فهرست مطالب

Nanoscience and Nanotechnology - Volume:13 Issue: 1, Winter 2017

International Journal Of Nanoscience and Nanotechnology
Volume:13 Issue: 1, Winter 2017

  • تاریخ انتشار: 1395/12/28
  • تعداد عناوین: 8
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  • Z. S. Arabshahi, M. Akbarzadeh Pasha *, F. Shahi Pages 1-9
    In this research carbon nanotubes were produced by chemical vapor deposition of acetylene over a mixture of iron and cobalt catalysts supported on nanometric TiO2 and the influences of two synthesis parameters: growth temperature and catalyst composition ratio on properties of end-product carbon nanotubes were investigated. The catalytic basis was prepared by wet impregnation method with different wt% mass ratio of Fe-Co/TiO2=20-0/80, 15-5/80, 10-10/80, 5-15/80 and 0-20/80 wt%. The nanomaterials (catalysts and carbon nanotubes) were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray map of elemental distribution (Xmap) and Raman spectroscopy. The results confirmed that by increasing the growth temperature from 650°C to 800°C; the growth rate, the average diameter and the amount of impurities of grown carbon nanotubes increase and their length and density decrease. Furthermore, it was observed that in comparison with monometallic Fe or Co, bimetallic compositions of these metals exhibit better catalytic activity in growth of carbon nanotubes. The highest yield of carbon nanotubes possessing minimum average diameter was obtained on Fe-Co/TiO2 catalyst with a mass ratio of 10-10/80 wt%.
    Keywords: Carbon Nanotubes, Wet Impregnation, Chemical Vapor Deposition, TiO2 Nanopowder, Bimetallic Catalyst Composition
  • A. Ghozatloo *, M. Shariaty Niassar, A. Rashidi Pages 11-18
    In this research, Graphene was synthesized by chemical vapor deposition (CVD) method in atmosphere pressure (14.7 psi). Different functionalization method was used for oxidizing of graphene such as acid and alkaline treatments. The Functionalized graphene (FG) was characterized by FTIR and Raman spectroscopy. Nanofluid with water and different concentration (0.05, 0.15 and 0.25 wt %) of FG were prepared. Thermal conductivity of nanofluids was measured by transient hot wire method. The acid functionalization introduces significant defects in graphene structure, degrading its unique properties such as superior carrier mobility, mechanical strength and chemical stability. In alkali functionalization method, the graphene is not effectively defected. Therefore, the transport properties of graphene maintained and this method showed enhancement in thermal conductivity more than acid fictionalization in same conditions. In optimum condition (0.25 wt % graphene of alkaline method in water), thermal conductivity ratio were increased (24.4% at 20°C and 33.9% at 60°C).
    Keywords: Graphene, Functionalization, Nanofluid Thermal conductivity, Alkaline, Acid
  • T. Iqbal *, S. Tufail, S. Ghazal Pages 19-52
    Nano technology has a large number of applications in different fields of science and technology. Nano particle are the tiny particles which are being used in upcoming technology due to their small size and high capability. The properties of nanoparticles depend largely on their synthesis procedures. There are different methods for the synthesis of nano particles using different conditions. In this review synthesis of five nano particles namely chromium, manganese, silver, iron and tin has been discussed. Possible methods of their preparation, conditions and properties are the main concern of this review. The results from various investigations performed by different scientists using some methods have been summarized. The applications, conveniences and difficulties of each synthesis method are also discussed in-detail. Applications of nano particles and metal oxide are also elaborated.
    Keywords: Nano Particles, Synthesis Procedures, Chromium, Manganese, Silver, Iron, Tin
  • A. Rezaei * Pages 53-58
    Complementary metal-oxide semiconductor (CMOS) technology has been the industry standard to implement Very Large Scale Integrated (VLSI) devices for the last two decades. Due to the consequences of miniaturization of such devices (i.e. increasing switching speeds, increasing complexity and decreasing power consumption), it is essential to replace them with a new technology. Quantum-dot cellular automata (QCA) is one of the alternative technologies proposed as a replacement solution to the fundamental limits of CMOS technology. QCA has the potential to be one of the features promising nanotechnologies because of its higher speed, smaller size and lower power consumption in comparison with transistor-based technology. This work proposes optimized QCA RS (Reset Set) flip flops. The proposed structures are simulated and validated using QCADesigner software. In comparison with the previous works the proposed QCA RS flip flops require the minimum number of cells, area and delay. Also, in comparison with CMOS technology our QCA designs are more efficient in terms of area, delay and frequency. Therefore, these structures can be used to design nanoscale circuits.
