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Mehdi Rahimi-nasrabadi - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of some transition MWO_4 (M: Mn, Fe, Co, Ni, Cu, Zn, Cd) nanostructures by hydrothermal method
Journal of Materials Science: Materials in Electronics, 2019Co-Authors: Saeid Pourmasoud, Mohammad Eghbali-arani, Vahid Ameri, Mehdi Rahimi-nasrabadi, Farhad Ahmadi, Ali Sobhani-nasabAbstract:The morphology, favored shape with certain particle size, of nanostructures is considered as one of the most attractive fields of nanomaterials. To obtain the design of nanostructures, hydrothermal method is one of the most appropriate procedures by which preferable structures such as star anise-, desert rose-, sphere-, soya bean-, plate-, leaf-, and rod-like, can be prepared. These, can be synthesized through modifying some parameters. Thanks to bivalent transition metals are technologically important, this review emphasizes on the synthesis of bivalent metals Tungstates, MWO_4, (M = Mn, Fe, Co, Ni, Cu, Zn, Cd) through hydrothermal method and investigation on various morphologies of compounds containing Tungstate. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques have been employed to show the size and morphology of as-fabricated samples. Moreover, chemical composition of samples is characterized through X-ray diffraction (XRD) analysis, and the properties and applications of these compounds were investigated as well.
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Synthesis procedure optimization and characterization of europium (III) Tungstate nanoparticles
Journal of Molecular Structure, 2014Co-Authors: Mehdi Rahimi-nasrabadi, Seied Mahdi Pourmortazavi, Mohammad Reza Ganjali, Ali Reza Banan, Farhad AhmadiAbstract:Abstract Taguchi robust design as a statistical method was applied for the optimization of process parameters in order to tunable, facile and fast synthesis of europium (III) Tungstate nanoparticles. Europium (III) Tungstate nanoparticles were synthesized by a chemical precipitation reaction involving direct addition of europium ion aqueous solution to the Tungstate reagent solved in an aqueous medium. Effects of some synthesis procedure variables on the particle size of europium (III) Tungstate nanoparticles were studied. Analysis of variance showed the importance of controlling Tungstate concentration, cation feeding flow rate and temperature during preparation of europium (III) Tungstate nanoparticles by the proposed chemical precipitation reaction. Finally, europium (III) Tungstate nanoparticles were synthesized at the optimum conditions of the proposed method. The morphology and chemical composition of the prepared nano-material were characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, FT-IR spectroscopy and fluorescence.
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Eggshell bioactive membrane assisted synthesis of barium Tungstate nanoparticles
Materials Letters, 2014Co-Authors: Seied Mahdi Pourmortazavi, Mehdi Taghdiri, Nasim Samimi, Mehdi Rahimi-nasrabadiAbstract:Abstract Taguchi robust design was used to optimize process parameters for facile synthesis of barium Tungstate nanoparticles by controlled precipitation reaction using eggshell as a bioactive membrane. Effects of various parameters such as barium and Tungstate concentrations, time of reaction, and stirring rate of solution in the reactor on particle size of synthesized barium Tungstate were investigated. Analysis of variance for the obtained results showed that particle size of barium Tungstate could be tuned by setting significant process variables especially barium and Tungstate concentrations. Particle size of prepared BaWO 4 at optimum conditions was 14 nm.
