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    Critical Current Density Optimization of High-T_c Superconductor

    , M.Sc. Thesis Sharif University of Technology Baharlooie, Elahe (Author) ; Fardmanesh, Mehdi (Supervisor)
    Fabrication of bulk superconductors with high critical current density widely has been studied because they have many applications, for example, Fault Current Limiter (SFCL), Superconducting Magnetic Energy Storage (SMES), and magnetic levitation. Providing pinning center by addings impurity into superconductor is usual and simple solution for increasing the superconductor critical current density. In this project we have fabricated superconductor YBCO bulk and optimized its critical current density. There are two major stream in this thesis, first design of Vibrating System Magnetization (VSM) for critical current measurements and then fabrication of YBCO bulk and optimization of its... 

    Design and Implementation of Vibrating Sample Magnetometer Based on Gradiometer RF SQUID

    , M.Sc. Thesis Sharif University of Technology Hosseini, Nahid (Author) ; Fardmanesh, Mehdi (Supervisor)
    The aim of this project is design and implementation of the “gradiometer RF SQUID base Vibrating Sample Magnetometer (VSM)”. Different sections of the system have been designed such as pick up coils, vibration system and electronic circuits. The piezoelectric crystal has been concerned for vibration system. At the first step, we have implemented the basic VSM system. In the basic system, voltage induces in two series opposite pick up coils and its output is recognizable via electronic circuits. At the second phase of the project, the electronic circuits of basic VSM system have been replaced with the RF SQUID gradiometer and its electronic circuits. Afterwards, the sensitivity and the gain... 

    Optimized design and implementation of low-cost, sensitive and versatile vibrating sample magnetometer

    , Article ICEE 2012 - 20th Iranian Conference on Electrical Engineering, 15 May 2012 through 17 May 2012 ; May , 2012 , Pages 202-205 ; 9781467311489 (ISBN) Hosseini, N ; Khiabani, S ; Sarreshtedari, F ; Fardmanesh, M ; Sharif University of Technology
    Geometry of different electromagnetic parts of Vibrating Sample Magnetometer (VSM) is a major factor of VSM output voltage. In this paper design, geometry optimization and implementation of a sensitive, versatile and relatively inexpensive VSM system has been described. Considering all effective geometrical parameters in the system output voltage, the induced voltage in the pick-up coils has been obtained analytically and the geometry of the pick-up coils has been optimized for maximum output induced voltage. Two opposite series of pick-up coils, piezoelectric based vibration system and required electronic circuits have been designed and the VSM system has been implemented. The implemented... 

    Effects of Ce–Co substitution on structural, magnetic and dielectric properties of M-type barium hexaferrite nanoparticles synthetized by sol–gel auto-combustion route

    , Article Journal of Materials Science: Materials in Electronics ; Volume 26, Issue 4 , 2015 , Pages 2134-2144 ; 09574522 (ISSN) Lalegani, Z ; Nemati, A ; Sharif University of Technology
    Springer New York LLC  2015
    M-type Ce–Co substituted barium hexaferrite nanoparticles were synthesized by sol–gel auto-combustion route. The general formula of ferrites was Ba1−xCexFe12−xCoxO19 in which the x was considered to be: x = 0, 0.1, 0.2, and 0.3. The formed phases in the samples were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, Mössbauer spectroscopy and vibrating sample magnetometer. The results indicated that an increase in substitutional ion amount caused to decrease vibration frequencies of Fe–O band in the tetrahedral site due to the substitution of heavier Co2+ ion for Fe3+ ion in the tetrahedral site. Moreover, some of Ce3+ ions was transformed to Ce4+ and... 

