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    Nanothickness films, nanostructured films, and nanocrystals of barium titanate obtained directly by a newly developed sol–gel synthesis pathway

    , Article Journal of Materials Science: Materials in Electronics ; Vol. 25, issue. 12 , 2014 , p. 5345-5355 Ashiri, R ; Nemati, A ; Sasani Ghamsari, M ; Dastgahi, M. M ; Sharif University of Technology
    This work aims to develop a chemically modified sol–gel synthesis pathway for obtaining various barium titanate nanostructures. The method is able to prepare different BaTiO3 nanostructures such as highly stable nanoparticle embedded colloids, highly transparent amorphous nanolayers, nanocrystalline BaTiO3 powders and ultrathin BaTiO3 nanostructured films directly from a precursor solution. All the products have been prepared at a lower temperature and in a more cost-effective way in contrast to other established sol–gel methods. The results show that the optical transparency of the thin films has been significantly improved in contrast to the similar researches. The deposited thin film is... 

    Investigating the effect of calcination repetitions on the lifetime of Co/γ-Al2O3 catalysts in Fischer-Tropsch synthesis utilising the precursor's solution affinities

    , Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 44, Issue 2 , 2013 , Pages 205-213 ; 18761070 (ISSN) Hemmati, M. R ; Kazemeini, M ; Khorasheh, F ; Zarkesh, J ; Sharif University of Technology
    Cobalt-based catalysts were prepared on different alumina supports, and their behaviour for different Fischer-Tropsch synthesis (FTS) conditions assessed. Although Co/γ-Al2O3 is a well-known FTS catalyst, its durability ought to be improved to make the industrial process economically feasible. Here calcination repetitions effects on the catalyst lifetime were examined utilising reactor tests and characterisation techniques including XRD, TPR, ICP and N2 porosimetry. Results revealed that fewer calcination repetitions improved catalyst activity and selectivity. Based upon the XRD results, these findings appeared to be due to the improved size of cobalt crystals on the pore surfaces. These... 

    Ag doping of organometal lead halide perovskites: morphology modification and p-type character

    , Article Journal of Physical Chemistry C ; Volume 121, Issue 7 , 2017 , Pages 3673-3679 ; 19327447 (ISSN) Shahbazi, S ; Tsai, C. M ; Narra, S ; Wang, C. Y ; Shiu, H. S ; Afshar, S ; Taghavinia, N ; Wei Guang Diau, E. ? ; Sharif University of Technology
    We report a simple synthetic approach to grow uniform CH3NH3PbI3 perovskite (PSK) layers free of pinholes via varied portions of silver iodide (AgI) added to the precursor solution. XRD/EDS elemental mapping experiments demonstrated nearly uniform Ag distribution inside the perovskite film. When the 1% AgI-assisted perovskite films were fabricated into a p-i-n planar device, the photovoltaic performance was enhanced by ∼30% (PCE increased from 9.5% to 12.0%) relative to the standard cell without added AgI. Measurement of electronic properties using a hall setup indicated that perovskite films show p-type character after Ag doping, whereas the film is n-type without Ag. Transients of... 

    The role of a vapor-assisted solution process on tailoring the chemical composition and morphology of mixed-halide perovskite solar cells

    , Article CrystEngComm ; Volume 20, Issue 31 , 2018 , Pages 4428-4435 ; 14668033 (ISSN) Tafazoli, S ; Timasi, N ; Nouri, E ; Mohammadi, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2018
    Herein, we report a modified two-step method to construct a uniform and pinhole-free polycrystalline perovskite film with large grains up to the microscale using lead mixed-halide (PbI2-PbCl2) precursor solutions to guarantee the device functioning. Commonly used sequential deposition methods based on dip- and spin-coatings are combined with a vapor-assisted solution process to improve the perovskite morphology and tune the residual lead mixed-halides. These can enhance the optical absorption and efficiency of perovskite solar cell (PSC) devices. The impact of the Cl content in the lead mixed-halide precursors and the employed preparation methods on the photovoltaic performance of PSCs are... 

