فهرست مطالب

  • Volume:15 Issue:1, 2019
  • تاریخ انتشار: 1398/01/19
  • تعداد عناوین: 8
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  • M. Akbari, M. Shariaty, Niassar , T. Matsuura, A. Fauzi Ismail Pages 1-10
    In this study, effect of asymmetric functionalized graphene oxide (Janus GO) on Young′s modulus and glass transition temperature of Polysulfone (PSf) ultrafiltration membranes was investigated. The membranes were prepared via phase inversion method and GO nanosheets were dispersed in casting solution by sonication. Results showed that the Normalized Young’s modulus (on the basis of neat PSf membrane Young’s modulus) increased from 1 to 1.35 for neat PSf membrane compared to the membrane with 1% Janus GO nanosheets. This enhancement indicated the improvement of mechanical properties of modified membranes. Also, application of Janus GO nanosheets caused enhancement of thermal stability of modified membranes by increasing glass transition temperature to 182.97 °C compared to 180.1 °C for neat PSf membrane. These improvements were ascribed to the enhancement of dispersion and stability of Janus GO nanosheets in membranes matrix.
    Keywords: Janus graphene oxide, Ultrafiltration membrane, Young’s modulus, Glass transition temperature
  • A. Ameri, R. Ansari, Sh. Ajori Pages 11-19
    This paper explores the mechanical properties and fracture analysis of C2N-h2D single-layer sheets using classical molecular dynamics (MD) simulations. Simulations are carried out based on the Tersoff potential energy function within Nose-Hoover thermostat algorithm at the constant room temperature in a canonical ensemble. The influences of boron (B) doping on the mechanical properties, i.e. Young’s and bulk moduli and ultimate strength and strain of C2N-h2D single-layer sheets are studied and the effects of size and doping percentage on the aforementioned properties are explored. The results demonstrate lower strength and stiffness of C2N-h2D single-layer sheets compared to graphene. It is also demonstrated that unlike the strength of C2N-h2D single-layer sheet, the stiffness of C2N-h2D single-layer sheet is larger than that of silicene nanosheet. In addition, it is observed that doping of B atoms on C2N-h2D single-layer sheets intensely reduces the mechanical properties, whereas this reduction increases by rising the percentage of B-doping. Furthermore, the fracture process of C2N-h2D and B-doped C2N-h2D single-layer sheets is illustrated.
    Keywords: C2N-h2D, Doping, Molecular dynamics simulations, Mechanical properties, Fracture
  • F. Ghasemzadeh, F. Kanjouri Pages 21-26
    We have investigated the electronic and optical properties of AlN hexagonal nanosheets under different kinds of strains, using the band structure results obtained through the full potential linearized augmented plane wave method within the density functional theory. The results show that 10% uniaxial strain along the zig-zag direction induces an indirect to direct band-gap transition. The dielectric tensor and corresponding optical properties are derived within the random phase approximation. Specifically, the dielectric function, reflectivity and refractive index of AlN nanosheets are calculated for both parallel ( ) and perpendicular ( ) electric field polarizations.
    Keywords: 2D Nanosheet, Electronic properties, Optical properties, Strain
  • Negin Piri Pages 27-36
    The area of nano-pigments is a limitless field with exceptional potential applications in industry, and their application is becoming the focus of many research groups worldwide in recent years due to their outstanding and tunable properties. Titanium dioxide (TiO2) nanoparticles, on the other hand, are among the most widely used pigment particles, and the interest for utilization of these nanoparticles as spectrally selective pigment is continually growing. Accordingly, this contribution utilizes Mie scattering theory and Multi Flux model to study the effect of particle size and concentration on radiative properties and optical performance of TiO2 pigmented coatings in solar spectrum with special emphasis on UV and NIR regions. Optical behaviors of TiO2 pigments were subsequently evaluated based on AATCC test method 183-2004 for UV-A and UVB regions and standard test method ASTM G 107-03 and ASTM G173-03 for NIR region. At the final step, some experiments have been carried out to evaluate the performance of proposed method.
