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Feasibility Study of Deposition by SUT-PF
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor)
Abstract
Sharif University of Technology Plasma Focus (SUT-PF) is a Mather Type DPF device which has a 39 μF capacitor bank with 14 KV charging ability at its ultimate limit corresponding to 7 KJ stored energy. In the first step of this experiment, a test has been done at three distances 5, 7, 10 cm from anode tip with the different number of shots 20, 30, and 40 at 0 constant angles.In the following, a test is done at 5 and 10 degrees with 40 shots, and PF chamber has been filled up with nitrogen gas. Various tests have carried out for survey of this experiment, the result of which are as follow:The X-ray diffraction (XRD) analysis are used in order to reveal if the Nickel or Nickel nitride have...
Transport Properties in Heterostructures of 2D Layers of Graphene with WS2 and hBN Quantum Dots
, M.Sc. Thesis Sharif University of Technology ; Simchi, Abdolreza (Supervisor)
Abstract
Graphene based photodetectors which are modified with quantum dots, are the new generation of detectors. In these supplies an integration of graphene’s unique characteristics like high conductivity and mobility and the high light absorption of quantum dots, are used.In this research graphene by chemical vapor deposition in centimetric large scales, tungsten disulfide quantum dots, boron nitride and graphene quantum dots and 2D tungsten disulfide have been synthesized. In the next step each of them were characterized to modify the quality of used layers in heterostructure.Based on the characteristic tests, quantum dots aspect ratios were 1 to 5 nanometers. Also tungsten disulfide was obtained...
Experimental Investigation of Asphaltene Precipitation and Deposition in Enhanced Oil Recovery by Low Salinity Waterflooding
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahabadin (Supervisor) ; Fatemi, Mobin (Supervisor)
Abstract
Asphaltenes are a polydisperse mixture of the heaviest and most polarizable fractions of the crude oil. They are defined according to their solubility properties as being soluble in aromatic solvents but insoluble in light paraffin solvents. Asphaltenes are usually responsible for many problems like wettability changes of the reservoir rock, pore clogging in the reservoir porous matrix and fouling in wellbore tubing and production surface facilities. Most of the studies in the literature, addressing the asphaltene precipitation and deposition (APD), are investigating natural depletion or gas injection process such as CO2 flooding. These studies show that asphaltene deposition and...
The Effect of Surface, Morphology, and Composition of Semiconductor Layer on the Back Reaction of Electrons in Dye Sensithized Solar Cells:Theoritical and Experimental Investigation
, Ph.D. Dissertation Sharif University of Technology ; Taghavinia, Nima (Supervisor) ; Nafari, Nasser (Supervisor)
Abstract
This thesis deals with a theoretical and experimental investigation of different approaches for reduction of electronic recombination in the semiconductor/Dye interface of dye sensitized solar cells (DSSC) including dye coverage, core-shell structures and energy level distributions. Interface of ZnO/TiO2 in the core-shell structure have been studied by density functional theory and the energy level distribution of surface atoms, recombination and Fermi level changes, open circuit voltage and surface dipole distributions have been discussed.
The presence of TiO2 shell increases the ZnO surface dipole moment, and shifts the ZnO conduction and valence bands to higher energies. Also, it...
The presence of TiO2 shell increases the ZnO surface dipole moment, and shifts the ZnO conduction and valence bands to higher energies. Also, it...
Electrodeposition of Cu/WC Nanocomposite
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor) ; Afshar, Abdollah (Supervisor)Design and Fabrication of Electronic Subsystems for NFCVD
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bizhan (Supervisor)
Abstract
The fabrication of future electronic and optical devices will require advanced nanofabrication techniques that realize high spatial resolution and high precision in controlling size and position, and that are applicable to various materials. Near-field CVD (NF-CVD) was proposed to solve these problems with no need to perform nanolithography prcesses. NFCVD system has two major subsystems, first vacuum chamber and gas distribution system for delivering parent gases to the chamber and second, a nanopositiong system to keep the probe and the sample in the constant systems.In this dissertation we have set up a piezoelectric nanopositiong system and its driver modules. The positioning accuracy...
Using of SnS2 Nanostructured Layer as an Electron Transport Layer in the Perovskite Solar Cells
, Ph.D. Dissertation Sharif University of Technology ; Mahdavi, Mohammad (Supervisor) ; Taghavinia, Nima (Supervisor) ; Mohammadpour, Raheleh (Co-Supervisor)
Abstract
In this research, we focus on study and investigation of the role of Tin(IV) Sulfide (SnS2) nanostructured layer as electron transport layer in perovskite and chalcogenide thin film solar cells. For this purpose, SnS2 powder was prepared through hydro/solvo-thermal method, utilizing different ratios of water and ethanol as solvent and various sulfur sources (thioacetamide and thiourea). Afterwards, different solvents were investigated to achieve a stable ink (about one month) with uniform dispersion. After determining the appropriate ink and powder, thin films of SnS2 were prepared employing spin coating, spray pirolysis and laser pulsed deposition (PLD) methods and characterized. With each...
