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    Cu surface segregation in Ni/Cu system

    , Article Vacuum ; Volume 84, Issue 4 , 8 December , 2009 , PP. 469-473 Rasuli, R. (Reza.) ; Iraji Zad, A. (Azam) ; Ahadian, M. M. (Mohammad M.) ; Sharif University of Technology
    We report experimental evidence of Cu surface segregation in Ni/Cu system, during deposition of Ni film onto Cu substrate at room temperature and during heat treatment in vacuum. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) by Tougaard's analysis results show that surface segregation defeats in competition with increase in Ni thickness and terminates when thickness of Ni increase to more than 4 nm. Surface energy and concentration were calculated using contact angle measurements and the results confirm that segregation reduces the surface energy. Surface segregation during heat treatment at 150–220 °C range as a function of time initially shows linear mass... 

    Nickel Nano Particles Pulse Electrodeposition

    , M.Sc. Thesis Sharif University of Technology Afsari, Maryam (Author) ; Dolati, Abolghasem (Supervisor)
    Syntheses of coats including nickel nano-particles by electrodeposition have been
    investigated for over 10 years. A method of testing according to surface reply was chosen
    to reveal the effect of each pulse parameters (including duty cycle, frequency, average
    current density, off time (toff) and on time (ton)) and the effect of saccharin concentration
    on electroplating cathode efficiency, nanostructure. Pulse electroplating test of nickel was
    composed by 30 tests. Pulse electroplating with relatively high peak current density was
    employed and saccharine was added to increase deposition and rate of nickel nucleation on
    surface. According to the results of cathode... 

    Pulsed laser deposition of W-V-O composite films: preparation, characterization and gasochromic studies

    , Article Solar Energy Materials and Solar Cells ; Volume 92, Issue 8 , 2008 , Pages 878-883 ; 09270248 (ISSN) Ranjbar, M ; Mahdavi, S. M ; Iraji zad, A ; Sharif University of Technology
    Modified tungsten oxide films by vanadium oxide provide neutrally coloring electrochromic electrodes for smart windows technology. In this study W-V-O mixed oxide films were fabricated by Nd:YAG pulsed laser deposition (PLD), λ=1064 nm, from mixed pressed powders of (WO3)1-x(V2O5)x, x=0, 0.09, 0.17, 0.23, 0.29 and 0.33, at 13.3 Pa oxygen partial pressure and 200 °C temperature on glass substrates. X-ray photoelectron spectroscopy (XPS) revealed V5+, V4+, W6+ and W5+ surface oxide states, where the ratio of W5+/W6+ enhances by the amount of vanadium in the films. Surface morphology was studied by scanning electron microscope (SEM) and optical properties by transmission-reflection spectra.... 

    Enhanced inter-plane coupling of Mg doped Cu0.5Tl0.5Ba2Ca2- xMgxCu3O10-δ superconductors: XPS and FTIR studies

    , Article Physica C: Superconductivity and its Applications ; Volume 468, Issue 5 , 2008 , Pages 405-410 ; 09214534 (ISSN) Khurram, A. A ; Khan, N. A ; Ahadian, M. M ; Iraji zad, A ; Sharif University of Technology
    A comparison of X-ray photoemission spectroscopy of Mg doped Cu0.5Tl0.5Ba2Ca1.5Mg 0.5Cu3O10-δ and Mg free Cu0.5Tl0.5Ba2Ca2Cu 3O10-δ superconductor samples have been made. The main objective of these studies is to see the effect of Mg doping in developing better inter-plane coupling among the CuO2 planes and its effects on the chemical shift of the bonding species. Through these studies it is observed that thallium is in Tl+1 oxidation state in the Cu0.5Tl0.5Ba2O4- δ charge reservoir layer in both Mg doped and Mg free samples, however, the XPS line related to Ba atoms are shifted to higher binding energy side by 0.32 eV in Mg doped sample. This chemical shift is most likely due to presence of... 

    Characterization of Pd nanoparticle dispersed over porous silicon as a hydrogen sensor

    , Article Journal of Physics D: Applied Physics ; Volume 40, Issue 23 , 2007 , Pages 7201-7209 ; 00223727 (ISSN) Rahimi, F ; Iraji Zad, A ; Sharif University of Technology
    Porous silicon samples were obtained by the electrochemical method and were impregnated with Pd by the electroless process. X-ray photoelectron spectroscopy illustrated that the surface of the samples is oxidized during the palladium deposition. Scanning electron microscopy showed how factors such as morphology and pre-oxidations of porous samples and the plating parameters including Pd-salt concentration, HCl concentration, temperature of the electroless solution and the time of process affect the growth and nucleation of Pd particles. Observations demonstrated that the illumination-assisted process on p-type samples has a drastic effect on the growth of palladium. Hydrogen sensing of these... 

