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    Fabrication of a highly flexible and affordable transparent electrode by aligned u-shaped copper nanowires using a new electrospinning collector with convenient transferability

    , Article ACS Omega ; Volume 4, Issue 25 , 2019 , Pages 21260-21266 ; 24701343 (ISSN) Nikzad, M. J ; Mohamadbeigi, N ; Sadrnezhaad, Kh ; Mahdavi, M ; Sharif University of Technology
    American Chemical Society  2019
    By making aligned and suspended copper nanowires, a high performance, transferable, and flexible transparent electrode is reported. Indium tin oxide is often used in devices such as displays, solar cells, and touchscreens that require transparent and conductive plates. Because of problems such as brittleness, high cost, and environmental effects, this material is facing rivals, the most serious of which are metallic nanowire meshes, especially copper. We developed a simple technique which uses a U-shaped collector in the electrospinning process with three advantages including the enhancement of the figure of merit (which is related to the surface resistance Rs and the transmittance T) by... 

    Synthesis of nanostructured CuInSe 2 (CIS) powder via solvothermal processing using diethylamine as a solvent

    , Article Journal of Ceramic Processing Research ; Volume 12, Issue 6 , 2011 , Pages 695-698 ; 12299162 (ISSN) Najafi, M ; Vaezi, M. R ; Sadrnezhaad, S. K ; Sharif University of Technology
    In this paper, CuInSe 2 (CIS) nanostructures have been synthesized via a solvothermal method using diethyamine as a solvent. Various morphologies of CuInSe 2 were obtained from the reaction of cupric chloride, indium chloride and selenium powder by changing the solvothermal conditions. The effect of the experimental parameters such as reaction time, temperature and concentration of the selenium powder were studied. The crystalline structures and morphologies of the products were characterized by means of X- ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) techniques, respectively. The results show that the morphology and dimensions of the CIS nanostructures... 

    Using and evaluating new confidence measures in word-based isolated word recognizers

    , Article 2007 9th International Symposium on Signal Processing and its Applications, ISSPA 2007, Sharjah, 12 February 2007 through 15 February 2007 ; 2007 ; 1424407796 (ISBN); 9781424407798 (ISBN) Vaisipour, S ; Babaali, B ; Sameti, H ; Sharif University of Technology
    In this paper a method for detecting out of vocabulary words in isolated word recognizers is introduced, our method utilized new kinds of confidence measure. After recognition task was completed and consequently confidence measure was extracted, a classifier would accept or reject result of recognition task using this CM. We used two different kinds of confidence measure where for extracting each one a different information source was used. Amount of competition between hypotheses through the recognition task was used for extracting first CM. The second one was extracted using information about manner of distribution of feature vectors in the states of winner HMM model. Both of these CMs... 

    Investigation on Optical and Catalytic Properties of Noble Metallic Nanoparticles in SiO2 and TiO2 Matrix

    , Ph.D. Dissertation Sharif University of Technology Sangpour, Parvaneh (Author) ; Moshfegh, Alireza (Supervisor) ; Akhavan, Omid (Supervisor)
    Doping metal or semiconductor nanoparticles in transparent matrix have attracted much attention for practical application in recent years. From fundamental veiw point, limiting the charge carriers and exitons in nanometric scales resulted in new quantum phenomena. In this context, transparent films containing metal nanoparticles shows an absorption peak in visible region of spectrom. Thus, by choosing an appropriate metal and controlling the size and concentration of particles in corresponding matrix, we can provide coatings with a wide rang of colors. Furthermore, thin films containing metal or metal oxide nanoparticles had been considered as nanostructure materials in research and... 

    Electrical and Optical Properties of Doped (Ba, Sr)TiO3 Layers Prepared Via Sol-gel Method

    , M.Sc. Thesis Sharif University of Technology Emadi, Fahimeh (Author) ; Nemati, Ali (Supervisor)
    The main purpose of this research was simultaneous doping of carbon and nickel in the structure of barium strontium titanate, in order to investigate its dielectric and optical properties. Powders and films of BST, was synthesized by the sol-gel method in six different compositions: without any dopant, 0.04mol nickel dopant, 0.04mol nickel dopant accompanied by different amounts of carbon (0.01, 0.02, 0.03 and 0.04 mol). Suspensions were dip coated on alumina and quartz substrates. Structural features and chemical bonds, were studied through thermal analysis, XRD, FT-IR, FESEM and AFM. For electrical and optical properties, LCR-meter and UV-Vis were used. XRD and FESEM proved that nickel... 

