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    Synthesis of TiO2 hollow spheres using titanium tetraisopropoxide: Fabrication of high efficiency dye sensitized solar cells with photoanodes of different nanocrystalline TiO2 sub-layers

    , Article RSC Advances ; Vol. 4, issue. 101 , Oct , 2014 , p. 58064-58076 Marandi, M ; Feshki, S ; Naeimi Sani Sabet, M ; Anajafi, Z ; Taghavinia, N ; Sharif University of Technology
    Abstract
    In this research TiO2 hollow spheres with different diameters were prepared using titanium tetraisopropoxide (TTIP) as the TiO2 precursor. Carbon spheres with average sizes of 230, 325 and 450 nm were prepared as the templates by hydrothermal method. Then TiO2 was deposited on the surface of the carbon spheres through a liquid phase deposition (LPD) process. This two dimensional growth was performed in an appropriate concentration of TTIP and different LPD times. Finally the TiO2 hollow spheres were achieved for specific LPD times by burning the carbon templates. Two kinds of TiO2 nanocrystals with sizes around 20 nm were hydrothermally grown in acidic (pH = 1.5) and basic (pH = 10)... 

    The laser-assisted field effect transistor gas sensor based on morphological zinc-excited tin-doped in2o3 nanowires

    , Article Surface Review and Letters ; Volume 24, Issue 8 , 2017 ; 0218625X (ISSN) Shariati, M ; Khosravinejad, F ; Sharif University of Technology
    Abstract
    The gas nanosensor of indium oxide nanowires in laser assisted approach, doped with tin and zinc for gas sensing and 1D growth purposes respectively, was reported. The nanowires were very sensitive to H2S gas in low concentration of 20 ppb gas at room temperature. The fast dynamic intensive and sensitive response to gas was in a few seconds with an on/off sensitivity ratio of around 10. The square cross-section indium oxide nanowires were fabricated through physical vapor deposition (PVD) mechanism and annealing approach. The field emission scanning electron microscopy (FESEM) observations indicated that the annealing temperature was vital in nanostructures' morphology. The fabricated... 

    The highly crystalline tellurium doped ZnO nanowires photodetector

    , Article Journal of Crystal Growth ; Volume 522 , 2019 , Pages 214-220 ; 00220248 (ISSN) Khosravi Nejad, F ; Teimouri, M ; Jafari Marandi, S ; Shariati, M ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    In this paper, the stable and reproducible tellurium doped ZnO nanowires (Te-ZnO NWs) photodetector with intensive responsively is presented. The Te-ZnO NWs were fabricated by physical vapor deposition (PVD) growth mechanism. Field emission scanning electron microscope (FESEM) images showed that the fabricated nanowires were 50 nm in diameter and several microns in length. The high resolution transmission electron microscopy indicated that the synthesized nanowires were crystalline and their phase characterization was validated by the X-ray diffraction (XRD). The photoluminescence (PL) studies of these nanowires showed a strong photoluminescence (PL) emission peak in the green region. It was... 

    Effects of preheating temperature and cooling rate on two-step residual stress in thermal barrier coatings considering real roughness and porosity effect

    , Article Ceramics International ; Vol. 40, Issue. 10 , December , 2014 , pp. 15925-15940 ; ISSN: 02728842 Rezvani Rad, M ; Farrahi, G. H ; Azadi, M ; Ghodrati, M ; Sharif University of Technology
    Abstract
    In this research, a finite element model was developed in order to simulate the two-step residual stress distribution of a thermal barrier coating system, considered to be used in diesel engine cylinder head, with a real roughness and real porosity. Two steps including the bond coat and the top coat deposition processes were taken into account. The real geometry of coating layers, including the roughness and the porosity, was also considered based on a scanning electron microscopy image. Then, effects of the convective heat transfer coefficient and initial substrate and substrate/bond coat preheating temperatures on the residual stress were studied. Obtained results illustrate that the... 