    Formation of gold nanoparticles in heat-treated reactive co-sputtered Au-SiO 2 thin films

    , Article Applied Surface Science ; Volume 254, Issue 1 SPEC. ISS , 2007 , Pages 286-290 ; 01694332 (ISSN) Sangpour, P ; Akhavan, O ; Moshfegh, A. Z ; Roozbehi, M ; Sharif University of Technology
    Elsevier  2007
    In this work, formation of gold nanoparticles in radio frequency (RF) reactive magnetron co-sputtered Au-SiO 2 thin films post annealed at different temperatures in Ar + H 2 atmosphere has been investigated. Optical, surface topography, chemical state and crystalline properties of the prepared films were analyzed by using UV-visible spectrophotometry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD) techniques, respectively. Optical absorption spectrum of the Au-SiO 2 thin films annealed at 800 °C showed one surface plasmon resonance (SPR) absorption peak located at 520 nm relating to gold nanoparticles. According to XPS analysis, it was... 

    Adsorption of TiO2 nanoparticles on glass fibers

    , Article Journal of Physical Chemistry C ; Volume 111, Issue 27 , 2007 , Pages 9794-9798 ; 19327447 (ISSN) Khajeh Aminian, M ; Taghavinia, N ; Irajizad, A ; Mahdavi, M ; Sharif University of Technology
    Titania was deposited on glass fibers with a partial epoxy layer coating from a solution containing TiO2 nanoparticles at T = 90°C, and the adsorption process was examined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, and photocatalytic activity measurements. XPS data demonstrated that about 25% of the surface was covered with TiO2 nanoparticles, with 10% on the epoxy layer and 15% on the glass body. It was found that TiO2 nanoparticles can be readily adsorbed on epoxy groups, whereas they have a low tendency to adsorb on carbon polymer chains. This difference can be... 

    An optical study of cobalt nanowires dispersed in liquid phase

    , Article Optics Communications ; Volume 274, Issue 2 , 2007 , Pages 471-476 ; 00304018 (ISSN) Azarian, A ; Iraji zad, A ; Dolati, A ; Sharif University of Technology
    The Co nanowires were electrodeposited in polycarbonate membrane (PCT). SEM, TEM and XPS techniques were used to characterize the morphology, structure and size of nanowires as well as chemical composition. The influence of different mediums was studied on the optical absorption of dispersed cobalt nanowires. The absorption spectrum of cobalt nanowires in water showed a broad shoulder at 290 nm, but in ethanol solution it was not observed in the visible region of the spectra up to 200 nm. Cobalt nanowires dispersed in methanol presented a peak at 236 nm. We attribute the data to oxidation of cobalt in water and low dielectric constant of methanol relative to ethanol and water. We found... 

    X-ray photo-emission studies of Cu1-xTlxBa2Ca3Cu4 O12-y superconductor thin films

    , Article Physica C: Superconductivity and its Applications ; Volume 449, Issue 1 , 2006 , Pages 47-52 ; 09214534 (ISSN) Khan, N. A ; Mumtaz, M ; Ahadian, M. M ; Iraji zad, A ; Sharif University of Technology
    X-ray photo-emission spectroscopy (XPS) studies of Cu1-xTlxBa2Ca3Cu4 O12-y superconductor thin films have been carried out for understanding the mechanism of superconductivity and to find out the reasons for the increase of zero resistivity critical temperature Tc(R = 0) with post-annealing in a nitrogen atmosphere. It is observed from these studies that reduction of charge state of thallium is a source of doping of carriers to the CuO2 planes. The reduced charge state of thallium (i.e. Tl1+) promotes lower oxygen concentration in the charge reservoir layer, which possibly results in movement of electrons to the conducting CuO2 planes. The higher density of electrons in the CuO2 planes... 

    An investigation on electrochromic properties of (WO3)1-x-(Fe2O3)x thin films

    , Article Thin Solid Films ; Volume 515, Issue 2 SPEC. ISS , 2006 , Pages 644-647 ; 00406090 (ISSN) Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
    Elsevier  2006
    In this research, the effect of Fe2O3 content on the electrochromic properties of WO3 in thermally evaporated (WO3)1-x-(Fe2O3)x thin films (0 ≤ x ≤ 0.4) has been studied. The atomic composition of the deposited metal oxides was determined by X-ray photoelectron spectroscopy analysis. The surface morphology of the thin films has been examined by atomic force microscopy. The surface roughness of all the films was measured about 1.3 nm with an average lateral grain size of 30 nm showing a smooth and nanostructured surface. The electrochromic properties of (WO3)1-x-(Fe2O3)x thin films deposited on ITO/glass substrate were studied in a LiClO4 + PC electrolyte by using ultraviolet-visible... 

