Euis Sustini

Molecular Dynamics Simulation of Smaller Granular Particles Deposition on a Larger One Due to Velocity Sequence Dependent Electrical Charge Distribution

Deposition of smaller granular particles on a larger nucleus particle has been simulated in two‐dimension using molecular dynamics method. Variation of sequences of velocity of deposited particles is conducted and reported in this work. The sequences obey a normal distribution function of velocity with the same parameters. It has been observed that for velocity in range of 0 to 0.02 the densest deposited site (15–17 % number of grains) is located at about angle π/4 where location of injection point is π/4. And the less dense is about π/4 + π/4. Different sequences give similar result.

A Theoretical Study on the Performance of SnO2/SiO2/n-Si Solar Cells

The performance of SnO2/SiO2/n-Si solar cells was studied by considering various transport mechanisms including minority-carrier diffusion, carrier recombination, and tunneling through insulating layer. The tunneling current through the SiO2 layer was obtained by employing the Airy-wavefunction approach. The efficiency was calculated to determine the performance of the cells under AM1 illumination for different values of insulating layer thickness, interface state density, hole life-time, doping density of silicon substrate, and cell thickness. It was shown that the efficiency increases as the insulating layer becomes thinner due to the decrease of short-circuit current. It was also shown that the efficiency increases as the doping density increases up to 6x1022/m3 and it then decreases for higher doping densities. As the interface state density decreases, the efficiency becomes higher. In addition, the increases in the hole lifetime and cell thickness enhance the efficiency of the solar cell.

Resistors Network Model of Bcc Cell for Investigating Thermal Conductivity of Nanofluids

A model was developed to investigate thermal conductivity of nanofluids. It was based on resistors circuit network in bcc cell as alternative form of simple cubic cell has been successfully developed. The present model has involved the Brownian motion of nanoparticles in the fluid with an assumption that the nanoparticles are in low volume fraction so the diameter size of nanoparticle can be neglected in comparison to particles distance. Generally, this model was very fit to experimental results has been obtained from some authors. As an example, for alumina‐water nanofluid, that is alumina (Al2O3) dispersed in water, it was found that the enhancement of its thermal conductivity calculated using this model was in good agreement with experimental results that it tended to increase as nanoparticle fraction increases. As in alumina‐water, the agreement was also shown in titania (TiO2)‐water and cuprum oxide (CuO)‐water. This model also showed the dependence of thermal conductivity enhancement to diameter siz...

Introducing Organization Parameter for Self‐Organized Nanoparticles

We introduced a parameter to distinguish how well (the quality) of organization of nanoparticles in self‐organized samples. This parameter measures how far the deviation of real particle positions in the sample with respect to positions of particles forming a perfect lattice of the corresponding packing structure. The perfect lattice was developed by taking the lattice site as the average distance between contacting particles in the sample.

Simple Method for Synthesizing Pt Nano-Droplets as Metal Catalyst in SiNW Deposition

Silicon nanowire (SiNW) deposition can be performed by introducing Si precursor onto metal catalyzed substrate as a lead on vapor‐liquid‐solid (VLS) mechanism. Nanosize metallic droplet as catalyst can be synthesized by annealing a very thin metallic film in order to break it into droplet. The simple method had been used for synthesizing Platinum (Pt) nano‐droplet. A very thin Pt film had been grown on a wafer silicon substrate using fine coat ion sputtering followed by annealing in which the temperature varied in the interval of 700–800° C, each for 30 minutes. The surface morphology of the film was done by scanning electron microscope (SEM) which showed that Pt nano‐droplet in the best formation obtained at the annealing temperature of 800° C. In addition, dependences of the film thickness and annealing time to produce Pt nano‐droplet formation, especially the nano‐droplet size, had been investigated.