    Optimization assisted asphaltene deposition modeling in porous media during a natural depletion scheme

    , Article Petroleum Science and Technology ; Volume 30, Issue 9 , Mar , 2012 , Pages 958-965 ; 10916466 (ISSN) Hematfar, V ; Bagheri, M ; Kharrat, R ; Ghazanfari, M ; Ghotbi, C ; Sharif University of Technology
    2012
    Abstract
    Changes in thermodynamic properties such as pressure, temperature, and composition may result in asphaltene precipitation and deposition in porous media. In addition, asphaltene deposition can cause wettability alteration, permeability reduction, and ultimately a decrease in the productivity of a reservoir. Natural depletion is one of the most common processes of asphaltene deposition in which pressure changes destabilize the dissolved asphaltene in the oil and settle them onto the rock surface. In this work, natural depletion experiments in consolidated core samples were performed under simulated reservoir conditions to obtain reliable data and analyze the asphaltene deposition mechanisms.... 

    Modeling and optimization of asphaltene deposition in porous media using genetic algorithm technique

    , Article Society of Petroleum Engineers - International Oil and Gas Conference and Exhibition in China 2010, IOGCEC, 8 June 2010 through 10 June 2010 ; Volume 1 , June , 2010 , Pages 479-491 ; 9781617388866 (ISBN) Hematfar, V ; Kharrat, R ; Ghazanfari, M. H ; Bagheri, M. B ; Sharif University of Technology
    2010
    Abstract
    Different models have been proposed for deposition of asphaltene on reservoir rocks that due to complexity of asphaltene nature, most of them have not been productive. Here, a reliable model is proposed which despite of previous models, considers the change in asphaltene saturation in the core. The obtained experimental data in the laboratory was used for model validation. In this work, a series of core flooding tests was carried out in presence of connate water at different solvent-oil volume ratios. Pressure drop was measured at three different terminals along the core. The obtained experimental data as well as mass balance equations, momentum equation, asphaltene deposition and... 

    Plasma surface functionalization of boron nitride nano-sheets

    , Article Diamond and Related Materials ; Volume 77 , 2017 , Pages 110-115 ; 09259635 (ISSN) Achour, H ; Achour, A ; Solaymani, S ; Islam, M ; Vizireanu, S ; Arman, A ; Ahmadpourian, A ; Dinescu, G ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    On silicon substrates, boron nitride nanosheets (BNNS) consisting of interconnected hexagonal boron nitride nano-layers were produced via chemical vapor deposition process at 1200 °C whose roughness's are at the micrometer- and nanometer-scale. The BNNS were functionalized in argon plasma admixed with ammonia or nitrogen or oxygen. The samples were characterized to investigate the surface chemistry and structural changes after plasma treatment using X-ray photoelectron spectroscope and Micro-Raman spectroscope techniques, respectively. While no significant changes in the surface features, upon plasma treatments of the BNNS, were noticed during SEM and TEM examination, the oxygen functional... 

    Measurement and prediction of the rate of deposition of flocculated asphaltene particles from oil

    , Article International Journal of Heat and Mass Transfer ; Volume 52, Issue 19-20 , 2009 , Pages 4624-4634 ; 00179310 (ISSN) Jamialahmadi, M ; Soltani, B ; Müller Steinhagen, H ; Rashtchian, D ; Sharif University of Technology
    2009
    Abstract
    Asphaltene deposition is one of the unresolved problems in oil industries. Little information is available on the critical question of "how fast" the flocculated asphaltene particles deposit across the production wells from the flowing oil. In this study, the mechanisms of deposition of flocculated asphaltene particles from oil have been studied experimentally and theoretically under forced convective conditions using an accurate thermal approach. The effects of oil velocity, flocculated asphaltene concentration and temperature on the rate of asphaltene deposition are investigated. It is observed that during the first few weeks the deposition mechanism is dominant and the erosion of the... 

    Electrocrystallization of Pb and Pb assisted Al on aluminum electrode from molten salt (AlCl3-NaCl-KCl)

    , Article Journal of Alloys and Compounds ; Volume 478, Issue 1-2 , 2009 , Pages 83-88 ; 09258388 (ISSN) Jafarian, M ; Danaee, I ; Maleki, A ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    2009
    Abstract
    Electrochemical deposition of aluminum and lead from basic molten AlCl3-NaCl-KCl mixture on an aluminum electrode at 180 °C was studied by the methods of voltammetry, potential and current transient and constant current deposition. The deposition of aluminum was found to proceed via a nucleation/growth mechanism, while the deposition of lead was found to be diffusion controlled. The diffusion coefficient calculated for Pb2+ ions in basic melt by voltammetry was in agreement with the deductions of transient method. The analysis of the chronoamperograms indicates that the deposition process of lead on Al substrates was controlled by 3D diffusion control, nucleation and growth. The processes... 