    Influence of coloring voltage and thickness on electrochromical properties of e-beam eaporated W O3 thin films

    , Article Journal of the Electrochemical Society ; Volume 153, Issue 2 , 2006 , Pages E11-E16 ; 00134651 (ISSN) Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
    In this investigation, the effect of coloring voltage and thickness on optical and also electrochromical properties of W O3 thin films has been studied. The W O3 thin films were grown on glass and indium tin oxide coated conducting glass substrates by e-beam evaporation at different thicknesses of 200, 400, and 700 nm. Optical properties of the deposited samples were characterized in the ultraviolet-visible range (300-1100 nm). The optical bandgap energy of the W O3 was obtained in a range of 3.3-3.5 eV showing its increase by decreasing the film thickness. The refractive index of the W O3 films was measured around 2 in the visible range. Surface chemical states of the films were studied by... 

    Structure and composition of the segregated Cu in V 2 O 5 /Cu system

    , Article Applied Surface Science ; Volume 253, Issue 5 , 2006 , Pages 2581-2588 ; 01694332 (ISSN) Ahadian, M. M ; Iraji zad, A ; Sharif University of Technology
    Elsevier  2006
    We have investigated segregation of copper at the surface of V 2 O 5 films deposited onto Cu substrate by employing surface analysis techniques. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) confirmed that the Cu is segregated at the surface and its chemical state is Cu 2 O. According to secondary ion mass spectroscopy (SIMS) and glow discharge spectroscopy (GDS), the Cu concentration inside the deposited V 2 O 5 layer is low. Ultraviolet photoelectron spectroscopy (UPS) and scanning tunneling spectroscopy (STS) revealed the segregation alters the surface local density of states. Surface analysis of deposited samples in ultra high vacuum (UHV) condition... 

    Tunable bandgap and spin-orbit coupling by composition control of MoS2 and MoOx (x = 2 and 3) thin film compounds

    , Article Materials and Design ; Volume 122 , 2017 , Pages 220-225 ; 02641275 (ISSN) Erfanifam, S ; Mohseni, S. M ; Jamilpanah, L ; Mohammadbeigi, M ; Sangpour, P ; Hosseini, S. A ; Iraji Zad, A ; Sharif University of Technology
    Elsevier Ltd  2017
    We report on the MoS2 and MoOx (x = 2 and 3) composite thin layers, electrodeposited, onto a Florine doped Tin Oxide (FTO) substrate. Our results show a change in relative content of these compounds in different thicknesses ranging from ∼20 to 540 nm. This change in the relative content at different thicknesses leads to a change in optical and electrical properties including bandgap and the type of semiconductivity. A sharp transition from p to n-type of semiconductivity is observed by scanning tunneling spectroscopy measurements. We find that the spin-orbit interaction of Mo 3d electrons in the MoS2 and MoO3 enhances by significant reduction of the MoO3 content in thicker layers. © 2017... 

    XPS study of size effects of Fe3O4 nanoparticles on crosslinking degree of magnetic TFN membrane

    , Article Polymer Testing ; Volume 73 , 2019 , Pages 232-241 ; 01429418 (ISSN) Tayefeh, A ; Poursalehi, R ; Wiesner, M ; Mousavi, S. A ; Sharif University of Technology
    Elsevier Ltd  2019
    The control of thin film nanocomposite (TFN) membranes cross-linking degree is an important factor to design new membranes and optimizing permeation characteristics. The Fe3O4 nanoparticle's based TFN membranes due to potentially added magnetic responsive properties to the membrane has a great importance in developing membrane architectures. Fe3O4/polyamide (PA) TFN membranes filled with nanoparticles in different sizes and concentrations have been synthesized. Cross-linking degree of PA layer characterized with Fourier transform spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS) methods to evaluate size dependency of the cross-linking degree of PA layer network. Obvious... 

    Investigation on Electrical Properties and Band Structure of Barium Strontium Titanate Thin Films Grown by Pulsed Laser Deposition

    , M.Sc. Thesis Sharif University of Technology Kashir, Alireza (Author) ; Nemati, Ali (Supervisor) ; Mahdavi, Mohammad (Co-Advisor)
    In this research the microstructural, electrical and optical properties of Strontium Titanate and Barium Strontium Titante thin films, fabricated through Pulsed Laser Deposition (PLD), were investigated. X-ray Photoelectron Spectroscopy and X-ray Diffraction study showed that the stoichiometry of the target material was highly preserved by using PLD method. Scanning Electon Microscopy as well as Atomic Force Microscopy depicted that the using of pressed and sintered target is a suitable metod for improving the surface quality of the thin films. Using the pressed target decreased the quality of the thin films and the average roughness of the films increased. The main reason for this... 