    Perovskite/hole transport layer interface improvement by solvent engineering of spiro-ometad precursor solution

    , Article ACS Applied Materials and Interfaces ; Volume 11, Issue 47 , 2019 , Pages 44802-44810 ; 19448244 (ISSN) Taherianfard, H ; Kim, G. W ; Ebadi, F ; Abzieher, T ; Choi, K ; Paetzold, U. W ; Richards, B. S ; Alrhman Eliwi, A ; Tajabadi, F ; Taghavinia, N ; Malekshahi Byranvand, M ; Sharif University of Technology
    American Chemical Society  2019
    Perovskite solar cells (PSCs) are one of the most promising emerging energy-conversion technologies because of their high power conversion efficiencies (PCEs) and potentially low fabrication cost. To improve PCE, it is necessary to develop PSCs with good interfacial engineering to reduce the trap states and carrier transport barriers present at the various interfaces of the PSCs' architecture. This work reports a facile method to improve the interface between the perovskite absorber layer and the hole transport layer (HTL) by adding a small amount of acetonitrile (ACN) in the Spiro-OMeTAD precursor solution. This small amount of ACN dissolves the surface of the perovskite layer, allowing the... 

    Photovoltaic performance improvement in vacuum-assisted meniscus printed triple-cation mixed-halide perovskite films by surfactant engineering

    , Article ACS Applied Energy Materials ; Volume 2, Issue 9 , 2019 , Pages 6209-6217 ; 25740962 (ISSN) Parvazian, E ; Abdollah Zadeh, A ; Dehghani, M ; Taghavinia, N ; Sharif University of Technology
    American Chemical Society  2019
    Scalable coating methods have recently emerged as practical alternative deposition techniques to the conventional spin-coating despite their lower yielding power conversion efficiencies (PCEs). The most important barrier acting against the use of scalable deposition methods to get a highly absorbing (>95%) film with controlled morphology in the high crystallinity of perovskite particles is the impossibility of antisolvent dripping during the deposition. Here, we demonstrate the positive role of both the surfactant-engineering and the vacuum-annealing (<100 Pa) process in improving the device performance to overcome this limit. A detailed optimization of the vacuum-assisted meniscus printing... 

    MOD growth of epitaxial cerium oxide buffer layer on LAO substrates for fabrication of c-axis oriented YBCO

    , Article Micro and Nano Letters ; Volume 7, Issue 10 , 2012 , Pages 1008-1010 ; 17500443 (ISSN) Hosseini, M ; Foroughi Abari, F ; Vesaghi, M. A ; Fardmanesh, M ; Sharif University of Technology
    Epitaxial cerium oxide (CeO2) buffer layer has been grown on lanthanum aluminate (LAO) single crystal substrates for fabrication of c-axis oriented YBa2Cu3O7-x (YBCO). Precursor solution of cerium acetylacetonates with viscosity of 0.6 centipoises was spin coated on the 1×1 cm area LAO substrates. The calcination was carried out by very slow ramp (1°C per minute) until the final temperature of 500°C in oxygen flow to remove most of the organic compounds. The final heat treatment has been done at 780°C by a ramp of 20° per minute in gas flow of mixed argon-oxygen with 5 Pa partial pressure of oxygen. The thickness of the deposited CeO2 buffer layer was 20 nm. Then, 100 nm thick YBCO film was... 

    Photoactive and self-cleaning TiO 2-SiO 2 thin films on 316L stainless steel

    , Article Thin Solid Films ; Volume 520, Issue 20 , 2012 , Pages 6355-6360 ; 00406090 (ISSN) Boroujeny, B. S ; Afshar, A ; Dolati, A ; Sharif University of Technology
    In this study, TiO 2-SiO 2 nanocomposite films with different amounts of SiO 2 were prepared by sol-gel process and were coated onto stainless steel 316L. The effect of addition of various amount of SiO 2 in the precursor solution on the photocatalysis, photo-generated hydrophilicity and self-cleaning property of TiO 2 thin films was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, water contact angle measurements and UV spectroscopy. In the tested ranges of SiO 2 content and sintering temperature, the highest photocatalytic activity and self-cleaning property were observed in the 15 mol% SiO 2 sample sintered at 750 °C. Addition of less than 30 mol% SiO 2 had a... 

    Production of granulated-copper oxide nanoparticles for catalytic application

    , Article Journal of Materials Research ; Volume 25, Issue 10 , 2010 , Pages 2025-2034 ; 08842914 (ISSN) Hosseinpour, M ; Ahmadi, S. J ; Mousavand, T ; Outokesh, M ; Sharif University of Technology
    Ultra fine CuO nanoparticles In the range of 2 ± 0.2 nm were synthesized by the supercritical hiydrotliermal method in a batch reactor. Itwas demonstrated that elevating the pH of the Cu2+ precursor solution to around 6 (neutral condition) not only does not lead to excessive agglomeration of the particles, but also reduces particle size and in general promotes their nanoscale characteristics. Prepared nanoparticles were immobilized in the biopolymcric matrix of barium alginate and calcined at different temperatures resulting in micro spherical granules of high porosity and elevated mechanical strength. The fabricated samples were characterized using x-ray diffractometry (XRD), transmission... 