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Facile Chemical Synthesis and Characterization of Copper Tungstate Nanoparticles
Journal of Inorganic and Organometallic Polymers and Materials, 2013Co-Authors: Seied Mahdi Pourmortazavi, Mehdi Rahimi-nasrabadi, Morteza Khalilian-shalamzari, Hamid Reza Ghaeni, Seiedeh Somayyeh HajimirsadeghiAbstract:Copper Tungstate nanoparticles were synthesized by a chemical precipitation reaction in aqueous ambient involving direct addition of copper ion solution to the solution of Tungstate reagent. Optimization of the synthesis procedure was carried out using Taguchi robust design as a statistical method. In order to controllable, simple and fast synthesis of copper Tungstate nanoparticles, effects of some synthesis conditions such as reagents concentrations (i.e., copper and Tungstate ions), flow rate of copper feeding and temperature of the reactor on the particle size of synthesized copper Tungstate were investigated by the aid of an orthogonal array. The results of optimization process showed that copper Tungstate nanoparticles could be prepared by controlling the effective parameters and at optimum conditions of synthesis procedure, the size of prepared copper Tungstate particles was about 56 nm. Chemical composition and microstructure of the prepared copper Tungstate nanoparticles were characterized by means of X-ray diffraction, scanning electron microscopy, UV–Vis spectrophotometry, FT-IR spectroscopy and Photoluminescence.
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Optimization of synthesis procedure and structure characterization of manganese Tungstate nanoplates
Open Chemistry, 2013Co-Authors: Mehdi Rahimi-nasrabadi, Seied Mahdi Pourmortazavi, Morteza Khalilian-shalamzari, Seiedeh Somayyeh Hajimirsadeghi, Mir Mahdi ZahediAbstract:A simple and fast chemical method was used for synthesis of manganese Tungstate nanoplates in flower-like clusters; while Taguchi robust design was employed as statistical method for optimization of the experimental parameters for the procedure. Ultrafine manganese Tungstate plates in flower-like clusters were synthesized via a direct precipitation method involving addition of manganese ion solution to the aqueous Tungstate reagent. Effects of various reaction conditions such as manganese and Tungstate concentrations, flow rate of reagent addition and reactor temperature on the thickness of the synthesized manganese Tungstate plates were investigated experimentally. Analysis of variance (ANOVA) showed that manganese Tungstate nanoplates could be effectively synthesized by tuning significant parameters of precipitation procedure. Meanwhile, optimum conditions for synthesis of MnWO4 nanoplates via this simple, fast, and cost effective method were proposed. The structure and composition of the prepared nanoplates under optimum conditions were characterized by EDX, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR spectroscopy, and photoluminescence techniques. Open image in new window
Seied Mahdi Pourmortazavi - One of the best experts on this subject based on the ideXlab platform.
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Silver Tungstate nanostructures: electrochemical synthesis and its statistical optimization
Journal of Materials Science: Materials in Electronics, 2015Co-Authors: Majid Ramezani, Seied Mahdi Pourmortazavi, M. Sadeghpur, A. Yazdani, Iraj KohsariAbstract:Silver Tungstate (Ag2WO4) nanoparticles were synthesized by a simple electrochemical method with the aid of silver electrode and sodium Tungstate as starting reagents. In this study, synthesis conditions of silver Tungstate nanoparticles were optimized by Taguchi robust design. Besides, the effects of several synthesis conditions such as Tungstate ion concentration, applied voltage, stirring rate, and reaction temperature on the particle size of product were investigated by SEM images. Furthermore, the significance of these factors on the diameter of silver Tungstate nanoparticles was evaluated by the analysis of variance and the optimum conditions for the preparation of silver Tungstate nanoparticles by electrochemical method was investigated. The resulted nanoparticles were characterized by different routes, i.e., XRD, FTIR, SEM, and PL analysis. Also, the optical band gap corresponding to the resulted Ag2WO4 nanoparticles was predicted to be 2.75 eV.
