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Nickel Nano Particles Pulse Electrodeposition
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor)
Abstract
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...
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...
Study of CdS thin Film Deposition on Single Layer Grapheme using Close Space Sublimation and SILAR Methods
, M.Sc. Thesis Sharif University of Technology ; Asgari, Sirous (Supervisor)
Abstract
Cadmium sulfide (CdS) thin films were successfully fabricated in argon atmosphere on glass slides and Single Layer Graphene(SLG)/Cu foil stack by close space sublimation technique in three different deposition temperatures. Successive Ionic Layer Adsorption and Reaction (SILAR) technique is used as a complementary technique for better and denser layers. Analysis techniques such as Grazing Incident X-ray Diffraction (GIXRD) and Scanning Electron Microscope images were used for structural study of the deposited layers. Polycrystallinity and hexagonal wurtzite structure of the thin films is confirmed. For band gap calculations and for determination of optical behavior of the layers in different...
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 ; Nemati, Ali (Supervisor) ; Mahdavi, Mohammad (Co-Advisor)
Abstract
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...
Enhancing glass ionomer cement features by using the HA/YSZ nanocomposite: A feed forward neural network modelling
, Article Journal of the Mechanical Behavior of Biomedical Materials ; Vol. 29 , January , 2014 , pp. 317-327 ; ISSN: 17516161 ; Salehi, S ; Nemati, A ; Tavakoli, R ; Solati Hashjin, M ; Sharif University of Technology
Abstract
Despite brilliant properties of glass ionomer cement (GIC), its weak mechanical property poses an obstacle for its use in medical applications. The present research aims to formulate hydroxyapatite/yttria-stabilized zirconia (HA/YSZ) in the composition of GIC to enhance mechanical properties and to improve fluoride release of GIC. HA/YSZ was synthesized via a sol-gel method and characterized by applying X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photo-emission spectroscopy (XPS) and simultaneous thermal analysis (STA) along with transmission electron microscopy (TEM) methods. The synthesized nanocomposite was mixed with GIC at a fixed composition of 5....
Visible light-induced photocatalytic reduction of graphene oxide by tungsten oxide thin films
, Article Applied Surface Science ; Volume 276 , 2013 , Pages 628-634 ; 01694332 (ISSN) ; Akhavan, O ; Sharif University of Technology
2013
Abstract
Tungsten oxide thin films (deposited by thermal evaporation or sol gel method) were used for photocatalytic reduction of graphene oxide (GO) platelets (synthesized through a chemical exfoliation method) on surface of the films under UV or visible light of the environment, in the absence of any aqueous ambient at room temperature. Atomic force microscopy (AFM) technique was employed to characterize surface morphology of the GO sheets and the tungsten oxide films. Moreover, using X-ray photoelectron spectroscopy (XPS), chemical state of the tungsten oxide films and the photocatalytic reduction of the GO platelets were quantitatively investigated. The better performance of the sol-gel tungsten...
Effect of electrolyte concentration on microstructure and properties of micro arc oxidized hydroxyapatite/titania nanostructured composite
, Article Materials Science and Engineering C ; Volume 33, Issue 5 , 2013 , Pages 2555-2561 ; 09284931 (ISSN) ; Golestani Fard, F ; Mirhosseini, S. M. M ; Ziaee, A ; Mehrjoo, M ; Sharif University of Technology
2013
Abstract
Micro arc oxidation was employed to grow TiO2/hydroxyapatite composite layer on titanium substrate. The correlation between electrolyte concentration, diameter and density of the pores in fabricated layers was investigated. Therefore, the effect of electrolyte concentration on composition and morphology of grown layers was studied using SEM, EDX, XRD and XPS techniques. Samples were coated in electrolytes containing 5, 10 and 15 g/l calcium acetate and 1, 3 and 5 g/l β-glycerophosphate, at optimized voltage for 3 min. Pore size variations obey a similar pattern by the addition of both calcium acetate and β-glycerophosphatein various concentrations based on SEM observations. However,...
