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    Optimization of the magnetic properties and microstructure of Co 2+-La3+ substituted strontium hexaferrite by varying the production parameters

    , Article Ceramics International ; Vol. 40, issue. 4 , May , 2014 , pp. 5675-5680 ; ISSN: 02728842 Nourbakhsh, A. A ; Vahedi, A ; Nemati, A ; Noorbakhsh, M ; Mirsatari. S. N ; Shaygan, M ; Mackenzie, K. J. D ; Sharif University of Technology
    The aim of this paper was to improve the magnetic properties of magnetoplumbite-type (M-type) strontium hexaferrite substituted with Co 2+-La3+ produced by conventional ceramic forming techniques. The effect on the magnetic properties of varying the composition of the target compound Sr1-xLaxFe12-yCo yO19 and the primary and secondary firing temperatures was investigated. Microstructure studies and XRD phase analysis indicated that optimum values of the remanent magnetization Br and coercive field Hcj were obtained with a primary firing temperature of 1240 C and a final firing temperature of 1180 C, where (x=y)th 1=0.15, (y/x)exp 2=0.75 and the molar ratio of ferric oxide to strontium... 

    Formation of Lanthanum hydroxide nanostructures: effect of NaOH and KOH solvents

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 21, Issue 2 , 2008 , Pages 169-176 ; 1728-144X (ISSN) Mazloumi, M ; Zanganeh, S ; Kajbafvala, A ; Shayegh, M. R ; Sadrnezhaad, S. K ; Sharif University of Technology
    Materials and Energy Research Center  2008
    Lanthanum hydroxide (La(OH)3) nanostructures, including elliptical nanoparticles, octahedral rods and irregular nanoparticles were prepared chemically in NaOH and KOH solutions with 10 M concentration. The obtained powders were characterized with XRD, SEM, TEM and DTA. Crystallinities, morphologies and thermal behavior of the obtained nanostructure powders were investigated under the influence of above mentioned solvents. The effect of chemical's temperature was also determined in one of the solvents (i.e. NaOH). The formation of growth in nanostructure mechanism under the influence of alkali solutions (i.e., KOH and NaOH) have been discussed considerably in this paper  

    Effect of lanthanum doping on the lifetime of Co/γ-Al 2O 3 catalysts in Fischer-Tropsch synthesis

    , Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 43, Issue 5 , September , 2012 , Pages 704-710 ; 18761070 (ISSN) Hemmati, M. R ; Kazemeini, M ; Zarkesh, J ; Khorasheh, F ; Sharif University of Technology
    Elsevier  2012
    Cobalt-based catalysts were prepared on gamma alumina supports, and their behaviour for different Fischer-Tropsch synthesis (FTS) conditions was assessed. Although Co/γ-Al 2O 3 is a well-known FTS catalyst, its durability ought to be improved to make the industrial process economically feasible. The effect of lanthanum doping on the catalyst lifetime was examined utilising reactor tests and catalyst characterization techniques including TPR, ICP and N 2 porosimetry. Reactor test results revealed that an optimum amount of lanthanum improved catalyst activity and selectivity. Increasing amounts of lanthanum doping up to about 1.1wt% seemed to modify the chemical composition of the support... 

    Fractional factorial design for the optimization of hydrothermal synthesis of lanthanum oxide nanoparticles under supercritical water condition

    , Article Journal of Supercritical Fluids ; Volume 52, Issue 3 , 2010 , Pages 292-297 ; 08968446 (ISSN) Jafari Nejad, Sh ; Abolghasemi, H ; Moosavian, M. A ; Golzary, A ; Ghannadi Maragheh, M ; Sharif University of Technology
    In this research, synthesis of lanthanum oxide nanoparticles using supercritical water as a reaction medium in batch type reactor was studied. The crystallographic identity and morphology of the synthesized nanoparticles were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns indicate that the well-crystallized lanthanum oxide nanocrystals can be easily obtained under the current synthetic conditions. The effect of four parameters includes temperature, reaction time; primary concentration of aqueous solution of lanthanum (III) nitrate and pH of starting solution on reaction efficiency, particle size and the BET surface area were investigated... 