    Keywords: Quantum-dot Cellular Automata, Majority Gate, QCADesigner, RS Flip Flop
  • S. Sam Daliri *, J. Javidan, A. Bozorgmehr Pages 59-67
    Multiplier is one of the important components in many systems such as digital filters, digital processors and data encryption. Improving the speed and area of multipliers have impact on the performance of larger arithmetic circuits that are part of them. Wallace algorithm is one of the most famous architectures that uses a tree of half adders and full adders to increase the speed and reduce the area of multipliers. Compressors are adders which can be used to perform the partial product addition in Wallace tree. On the other hand, using new emerging technologies such as Carbon Nanotube Field Effect Transistors (CNTFET) leads to provide implementations faster and smaller circuits. This paper presents a new method to reduce the simplification of Wallace tree design using high order compressors based on carbon nanotube technology. These compressors use a high-speed full adder cell based on CNTFETs for low-voltage and high-frequency applications. The proposed method reduces the number of gates and transistors, critical path length and complexity of the Wallace tree hardware.
    Keywords: Carbon Nanotube Field Effect Transistor, Compressor, Full adder, Multiplier, Wallace Tree
  • Md Abdus Subhan * Pages 69-82
    The mixed metal nanocomposite MgO∙Al2O3∙ZnO has been prepared by coprecipitation method. The product was characterized by XRD. The average particle size was found to be 34.89 nm from XRD data. SEM and SEM-EDS were studied for evaluating surface morphology and elemental composition. The FTIR spectrum of prepared mixed metal nanocomposites MgO∙Al2O3∙ZnO and MgO∙Al2O3∙ZnO-curcumin were studied. The optical properties of the nanocomposites were studied by PL (Photoluminescence). The quantum efficiency (Φ) of MgO∙Al2O3∙ZnO and MgO∙Al2O3∙ZnO-curcumin was found to be 0.86 and 0.31, respectively in acetone. The photocatalytic activity of the nano composite, MgO∙Al2O3∙ZnO was investigated over methyl violet 6b (MV) dye under UV-Visible light irradiation. The photocatalytic activity was assessed with various parameters including variation of pH, effect of H2O2 and reusability. The dye degradation efficiency of nanocomposite was observed to be 48.7% and 93.42% for catalyst and catalyst with H2O2 at pH 9. The efficiency was 86.96% for catalyst with H2O2 at pH 7.
    Keywords: Nanostructures, Catalytic Properties, Luminescence, Optical Materials, Semiconductors
  • A. Moezzi *, S. Soltanali, A. Torabian, A. Hassani Pages 83-90
    Due to its ability in chemical oxidation of contaminants, iron nanoparticle is a material of choice to remove lead ions from aquatic solutions. In this study a reduction method in solution phase was applied to synthesize thenanoparticles. Afterwards, the size of the synthesized particles were confirmed by Scanning Electron Microscopy. It is worth noting that the nanoparticle dose-variations were examined in the range of 0.02-0.5mg while pH and exposure time were respectively investigated in the ranges of 3-11 and 1-40 min. Meanwhile, the removal efficiency of various concentrations of lead ions were evaluated in the range of 1-50 mg/l. The results indicated that the best removal efficiency (92.5%) occurred in the concentration range of 1 to 40 mg/l for a dose of 0.1 mg nanoparticles. By increasing concentration of lead ions to 50 mg/l, the optimum dose was achieved in 0.2 mg. Improved removal was observed with increasing exposure time up to 10 minutes while no improvement was recorded for exposure times of 20 minutes or longer. The results confirmed the effectiveness of synthesized iron nanoparticles in removing lead ions from aquatic solution.
    Keywords: Iron Nanoparticle, lead, Chemical Oxidation, heavy metal, Aquatic Environment
  • M. Salehian, A. Mohammadian, M. Vaezzadeh, M. Saeidi * Pages 91-95
    In This paper, the effect of size on melting temperature of metallic nanoparticles (Au, Pb and Bi) is theoretically simulated and explained. In this regard, the cause of difference in various experimental data is introduced, which is the difference between nanoparticles’ grain Gaussian distribution. This volume-depended model with the help of the Gaussian distribution can describe the relation between nanoparticle melting temperature and its size. The obtained results are interestingly consistent with reported experimental data.
    Keywords: Melting Temperature, Nanoparticles, Distribution Function