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Synthesis procedure optimization and characterization of europium (III) Tungstate nanoparticles
Journal of Molecular Structure, 2014Co-Authors: Mehdi Rahimi-nasrabadi, Seied Mahdi Pourmortazavi, Mohammad Reza Ganjali, Ali Reza Banan, Farhad AhmadiAbstract:Abstract Taguchi robust design as a statistical method was applied for the optimization of process parameters in order to tunable, facile and fast synthesis of europium (III) Tungstate nanoparticles. Europium (III) Tungstate nanoparticles were synthesized by a chemical precipitation reaction involving direct addition of europium ion aqueous solution to the Tungstate reagent solved in an aqueous medium. Effects of some synthesis procedure variables on the particle size of europium (III) Tungstate nanoparticles were studied. Analysis of variance showed the importance of controlling Tungstate concentration, cation feeding flow rate and temperature during preparation of europium (III) Tungstate nanoparticles by the proposed chemical precipitation reaction. Finally, europium (III) Tungstate nanoparticles were synthesized at the optimum conditions of the proposed method. The morphology and chemical composition of the prepared nano-material were characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, FT-IR spectroscopy and fluorescence.
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Eggshell bioactive membrane assisted synthesis of barium Tungstate nanoparticles
Materials Letters, 2014Co-Authors: Seied Mahdi Pourmortazavi, Mehdi Taghdiri, Nasim Samimi, Mehdi Rahimi-nasrabadiAbstract:Abstract Taguchi robust design was used to optimize process parameters for facile synthesis of barium Tungstate nanoparticles by controlled precipitation reaction using eggshell as a bioactive membrane. Effects of various parameters such as barium and Tungstate concentrations, time of reaction, and stirring rate of solution in the reactor on particle size of synthesized barium Tungstate were investigated. Analysis of variance for the obtained results showed that particle size of barium Tungstate could be tuned by setting significant process variables especially barium and Tungstate concentrations. Particle size of prepared BaWO 4 at optimum conditions was 14 nm.
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Facile Chemical Synthesis and Characterization of Copper Tungstate Nanoparticles
Journal of Inorganic and Organometallic Polymers and Materials, 2013Co-Authors: Seied Mahdi Pourmortazavi, Mehdi Rahimi-nasrabadi, Morteza Khalilian-shalamzari, Hamid Reza Ghaeni, Seiedeh Somayyeh HajimirsadeghiAbstract:Copper Tungstate nanoparticles were synthesized by a chemical precipitation reaction in aqueous ambient involving direct addition of copper ion solution to the solution of Tungstate reagent. Optimization of the synthesis procedure was carried out using Taguchi robust design as a statistical method. In order to controllable, simple and fast synthesis of copper Tungstate nanoparticles, effects of some synthesis conditions such as reagents concentrations (i.e., copper and Tungstate ions), flow rate of copper feeding and temperature of the reactor on the particle size of synthesized copper Tungstate were investigated by the aid of an orthogonal array. The results of optimization process showed that copper Tungstate nanoparticles could be prepared by controlling the effective parameters and at optimum conditions of synthesis procedure, the size of prepared copper Tungstate particles was about 56 nm. Chemical composition and microstructure of the prepared copper Tungstate nanoparticles were characterized by means of X-ray diffraction, scanning electron microscopy, UV–Vis spectrophotometry, FT-IR spectroscopy and Photoluminescence.
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Optimization of synthesis procedure and structure characterization of manganese Tungstate nanoplates
Open Chemistry, 2013Co-Authors: Mehdi Rahimi-nasrabadi, Seied Mahdi Pourmortazavi, Morteza Khalilian-shalamzari, Seiedeh Somayyeh Hajimirsadeghi, Mir Mahdi ZahediAbstract:A simple and fast chemical method was used for synthesis of manganese Tungstate nanoplates in flower-like clusters; while Taguchi robust design was employed as statistical method for optimization of the experimental parameters for the procedure. Ultrafine manganese Tungstate plates in flower-like clusters were synthesized via a direct precipitation method involving addition of manganese ion solution to the aqueous Tungstate reagent. Effects of various reaction conditions such as manganese and Tungstate concentrations, flow rate of reagent addition and reactor temperature on the thickness of the synthesized manganese Tungstate plates were investigated experimentally. Analysis of variance (ANOVA) showed that manganese Tungstate nanoplates could be effectively synthesized by tuning significant parameters of precipitation procedure. Meanwhile, optimum conditions for synthesis of MnWO4 nanoplates via this simple, fast, and cost effective method were proposed. The structure and composition of the prepared nanoplates under optimum conditions were characterized by EDX, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR spectroscopy, and photoluminescence techniques. Open image in new window
Deepesh Kumar Dixit - One of the best experts on this subject based on the ideXlab platform.