    Structural Rietveld refinement and magnetic features of prosademium (Pr) doped Cu nanocrystalline spinel ferrites

    , Article Ceramics International ; Volume 45, Issue 8 , 2019 , Pages 10187-10195 ; 02728842 (ISSN) Niaz Akhtar, M ; Babar, M ; Qamar, S ; ur Rehman, Z ; Azhar Khan, M ; Sharif University of Technology
    Elsevier Ltd  2019
    Pr doped spinel nanoferrites having following composition Cu Pr x Fe 2-x O 4 (x = 0, 0.25, 0.50, 0.75, 1.00) were synthesized using sol-gel route. Prosademium (Pr) which is a rare earth metal was doped to tailor the properties of the Cu spinel nanoferrites. Characterization tools such as FTIR, XRD, FESEM and VSM were employed to investigate the phase, absorption bands, structure, microstructure and magnetic properties. FTIR was used to see the absorption bands and force constants of the Pr doped Cu spinel nanoferrites. Crystallite size, lattice parameters, cell volume and micro strains were determined from XRD data. Bulk density, X-ray density and porosity of the Pr doped Cu spinel... 

    Solution Combustion Synthesis of Spinel-type (Cu,Co) 3O4 Nanopowder

    , M.Sc. Thesis Sharif University of Technology Ghorbanzadeh, Milad (Author) ; Yoozbashizadeh, Hossein (Supervisor)
    In this study, nano-powders of copper-cobalt spinel (CuCo2O4) were fabricated by solution combustion synthesis (SCS) of Cu and Co nitrates with urea, glycine,acid citric and alanine. The method involved exothermic decomposition of viscous liquid nitrates and the fuel. Products which were synthesized by using this fuels contained less impurity constituents. Duo to low purity, other factors which have influence on synthesis process investigated and observed that pH have key role on process. X-ray diffraction (XRD) patterns gave crystal structure and the existing phases. Particle size distribution and morphology changes were studied by dynamic light scattering (DLS) and field emission scanning... 

    Nano-magnetic poly (vinyl alcohol) hydrogels

    , Article Advanced Materials Research ; Volume 829 , 2014 , Pages 539-543 ; ISSN: 10226680 ; ISBN: 9783037859070 Asadi, S ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
    Surface modified magnetic nanoparticles (M-NPs) were synthetized and stabilized in poly (vinylalcohol) solution. The solutions with various magnetic nanoparticles contents were gammairradiated and magnetic poly (vinyl-alcohol) (M-PVA) hydrogels were synthesized. The magnetic hydrogels and also the un-irradiated magnetic poly (vinyl alcohol) nanocomposite films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR) and mechanical measurement. The M-NPs were uniformly dispersed in the polymer matrix due to a strong interaction between the surface-modified M-NPs and polymer matrix.... 

    Effect of Ti-Zn substitution on structural, magnetic and microwave absorption characteristics of strontium hexaferrite

    , Article Journal of Alloys and Compounds ; Vol. 583, issue , 2014 , p. 325-328 Baniasadi, A ; Ghasemi, A ; Nemati, A ; Azami Ghadikolaei, M ; Paimozd, E ; Sharif University of Technology
    SrFe12-xTix/2Zn x/2O19 (x = 0-2.5) powders were synthesized by use of chlorides through co-precipitation method. The obtained powders were then milled by high energy ball mill to crash hard agglomerates and achieve nanoparticles. In order to evaluate microwave absorption versus frequency, composites including ferrite, as a filler, and matrix of polyvinylchloride (PVC) with weight ratio of 70% ferrite were prepared. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) were employed to study the structural, magnetic and microwave absorption properties... 

    L10 FePt Nanoparticles Processing with Applied Magnetic Field

    , Article Journal of Inorganic and Organometallic Polymers and Materials ; Volume 23, Issue 4 , April , 2013 , Pages 881-887 ; 15741443 (ISSN) Sebt, S. A ; Khajehnezhad, A ; Dariani, R. S ; Akhavan, M ; Sharif University of Technology
    Due to the strong magnetic anisotropy energy, the L10 FePt nanocrystals are considered as one of promising candidates for magnetic recording media with ultrahigh densities. The surfaces of Si and SiO2 wafers have been covered by FePt nanoparticles (NPs) and heated at 600 °C for 1 h to form the L10 phase. Bonding of NPs with the SiO2 surface in the presence of magnetic field during annealing process controls the L10 FePt NPs size and their uniform surface distribution. In the presence of perpendicular magnetic field to the surface, the size of NPs obtains up to 30 nm with coercivity of 5.8 kOe and in parallel magnetic field, the NPs size reaches to 45 nm with coercivity of 2.9 kOe. These... 