Solid-phase Microextraction of BTEXs by Sol-Gel-Based Trimethoxy Silyl Propyl Methacrylate Fiber
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
Conventional solid phase microextraction fibers posses relatively low recommended operating temperature, instability and swelling in organic solvents, breakage of the fiber, stripping of coatings, and bending of the needle. Some of these problems have been obviated by covalent bonding of the polymer phase to the fused-silica substrate by sol-gel technology, but the easy breakage of the fiber still is a remaining challenge In this work, after successful fabrication of unbreakable SPME fibers based on 3-(trimethoxysilyl)propyl methacrylate precursor deposited on the surface of copper wire, the same approach was carried out to synthesis new sol-gel based SPME fibers. Three different coated...
Kinetic Modeling of Coke Formation and Deactivation in Catalytic Dehydrogenation of Propane
, M.Sc. Thesis Sharif University of Technology ; Khorasheh, Farhad (Supervisor) ; Nazeran, Iraj (Co-Advisor)
Abstract
The study on the propane dehydrogenation process has been receiving significant attention due to the growing demand for propylene. Many efforts have been made to enhance the propylene yield by developing new catalysts with high-activity, high-stability and high-selectivity. Among these, platinum supported catalysts have been reported widely. Firstly, the current study mentions related work in the modeling of coke formation and deactivation of catalyst, experimental setup and catalysts which are conventionally used for propane dehydrogenation reaction. Then, a monolayer–multilayer mechanism is proposed for modelling the coke formation. In addition, the reaction rate of coke formation and its...
Synthesis and properties of Fe-Pd Shape Memory thin Films by Electrodeposition
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor) ; Dolati, Abolghasem (Supervisor)
Abstract
In this study, an alkaline bath for co-deposition of Fe and Pd was selected. In order to investigate the mechanism of deposition, each of the metals iron and palladium electrodeposited from selected bath separately; and the kinetics of electrodeposition by electrochemical techniques such as linear voltammetry, cyclic voltammetry, chronoamperometry and chronopotentiometry were evaluated. Electrodeposition processes of Fe, Pd and their alloy were irreversible and under diffusion of reducing agents are controlled. Moreover the electroreduction of palladium from utilized bath was performed in two steps. At following, the mechanism of iron– palladium alloy electrocrystallization was discussed and...
Deposition and Analysis of Indium-Tin-Oxide NanoStructures Using Sputtering
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bijan (Supervisor)
Abstract
Transparent conductive materials have been widely used in semiconductor technology. Among them all, Indium tin oxide (ITO) has been utilized as electrodes in liquid crystal displays, solar cells, heat reflecting films and gas sensors.In general, the desired properties of transparent conductive oxides are high conductance and transmission. However, due to the complexity of ITO molecular structure, the film properties strongly depend on the depositon parameters.In first part of this thesis, physical properties and electrical characteristic of ITO films, different deposition techniques, and effects of deposition parameters (substrate temperature, pressure, power, etc. ) on film properties are...
Experimental and Theoretical Study of Hydrodynamic Behavior and Mechanisms of Asphaltene Deposition
, Ph.D. Dissertation Sharif University of Technology ; Ghotbi, Cyrus (Supervisor) ; Taghikhani, Vahid (Supervisor) ; Shahrabadi, Abbas (Supervisor)
Abstract
In this work, a new model based on the multilayer adsorption kinetic mechanism and four material balance equations for oil, asphaltene, gas and water phase has been developed to account asphaltene deposition in porous media under dynamic condition and the model was verified using experimental data obtained in this work and also with those reported in the literature. The results showed that the developed model can correlate more accurately the oil flooding experimental data in comparison to the previous models based on the mechanical plugging mechanism, in particular in carbonate core samples. Also, a series of experiments was carried to determine the permeability reduction of carbonate,...
Synthesis of Graphene Structures by Chemical Vapor Deposition Method and Evaluation of their Electrical and Biological Properties
, M.Sc. Thesis Sharif University of Technology ; Simchi, Abdolreza (Supervisor)
Abstract
Graphene is a newly developed nanomaterial that has resived considerable attention in recent years. Graphene – based structures having remarkable properties, e.g. high specific surface area, ultrahigh electrical conductivity and good biocompability, are ideal choices for nanomedical applications such as biosensors and cell culture scaffolds. So, in this project 2D graphene and 3D graphene foam structures were synthesized by chemical vapor deposition (CVD) method and their electrical and biological properties were evaluated. First step of this project was to design and make a CVD system suitable for the synthesis of high quality graphene structures, i.e. single layer graphene and 3D graphene...
Functional Design of a Coating System for the Telescope Mirrors, A Recognition to Telescope of Iranian National Observatory
, M.Sc. Thesis Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Khosroshahi, Habib (Co-Advisor)
Abstract
Functional design of coating system for the primary mirror of the Iranian National Observatory (INO) is done. This telescope has a 3.4 m primary mirror in diameter, made of Zerodur from Schott. Although similar coating systems are in use since years ago, this is the first attempt to design a system for such a large surface case in Iran. Systematic approach led us first to clarify and identifying the design requirements. Lower limit of 80% for reflectance on all wavelength range from 325-1000 nm, thickness of 100 nm with un-uniformity of 5 nm, adhesion enough to pass the selotape test and surface roughness of less than 8 nm. Study of the available methods for coating and selection of the best...