Synthesis of W17O47 nanothick plates with preferred orientation and their photocatalytic activity
, Article Surface and Interface Analysis ; Volume 43, Issue 11 , 2011 , Pages 1397-1402 ; 01422421 (ISSN) ; Khosravi, P ; Moshfegh, A. Z ; Sharif University of Technology
Abstract
A simple method for synthesis of W17O47 nanothick plates by annealing sol-gel-deposited tungsten oxide thin films on soda lime substrate has been reported. After heat treatment of the dried thin films at 700 °C in N2 ambient for 60 min, W17O47 nanothick plates with [100] orientation were obtained. The synthesized product was characterized and analyzed by, X-ray diffraction (XRD), SEM, XPS and ultraviolet-visible spectrophotometery. According to SEM observations, nanothick plates grew with random orientations on the surface. In addition, it was observed that some of the nanothick plates were constituted from several nanosheets. XRD analysis determined that the nanothick plates were mainly...
Effect of annealing temperature on growth of Ce-ZnO nanocomposite thin films: X-ray photoelectron spectroscopy study
, Article Thin Solid Films ; Volume 520, Issue 2 , November , 2011 , Pages 721-725 ; 00406090 (ISSN) ; Azimirad, R ; Amiri, M ; Moshfegh, A. Z ; Sharif University of Technology
2011
Abstract
Ce-doped ZnO nanocomposite thin films with Ce/Zn ratio fixed at optimum value (10 at.%) have been prepared via sol-gel method at different annealing temperatures varied from 180 to 500 °C. The synthesized samples were characterized employing atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) techniques. According to AFM analysis, the average grain size increased from about 70 nm to 150 nm by increasing the annealing temperature from 300 to 500 °C. Moreover, based on the XPS data analysis, it was found that three major metal ions namely Ce 3+, Ce4+, and Zn2+ coexist on the surface of the nanocomposite films. XPS data analysis also revealed that...
Photoresponse and H2 production of topographically controlled PEG assisted Sol-gel WO3 nanocrystalline thin films
, Article International Journal of Hydrogen Energy ; Volume 36, Issue 21 , October , 2011 , Pages 13461-13472 ; 03603199 (ISSN) ; Yousefzadeh, S ; Daryaei, E ; Moshfegh, A. Z ; Sharif University of Technology
2011
Abstract
WO3 thin films were fabricated by sol-gel method using polyethylene glycol (PEG) as dispersing agent. Physical and photoelectrochemical properties of the synthesized nanocrystalline films were studied by varying weight ratio of PEG to tungsten precursor (x). Based on AFM observations and statistical modeling of the WO3 surface, the thickness of the films increased by increasing the amount of x with a nearly linear fashion while the surface roughness reached to a saturated value. However, the film synthesized with x = 4 showed a chaotic surface behavior. Optical analysis revealed that by increasing the x, transmittance of the films decreased while their band gap energies remained unchanged....
Enhanced photoelectrochemical activity of Ce doped ZnO nanocomposite thin films under visible light
, Article Journal of Electroanalytical Chemistry ; Volume 661, Issue 1 , 2011 , Pages 106-112 ; 15726657 (ISSN) ; Amiri, M ; Azimirad, R ; Moshfegh, A. Z ; Sharif University of Technology
Abstract
Ce-doped ZnO and pure ZnO nanocomposite thin films with different Ce/Zn ratios (0, 2, 5, 10, 15, 20, and 30 at.%) have been prepared by sol-gel method at optimum annealing temperature of 500 °C. The synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectrophotometry. According to our XPS data analysis, there are three major metal ions namely Ce3+, Ce4+ and Zn 2+ that coexist on the surface. The XRD measurements indicate that the ZnO thin films have a hexagonal wurtzite structure, and CeO2 crystallites formed in the Ce-doped ZnO nanocomposite thin films. Photoelectrochemical property of the samples was studied by three...
A photocatalytic approach in micro arc oxidation of WO3-TiO 2 nano porous semiconductors under pulse current
, Article Materials Chemistry and Physics ; Volume 128, Issue 3 , 2011 , Pages 427-432 ; 02540584 (ISSN) ; Golestani Fard, F ; Moshfegh, A. Z ; Molaei, R ; Sharif University of Technology
2011
Abstract
Since ultraviolet (UV) irradiation cannot be applied for a long time in practical applications, it is necessary to develop a narrow band gap photocatalyst to decompose environmental pollutants under visible irradiation. In this research, (WO3)x-(TiO2)1-x nano-porous layers were fabricated by micro arc oxidation (MAO) and influence of the electrical current type on their physical and chemical properties was investigated. Morphological studies, performed by SEM technique, revealed that pore size and roughness decreased with the frequency and increased with the duty cycle. The pulse-grown layers had a finer structure when compared to those fabricated under direct current. XRD and XPS results...