    Keywords: Titanium dioxide nano-pigments, Pigmented coatings, Radiative properties, Spectral performance, UV shielding, NIR reflectance
  • A. Senthil Kumar , R. Balaji, S. Jaykumar Pages 37-44
    In the present work, Gadolinium Doped ceria (GDC) based solid electrolyte was successfully synthesized through wet chemical method to operate at intermediate temperature (500–700°C) for SOFCs. DSC study revealed the formation of GDC phase at 900°C during calcination. The crystal structure of GDC was identified as cubic fluorite phase and the crystallite size was found to be around 23 nm. The density of the material was found to increase with increase the conventional sintering temperature and the concentration of gadolinium content. SEM analysis revealed that the particles were uniform in size and shape. From the above results it was understood that the obtained particle was a single crystallite with the absence of agglomeration. Functional group analysis, confirmed the O-H bond stretching. Hence, GDC based electrolyte can be a good choice for SOFC applications.
    Keywords: GDC, Conventional sintering, Electrolyte, SOFCs
  • H. Amrollahi Bioki , M. Borhani Zarandi Pages 45-53
    Hybrid polyaniline (PANI) based composites incorporating zinc sulfide (ZnS) nanoparticles (NPs) have been synthesized by using chemical oxidation technique. Schottky junction is constructed by depositing Polyaniline-zinc sulfide nanocomposite (PANI-ZnS NCs) on Au electrode. The results were compared with pure polyaniline. The I–V characteristics of the PANI-ZnS NCs heterojunction have shown the rectifying behavior. The detailed electrical measurement of the devices is performed under the different ratio of ZnS nanoparticles. An abnormal increase in the barrier height and decrease in the ideality factor with increasing 10 wt.% ZnS nanoparticles have been shown. The ideality factor (h) and barrier height (fb) of the heterojunction diode at room temperature are found to be 3.41 and 0.82 eV, respectively. These results showed the interaction between ZnS nanoparticles and PANI molecular chains.
    Keywords: Electrical properties, Nanocomposite, Polyaniline, Schottky diode, Zinc Sulfide
  • Z. Danesh Kaftroudi , A. Mazandarani Pages 55-64
    Self-heating leads to a temperature rise of the laser diode and limits the output power and efficiency due to increased loss and decreased differential gain. To control device self-heating, it is required to design the laser structure with a low optical loss, while the heat flux must spread out of the device efficiently. In this study, a new asymmetric waveguide design is proposed and the thermal performance of the laser with this new design is theoretically analyzed and compared with conventional symmetric waveguide laser. For this purpose, the simulation PICS3D software is used, which self-consistently combines 3D simulation of carrier transport, self-heating, and optical wave-guiding. According to the numerical simulation results, when the asymmetric waveguide is used the semiconductor laser shows a higher output light power and slope efficiency. The results show that Joule heating decreases and recombination heat increases, but heat dissipation occurs more effectively due to increased cooling densities. Overall, the maximum laser operation temperature decreases, confirming that our new asymmetric waveguide structure improves laser thermal characteristics.
    Keywords: Semiconductor laser, Simulation, Asymmetric waveguide, Self-heating
  • V. Velayudhan Nair Girija, S. Vasu Pages 65-73
    Magnetic iron oxide nanoparticles have numerous applications in the biomedical field. This paper reports the preparation and properties of iron oxide nanoparticles synthesised by thermal decomposition method from iron chelates. The iron oxide nanoparticles were characterized by FTIR, powder XRD, VSM, SEM and TEM techniques. FTIR and powder XRD studies show that iron oxide was formed as α - Fe2O3 in its pure form. VSM study shows that the particles have got ferromagnetic property. XRD, SEM and TEM images show that the particles formed are in nanometre crystallite size.
    Keywords: Thermal decomposition, Nanoparticles, Iron chelates, Hematite, VSM, TG-DTG