    Carbon nanoparticles in high-performance perovskite solar cells

    , Article Advanced Energy Materials ; Volume 8, Issue 12 , 2018 ; 16146832 (ISSN) Yavari, M ; Mazloum Ardakani, M ; Gholipour, S ; Marinova, N ; Delgado, J. L ; Turren Cruz, S. H ; Domanski, K ; Taghavinia, N ; Saliba, M ; Gratzel, M ; Hagfeldt, A ; Tress, W ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    In the past few years, organic–inorganic metal halide ABX3 perovskites (A = Rb, Cs, methylammonium, formamidinium (FA); B = Pb, Sn; X = Cl, Br, I) have rapidly emerged as promising materials for photovoltaic applications. Tuning the film morphology by various deposition techniques and additives is crucial to achieve solar cells with high performance and long-term stability. In this work, carbon nanoparticles (CNPs) containing functional groups are added to the perovskite precursor solution for fabrication of fluorine-doped tin oxide/TiO2/perovskite/spiro-OMeTAD/gold devices. With the addition of CNPs, the perovskite films are thermally more stable, contain larger grains, and become more... 

    Effect of CsCl additive on the morphological and optoelectronic properties of formamidinium lead iodide perovskite

    , Article Solar RRL ; Volume 3, Issue 11 , 2019 ; 2367198X (ISSN) Chavan, R. D ; Prochowicz, D ; Yadav, P ; Tavakoli, M. M ; Nimbalkar, A ; Bhoite, S. P ; Hong, C. K ; Sharif University of Technology
    Wiley-VCH Verlag  2019
    The quality of perovskite films plays a crucial role in improving the optoelectronic properties and performance of perovskite solar cells (PSCs). Herein, high-quality CsxFA1−xPbI3 perovskite films with different compositions (x = 0, 5, 10, and 15) are achieved by controlling the amount of cesium chloride (CsCl) in the respective FAPbI3 precursor solution. The effects of CsCl addition on the morphological and optoelectronic properties of the resulting perovskite films and on the performance of the corresponding devices are systematically studied. Introduction of CsCl into FAPbI3 shows a great potential to stabilize the α-FAPbI3 perovskite phase by forming CsxFA1−xPbI3 films with improved... 

    A comprehensive review on ultrasonic spray pyrolysis technique: Mechanism, main parameters and applications in condensed matter

    , Article Journal of Analytical and Applied Pyrolysis ; Volume 141 , 2019 ; 01652370 (ISSN) Rahemi Ardekani, S ; Sabour Rouh Aghdam, A ; Nazari, M ; Bayat, A ; Yazdani, E ; Saievar Iranizad, E ; Sharif University of Technology
    Elsevier B.V  2019
    Nanostructured materials have attracted much attention in recent decades. Nowadays, there are numerous nanomaterials with several applications. The ultrasonic spray pyrolysis method is a cost-effective and adaptable technique based on an aerosol process for synthesizing nanoparticles and depositing thin films. The technique is capable of synthesizing metal, oxide, and composite nanomaterials with precisely controllable morphologies and chemical compositions using metal salts in aqueous solvents. More importantly, it is popular, as evident from the growing number of studies being conducted on the technique. Here, we review studies conducted on basic principles and applications of the... 

    Engineering of perovskite materials based on formamidinium and cesium hybridization for high-efficiency solar cells

    , Article Chemistry of Materials ; Volume 31, Issue 5 , 2019 , Pages 1620-1627 ; 08974756 (ISSN) Prochowicz, D ; Runjhun, R ; Tavakoli, M. M ; Yadav, P ; Saski, M ; Alanazi, A. Q ; Kubicki, D. J ; Kaszkur, Z ; Zakeeruddin, S. M ; Lewiński, J ; Grätzel, M ; Sharif University of Technology
    American Chemical Society  2019
    Engineering the chemical composition of inorganic-organic hybrid perovskite materials is an effective strategy to boost the performance and operational stability of perovskite solar cells (PSCs). Among the diverse family of ABX3 perovskites, methylammonium-free mixed A-site cation CsxFA1-xPbI3 perovskites appear as attractive light-absorber materials because of their optimum band gap, superior optoelectronic property, and good thermal stability. Here, we develop a simple and very effective one-step solution method for the preparation of high-quality (Cs)x(FA)1-xPbI3 perovskite films upon the addition of excess CsCl to the FAPbI3 precursor solution. It is found that the addition of CsCl as a... 

