Papers by Keyword: Morphology

Abstract: The aging of the precipitate product is a crucial stage in forming particles using the precipitation method. In this study, the aging time in atmospheric ambient was investigated for its impact on the formation and properties of zinc oxide particles. The zinc oxide particles were synthesized using an ultrasound-assisted precipitation method. The diffraction pattern confirmed the crystallinity and crystallite size of zinc oxide decreases with increasing aging time. The UV-Vis absorption spectrum analysis revealed that 24 hours of aging resulting zinc oxide with a bandgap close to that bulk zinc oxide band gap energy. The scanning electron microscope image showed an alteration of zinc oxide morphology from rod to flake-like particle as the aging time. The crystallinity, morphology, and optical properties of zinc oxide particles are significantly affected by aging time. The results suggested that aging time in the ultrasound-assisted precipitation method can be used to engineer the suitable properties of zinc oxide particles for its application.

Abstract: This research developed the modified-recycled poly (ethylene terephthalate) (modified-rPET) filament by decreasing the crosslinked-gel content inside the filament, by adding various contents of hydrophobic nanosilica (h-NS). This research also studies the viscosity, morphology, h-NS dispersion, and mechanical properties of the modified-rPET/h-NS, by using a rotational rheometer, a scanning electron microscope, a micro-XRF spectrometer, and a universal testing machine, respectively. rPET flakes were dried to deplete the moisture. Then, they were mixed with additives and h-NS at 0, 1, 2, 3, 4, and 5 pph, and were extruded to be compound using twin screw extruder. The modified-rPET/h-NS extrudates were investigated into two parts. Firstly, was observed on the process-ability, morphology, and gel content along the filament. Consequently, the viscosity, mechanical properties, and h-NS dispersion were investigated. The results showed that the best formulation that is easy to process and has the lowest gel content along the filament, was NS1. Other results, shear-thinning rheology behaviors were observed for all formulations. The mechanical properties, including ultimate tensile strength and elongation at break decreased, as the h-NS content increased. At higher content of h-NS (NS4 and NS5), the gel content increased significantly, therefore the h-NS agglomeration occurred, which was different from crosslinked gels.

Abstract: Free standing wafers of the cubic polytype of silicon carbide (3C-SiC) grown on micromachined silicon substrates can be a platform for new power electronic devices, provided that suitable device fabrication processes are understood and optimized. In this frame, p-type doping is still an open issue, as results on the electrical activation of ion implanted Al in 3C-SiC are limited. This work analyses high level p-type doping with post-implantation annealing carried out at temperatures in the range 1650-1850 °C with different durations. A coherent picture emerges, showing that the resulting resistivity in 3C-SiC Al-implanted layers is higher than the one obtained in 4H-SiC implanted layers, the result being ascribed to low carrier mobility and possibly presence of compensation centers, rather than to poor Al electrical activation. The reported results highlight the importance of working on material and processing optimization.

Abstract: The microstructure of carbon fibers with different properties also varies. Even with considerable mechanical properties, the microstructure characteristics of carbon fibers produced by different manufacturers or processes are different. Although current characterization testing methods can provide a fundamental analysis of the relationship between the microstructure and mechanical properties of carbon fibers, there is still no systematic theory on how to control the evolution of their microstructure during the production process of carbon fibers and develop high-performance and high-quality fibers. There is still a certain gap in the performance of carbon fibers in China compared to foreign countries. Therefore, this article analyzes and summarizes various publicly published models of carbon fiber microstructure in recent years, providing reference for establishing a recognized analysis model that can predict the mechanical properties of carbon fibers in engineering, providing effective direction for improving carbon fiber manufacturing processes, and providing technical support for developing high-performance and high-quality carbon fibers.