Melatonin as a powerful bio-antioxidant for reduction of graphene oxide
, Article Journal of Materials Chemistry ; Volume 21, Issue 29 , 2011 , Pages 10907-10914 ; 09599428 (ISSN) ; Akhavan, O ; Irajizad, A ; Sharif University of Technology
2011
Abstract
Graphene is usually synthesized through deoxygenation of graphene oxide (GO) by hydrazine as the most common and one of the strongest reducing agents. But, due to the high toxicity of hydrazine, it is not a promising reductant in large-scale production of graphene. Here, for the first time, we used melatonin (MLT), as a powerful antioxidant and a biocompatible competitor of hydrazine in reduction of GO suspension. X-ray photoelectron spectroscopy (XPS), current-voltage and optical characteristics of the sheets indicated that the deoxygenation efficiency of the GO suspensions by MLT and under heating in an alkaline condition for 3 h was comparable with the efficiency obtained by hydrazine in...
CuO/Cu(OH)2 hierarchical nanostructures as bactericidal photocatalysts
, Article Journal of Materials Chemistry ; Volume 21, Issue 26 , May , 2011 , Pages 9634-9640 ; 09599428 (ISSN) ; Azimirad, R ; Safa, S ; Hasani, E ; Sharif University of Technology
2011
Abstract
Various morphologies of CuO/Cu(OH)2 nanostructures with different adsorbed -OH contents were synthesized on an acid-treated Cu foil through variation of NaOH concentration from 0 to 50 mM with an in situ oxidation method. X-ray diffractometry and X-ray photoelectron spectroscopy (XPS) indicated formation of CuO on the Cu(OH)2 crystalline phase at a growth temperature of 60°C for 20 h. Antibacterial activity of the nanostructures against Escherichia coli bacteria was studied in the dark and under light irradiation. The nanostructures grown at a NaOH concentration of 30 mM showed the highest surface area and the strongest antibacterial activity among the samples. After elimination of the...
A strategy for single-step elaboration of V2O 5-grafted TiO2 nanostructured photocatalysts with evenly distributed pores
, Article Journal of Alloys and Compounds ; Volume 509, Issue 21 , 2011 , Pages 6236-6241 ; 09258388 (ISSN) ; Molaei, R ; Moshfegh, A. Z ; Golestani-Fard, F ; Sharif University of Technology
2011
Abstract
V2O5-TiO2 nanostructured porous layers were grown through micro arc oxidation of titanium in vanadate containing electrolytes. This study sheds light on the effect of the electric current type on the photocatalytic performance of the layers. Surface morphology of the layers was investigated by SEM. The results revealed a porous structure with a pores size of 30-180 nm depending on the frequency and the duty cycle. A uniform porous structure was obtained under the pulse-DC regime. Topographical investigations revealed a rough surface which is favorable for catalytic applications. Our XRD and XPS results showed that the layers consisted of anatase, rutile, and vanadium oxide phases whose...
Hydrogen sensor based on surface activated WO3 films by Pd nanoclusters
, Article World Academy of Science, Engineering and Technology ; Volume 76 , 2011 , Pages 639-642 ; 2010376X (ISSN) ; Zad, A. I ; Mahdavi, S. M ; Sharif University of Technology
2011
Abstract
Tungsten trioxide has been prepared by using P-PTA as a precursor on alumina substrates by spin coating method. Palladium introduced on WO 3 film via electrolysis deposition by using palladium chloride as catalytic precursor. The catalytic precursor was introduced on the series of films with different morphologies. X-ray diffractometry (XRD), Scanning electron microscopy (SEM) and XPS were applied to analyze structure and morphology of the fabricated thin films. Then we measured variation of samples' electrical conductivity of pure and Pd added films in air and diluted hydrogen. Addition of Pd resulted in a remarkable improvement of the hydrogen sensing properties of WO 3 by detection of...