The Effects of Catalyst Preparation Parameters on Carbon Nanotube Growth
, Ph.D. Dissertation Sharif University of Technology ; Vessaghi, Mohammad Ali (Supervisor) ; Taghavinia, Nima (Co-Advisor) ; Shafiekhani, Azizollah (Co-Advisor)
Abstract
In this study three different methods; hot filament chemical vapor deposition (HFCVD), pulsed laser ablation (PLA) and electrochemical deposition were utilized to prepare catalyst thin films or nanoparticles and thermal chemical vapor deposition (TCVD) was used to grow multiwall carbon nanotubes (MWCNTs). We found that even though the three mentioned techniques have been rarely applied by researchers, they are appropriate and efficient methods to produce catalytic basis for CNT growth. In the TCVD step, liquid petroleum gas (LPG) was applied as carbon source. Although, this gas is a mixture of different hydrocarbons and further contains some sulfur, our results verify that utilizing of LPG...
Investigation on Parameters of Carbon Nanotubes Growth and Effect of Interaction between H2 Gas and their Surfaces and Determining Capacity of Hydrogen Storage
, Ph.D. Dissertation Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Nozad, Ahmad (Supervisor)
Abstract
In this study, growth of MWCNTs in form of thin film and powder for hydrogen storage was investigated. Different analytical techniques including SEM, TEM, STA, XRD, XPS, BET, BJH and Raman spectroscopy were applied to characterize the samples. The results showed that substrate, catalyst thickness and type of catalyst are influenced in yield of the growth, structure and quality of MWCNTs. The study has also indicated that MWCNTs grown on Fe-Pd bimetallic catalyst with 25-75 proportion had the highest growth yield. Moreover, decreasing of the growth temperature from 970 to 920 oC produced single-walled carbon nanotubes (SWCNTs) with high quality (IG/ID = 15.8) and low growth yield....
Electrochemical Preparation and Study of Transitional Metal Mixed Oxides as Supercapacitor Electrodes
, Ph.D. Dissertation Sharif University of Technology ; Gobal, Fereydoon (Supervisor)
Abstract
In this thesis, the improving effects of deposited metal oxides onto or next to each other and the advantages of every metal oxide were considered. In the next step, the substrate improvement was studied and the porous metal oxides with ideal supercapacitive properties with porosity increase of substrate were obtained.CoFeO2 supercapacitor was prepared by chronoamperometric ethod.CoFeO2waselectrodeposited at room temperature and presents wide potential window and good capacitive properties in comparison with other metal oxides.Layers of cobalt and manganese oxides were co-deposited or deposited on top of each other or next to each other by chronometric method onto stainless steel substrate....
Synthesize and Characterization of 2D WS2 Nano-layers for Next Generation Optoelectronic Devices
, M.Sc. Thesis Sharif University of Technology ; Simchi, Abdolreza (Supervisor)
Abstract
Transition Metal Dichalcogenids (TMD) are types of 2D materials that exibit wide range of electronic, optical, mechanical, chemical, and thermal properties. These materials with MX2 general formula, have atract attentions with respect to their unusual properties because of their very limited dimensions. Their tunable properties and materials availibility make them attractive for wide range of applications. In recent years, chemical vapor deposition (CVD) methods are promising in preparing high quality TMD with scalable size, controllable thickness, and very excellent electronic properties. Also, chalenges are remaining in synthesis and transfering of TMD are difficulty for most of...
Investigation of Asphaltene Electro-deposition In Presence of Addetives
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahabodin (Supervisor) ; Dehghani, Farzaneh ($item.subfieldsMap.e)
Abstract
Given the decreasing trend of light petroleum reserves and the necessity to produce heavy and extra-heavy oil resources, the challenge of dealing with existing asphaltene related problems, which is the heaviest and the most complex component of crude oil, has become increasingly tangible. Asphaltene precipitates and deposits due to pressure, temperature or composition alterations which leads to obstruction of porous media and production facilities. Set the costly methods aside, one of the available approaches to prevent asphaltene precipitation, is to apply an electric field upon the suspected zone, which is cheap and uncomplicated. Besides, utilizing nano-particles while applying electric...
Control of Size of Graphene Domain Synthesized by Chemical Vapor Deposition
, M.Sc. Thesis Sharif University of Technology ; Ghotbi, Sirus (Supervisor) ; Karimi Sabet, Javad (Supervisor)
Abstract
The chemical vapor deposition (CVD) of graphene from methane on a copper substrate is the most promising method for production of large-area graphene films. There have been long-standing challenges in this field such as controlling the graphene coverage, film quality, the number of layers, and the nucleation density of graphene domain. These challenges can be overcome by developing a fundamental understanding of the graphene growth process. The main aim of this study is to control nucleation density of graphene domains. Chemical vapor deposition (CVD) graphene is polycrystalline, and grain boundaries in graphene film have been identified to degrade the properties of graphene as a membrane...