    An improved version of persian/arabic text steganography using "La" word

    , Article Proceedings of IEEE 2008 6th National Conference on Telecommunication Technologies and IEEE 2008 2nd Malaysia Conference on Photonics, NCTT-MCP 2008, 26 August 2008 through 28 August 2008, Putrajaya ; 2008 , Pages 372-376 ; 9781424422159 (ISBN) Shirali Shahreza, M ; Shirali Shahreza, M. H ; Sharif University of Technology
    By expanding communication, in some cases there is a need for hidden communication. Steganography is one of the methods used for hidden exchange of information. Steganography is a method to hide the information under a cover media such as image or text. One of the text steganography methods for Persian and Arabic texts is "La" steganography method. But that method increases the file size and changes the apparent of the text. In this paper a method for solving these problems is proposed. In Persian and Arabic, each letter can have four different shapes regarding to its position in the word. In this method by using this feature of Persian and Arabic languages and the way which documents are... 

    3D bundles of self-assembled lanthanum hydroxide nanorods via a rapid microwave-assisted route

    , Article Journal of Alloys and Compounds ; Volume 473, Issue 1-2 , 2009 , Pages 283-287 ; 09258388 (ISSN) Mazloumi, M ; Shahcheraghi, N ; Kajbafvala, A ; Zanganeh, S ; Lak, A ; Mohajerani, M. S ; Sadrnezhaad, K ; Sharif University of Technology
    Three-dimensional (3D) bundles of self-assembled lanthanum hydroxide nanorods with average crystallite size of about 20 nm were fabricated via a facile and rapid microwave-assisted chemical route. The obtained material was characterized with X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations. The obtained nanorods have average diameter of about 115 nm and average length of about 730 nm. Self-assembly of primary La(OH)3 nanoparticles and their subsequent anisotropic growth along 〈2 0 0〉 direction, was proposed to be the mechanism for the formation of 3D bundles of nanorods, using TEM images. The thermal behavior of the... 

    Lanthanum Chromite Coating on Stainless Steel by sol–Gel Dip Coating Technique

    , M.Sc. Thesis Sharif University of Technology Rashtchi, Hamed (Author) ; Faghihi Sani, Mohammad Ali (Supervisor)
    Because of the high operating temperature, interconnect surface tends to be oxidized and Cr2O3 oxide layer will be created on the surface. This phenomenon is undesirable due to decreasing electrical conductivity, so a preservative coating is needed to improve the interconnect properties. In this paper, a dense perovskite thin film was successfully synthesized on a ferritic stainless steel (type 430) substrate by a sol-gel dip coating method. This coating improved chemical stability, oxidation behavior of the substrate and decreased cathode poisoning. The lanthanum chromite was coated on the substrate by sol-gel dip coating process. First, during a hydrolyze process, a stable sol was made up... 

    Experimental Investigation for Enhancing the Lifetime of Co,Ru/La(γ-Al2O3) Catalyst in Fischer Tropsch Synthesis

    , Ph.D. Dissertation Sharif University of Technology Hemmati Mahmoudi, Mohammad Reza (Author) ; Kazemeini, Mohammad (Supervisor) ; Khorasheh, Farhad (Supervisor) ; Zarkesh, Jamshid (Co-Advisor)
    Fischer-Tropsch synthesis (FTS) is the main part of a Gas to Liquid (GTL) process. In this reaction which shall be done based upon iron or cobalt catalysts, H2 and CO molecules (namely Syngas) transform to long hydrocarbon chains. Regarding all of the advantages of cobalt catalysts in comparison with iron counterparts, Research Institute of Petroleum Industry (RIPI) began investigations since two decade ago. The present catalyst comprised of cobalt as active metal, ruthenium as activity promiter and lanthanum as support (gamma alumina) modifier. By the way, still some areas such as its lifetime duration and deactivation needs to be improved by complimentary researches. The present... 