    Magnetic removal of crystal violet from aqueous solutions using polysaccharide-based magnetic nanocomposite hydrogels

    , Article Polymer International ; Volume 62, Issue 7 , 2013 , Pages 1038-1044 ; 09598103 (ISSN) Pourjavadi, A ; Hosseini, S. H ; Seidi, F ; Soleyman, R ; Sharif University of Technology
    Magnetic Fe3O4@SiO2 starch-graft-poly(acrylic acid) (SPAA) nanocomposite hydrogels were prepared and used as absorbents for removal of crystal violet from aqueous solutions. Dynamic swelling, effect of contact time, absorption kinetics and nanocomposite hydrogel mass for removal of crystal violet dyes from aqueous solutions were studied. Fourier transform infrared spectroscopy, scanning electron microscopy and vibrating sample magnetometer measurements were used for the characterization of the nanocomposite hydrogels. The nanocomposite hydrogels had high magnetic sensitivity under an external magnetic field, which allowed their magnetic separation from water, thus avoiding secondary... 

    Effect of synthesis method on magnetic and thermal properties of polyvinylidene fluoride/Fe3O4 nanocomposites

    , Article Journal of Reinforced Plastics and Composites ; Volume 32, Issue 14 , 2013 , Pages 1044-1051 ; 07316844 (ISSN) Frounchi, M ; Hadi, M ; Sharif University of Technology
    Polyvinylidene fluoride magnetic nanocomposite films were prepared by solution casting using two types of magnetic nanoparticles: (a) magnetic nanoparticles synthesized by co-precipitation method using oleic acid as a coating agent and (b) Fe3O4 nanoparticles prepared by hydrolysis method without using a coating agent. Dynamic light scattering measurements showed mean diameters of 135 and 46 nm in co-precipitation and hydrolysis methods, respectively. Scanning electron microscopy showed that the magnetic nanoparticles were uniformly dispersed inside the polymer matrix. X-ray diffraction confirmed that Fe3O4 nanoparticles induced nucleation of β- crystalline phase in the matrix polymer. The... 

    Facile fabrication and characterization of amino-functionalized Fe 3O4 cluster@SiO2 core/shell nanocomposite spheres

    , Article Materials Research Bulletin ; Volume 48, Issue 6 , 2013 , Pages 2023-2028 ; 00255408 (ISSN) Kalantari, M ; Kazemeini, M ; Arpanaei, A ; Sharif University of Technology
    We developed a modified straightforward method for the fabrication of uniformly sized silica-coated magnetite clusters core/shell type nanocomposite particles. Proposed simple one-step processing method permits quick production of materials in high yield. The structural, surface, and magnetic characteristics of the nanocomposite particles were investigated by transmission electron microscopy (TEM), scanning electron microscope (SEM), powder X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Fourier-transform infrared (FTIR). The sphere-shaped particles almost have the average diameter of 120 nm, with a magnetic cluster core of 80 ± 15 nm, and a silica shell of 25 ± 10 nm... 