    Modeling of J sc and V oc versus the grain size in CdTe, CZTS and Perovskite thin film solar cells

    , Article Superlattices and Microstructures ; Volume 128 , 2019 , Pages 421-427 ; 07496036 (ISSN) Nazem, H ; Pourasiab Dizaj, H ; Gorji, N. E ; Sharif University of Technology
    Academic Press  2019
    Abstract
    A modeling approach is presented for the first time to model the dependence of short-circuit current density (J sc ) and open-circuit voltage (V oc ) on the grain size g in three thin film solar cells including the emerging perovskites. The variation of J sc and V oc with the grain size (g) of three different solar cells with CdTe, CZTS and perovskite absorber layers are modelled and fitted with the experimental dataset collected from relevant literature. The experimental literature suggested that the grain size of absorber layers in solar cells is controlled during the deposition process by adjusting the growth rate, temperature and ambient. The model has been successfully applied to the... 

    A novel low-temperature growth of uniform CuInS2 thin films and their application in selenization/sulfurization-free CuInS2 solar cells

    , Article Materials Today Communications ; Volume 26 , 2021 ; 23524928 (ISSN) Dehghani, M ; Parvazian, E ; Alamgir Tehrani, N ; Taghavinia, N ; Samadpour, M ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    In terms of manufacturability, there is a high tendency to deposit light-absorbing CuInS2 films by solution processing methods like ink-based depositions. In particular, for nanoparticle inks, the synthesis of highly dispersed and stable inks, with uniformity in the deposition process, is a serious challenge. Here, we demonstrate a novel two-step low-temperature CuInS2 film deposition method in which the In2S3 is deposited first. It then partially is converted into CuInS2 through the infiltration of Cu+ ions in the In2S3 layer in a dip-coating process. The resulting films are highly uniform, with diffraction peaks indicating the formation of pure CuInS2 phase. The proper stoichiometry of... 

    One step electrodeposition of V2O5/polypyrrole/graphene oxide ternary nanocomposite for preparation of a high performance supercapacitor

    , Article International Journal of Hydrogen Energy ; Volume 42, Issue 33 , 2017 , Pages 21073-21085 ; 03603199 (ISSN) Asen, P ; Shahrokhian, S ; Iraji zad, A ; Sharif University of Technology
    Abstract
    A new ternary nanocomposite based on graphene oxide (GO), polypyrrole (PPy) and vanadium pentoxide (V2O5) is obtained via one-step electrochemical deposition process. Electrochemical deposition of V2O5, PPy and GO on a stainless steel (SS) substrate is conducted from an aqueous solution containing vanadyl acetate, pyrrole and GO to get V2O5/PPy/GO nanocomposite. Characterization of the electrode material is carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). The electrochemical performance of the as-prepared nanocomposite is evaluated by... 

    Template-based growth of titanium dioxide nanorods by a particulate sol-electrophoretic deposition process

    , Article Particuology ; Volume 9, Issue 2 , 2011 , Pages 161-169 ; 16742001 (ISSN) Mohammadi, M. R ; Ordikhani, F ; Fray, D. J ; Khomamizadeh, F ; Sharif University of Technology
    Abstract
    TiO2 nanorods have been successfully grown into a track-etched polycarbonate (PC) membrane by a particulate sol-electrophoretic deposition from an aqueous medium. The prepared sols had a narrow particle size distribution around 17 nm and excellent stability against aging, with zeta potentials in the range of 47-50 mV at pH 2. It was found that TiO2 nanorods were grown from dilute aqueous sol with a low, 0.1-M concentration. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed that a full conversion of titanium isopropoxide was obtained by hydrolysis, resulting in the formation of TiO2 particles. X-ray diffraction (XRD) results revealed that TiO2 nanorods dried at 100 °C were a...