Micro arc oxidation of nano-crystalline Ag-doped TiO2 semiconductors
, Article Materials Letters ; Volume 65, Issue 5 , March , 2011 , Pages 840-842 ; 0167577X (ISSN) ; Aminzare, M ; Molaei, R ; Sadrnezhaad, S. K ; Sharif University of Technology
2011
Abstract
Simple synthesis of silver doped TiO2 nanostructured layers by micro arc oxidation process is reported for the first time. The layers consisted of anatase and rutile phases whose characteristic XRD-peaks shifted toward lower diffraction angles when compared to the pure micro arc oxidized TiO 2 layers. Silver-doping was confirmed by XPS technique. The anatase phase crystalline size was determined as 27.6 and 21.8 nm for the layers grown under the voltages of 350 and 500 V. Employing a UV-Vis spectrophotometer, a red shift in the absorption edge of the layers was observed when silver was incorporated into the titania lattice
Field-emission enhancement of molybdenum oxide nanowires with nanoprotrusions
, Article Journal of Nanoparticle Research ; Volume 13, Issue 1 , January , 2011 , Pages 115-125 ; 13880764 (ISSN) ; Azimirad, R ; Nien, Y. T ; Moshfegh, A. Z ; Sharif University of Technology
2011
Abstract
The field-emission properties of molybdenum oxide nanowires grown on a silicon substrate and its emission performance in various vacuum gaps are reported in this article. A new kind of molybdenum oxides named nanowires with nanoscale protrusions on their surfaces were grown by thermal vapor deposition with a length of ~1 μm and an average diameter of ~50 nm. The morphology, structure, composition and chemical states of the prepared nanostructures were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). According to XRD, XPS, and TEM analyses, the synthesized samples...
Structural ordering, morphology and optical properties of amorphous AlxIn1- xN thin films grown by plasma-assisted dual source reactive evaporation
, Article Journal of Alloys and Compounds ; Volume 632 , May , 2015 , Pages 741-747 ; 09258388 (ISSN) ; Ganesh, V ; Mehdipour, H ; Nazarudin, N. F. F ; Goh, B. T ; Shuhaimi, A ; Rahman, S. A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Amorphous aluminum indium nitride (AlxIn1- xN) thin films were deposited on quartz substrates by plasma-assisted dual source reactive evaporation system. In-rich (x = 0.10 and 0.18) and Al-rich (x = 0.60 and 0.64) films were prepared by simply varying an AC voltage applied to indium wire. The X-ray-diffraction patterns revealed a small broad peak assigned to Al0.10In0.90N (0 0 2) plane, but no perceivable peaks assigned to crystalline AlxIn1- xN were observed for the films with x = 0.18, 0.60 and 0.64. The morphology of the film was changed from clusters of small grains to uniformly shaped particles with decrease of x. The band gap energy of the films increased from 1.08 eV to 2.50 eV as the...
Hydrogen-rich water for green reduction of graphene oxide suspensions
, Article International Journal of Hydrogen Energy ; Volume 40, Issue 16 , 2015 , Pages 5553-5560 ; 03603199 (ISSN) ; Azimirad, R ; Gholizadeh, H. T ; Ghorbani, F ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Abstract H2-rich water as a green antioxidant was applied for deoxygenation of graphene oxide (GO) suspensions. The ability of H2-rich water for deoxygenation of GO sheets was found comparable to the ability of hydrazine (as a standard and powerful reductant), using X-ray photoelectron spectroscopy. In fact, the O/C ratio of GO sheets could be reduced from 0.51 to 0.21 and 0.16 by H2-rich water and hydrazine, respectively. More importantly, while C-N bond formation is one of the side effects of GO reduction by hydrazine, no chemical C-N bond was found on the H2-water-reduced GO (rGO) sheets. This also resulted in a better restoration of the graphitic structure of the H2-water-rGO, as...
On the photocatalytic activity of the sulfur doped titania nano-porous films derived via micro-arc oxidation
, Article Applied Catalysis A: General ; Volume 389, Issue 1-2 , 2010 , Pages 60-67 ; 0926860X (ISSN) ; Moshfegh, A. Z ; Golestani Fard, F ; Sharif University of Technology
2010
Abstract
Sulfur doped TiO2 layers containing nano/micro-sized pores were synthesized by micro-arc oxidation process. Effect of the applied voltage and the electrolyte composition on physical and chemical properties of the layers was investigated using SEM, AFM, XRD, XPS, and EDS techniques. A UV-vis spectrophotometer was also used to study optical properties of the layers. It was found that the doped layers were porous with a pore size of 40-170 nm. They consisted of anatase and rutile phases with varying fraction depending on the applied voltage and electrolyte concentration. Our XPS investigations revealed the existence of sulfur in the forms of S4+ and S6+ states which substituted Ti4+ in the...