    Controlled microwave-assisted synthesis of ZnFe 2 O 4 nanoparticles and their catalytic activity for O-acylation of alcohol and phenol in acetic anhydride

    , Article Scientia Iranica ; Volume 19, Issue 6 , December , 2012 , Pages 1597-1600 ; 10263098 (ISSN) Matloubi Moghaddam, F ; Doulabi, M ; Saeidian, H ; Sharif University of Technology
    ZnFe2O4 nanoparticles have been successfully prepared through a controlled microwave-assisted co-precipitation. X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) were used for the structural, morphological and magnetic investigation of the product. SEM micrographs of ZnFe2O4 nanopowder also reveal that nanoparticles have spherical shape. Average particle size was obtained as 12 nm from XRD. Catalytic activity of ZnFe2O4 nanopowder for O-acylation of alcohol and phenol has been investigated. A trace amount of ZnFe2O4 has been effectively used as a nanocatalyst for the acylation of alcohol and... 

    Experimental investigation on thermal conductivity of water based nickel ferrite nanofluids

    , Article Advanced Powder Technology ; Volume 26, Issue 6 , November , 2015 , Pages 1529-1536 ; 09218831 (ISSN) Karimi, A ; Sadatlu, M. A. A ; Saberi, B ; Shariatmadar, H ; Ashjaee, M ; Sharif University of Technology
    Elsevier  2015
    Experimental investigations are performed in order to determine the thermal conductivity of NiFe2O4 nanoparticles dispersed in deionized water. The magnetic nanoparticles are synthesized using a microemulsion method. The X-ray diffraction (XRD), transmission electronic microscopy (TEM), and vibration sample magnetometer (VSM) are used to characterize the structure, the size and the magnetic properties of the nanoparticles. The VSM results disclose that the NiFe2O4 nanoparticles are ferromagnetic at room temperature. Experimental measurements on thermal conductivity of the prepared nanofluids are conducted at different volume concentrations between 0% and 2% and in the temperature range of... 

    Influence of annealing treatment on micro/macro-texture and texture dependent magnetic properties in cold rolled FeCo-7.15V alloy

    , Article Journal of Magnetism and Magnetic Materials ; Volume 378 , March , 2015 , Pages 253-260 ; 03048853 (ISSN) Hasani, S ; Shamanian, M ; Shafyei, A ; Behjati, P ; Nezakat, M ; Fathi Moghaddam, M ; Szpunar, J. A ; Sharif University of Technology
    Elsevier  2015
    The influence of annealing treatment on macro- and micro-texture of cold-rolled FeCo-7.15V ferro-magnetic ultra-thin foils were studied. The microstructural studies performed by field emission scanning electron microscope (FE-SEM) showed the formation of paramagnetic precipitations ((Fe, Co)3V) during annealing. During cold rolling of the FeCo-7.15V magnet, the texture components of type (113)[110], (001)[110], (111)[110], and (111)[121], all related to α and γ-fibers were formed. X-ray diffraction (XRD) and local texture measurements performed by electron backscatter diffraction (EBSD) were made on the annealed samples. Both methods revealed that the recrystallized samples have texture... 

    Application of [M(en)3]3[Fe(ox)3]2 (M = Zn, Cd, Ni) complexes as new precursor for the synthesis of ferrite micro/nanostructures

    , Article Advanced Powder Technology ; Volume 27, Issue 2 , 2016 , Pages 388-394 ; 09218831 (ISSN) Hashemi, M ; Mohandes, F ; Salavati Niasari, M ; Sharif University of Technology
    Elsevier B.V  2016
    This work presents solid-state thermal decomposition synthesis of transition metal ferrites (MFe2O4, M = Zn, Ni, Cd). In this method, binary complexes of [Zn(en)3]3[Fe(ox)3]2, [Cd(en)3]3[Fe(ox)3]2 and [Ni(en)3]3[Fe(ox)3]2 (where en = ethylenediamine and ox = oxalate) are introduced as new single-source precursors to fabricate ZnFe2O4, CdFe2O4 and NiFe2O4 micro/nanostructures, respectively. X-ray powder diffraction (XRD) patterns show that pure CdFe2O4 and NiFe2O4 are formed by thermal decomposition of the single-source precursors at 800°C. When thermal decomposition of [Zn(en)3]3[Fe(ox)3]2 complex is carried out at 700 and 800°C, the final products are composed of ZnFe2O4 and metal oxides.... 