    an Investigation on REEs' Cerium, Lanthanum, Neodymium leaching from Phosphate Concentrate of Iron Ore Waste in Acidic Environment and Studing Purification and Concentration of the Solution

    , M.Sc. Thesis Sharif University of Technology Aghaeian, Soroush (Author) ; Yoozbashizadeh, Hossein (Supervisor)
    The term “Rare Earth”, represents 17 metalic elements such as Sc, Y and Lanthanides wich have similar chemical properties. Lanthanides are a group of elements with atomic numbers of 57 to 71 that all of them exept Pm are present in nature. Rare earth elements are never concentrated in a special mine rock, but they could be found in various rocks and at very low concentrations. In the present study, apatite concentrate of Chadormalu was used for leaching and solvent extraction of Cerium, Lanthanum and Neodymium. After leaching step, its optimum conditions were found as follow: 30% nitric acid, 10 mins time and 10% for solid to liquid ratio. After finding optimum conditions, sufficient leach... 

    On the rate of oxidation of co on La2O3 doped NiO/Al2O3 catalysts: An artificial neural network approach

    , Article Reaction Kinetics and Catalysis Letters ; Volume 85, Issue 2 , 2005 , Pages 347-353 ; 01331736 (ISSN) Ardakani, S. J ; Gobal, F ; Sharif University of Technology
    The rate constants of the oxidation of CO on a number of pure and La 2O3 doped NiO/Al2O3 solid catalysts were correlated with the mole percent of dopant, calcinations temperature, surface area, pore volume and pore mouth diameter by an artificial neural network simulator. The cross validation method had to be used due to the scarcity of the data. A three-layer network with 3 nodes in the hidden layer was found to simulate the system well. © Akadémiai Kiadó, Budapest. All rights reserved  

    Process optimization and kinetics for leaching of cerium, lanthanum and neodymium elements from iron ore waste's apatite by nitric acid

    , Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 27, Issue 2 , 2017 , Pages 420-428 ; 10036326 (ISSN) Ferdowsi, A ; Yoozbashizadeh, H ; Sharif University of Technology
    Nonferrous Metals Society of China  2017
    The leaching of rare earth elements (REEs) including cerium, lanthanum and neodymium from apatite concentrate obtained from iron ore wastes by nitric acid was studied. The effects of nitric acid concentration, solid to liquid ratio and leaching time on the recoveries of Ce, La and Nd were investigated using response surface methodology. The results showed that the acid concentration and solid to liquid ratio have significant effect on the leaching recoveries while the time has a little effect. The maximum REE leaching recoveries of 66.1%, 56.8% and 51.7% for Ce, La and Nd, respectively were achieved at the optimum leaching condition with 18% nitric acid concentration, 0.06 solid to liquid... 

    Long term performance degradation analysis and optimization of anode supported solid oxide fuel cell stacks

    , Article Energy Conversion and Management ; Volume 133 , 2017 , Pages 20-30 ; 01968904 (ISSN) Parhizkar, T ; Roshandel, R ; Sharif University of Technology
    Elsevier Ltd  2017
    The main objective of this work is minimizing the cost of electricity of solid oxide fuel cell stacks by decelerating degradation mechanisms rate in long term operation for stationary power generation applications. The degradation mechanisms in solid oxide fuel cells are caused by microstructural changes, reactions between lanthanum strontium manganite and electrolyte, poisoning by chromium, carburization on nickel particles, formation of nickel sulfide, nickel coarsening, nickel oxidation, loss of conductivity and crack formation in the electrolyte. The rate of degradation mechanisms depends on the cell operating conditions (cell voltage and fuel utilization). In this study, the degradation... 

