed by ball milling method and calcined powders at 1,073 K for 4 h and the sintered at 1,343 K for 2 h in air. The crystal structure was analyzed by XRD technique, the crystallite size was identified by Scherrer’s equation and calculated the theoretical density. It was found that, the XRD patterns of the KNNL–Mn ceramics added with Mn contents was indicated the tetragonal structure and. the crystallite size of Mn = 0, 1.50 and 3 mol% about 32 nm, 34 nm and 57 nm, respectively. The physical properties of the KNNL–Mn ceramics was found that the maximum theoretical density of 90.79 % for Mn = 1.50 mol%. The dielectric constant was found to be maximum of 909.77 and dielectric loss of 0.48 for Mn = 3 mol%.

Abstract: InGaAsN on Ge (001) is proposed to be a part of the InGaP(N)/InGaAs/InGaAsN/Ge four-junction solar cell to increase a conversion efficiency over 40%. In this work, InGaAsN lattice-matched film and GaAs buffer layer grown on Ge (001) substrate by metal organic vapor phase epitaxy (MOVPE) were examined by transmission electron microscopy (TEM). Electron diffraction pattern of InGaAsN taken along the [110]-zone axis illustrates single diffracted spots, which represent a layer with a uniformity of alloy composition. Cross-sectional bright field TEM image showed line contrasts generated at the GaAs/Ge interface and propagated to the InGaAsN layer. Dark field TEM images of the same area showed the presence of boundary-like planar defects lying parallel to the growth direction in the InGaAsN film and GaAs buffer layer but not in the Ge substrate. TEM images with the (002) and (00-2) reflections and the four visible {111} planes reflections illustrated planar defects which are expected to attribute to antiphase boundaries (APBs). Moreover, the results observed from atomic force microscopy (AFM) and field emission electron microscopy (FE-SEM) demonstrated the surface morphology of InGaAsN film with submicron-sized domains, which is a characteristic of the APBs.

Abstract: In this study, leadbased ferroelectric ceramics Pb_0.91La_0.09Zr_0.65Ti_0.35O₃ PLZT (9/65/35) were fabricated by solid solution method. The electrical and mechanical properties were measured by modified Michelson interferometer and Sawyer-Tower circuit to investigate electric field induced strain and polarization (s-P-E) of PLZT (9/65/35) at 30-70 °C. The induced strain and polarization were changed when the temperature was increased indicating the change of spontaneous polarization inside the ferroelectric materials.

Abstract: Porosity plays an important role on a particle deposition process which determines the strength of material. The structure of a material from deposition process can be viewed as a random close packed. References show that random close packing structure of uniform-sized particles gives a porosity of around 36%. In this work we simulate the deposition process using a particle method to study the effect of particle size ratio into a porosity of a material with the ratio of particles’ radius is ranged from 1:1 to 1:5. From the simulation we get an interesting result that shows the porosity is decreased when the size ratio is increased in range from 1:1 to 1:1.5 with its minimum porosity is 31.92% at ratio 1:1.5. Then as the ratio increases from 1:1.5 to 1:5, the porosity is also increasing.

Abstract: In this work, ceramics of Sr(Fe_0.5Nb_0.5O₃) doped with Ba(Zr_0.25Ti_0.75)O₃ (10 mol%), were synthesized by a solid-state reaction technique. The powders were calcined at 1300 °C for 12 hr and then sintered at 1400-1500 °C for 4 hr. Effects of sintering temperature on the properties of the ceramic were studied. Phase formation, microstructure, and dielectric properties were investigated. The ceramics exhibited a perovskite structure with cubic symmetry. Grain size of the ceramics increased with increasing the sintering temperature. The ceramics exhibited a dielectric relaxation like behavior with high dielectric constants over a wide temperature range

Abstract: By scanning and transmission electron diffraction microscopy method the analysis of structure-phase states and defect substructure of silumin subjected to high-intensity electron beam irradiation in various regimes and subsequent fatigue loading up to failure was carried out. It is revealed that the sources of fatigue microcracks are silicon plates of micron and submicron sizes that are not soluble in electron beam processing. The possible reasons of the silumin fatigue life increase under electron-beam treatment are discussed.

Abstract: The acicular iron intermetallic compound, β-Al₅FeSi, is often quoted as disadvantages in aluminum based alloy ingots because of its brittleness. This undeniable phase, however, is found to show less effects on the ingots properties if trace manganese is added. The modified round ended and Chinese script-like structure showed significant higher ductility. The present work reports results of prospective experiments designed for obtaining shape modification of the iron intermetallic compound exclusively from readily available scrap aluminum cans as a source of manganese. A356 aluminum alloy with 1 wt.% iron and 10 wt. % manganese calculated from recycled aluminum can was melted in a laboratory furnace. The molten metal was soaked at 800°C for different aging times ranging from 15, 60 to 120 minutes before undergoing the conventional casting process. The produced ingots were characterized concerning their microstructures, hardness and final composition, which allows estimating the proper aging time for the microstructure improvement. It was observed that the 60 minute-aging time yielded the best modification of 14 micron round ended needle morphology. However, the longer aging time resulted in lower hardness as the result of the obtained Al₁₅(MnFe)₃Si₂ as a majority phase.

Abstract: In present study, the removal of Cu (II) ions from aqueous solution was investigated by both biosorption and investigated by X-ray Diffraction (XRD), Energy Dispersive X-ray Fluorescence (EDXRF) and Fourier transform infrared (FT-IR) spectroscopy. The variable of the batch experiment include solution pH, content time, were conducted to determine the factors affecting capacities sorption of Cu (II). The experimental result explored that that the maximum pH for efficient sorption of Cu (II) was 9. The optimum condition of sorption were found to be contact time of 180 min, and initial Cu concentration 200 mg/L, while the result of XRD reveal that the Paphia undulate shell have aragonite phase and change to mixture phase after sorption which corresponding, with the result of EDXRF which increasing the concentration of Cu

Abstract: The calcium carbonate was extracted from Pomacea Canaliculata Lamarck (Cherry shell) by using the hydrothermal method. Cherry shell was washed and crushed by DI water and mortar. The powder size was analyzed by particle (aperture Size 63 μm), added x HCl (x = 2, 3, 4) and y Na₂CO₃ (y = 1, 1.5, 2) mixed with fine powder from Cherry shell. The mixed power was filtered annealed by autoclave at controlled temperature at 333 K for 20 h. The crystal structure was characterized by X−ray diffraction method. The phase transformation of CaCO₃ was analyzed by Fourier transform infrared spectroscopy (FTIR). The morphology of Cherry shell and CaCO₃ powders were observed by using scanning electron microscope (SEM). It was found that the extracted CaCO₃ shows single phase of CaCO₃ crystal structure. Smallest crystallite size was found about of 0.54 μm.

Abstract: The novel modified electrode of voltammetric technique was applied to detect p-nitrophenol quantity released from the synthetic substrate p-nitrophenyl-β-D-glucopyranoside (pNPG) for β-glucosidase activity measurement. The results from the developed bismuth film modified screen printed carbon electrode (Bi/SPCE) for p-nitrophenol detecting, can be used for enzyme activity assay during purification steps. The further work, the condition of convenient voltammetric method will be optimized the condition suitable for applying to the β-glucosidase enzyme purification from Terminalia ivorensis C. seeds.