    The effects of thickness on magnetic properties of FeCuNbSiB sputtered thin films

    , Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 3521-3525 ; 10263098 (ISSN) Shivaee, H. A ; Celegato, F ; Tiberto, P ; Castellero, A ; Baricco, M ; Hosseini, H. R. M ; Sharif University of Technology
    Thin films of Fe73.1Cu1Nb3.1Si14.7B8.2 alloy with 200, 500, and 800 nm thicknesses have been deposited by RF sputtering. Their magnetic properties have been characterized using Alternating Gradient Field Magnetometer (AGFM) and Vibrating Sample Magnetometer (VSM). The effects of residual stresses investigated by nanoindentation experiments were conducted on the as-deposited samples. It is observed that the coercivity of as-deposited films is inversely proportional to the thickness in relation with the residual stress induced during sputtering. © 2017 Sharif University of Technology. All rights reserved  

    Novel synthesis of cobalt/poly vinyl alcohol/gamma alumina nanocomposite for catalytic application

    , Article Applied Physics A: Materials Science and Processing ; Volume 123, Issue 5 , 2017 ; 09478396 (ISSN) Hatamie, S ; Ahadian, M. M ; Rashidi, A ; Karimi, A ; Akhavan, O ; Sharif University of Technology
    Springer Verlag  2017
    In this manuscript, synthesis of cobalt/poly vinyl alcohol (PVA)/gamma alumina nanocomposite via a simple room temperature, as well as its catalyst performance were explored. Brunauer–Emmett–Teller analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were conducted. The surface area of the polymeric composite was obtained to be 280 m2/g. The cobalt loading on the nanocomposite was measured using inductivity couple plasma. Transmission electron microscopy analysis showed that the size of cobalt crystalline encapsulate inside the polymer was confined to 5 nm. Magnetic property analysis, using vibrating sample magnetometer, confirmed... 

    Gold-Decorated 3D 2,6-diaminopyridine network: a robust catalyst for the bromination of aromatic compounds

    , Article Industrial and Engineering Chemistry Research ; Volume 57, Issue 37 , 2018 , Pages 12314-12322 ; 08885885 (ISSN) Pourjavadi, A ; Keshavarzi, N ; Hosseini, S. H ; Matloubi Moghaddam, F ; Sharif University of Technology
    American Chemical Society  2018
    This article reports the synthesis of a magnetic heterogeneous catalyst through the decoration of gold ions onto the cross-linked polymeric nanocomposite from 2,6-diaminopyridine. The activity of the resulting catalyst was then evaluated in the bromination of aromatic compounds. The nitrogen rich support showed a high affinity to gold ions, and the measured content of Au was 0.76 mmol g-1. The structure of the catalyst was fully characterized by using Fourier-transform infrared spectroscopy, thermogravimetric analysis, atomic absorption spectroscopy, transmission electron microscopy, scanning electron microscope, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller surface area... 

    Effect of Cysteine Substitutions on the Structural and Magnetic Properties of Fe3O4–Cysteine/RGO and Fe3O4/RGO–Cysteine Nanocomposites

    , Article Journal of Superconductivity and Novel Magnetism ; 2018 ; 15571939 (ISSN) Sahebalzamani, H ; Mehrani, K ; Madaah Hosseini, H. R ; Zare, K ; Sharif University of Technology
    Springer New York LLC  2018
    We synthesized by electrostatic self-assembly route in basic solution Fe3O4–cysteine/RGO and Fe3O4/RGO–cysteine nanocomposites. In this method, electrostatic interaction was created via negatively charged surface of the reduced graphene oxide and reduced graphene oxide–cysteine sheets and positively charged surface of the Fe3O4 and Fe3O4–Cys nanoparticles in aqueous solution. The structural and magnetic properties of the prepared samples were analyzed by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM), respectively. The dependences of magnetization as a function of...