    Modified LaCoO3 nano-perovskite catalysts for the environmental application of automotive CO oxidation

    , Article Chemical Engineering Journal ; Volume 148, Issue 2-3 , 2009 , Pages 306-311 ; 13858947 (ISSN) Seyfi, B ; Baghalha, M ; Kazemian, H ; Sharif University of Technology
    Modified perovskite-type oxides were synthesized through co-precipitation and conventional citrate methods. The synthesized perovskite materials had the nominal compositions of LaCoO3, LaCo0.8Cu0.2O3, La0.8Sr0.2Co0.8Cu0.2O 3, and La0.8M0.2FeO3 (where M = Ce and Sr). The catalytic activity of the perovskite samples (for low-temperature CO oxidation) was measured using a quartz reactor with an inlet gas mixture containing 97% N2, 1% O2, and 2% CO. The prepared perovskite samples were characterized by SEM, nitrogen adsorption (BET), XRF, and XRD analyses. The perovskite catalysts showed good structural and chemical stability up to 600 °C and high activity for the catalytic CO oxidation... 

    Improving oxygen incorporation rate on (La0.6Sr0.4)0.98FeO3-δ via Pr2Ni1-xCuxO4+δ surface decoration

    , Article Journal of Power Sources ; Volume 457 , May , 2020 Khoshkalam, M ; Tripković, Ð ; Tong, X ; Faghihi Sani, M. A ; Chen, M ; Hendriksen, P. V ; Sharif University of Technology
    Elsevier B. V  2020
    Insufficient electrocatalytic activity for oxygen reduction/evolution in lanthanum strontium ferrite (LSF) perovskites at temperatures below 700 °C, limits the utilization of these Co-free oxides as oxygen electrodes for intermediate-temperature solid oxide fuel/electrolysis cells (SOFC/SOEC). Marked performance improvement is here reported by decorating the surface with Pr2Ni1-xCuxO4 catalyst particles. Infiltrating porous LSF electrodes with aqueous nitrates solutions containing Pr, Ni and Cu, targeting the compositions Pr2Ni0.7Cu0.3O4 and Pr2Ni0.6Cu0.4O4, significantly reduces the polarization resistance at 650 °C from 0.98 Ω cm2 to 0.16 Ω cm2 and 0.13 Ω cm2 respectively. Electrical... 

    Leaching, Solvent Extraction and Separation of Cerium, Lanthanum, Neodymium Rare Earth Elements from Apatite Concentrate of Chadormalu Mine

    , Ph.D. Dissertation Sharif University of Technology Ferdowsi, Ali (Author) ; Youzbashizadeh, Hossein (Supervisor)
    Waste of iron ore concentrate production plant of Chadormalu contains apatite mineral. The content of rare earths elements (REEs) in apatite concentrate of Chadormalu is about one percent. However, considering apatite deposite and production rate, extraction of REEs from apatite is one of valuable source for production of REEs. Lanthanum, cerium and neodymium which have most application amonge other REEs and have the highest frequency in the apatite. Due to their similar physical and chemical properties, it is difficult to separate individual rare earths from each other and the separation process are too complicated. In this study, in order to extract REEs from apatite, it was leached by... 

    Fabrication and Evaluation of Mechanical and Anti-corrosion Properties of Epoxy Resin/Carbon Nanofibers Containing Organic Corrosion Inhibitors

    , M.Sc. Thesis Sharif University of Technology Ghaderi, Mohammad (Author) ; Ramazani Saadat Abadi, Ahmad (Supervisor) ; Mahdavian Ahadi, Mohammad (Supervisor)
    To protect mild steel against corrosion, an intelligent self-healing epoxy (EP) coating including carbon nanofiber (CNF) modified with polydopamine (PDA)-La (III) complex was successfully fabricated. The high aspect ratio and unique thermal and electrical characteristics of CNF made it an ideal physical barrier against the penetration of corrosive ions. Due to the poor dispersion of CNF, its surface was modified using PDA. PDA, which contains functional groups such as catechol, amine, and imine, can mitigate corrosion reaction by generating the Fe-Catechol complex and also boost the coating's adherence to the metal surface, in addition to anchoring La3+ inorganic corrosion inhibitor.... 