    Chemo-physical properties of renal capsules under ultraviolet-c exposure

    , Article Journal of Applied Physics ; Vol. 116, Issue. 5 , 2014 ; ISSN: 00218979 Baghapour, Sh ; Parvin, P ; Reyhani, A ; Mortazavi, S. Z ; Mokhtari, S ; Amjadi, A ; Sharif University of Technology
    The renal capsule tissue of lamb was irradiated with ultraviolet-C light and the treated samples were analyzed by uniaxial tensile test, dynamic mechanical analysis, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and contact angle measurements. It was shown that the skin cross-linking is dominant in low doses in accordance with the contact angle assessment. Conversely, the strong bulk degradation takes place at high doses. Similarly, the bulk cross-linking affects the mechanical tests as to enhance the stiffness at low doses, whereas strong degradation occurs at high doses that mainly arises from the strong bulk chain scission  

    Pulsed laser irradiation for environment friendly reduction of graphene oxide suspensions

    , Article Applied Surface Science ; Vol. 301 , May , 2014 , pp. 183-188 ; ISSN: 01694332 Ghadim, E. E ; Rashidi, N ; Kimiagar, S ; Akhavan, O ; Manouchehri, F ; Ghaderi, E ; Sharif University of Technology
    Graphene oxide (GO) sheets were synthesized through a modified Hummers' method. Using high resolution transmission electron microscopy the thickness of the GO sheets in a multilayer structure of stacked GO sheets was found ∼0.8 nm. A nanosecond pulsed laser (with wavelength of 532 nm and average power of 0.3 W) was applied for effective and environment friendly reduction of the GO sheets in an ammonia solution (pH ∼9) at room temperature conditions. The deoxygenation of the GO sheets by the pulsed laser reduction method was confirmed by using UV-visible, Fourier transform infrared, X-ray photoelectron spectroscopy (XPS) and thermo gravimetric analysis. Based on XPS analysis, the O/C ratio of... 

    Vertically aligned ZnO@CdS nanorod heterostructures for visible light photoinactivation of bacteria

    , Article Journal of Alloys and Compounds ; Vol. 590 , 2014 , pp. 507-513 ; ISSN: 09258388 Zirak, M ; Akhavan, O ; Moradlou, O ; Nien, Y. T ; Moshfegh, A. Z ; Sharif University of Technology
    Vertically aligned ZnO@CdS nanorod heterostructure films with various loadings of CdS nanoparticle shell were synthesized and applied in photoinactivation of Escherichia coli bacteria under visible light irradiation. While neither the bare ZnO nanorods (with band-gap energy (Eg) of ∼3.28 eV) under visible light irradiation nor the nanorod heterostructures in dark exhibited any significant antibacterial activity, the ZnO@CdS nanorod heterostructures (with Eg ∼2.5-2.6 eV) could successfully inactivate the bacteria under visible light irradiation. Furthermore, it was found that an optimum loading of the CdS shell (corresponding to the effective thickness less than ∼15 nm) is required to achieve... 

    Optimal Ag2S nanoparticle incorporated TiO2 nanotube array for visible water splitting

    , Article RSC Advances ; Volume 4, Issue 15 , 2014 , Pages 7838-7844 ; ISSN: 20462069 Gholami, M ; Qorbani, M ; Moradlou, O ; Naseri, N ; Moshfegh, A. Z ; Sharif University of Technology
    Free-standing TiO2 nanotube array (TNA) films were fabricated via two-step anodization of a titanium sheet. The X-ray diffraction pattern indicated amorphous TNAs were transformed into anatase after annealing the films at 500 °C in air. The surface of TNA was modified by a sequential-chemical bath deposition (S-CBD) method to fabricate Ag2S nanoparticles and forming TNA/Ag2S-n nanostructure, by varying the number of cycles (n). Based on SEM observations, the produced films consisted of vertically ordered tubular structure arrays, each with 125 nm in diameter and 4.1 μm in length containing silver sulphide nanoparticles of ∼12 nm diameter. X-Ray photoelectron spectroscopy (XPS) confirmed the... 

    Synthesis of graphene from natural and industrial carbonaceous wastes

    , Article RSC Advances ; Vol. 4, issue. 39 , 2014 , p. 20441-20448 Akhavan, O ; Bijanzad, K ; Mirsepah, A ; Sharif University of Technology
    Graphene oxide (GO) and reduced graphene oxide (rGO) sheets have usually been synthesized through Hummers' method by using highly pure graphite (HPG) as the main starting material. However, HPG can be relatively expensive for mass production of high-quality graphene. In this work, a general method for synthesis of high-quality GO and rGO sheets from various natural and industrial carbonaceous wastes such as vegetation wastes (wood, leaf, bagasse, and fruit wastes), animal wastes (bone and cow dung), a semi-industrial waste (newspaper), and an industrial waste (soot powders produced in exhaust of diesel vehicles) was developed. Based on atomic force microscopy, Raman spectroscopy, X-ray...