    Production of high quality ammonium uranyl carbonate from “uranyl nitrate + carbonate” precursor solution

    , Article Progress in Nuclear Energy ; Volume 122 , 2020 Sadeghi, M. H ; Outokesh, M ; Zare, M. H ; Sharif University of Technology
    Elsevier Ltd  2020
    The purpose of this study is to investigate production of high quality ammonium uranyl carbonate (AUC) from “uranyl nitrate + ammonium bicarbonate”, or “uranyl nitrate + sodium carbonate” precursor solutions, by controlled injection of ammonium carbonate solution which could be applicable in material testing reactor (MTR) fuel production plant for recycling of rejected uranium oxide powder. The experimental observations revealed: at pHs higher than 6, precipitation proceeds with formation of no intermediate, thus ensuing a better morphology and size distribution of the AUC products. The results of scanning electron microscopy, X-ray diffraction, particle size analysis, and uranium content... 

    Aqueous spray pyrolysis of CuInSe2 thin films: Study of different indium salts in precursor solution on physical and electrical properties of sprayed thin films

    , Article Materials Science in Semiconductor Processing ; Volume 126 , 2021 ; 13698001 (ISSN) Hashemi, M ; Bagher Ghorashi, S. M ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
    Elsevier Ltd  2021
    Herein, we deposited CuInSe2(CISe) thin films by using aqueous spray deposition method and post selenization process. The effect of different indium precursor salts including indium chloride, indium nitrate and indium acetate on the structural, morphological, optical and electrical properties of sprayed CISe layers has been studied by using x-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM-EDS), optical transmission (UV–Vis), Mott-Schottky analysis, I–V dark measurements. Although all the deposited thin films show a chalcopyrite tetragonal ordering structure of CISe, the crystallinity, morphology, and electrical characteristics are strongly influenced by the type of... 

    Rapid formation of hydroxyapatite nanostrips via microwave irradiation

    , Article Journal of Alloys and Compounds ; Volume 469, Issue 1-2 , 2009 , Pages 391-394 ; 09258388 (ISSN) Arami, H ; Mohajerani, M ; Mazloumi, M ; Khalifehzadeh, R ; Lak, A ; Sadrnezhaad, S. K ; Sharif University of Technology
    Hydroxyapatite (HAp) nanostrips were rapidly obtained during a mild microwave heating method. Applying microwave irradiation to Ca(NO3)2·4H2O/CTAB/Na2HPO4 precursor solution, the HAp precipitation process was occurred directly and without common crystallographic transformations including dissolution and slow recrystallization. The cationic surfactant CTAB was used as a soft template to modify nucleation and growth process. TEM investigations showed that the fabricated nanostrips had a width and length of about 10 and 55 nm, respectively. The X-ray diffraction pattern revealed that the fabricated well-crystallized and high purity hydroxyapatite nanostrips had a pattern similar to the bone... 

    Design, modeling and optimization of a piezoelectric pressure sensor based on thin-film PZT diaphragm contain of nanocrystalline powders

    , Article 2009 6th International Symposium on Mechatronics and its Applications, ISMA 2009, Sharjah, 23 March 2009 through 26 March 2009 ; 2009 ; 9781424434817 (ISBN) Mohammadi, V ; Sheikhi, M. H ; Torkian, S ; Barzegar, A ; Masumi, E ; Mohammadi, S ; Sharif University of Technology
    In this paper fabrication of a 0-3 ceramic/ceramic composite lead zirconate titanate, Pb(Zr0.52Ti0.48)O3 thin film has been presented and then a pressure sensor based on multilayer thin-film PZT diaphragm contain of Lead Zirconate Titanate nanocrystalline powders was designed, modeled and optimized. This multilayer diaphragm in general acts as sensor or actuator. ANSYS was used for simulation of diaphragm. Dynamics characteristics of this multilayer diaphragm have been investigated. By this simulation the effective parameters of the multilayer PZT diaphragm for improving the performance of a pressure sensor in different ranges of pressure are optimized. The optimized thickness ratio of PZT...