Search for: sol-gel-methods
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    Synthesis of TiO2 nano powder by the sol-gel method and its use as a photocatalyst

    , Article Journal of the Iranian Chemical Society ; Volume 7, Issue SUPPL. 1 , 2010 , Pages S154-S160 ; 1735207X (ISSN) Karami, A ; Sharif University of Technology
    In this work the titanium dioxide powder was prepared by the optimized and simple Sol-Gel method and then characterized. The gelling pH was set to values of 3 (TiO2-A), 7 (TiO2-N) and 9 (TiO2-B) to observe the effect on the properties of the material. In these three cases nanoparticulated materials were obtained with particle sizes between 10nm and 20nm. The larger surface areas were obtained at pH 3, which is several times larger than the others. Furthermore, with the gelling condition pH 3, it was possible to synthesize pure anatase phase titania. Some preliminary results on the test of the photocatalytic activity of the synthesized materials in the reduction of nitric oxide are presented.... 

    Effective photocatalytic degradation of an azo dye over nanosized Ag/AgBr-modified TiO2 loaded on zeolite

    , Article Journal Chemical Papers ; Volume 65, Issue 3 , June , 2011 , pp 280-288 ; 1336-9075 Padervand, M. (Mohsen) ; Tasviri, M. (Mahboubeh) ; Gholami, M. R. (Mohammad Reza) ; Sharif University Of Technology
    Zeolite-based photocatalysts were prepared by the sol-gel and deposition methods. The photocatalysts were characterised by X-ray diffraction, nitrogen adsorption-desorption isotherms, FTIR spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectrometry. The activity of the prepared photocatalysts was evaluated by the UV-induced degradation of acid blue 92, a textile dye in common use. The effect of various parameters, such as catalyst concentration, initial dye concentration, thiosulphate concentration and pH, on the rate and efficiency of the photocatalytic degradation of acid blue 92 was investigated. The results showed that each parameter influenced the degradation... 

    Kinetics Investigation of the Photocatalytic Degradation of Acid Blue 92 in Aqueous Solution Using Nanocrystalline TiO2 Prepared in an Ionic Liquid

    , Article Progress in Reaction Kinetics and Mechanism ; vol, 34 , March , 2009 , PP. 55–76 Ghasemi, S. (Shahnaz) ; Rahimnejad, S. (Sara) ; Rahman Setayesh, S. (Shahrbanoo) ; Hosseini, M. (Mohammad) ; Gholami, M. R. (Mohammad Reza) ; Sharif University of Technology
    TiO2 nanoparticles were prepared by the sol - gel process using 2-hydroxylethy- lammonium formate as an ionic liquid. Nanoparticles were crystallized at various temperatures (300-700°C). The products were characterized using X-ray diffraction (XRD), nitrogen adsorption - desorption isotherms and scanning electron microscopy (SEM) techniques. It was found that the resulting TiO2 nanoparticles had good thermal stability either to resist collapse or the anatase-to-rutile phase transformation during heat treatment. The photocatalytic activity of the nanocrystalline TiO2 was evaluated by the degradation of Acid Blue 92 (AB92) which is\ commonly used as a textile dye. The results showed that the... 

    Structural phase of y358 superconductor comparison with Y123

    , Article Journal of Superconductivity and Novel Magnetism ; Volume 25, Issue 7 , October , 2012 , Pages 2253-2258 ; 15571939 (ISSN) Gholipour, S ; Daadmehr, V ; Rezakhani, A. T ; Khosroabadi, H ; Tehrani, F. S ; Akbarnejad, R. H ; Sharif University of Technology
    Springer  2012
    We analyze an experiment in which two distinct superconducting phases YBa2Cu3O7-δ (Y123) and Y 3Ba5Cu8O18-δ (Y358) coexisted. This experiment enabled us to characterize the recently introduced Y358 phase in contrast to the Y123 phase, thus to resolve some discrepancies reported in associated properties of Y358. Specifically, our experiment indicates the transition temperature Tmid C = 105 K and 94 K for Y358 and Y123, respectively, and that Y358 has five CuO2 planes and three CuO chains, with Pmm2 symmetry and lattice parameter (a, b, c) = (3.845, 3.894, 31.093) Å, in agreement with density functional theory predictions for this specific structure  