The effects of insulator thickness and substrate doping density on the performance of ZnO/SiO2/n-Si solar cells

ABSTRACT The insulator layer and the substrate material play an important role in determining the performance of metal-insulator-semiconductor type solar cells. Here, the effects of insulator layer thickness and substrate doping density on the efficiency of a ZnO/SiO2/n-Si solar cell were studied. Semi-analytical calculations wer performed to obtain the current–voltage dark current, efficiency, and current–voltage characteristics of the cell. An efficiency of 20% was obtained with an insulating layer thickness of around 19 Å. It was also found that the efficiency started to decrease when an insulator layer thicknesses greater than the optimum thickness was used. Furthermore, the efficiency of the cells decreased with increasing substrate doping density, and the maximum efficiency was obtained with a substrate doping density of 6 × 1022 m−3. By optimizing the insulating layer thickness and substrate doping density an efficiency of 20% was achieved at a cell thickness of 25 μm.

Titania Coated Ceramic Membrane from Clay and Muntilan Sand for Wastewater Filter Application

A ceramic membrane was fabricated from clay and Muntilan sand using sol-gel method with certain amount of titania coated on the membrane surface. Polyethylene glycol (PEG) was used as a pore-agent. The main steps of the process are hot-pressing and calcination. Varying the clay:sand:PEG ratio membranes permeability was obtained between 6.39 x 10-13 m2/Pa.s and 1.39 x 10-11 m2/Pa.s. The addition of sand volume fraction improves the permeability produced as result of the larger of the sand particle producing the higher pores. The filtration performance was tested using aqueous solutions of methylene blue (MB) as one of the main pollutants produced from textile industries. Under a pressure difference of 4 kPa, the concentrations of MB remaining in the solution varied from 1.73% to 10.29% depending on the permeability. Therefore, the membrane is very potential to be applied as wastewater filter for coping with the availibity of clean water.

NONLINEAR OSCILLATION MODEL FOR EXPLAINING THE DISTRIBUTION OF POSITION DEVIATION IN SELF-ORGANIZED NANOPARTICLES

A model for explaining deviations of positions in self-organized nanoparticles on a substrate from their corresponding positions in perfect organization is proposed. The model predictions were compared with SEM/TEM images and reported by some authors. We found a consistence between the model predictions with the data of Ag, Fe3O4 and SiO2 nanoparticles organization on various substrates.

Optimization of Coating Temperature of TiO2 Nanoparticles on the Polypropylene Copolymer Surface for Photodegradation of Methylene Blue

TiO2 nanoparticles have been coated on the polypropylene (PP) copolymers using a milling method with temperature controller modification. These experiments were carried out at different milling temperature: 100 °C, 110 °C, 120 °C and 130 °C for 90 minute milling time for each experiment. Photocatalytic degradation of methylene blue (MB) was investigated using TiO2 coated PP copolymer which floats on the MB solution and illuminated under sunlight for 36 hours. It was found that TiO2 coated PP polymer at temperature of 100 °C resulted in optimum decomposition of MB solution. The concentration of MB in a test solution after 18 hours of exposure to the sun was 15.42%. The reaction rate constants (k) and the half‐reaction (t1/2) in the MB photodegradation using the catalysts with a coating temperature of 100 °C, are 0.106 hours−1 and 6.53 hours, respectively. This coated material is very potential for repeated use to purify bulk water in high sunlight intensity region.

Effect of Silica Nanoparticles on Compressive Strength of Leaves-Waste Composite

The utilization of solid‐waste, especially leaves‐waste is one of interesting research of environmental field. One of them is making a composite using polyvinyl acetate (PVAc) polymer as binder (matrix) and silica nanoparticles as reinforcement (filler) to improve the strength of composite‐produced. Those raw materials preliminary were mixed by simple mixing with varied compositions and then hot‐pressed at 36 MPa and 100 °C for 20 minutes. From compressive strength test, it was found that composite with composition 7:8 of PVAc and leaves‐waste had maximum compressive strength, i.e. 57.60 MPa. It was also that the enhancement of strength due to PVAc fraction (w/w) increasing is a percolation behavior, even though its mathematical explanation has not been performed. Into composition of maximum strength above, silica with average size is 74 nm then was added to improve the strength and found that at silica weight fraction of 0.79 (%w/w), the composite had optimum compressive strength, i.e. 70.5 MPa, or incre...