Abstract: Cd_1-0.06Mn_0.06Te epitaxial thin films were synthesis on glass substrates by the Molecular Beam Condensation (MBC) method in the vacuum evaporation equipment УВН-71-ПЗ with steam-oil pumping and nitrogen trap at working pressure of residual gas (1÷2)x10^-4 Pa. By using additional source of Te vapor and controlling temperature, it has been determined the optimum conditions for obtaining Cd_1-0.06Mn_0.06Te epitaxial films with a perfect structure, clean and smooth surface, without of second phase inclusions. XRD investigations showed that Cd_1-0.06Mn_0.06Te epitaxial films grow on glass substrates on the (111) plane of the face-centered cubic lattice with the lattice parameter of a = 6.481 Å. Effect of γ-irradiation on XRD spectra of Cd_1-0.06Mn_0.06Te epitaxial films reveals that, XRD patterns of initial and γ-irradiated samples did not show any phase transformations, however there is a variation in relative intensities of diffraction peaks. It has been found that Cd_1-0.06Mn_0.06Te epitaxial films with a film thickness of d=15 µm, absorb light up to a wavelength of λ=765 nm and at λ>765 nm the absorption begins to gradually decrease and then the material becomes transparent. The obtained results indicate that Cd_1-0.06Mn_0.06Te epitaxial films absorb light quanta in the visible and infrared spectral regions. Iirradiation of Cd_1-0.06Mn_0.06Te epitaxial films with γ rays at low irradiation doses leads to a change in the optical parameters, the profile of the spectrum curves and the intrinsic absorption edge. In additions to experimental studies, a theoretical ab initio calculations of band structure (BS) of ideal and defective semiconductors of Cd_1-0.06Mn_0.06Te has been also carried out by using Density Functional Theory (DFT) method via Atomistix ToolKit computer program. The band gap energy has been calculated as E_g = 1.6 eV for ferromagnetic (FM) and E_g = 1.7 eV for antiferromagnetic (AFM) state of Cd_1-0.06Mn_0.06Te compound. The results of theoretical calculations on the band gap energy of ideal and defective Cd_1-0.06Mn_0.06Te semiconductors are in a good agreement with experimental findings.

Abstract: In this work, composition ratios of high-density polyethylene and polyolefin elastomer (HDPE/POE) for 60:40 and 40:60 were prepared with 10%, 20%, 30%, and 40% of corn husk fibre (CHF) by using an internal mixer. The effects of CHF content on mechanical properties, water absorption and morphology on the biocomposites were investigated. The tensile strength for the biocomposites 60:40 ratio displayed optimum at 20% of fibre content; while the biocomposites 40:60 ratio has decreasing tensile strength from 10% to 30% of fibre content. The more fibre is needed to hold the matrix in place for biocomposites with POE dominance. At all compositions, the tensile modulus for the biocomposites 60:40 and 40:60 HDPE/POE ratios exhibited increasing patterns. However, the results of impact strength and elongation at break for the 60:40 and 40:60 ratios showed declining trends. The results demonstrate the addition of CHF increases the stiffness of the HDPE/POE matrix while decreasing the composites' flexibility. The water absorption biocomposites 60:40 ratio was higher than 40:60 ratio at all compositions due to a better surface interaction in composition HDPE/POE with 40:60 compared to 60:40 ratio, and also revealed by morphological studies on fracture surface biocomposites by using field emission scanning electron microscopy (FESEM).

Abstract: In the present work, NaBi(MoO₄)₂ (NBM) phosphor has been successfully synthesized by doping 1.0 mol% of Eu³⁺ via the conventional solid state reaction technique. The undoped synthesized NBM sample and 1.0 mol% Eu³⁺ doped phosphor were characterized to explore crystal structure, morphology, photoluminescence (PL) and colorimetric properties using various characterization techniques. The structural properties were analysed via x-ray diffraction and diffraction peaks were compared with the standard JCPDS (card no. 79-2240) pattern. The morphological studies of the sample have been done through FE-SEM micrograph. From the photoluminescence emission spectra, it has been observed that an intense peak was obtained in the at 615 nm under blue excitation. Colorimetric property of 1.0 mol% of Eu³⁺ doped NBM phosphor has been investigated and traced in the red region with high color purity of 92.79%. The aforementioned characteristics demonstrate that the NaBi(MoO₄)₂: 1.0Eu³⁺ phosphor has great potential in the field of w-LED applications.