    Interface effect on the formation of a dipole of screw misfit dislocations in an embedded nanowire with uniform shear eigenstrain field

    , Article European Journal of Mechanics, A/Solids ; Volume 51 , May–June , 2015 , Pages 154-159 ; 09977538 (ISSN) Shodja, H. M ; Enzevaee, C ; Gutkin, M. Y ; Sharif University of Technology
    Elsevier Ltd  2015
    The critical condition for the generation of a screw misfit dislocation dipole (MDD) at the interface between a nanowire (NW) with uniform shear misfit strain and its surrounding unbounded matrix within surface/interface elasticity theory is of particular interest. The analysis is carried out using the complex potential variable method. It is shown that the critical radius of the NW corresponding to the onset of the MDD generation decreases with the increase in the uniform shear eigenstrain inside the NW as well as when the stiffness of the NW increases with respect to the matrix. The critical radius strongly depends on the non-classical interface parameter. Comparison is made with classical... 

    The effect of particle size on the structural, magnetic and electrical properties of La0.9Ba0.1MNO3 manganite samples

    , Article Phase Transitions ; Volume 92, Issue 11 , 2019 , Pages 949-959 ; 01411594 (ISSN) Shogh, S ; Eshraghi, M ; Sharif University of Technology
    Taylor and Francis Ltd  2019
    In this work, the magnetic and transport properties of micro and nanometer-sized samples of La0.9Ba0.1MnO3 manganite have been studied. The temperature variation of ac susceptibility of the nanometer-sized sample shows one transition at high temperature (265 K). On the contrary, the ac susceptibility of the micrometer-sized sample shows two transitions with a high-temperature transition occurring at 240 K and low-temperature transition around 100 K. The high-temperature transition corresponds to the paramagnetic-ferromagnetic (PM–FM) transition (Tc) and is independent of frequency, while the low-temperature transition is frequency-dependent and shifts toward high temperatures by increasing... 

    Substrate and device pattern dependence of the thermal crosstalk in y Ba 2Cu 3O 7-δ transition edge bolometer arrays

    , Article IEEE Transactions on Applied Superconductivity ; Volume 16, Issue 4 , 2006 , Pages 1953-1958 ; 10518223 (ISSN) Bozbey, A ; Fardmanesh, M ; Schubert, J ; Banzet, M ; Sharif University of Technology
    Using YBa 2Cu 3O 7-δ (YBCO) thin films, pulsed laser deposited on 1-mm-thick LaAlO 3 or SrTiO 3 substrates, we made 4 × 1 pixel arrays of transition edge bolometers with separations between neighboring pixels ranging from 40 μm to 170 μm for testing purposes. We investigated the effects of the YBCO film thickness (200 and 400 nm), substrate material, and back-etching of the substrate, on the crosstalk between the pixels of the arrays. The investigation was based on the analysis of the voltage response of the dc current biased bolometers versus the modulation frequency of a near-infrared laser source. We observed that the bolometer arrays made of 400-nm-thick films had less interpixel thermal... 

    Electrical behavior of nano-polycrystalline (La1-yK y)0.7Ba0.3MnO3 manganites

    , Article Journal of Magnetism and Magnetic Materials ; Volume 322, Issue 21 , November , 2010 , Pages 3255-3261 ; 03048853 (ISSN) Mazaheri, M ; Akhavan, M ; Sharif University of Technology
    We present a study of the structural and electrical behavior of nano-polycrystalline mixed barium and alkali substituted lanthanum-based manganite, (La1-yKy)0.7Ba0.3MnO 3 with y=0.00.3. The samples were synthesized by the polymerization complex solgel method. The powder X-ray diffraction (XRD) data of the samples show a single-phase character with R3c space group. The magnetic and electrical transport properties of the nano-polycrystalline samples have been investigated in the temperature range 50300 K and a magnetic field up to 10 kOe. The metalinsulator transition temperature Tp of all the samples decreased with potassium doping, and also, it increased slightly with the application of...