    Effect of nanostructuring on thermal stability and decomposition of aluminium titanate (Al2TiO5): a phase transformation study

    , Article Materials Characterization ; Volume 173 , 2021 ; 10445803 (ISSN) Azarniya, A ; Madaah Hosseini, H. R ; Amutha, C ; Ramakrishna, S ; Sharif University of Technology
    Elsevier Inc  2021
    As a refractory ceramic, the thermal instability of aluminium titanate (AT or Al2TiO5) has been in the crosshairs of research works in recent years. The studies have indicated that different parameters such as atmosphere, grain size, additives, oxygen pressure, and synthesis method can bilaterally affect the thermal decomposition of AT ceramic and resultant physicomechanical properties. In the present study, the AT nanostructure was synthesized by a citrate sol-gel method and influence of nanostructuring nature on its thermal instability and reaction pathway was explored in some details. It was shown that the reduction of grain size down to 30 nm can destabilize AT, so that the reaction... 

    Synthesis and electrochemical properties of LiNi0.8Co 0.2O2 nanopowders for lithium ion battery applications

    , Article Journal of Power Sources ; Volume 196, Issue 1 , 2011 , Pages 337-342 ; 03787753 (ISSN) Jouybari, Y.H ; Asgari, S ; Sharif University of Technology
    Nitrates of lithium, cobalt and nickel are utilized to synthesize LiNi 0.8Co0.2O2 cathode material through sol-gel technique. Various synthesis parameters such as calcination time and temperature as well as chelating agent are studied to determine the optimized condition for material processing. Using TG/DTA techniques, the optimized calcination temperatures are selected. Different characterization techniques such as ICP, XRD and TEM are employed to characterize the chemical composition, crystal structure, size and morphology of the powders. Micron and nano-sized powders are produced using citric/oxalic and TEA as chelating agent, respectively. Selected powders are used as cathode material... 

    Synthesis and spectral properties of Nd-doped glass-ceramics in SiO 2-CaO-MgO system prepared by sol-gel method

    , Article Journal of Rare Earths ; Volume 31, Issue 6 , 2013 , Pages 595-599 ; 10020721 (ISSN) Masoud, E ; Zohreh, H ; Ali, N ; Sharif University of Technology
    SiO2-CaO-MgO glass and glass-ceramic powder doped with Nd 3+ were synthesized with sol-gel method. Tetraethylorthosilicate (TEOS), Ca(NO3)2·4H2O, Mg(NO 3)2·6H2O, Nd(NO3) 3·6H2O, ethanol, distilled water, and HNO 3 were used as starting materials. The synthesized powder's properties were examined with simultaneous thermal analysis (STA), X-ray diffraction (XRD), photoluminescence (PL) and scanning electron microscopy (SEM) analysis. The STA curves showed that the softening point and crystallization temperatures were shifted to higher temperatures with increasing dopant content. Regarding XRD patterns of glass samples, Nd was found to act as an intermediate oxide in glass matrix. The XRD... 

    Influence of hydrogen reduction on growth of tungsten oxide nanowires

    , Article Journal of Experimental Nanoscience ; Volume 7, Issue 6 , 2012 , Pages 597-607 ; 17458080 (ISSN) Azimirad, R ; Khosravi, P ; Moshfegh, A. Z ; Sharif University of Technology
    A simple method for synthesising W17O47 nanowires on tungsten oxide thin films deposited by sol-gel method on mica substrate has been reported. After thermally annealing thin films at 700 C in H2 ambient for different durations and subsequently in N2 ambient for 60 min, single-crystalline W17O47 nanowires along h0 01i direction were formed on the surface. Experimental results revealed that annealing under H2 ambient has an important effect on the growth of W17O47 nanowires. According to scanning electron microscopic observations, the synthesised nanowires have ∼70 nm in width and a few microns in length after annealing under H2 ambient for 30min and subsequently under N2 ambient for 60min. A... 