    Structural and optical properties of Pd 2+-doped mesoporous TiO 2 thin films prepared by sol-gel templating technique

    , Article Optoelectronics and Advanced Materials, Rapid Communications ; Volume 4, Issue 10 , 2010 , Pages 1572-1577 ; 18426573 (ISSN) Yarmand, B ; Sadrnezhaad, S. K ; Sharif University of Technology
    Pd 2+-doped TiO 2 thin films with mesoporous structure were produced on quartz substrate by sol-gel dip coating. The structural, morphological and optical properties of the film were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV/vis transmittance spectroscopy. By increasing the Pd 2+ concentration from 0 to 6 mol%, the crystallites appeared solely as the anatase phase and their average sizes decreased from 10.5 to 7.1 nm. Addition of Pd 2+ also resulted in increasing of the specific surface area and decreasing of the pore size of the layer. The transmittance of the films decreased in the... 

    Influence of annealing temperature on structural and optical properties of mesoporous TiO2 thin films prepared by sol-gel templating technique

    , Article Journal of Optoelectronics and Advanced Materials ; Volume 12, Issue 7 , 2010 , Pages 1490-1497 ; 14544164 (ISSN) Yarmand, B ; Sadrnezhaad, S. K ; Sharif University of Technology
    TiO2 thin films with mesoporous structure were deposited on quartz substrate by sol-gel dip coating. The structural, morphological and optical properties of the films were characterized by X-ray diffraction (XRD), simultaneous thermal analysis (STA), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), atomic force microscopy (AFM), transmission electron microscopy (TEM) and UV/Vis transmittance spectroscopy. Crystallization of the anatase phase was initiated at 300°C. Its transformation to the rutile phase occurred at 700°C. Anatase and rutile crystallites initially sized 3.2 and 15.3nm, respectively. The anatase phase was under tension; but the rutile phase was... 

    Production of zinc oxide nanoparticles by liquid phase processing: An investigation on optical properties

    , Article 2nd International Conference on Diffusion in Solids and Liquids, DSL-2006, Aveiro, 26 July 2006 through 28 July 2006 ; Volume 553 , 2007 , Pages 252-256 ; 02555476 (ISSN); 0878494383 (ISBN); 9780878494385 (ISBN) Vafaee, M ; Youzbashizade, H ; Sharif University of Technology
    Trans Tech Publications Ltd  2007
    In the recent years, many researchers have been interested in nanoparticles because of their unique properties. In this study, a method for producing ZnO nanoparticle colloids is proposed. The colloids were characterized by spectroscopic analyzer. By absorption spectrum study, we found out that colloids were consisted of nanoparticles with less than 10 nanometer size. The quantum confinement effect in these spectrums was recognized through blue shift of onset absorption wavelengths. These wavelengths shift from 370 nm to 340 nm by decreasing the particles size. Transmittion electron micrographs showed formation of zinc oxide nanoparticles  

    Stability, size and optical properties of silver nanoparticles prepared by laser ablation in different carrier media

    , Article Applied Physics A: Materials Science and Processing ; Volume 84, Issue 1-2 , 2006 , Pages 215-219 ; 09478396 (ISSN) Tilaki, R. M ; Irajizad, A ; Mahdavi, S. M ; Sharif University of Technology
    We studied the effects of the surrounding liquid environment on the size and optical properties of silver nanoparticles prepared by laser ablation by a pulsed Nd:YAG laser operated at 1.064 nm. The silver targets used were kept in acetone, water and ethanol. TEM observations and optical extinction were employed for characterization of particle size, shape and optical properties, respectively. Nano silver in acetone showed a narrow size distribution with a mean size of 5 nm and the colloidal solution was stable. In deionised water a rather narrow size distribution with a mean size of 13 nm was observed and nanoparticles were precipitated slowly after about two weeks. In ethanol, a broadening... 

    Influence of heavy nanocrystals on spermatozoa and fertility of mammals

    , Article Materials Science and Engineering C ; Volume 69 , 2016 , Pages 52-59 ; 09284931 (ISSN) Akhavan, O ; Hashemi, E ; Zare, H ; Shamsara, M ; Taghavinia, N ; Heidari, F ; Sharif University of Technology
    Elsevier Ltd 
    In recent years, quantum dots (QDs) have been widely used in upcoming nanotechnology-based solar cells, light-emitting diodes and even bioimaging, due to their tunable optical properties and excellent quantum yields. But, such nanostructures are currently constituted by heavy elements which can threat the human health and living environment. Hence, in this work, the in vivo effects of CdTe nanocrystals (NCs) (as one of the promising QDs) on spermatozoa of male mice and subsequently on fertility of female mice were investigated, for the first time. To do this, CdTe NCs were synthesized through an environment-friendly (aqueous-based solution) method. The sperm cells presented a high potential... 