Abstract: One of Indonesia's most significant issues with technological growth is the lack of electrical energy storage devices. Active materials have low electrical conductivity, accessibility, and ion diffusion. Therefore, it is urgently required to study the combination of higher electrical conductivity ZnO and high surface area of AC-Mn2O3. However, ZnO nanorods (ZnONR) can be modified from ZnO nanoparticles (ZnONP). The structure modification may increase energy density due to having a higher surface area than ZnONP. Three different electrodes with AC-Mn₂O₃ addition various spin coated of 1000 rpm (MZnONR1), 2500 rpm (MZnONR2), and 3000 rpm (MZnONR3). The electrodes were then packaged in a sandwich flat symmetric supercapacitor. The characterization was carried out using X-RD, SEM-EDX cross-section, FTIR, and Cyclic Voltammetric. It is obtained that the highest specific capacitance showed by symmetric supercapacitor MZnONR1 with low speed of spin coating. We also found that the greater the deposited ZnNR content, the lowest thickness until 43.76 μm, the crystallinity until 62% and the highest porosity until 79%. This shows that the MZnONR1 sample exhibits the best electrochemical performance, which is supported by its morphological properties. It is shown that the higher the Zn content, the stability performance AC-Mn₂O₃ supercapacitor higher. ZnONR1 sandwich flat symmetric supercapacitor have a specific capacitance 0.0086 Fg^-1 with an 0.00433 Whg^-1 energy density. Furthermore, it was found that the addition of the AC-Mn₂O₃ increased 2800x compared to the ZnONR1, which reached 28.04 Fg^-1 and an 14.09 Whg^-1 of capacitance specific and energy density, respectively.

Abstract: The effects of clay surface modified with 25-30 wt% of methyl dihydroxyethyl hydrogenated tallow ammonium (Clay-DHA) on morphology, mechanical and thermal properties of poly(lactic acid) (PLA)/propylene-ethylene copolymer (PEC)/Clay-DHA composites were investigated. The phase morphology of PLA/PEC blends showed phase separation due to weak interaction between PLA and PEC phase, and the droplet size of PEC phase increased with increasing PEC content. The addition of Clay-DHA significantly improved the compatibility between PLA and PEC phases due to PEC droplet size decreased dominantly in PLA matrix, so Clay-DHA could act as an effective compatibilizer. The tensile properties found that Young’s modulus of PLA/PEC blends decreased with increasing amount PEC while the strain at break increased. The incorporation of Clay-DHA improved Young’s modulus of the blends in a range of 10-20 wt% of PEC. The thermal properties showed that the addition of PEC and Clay-DHA had no effect on the melting temperature of PLA. The degradation temperature of PLA/PEC blends was higher than that of the PLA, so PEC could improve the thermal stability of the blends.

Abstract: Main initiative of this study is to report the changes occurred in the particle size and distribution of nano-hydroxyapatite powders due to the novel effect of Plant Leaf Mediated Natural Extracts (PLMNEs). Wet-Chemical precipitation method is used to obtain homogeneous nano-hydroxyapatite powders. These nano-hydroxyapatite powders have been synthesized by using different precursors and relative concentrations. The natural extracts used as Natural Stabilizers (NSs) are derived from Soya Leaves (SL) and Spinach Leaves (SpL) for the preparation of nano-hydroxyapatite. Present study reports the morphological changes in nano-hydroxyapatite and has been characterized using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Small Angle X-Ray Scattering (SAXS). Till now no studies have been reported on synthesis of nano-hydroxyapatite using Plant Leaf Mediated Natural Extracts as precursors. The Natural Stabilizers used have been found to show evidence of several medicinal effects.