    Development of hydroxyapatite nanorods-polycaprolactone composites and scaffolds derived from a novel in-situ sol-gel process

    , Article Tissue Engineering and Regenerative Medicine ; Volume 9, Issue 6 , 2012 , Pages 295-303 ; 17382696 (ISSN) Rezaei, A ; Mohammadi, M. R ; Sharif University of Technology
    Hydroxyapatite (HA) is the most substantial mineral constituent of a bone which displays splendid biocompatibility and bioactivity properties. Nevertheless, its mechanical property is not utmost appropriate for a bone substitution. Therefore, a composite consist of HA and a biodegradable polymer is usually prepared to generate an apt bone scaffold. In the present work polycaprolactone (PCL) was employed as a matrix and hydroxyapatite nanorods were used as a reinforcement element of the composite. HA/PCL nanocomposites were synthesized by a new in-situ sol-gel process using low cost chemicals. Chemical and physical characteristics of the nanocomposite were studied by X-ray diffraction (XRD),... 

    Synthesis and characterization of bioactive glass/forsterite nanocomposites for bone and dental implants

    , Article Ceramics - Silikaty ; Volume 56, Issue 4 , 2012 , Pages 331-340 ; 08625468 (ISSN) Kamalian, R ; Yazdanpanah, A ; Moztarzadeh, F ; Ravarian, R ; Moztarzadeh, Z ; Tahmasbi, M ; Mozafari, M ; Sharif University of Technology
    In this research, bioactive glass (BG) of the type CaO-P2O 5-SiO2 and nanocrystalline forsterite (NF) bioceramic were successfully synthesized via sol-gel processing method. Heat-treatment process was done to obtain phase-pure nanopowders. After characterization of each sample, the nanocomposite samples were prepared by cold pressing method and sintered at 1000°C. The samples were fully characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) analyses. The average nanocrystallite size was determined using the Debye-Scherrer's formula 19.6 nm. The bioactivity was examined in vitro... 

    Sintering of Al2O3-SiC composite from sol-gel method with MgO, TiO2 and Y2O3 addition

    , Article Ceramics International ; Volume 37, Issue 5 , 2011 , Pages 1681-1688 ; 02728842 (ISSN) Mohammad Rahimi, R ; Rezaie, H. R ; Nemati, A ; Sharif University of Technology
    Al2O3-SiC composite ceramics were prepared by pressureless sintering with and without the addition of MgO, TiO2 and Y2O3 as sintering aids. The effects of these compositional variables on final density and hardness were investigated. In the present article at first α-Al2O3 and β-SiC nano powders have been synthesized by sol-gel method separately by using AlCl 3, TEOS and saccharose as precursors. Pressureless sintering was carried out in nitrogen atmosphere at 1600 °C and 1630 °C. The addition of 5 vol.% SiC to Al2O3 hindered densification. In contrast, the addition of nano MgO and nano TiO2 to Al 2O3-5 vol.% SiC composites improved densification but Y2O3 did not have positive effect on... 

    The effect of multiwalled carbon nanotubes and activated carbon on the morphology and photocatalytic activity of TiO2/C hybrid materials

    , Article Catalysis Science and Technology ; Volume 1, Issue 2 , 2011 , Pages 279-284 ; 20444753 (ISSN) Zarezade, M ; Ghasemi, S ; Gholami, M. R ; Sharif University of Technology
    TiO2 nanoparticles supported on activated carbon (AC) and multiwalled carbon nanotubes (MWCNTs) were prepared by the sol-gel method using ultrasonic irradiation. All the prepared samples were calcined at different temperatures and characterized by X-ray diffraction, nitrogen adsorption/desorption isotherms, scanning electron microscopy, transmission electron microscopy and diffuse reflectance spectroscopy. The effects of size and type of carbon on the morphology and photocatalytic activity of the resulting hybrid materials were investigated. The results showed that a decrease in the size of the carbon led to a decrease in size of TiO2 nanoparticles. Both AC and MWCNTs retarded the... 