    Pressure induced structural, electronic, optical and thermal properties of CsYbBr3, a theoretical investigation

    , Article Journal of Materials Research and Technology ; Volume 10 , 2021 , Pages 687-696 ; 22387854 (ISSN) Saeed, M ; Ali, M. A ; Murad, S ; Ullah, R ; Alshahrani, T ; Laref, A ; Murtaza, G ; Sharif University of Technology
    Elsevier Editora Ltda  2021
    This article presents the variation of structural, electronic, thermal and optical properties of a halide perovskite CsYbBr3with increasing pressure, employing density functional theory. The pressure effect was determined in range of 0-15 GPa. In which stability of CsYbBr3remains valid, as, verified from negative values of enthalpy of formation and phonon dispersion curves. A significant change was observed in lattice constant, bond lengths, bulk modulus and its pressure derivative, volume and ground state energy, with increasing pressure. The calculated electronic properties presented CsYbBr3as a semiconductor with direct band gap of 3.61 eV. However, pressure rise shift the Yb-d states... 

    Synthesis, Characterization and Emission Properties of Unsupported Heteronuclear Pt/Au and Pt/Tl Complexes

    , M.Sc. Thesis Sharif University of Technology Maleka Ashtiani, Mona (Author) ; Jamali, Sirous (Supervisor)
    The preparation and optical properties of two new unsupported Pt/Au and Pt/Tl heteronuclear complexes have been described.The heterobinuclear complexe [(tBu3P)2Pt-Au(PPh3)], 2, has been synthesized from reaction of the cluster complex {[(PPh3)Au]3(µ-O)}BF4 with 3 equiv [(tBu3P)2Pt] and characterized by multinuclear NMR spectroscopy in solution and using X-ray crystallography in the solid state. The tetranuclear linear chain cluster [(tBu3P)2PtTl2Pt(tBu3P)2](PF6)2, 3,has been prepared from the reaction of platinum(0) complex [(tBuP)2Pt] with 1 equiv TlPF6 in dry acetone. Complex 3 shows strong red emission with 73% quantum yield. DFT and TD-DFT calculations show that the emission originated... 

    Optical and structural properties of copper doped CdS thin films prepared by pulsed laser deposition

    , Article Scientia Iranica ; Volume 15, Issue 3 , 2008 , Pages 360-365 ; 10263098 (ISSN) Mahdavi, S. M ; Irajizad, A ; Azarian, A ; Tilaki, R. M ; Sharif University of Technology
    Sharif University of Technology  2008
    This paper presents the study of the structural and optical properties of copper doped cadmium sulfide thin films prepared by pulsed Nd:YAG laser. The copper concentration in the targets was varied from 0.05% to 5% in weight and they were heated at a temperature of 500°C in air for one hour. It was observed that annealing un-doped and doped thin films at temperatures above 160°C leads to an abrupt increase in the optical transmission, changing from dark brownish to transparent yellowish. For annealed samples at 300°C, increasing Cu concentration from 0.0% to 2%, leads to an increase in the optical transmission up to 80%, at a wavelength of about 700 nm. XRD patterns showed the hexagonal... 

    Investigation and Fabrication of Cr2O3 Thin Film Coating on Soda Lime and Low Carbon Steel Substrate

    , M.Sc. Thesis Sharif University of Technology Sarhadi, Neda (Author) ; Dolati, Abolghasem (Supervisor)
    Chromium oxide coatings (Cr2O3) have been widely used due to their remarkable properties in corrosion, wear, optical and mechanical applications. So far, several methods have been used to prepare Cr2O3 thin films. In this study, the chromium oxide was produced by the sol-gel method and dip coated on the low carbon steel and glass substrates. In this context, we encountered with the problem of incoherency of the Cr2O3 ceramic coating to the steel substrates. It is highly likely that this problem be due to causes such as: a) thermal stresses due to the difference between the thermal expansion coefficients of the substrate and the coating, b) incoherent substrate/coating interface due to their... 

    Synthesis, Characterization and Study of the Optical Properties of Gold(I) Complexes Bearing Vinyl Pyridine and 1,8-Naphtyridine Ligands

    , M.Sc. Thesis Sharif University of Technology Alizadeh Kurdestani, Niyaz (Author) ; Jamali, Sirous (Supervisor)
    The reaction of AuCl(SMe2) with two equiv of 2-vinylpyridine(2-Vpy) and one equiv of AgOTf gave the gold(I) complex [Au(2-Vpy)2], 1. Also the cationic gold(I) complex [Au(1,8-Naph)2][NTf2], 2, in which NTf2 is Bis(trifluoromethanesulfonyl)imide, has been prepared from the reaction of AuCl(SMe2), two equiv 1,8-naphthyridine and one equiv Ag(NTf2). The partial replacement of the NTf2 counter ion by PF6 using the reaction of 2 with one equiv TlPF6 leads to formation of the gold(I) complex [Au(1,8-Naphthyridine)2]〖"[NTf2]" 〗_("1" ⁄"3" ) 〖"[PF6]" 〗_("2" ⁄"3" ), 3. The solid state structure of 3 was determined using X-ray crystallography and its optical properties have been studied at room... 

    Deposition of Indium-tin-oxide on Glass By Sol-gel and Effect of Noble Dopants on the Optical and Electerical Properties of Indium-tin-oxide Thin Films

    , M.Sc. Thesis Sharif University of Technology Mirzaee, Majid (Author) ; Dolati, Abolghasem (Supervisor)
    Thin film of Indium oxide doped with tin is used as a transparent electrode for different applications like screening panels, solar cells, touch panels and elechtrochromic tools. Trading thin films of ITO are precipitated using sputtering. However sol gel method can be simple and economic to make transparent electrodes. In this thesis first ITO sols is prepared using Indium nitrate and tin chloride with two or four capacities due to the production of transparent oxides on soda lime glass. Then the effect of tin chloride with two and four capacities is investigated on resistance and optic properties. Results show that tin chloride with four capacities in comparison with tin of two capacities... 

    A Study on Morphology, Structure and Properties of Silver and Gold Coatings Applied by a Chemical Reduction Deposition Method Using Double-Spray Device

    , M.Sc. Thesis Sharif University of Technology Bakhshizadeh, Ali (Author) ; Dolati, Abolghasem (Supervisor)
    Silver and gold are precious, expensive metals and are used in various applications, such as jewellery and ornamentals, electronics and optics. In the present study, soda-lime glass surfaces firstly were activated with acidic stannous chloride solution. Then, silver and gold were coated on these surfaces via simultaneous spraying of two solution: A silver- or gold-complex bearing solution and a reducing agent (Dextrose for Ag and H2O2 for Au) bearing solution. For silver coating, the effect of various parameters such as time, reducing agent concentration, number of passes, presence and concentration of Urotrpin and Decamethylcyclopentasiloxane (DMCPS) as microstructural modifiers and... 

    A Facile, Two-step Synthesis and Characterization of Fe3O4-Lcysteine- Graphene Quantum Dots as a Multifunctional Nanocomposite

    , M.Sc. Thesis Sharif University of Technology Alaghmand Fard, Amir Hossein (Author) ; Madah Hosseini, Hamid Reza (Supervisor)
    In this research, a facile, two-step synthesis was reported for 34-LCysteine- nanocomposites. The first step comprises the preparation of LCysteine functionalized magnetic nanoparticles (MNPs) core-shell structures via co-precipitation method. In the second step, graphene quantum dots (GQDs), which were synthesized by citric acid carbonization, added to the functionalized MNPs and finally refluxed at the appropriate time and temperature. LCysteine as a biocompatible, natural amino acid were used to link MNPs with GQDs. This nanocomposite was characterized by various techniques. XRD and FT-IR were used to investigate the formation of MNPs and LCysteine existence on the MNPs surface. XPS... 

    Some optical properties of four-level media via coherent and incoherent pumping fields

    , Article Journal of the Optical Society of America B: Optical Physics ; Volume 30, Issue 3 , 2013 , Pages 641-648 ; 07403224 (ISSN) Naseri, T ; Asadpour, S. H ; Sadighi Bonabi, R ; Sharif University of Technology
    Optical Society of American (OSA)  2013
    The optical properties of a four-level atomic system via coherent and incoherent pumping fields are investigated. The giant Kerr nonlinearity with reduced linear and nonlinear absorption, which has a major role in decreasing the threshold of optical bistability (OB), can be obtained with subluminal light propagation via adjusting the intensities of coupling fields. An incoherent pumping field is noticed to be an extra parameter to reduce the threshold of OB and multistability, and it can be used as an effective parameter in producing lasing with or without population inversion. In this model, optical multistability is achieved simply by tuning the intensity of coupling laser fields.... 

    Optical properties of defected silicene: the many-body approach

    , Article Optical and Quantum Electronics ; Volume 48, Issue 7 , 2016 ; 03068919 (ISSN) Zakerian, F ; Berahman, M ; Sharif University of Technology
    Springer New York LLC  2016
    Abstract: The electronic structure and excitonic optical properties of pristine and defected silicene are investigated within many-body Green’s function and Bethe–Salpeter equation formalism. We show that compared with pristine one, defects can significantly alter band structure and form much better metallic characteristics. Also, it is shown that low defects in pristine silicene can considerably alter optical absorption peaks and change these peaks to the lower energies. Such effect is illustrated for 5 % defects in the pristine silicene and two main peaks in the optical spectrum are shown, one in low energies and another wider one in the higher energies. These peaks can be used as a tool...