    Biodiesel production using CaO/γ-Al2O3 catalyst synthesized by sol-gel method

    , Article Canadian Journal of Chemical Engineering ; Volume 93, Issue 9 , July , 2015 , Pages 1531-1538 ; 00084034 (ISSN) Moradi, G ; Mohadesi, M ; Rezaei, R ; Moradi, R ; Sharif University of Technology
    Wiley-Liss Inc  2015
    In this study, 40% CaO/γ-Al2O3 catalyst was used for biodiesel production from corn oil. A transesterification reaction was done for 5h at a temperature of 65°C in the presence of corn oil, methanol (methanol to oil molar ratio of 12:1), and CaO/γ-Al2O3 catalyst (0.06g/g (6wt%)). Catalyst used in this study was synthesized using the sol-gel method. In this method, two parameters of gelation temperature and nitric acid concentration were used as variables in the catalyst synthesis step, and experiments were designed using central composite design (CCD). The results indicate that the optimal point is achieved at a gelation temperature of 70°C and... 

    Visible light photo-induced antibacterial activity of CNT-doped TiO 2 thin films with various CNT contents

    , Article Journal of Materials Chemistry ; Volume 20, Issue 35 , Jun , 2010 , Pages 7386-7392 ; 09599428 (ISSN) Akhavan, O ; Azimirad, R ; Safa, S ; Larijani, M. M ; Sharif University of Technology
    Carbon nanotube (CNT)-doped TiO2 thin films with various CNT contents were synthesized by sol-gel method for visible light photoinactivation of Escherichia coli bacteria. Post annealing of the CNT-doped TiO2 thin films at 450 °C resulted in anatase TiO2 and formation of Ti-C and Ti-O-C carbonaceous bonds in the film. By increasing the CNT content, the thin films could further inactivate the bacteria in the dark. Meanwhile, as the CNT content increased from zero to 40 wt% the effective optical band gap energy of the CNT-doped TiO2 thin films annealed at 450 °C decreased from 3.2-3.3 to less than ∼2.8 eV providing light absorption in the visible region. Concerning this, visible light... 

    Synthesis and characterization of nanocrystalline barium strontium titanate

    , Article Materials Science- Poland ; Volume 28, Issue 2 , 2010 , Pages 421-426 ; 01371339 (ISSN) Golmohammad, M ; Nemati, Z. A ; Faghihi Sani, M. A ; Sharif University of Technology
    Barium strontium titanate (BST) was prepared via the simple sol-gel method by using tetrabutyl ti-tanate, ethanol, citric acid and ethylene glycol as starting materials. Thermogravimetry and differential thermal analysis were used to examine the behaviour of the xerogel. The particle size of BST was approximately 21 nm, as calculated by the X-ray diffraction and confirmed by transition electron microscopy for the calcination temperature of 750 °C. It was found that the particles of BST powders calcined at 750 °C were smaller and more homogeneous and uniform than those obtained at 800 °C  

    Pd doped WO3 films prepared by sol-gel process for hydrogen sensing

    , Article International Journal of Hydrogen Energy ; Volume 35, Issue 2 , 2010 , Pages 854-860 ; 03603199 (ISSN) Fardindoost, S ; Iraji zad, A ; Rahimi, F ; Ghasempour, R ; Sharif University of Technology
    The sol gel method was employed to prepare peroxopolytungstic acid (P-PTA). Palladium chloride salt was dissolved in the sol with different Pd:W molar ratios and coated on Al2O3 substrates by spin coating method. XRD and XPS techniques were used to analyze the crystal structure and chemical composition of the films before and after heat treatment at 500 °C. We observed that Pd can modify the growth kinetic of tungsten trioxide nanoparticles by reducing the crystallite size and as a result can improve hydrogen sensitivity. Resistance-sensing measurements indicated sensitivity of about 2.5 × 104 at room temperature in hydrogen concentration of 0.1% in air. Considering all sensing parameters,... 

    Mixed-phase TiO2 nanoparticles preparation using sol-gel method

    , Article Journal of Alloys and Compounds ; Volume 478, Issue 1-2 , 2009 , Pages 586-589 ; 09258388 (ISSN) Mahshid, S ; Askari, M ; Sasani Ghamsari, M ; Afshar, N ; Lahuti, S ; Sharif University of Technology
    Biphase TiO2 nanoparticles have been prepared by sol-gel method. Water/titanium molar ratio (r) has been used to control the hydrolysis and condensation of titanium isopropoxide in solution producing titanium oxide with two different polymorphs. The influence of crystallite size and morphology of prepared TiO2 on the phase transformation of the resultant materials has been investigated. Synthesized powders were characterized by X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Different trends can be observed in the phase transformation and particle growth of the prepared titanium oxide nanomaterial. It was concluded that, the rate of particle... 

    Thermomechanical synthesis of hybrid in-situ Al-(Al3Ti+Al2O3) composites through nanoscale Al-Al2TiO5 reactive system

    , Article Journal of Alloys and Compounds ; Volume 789 , 2019 , Pages 493-505 ; 09258388 (ISSN) Ahmadvand, M. S ; Azarniya, A ; Madaah Hosseini, H. R ; Sharif University of Technology
    Elsevier Ltd  2019
    In this work, nanostructured aluminum titanate (Al2TiO5 or AT) was synthesized by the citrate sol gel method. Then, different volume fractions of this ceramic were blended with Al powder through different durations of the high-energy vibratory milling. The effect of mechanical milling on the thermal degradation of AT in exposure to Al and formation mechanism of in-situ Al2O3 and Al3Ti particles were explored in three conditions: (i) in the powder form; (ii) after annealing of green compact; and (iii) after hot extrusion. In the powder form, it was shown that the mechanical milling is able to significantly diminish the thermal stability of AT, so that the required temperature for the Al3Ti... 

    Application of nanostructured aluminium titanate (Al2TiO5) photocatalyst for removal of organic pollutants from water: Influencing factors and kinetic study

    , Article Materials Chemistry and Physics ; Volume 256 , 2020 Azarniya, A ; Soltaninejad, M ; Zekavat, M ; Bakhshandeh, F ; Madaah Hosseini, H. R ; Amutha, C ; Ramakrishna, S ; Sharif University of Technology
    Elsevier Ltd  2020
    In this study, aluminum titanate (Al2TiO5)-based nanostructure with the outstanding photocatalytic performance was prepared via the simple citrate sol-gel method. The effects of thee operational variables such as pH, temperature, catalyst dosage, and initial dye concentration on the photodegradation efficiency of methylene blue (MB) were explored in some details. The results showed that compared to TiO2, AT benefits a superior photocatalytic activity due to its narrow band gap (2.88 eV) and low recombination rate of charge carriers. Increasing the wastewater temperature from 25 to 60 °C can improve the degradation percent from 22.15 to 52%. Based on the thermokinetic calculations, the... 

    Synthesis and characterization of Al2O3-SiC nano composite by sol-gel method and the effect of tio2 on sintering

    , Article Journal of Nano Research ; Volume 13 , 2011 , Pages 7-19 ; 16625250 (ISSN) Rezaie, H. R ; Mohammad Rahimi, R ; Nemati, A ; Samadani, M ; Sharif University of Technology
    In the present article, α-Al2O3 nano powder was synthesized by a simple aqueous sol-gel method by using AlCl3 as precursor. It was shown that the gel calcined at 1000°C, 1100 °Cand 1200 °Cresulted in the formation of a crystalline ?-Al2O3 nano powder. In continue TEOS and saccharose was used to prepare SiO2 xerogels containing carbon nano particles. The conversion of the gel to β-SiC nano powders was accomplished by carbothermal reduction at 1500°Cfor 1 h in argon atmosphere. In second pace alumina matrix composites with nano particles of 5 vol% SiC were prepared with the addition of TiO 2 as sintering aid and densified by pressureless sintering method at 1600°Cand 1630°C for 2 h in nitrogen...