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Effect of addition of zirconium Tungstate, lead Tungstate and titanium dioxide on the proton conductivity of polystyrene porous membrane
International Journal of Hydrogen Energy, 2012Co-Authors: Krishna Gandhi, Brajesh Kumar Dixit, Deepesh Kumar DixitAbstract:Proton conducting polymer electrolyte membrane is the most important component of polymer electrolyte membrane fuel cells (PEMFC). The positive effect of addition of oxo-clusters of Ti, Zr, W and hydrophilic additives like SiO2, TiO2 and ZrO2 on the proton conductivity characteristics of Nafion membranes have been reported earlier. Here we report the effect of additives zirconium Tungstate, lead Tungstate and titanium dioxide on the proton conductivity of pure polystyrene porous membranes in aqueous solution. The enhancement of proton conductivity was observed to be highest for titanium dioxide (by factors of 4.63 for titanium dioxide alone, 1.37 and 16.17 for combinations of titanium dioxide plus zirconium Tungstate and titanium dioxide plus lead Tungstate) whereas the enhancement factor for zirconium Tungstate alone was 0.79 and that for lead Tungstate alone was 0.08. This showed that the effect of addition of titanium dioxide on proton conductivity was the highest, while that of zirconium Tungstate alone was marginal and that of lead Tungstate alone negative. The proton conductivities were calculated from the pH values measured at room temperature using an electrochemical cell and pH meter, on the basis of a proton transport model for porous membranes in aqueous solution, developed by us. The membranes were characterized by FTIR, SEM, TGA/DTA and the observed results are explained in terms of the hydrophilicity of the additives.
Petrova, Sophia A. - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and Properties of Vanadium Substituted Bismuth Tungstates with Fluorite-like Structure
'Ural Federal University', 2019Co-Authors: Kaimieva, Olga S., Sabirova, Irina E., Buyanova, Elena S., Petrova, Sophia A.Abstract:The samples of vanadium substituted bismuth Tungstates with a cubic structure were obtained by solid state method. The unit cell volume of the compounds slightly contracts with increasing tungsten content and in case of vanadium doping. Thermal expansion coefficient of bismuth Tungstate is equal to 13×10-6 °C-1. The electrical conductivity was investigated using ac impedance spectroscopy. The results showed that the substitution of tungsten with vanadium ions increased electrical conductivity values by one order of magnitude
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Synthesis and Properties of Vanadium Substituted Bismuth Tungstates with Fluorite-like Structure
'Ural Federal University', 2019Co-Authors: Kaimieva, Olga S., Sabirova, Irina E., Buyanova, Elena S., Petrova, Sophia A.Abstract:Received: 05.07.2019. Accepted: 23.07.2019. Published: 05.08.2019.The samples of vanadium substituted bismuth Tungstates with a cubic structure were obtained by solid state method. The unit cell volume of the compounds slightly contracts with increasing tungsten content and in case of vanadium doping. Thermal expansion coefficient of bismuth Tungstate is equal to 13·10–6 °C–1. The electrical conductivity was investigated using ac impedance spectroscopy. The results showed that the substitution of tungsten with vanadium ions increased electrical conductivity values by one order of magnitude.This work was performed within the State Assignment of the Ministry of Education and Science of the Russian Federation no. 4.2288.2017/4.6. Powder X‑ray diffraction studies were performed on the equipment of the Ural-M Shared Facility Center of the Institute of Metallurgy of the Ural Branch of the Russian Academy of Sciences (IMET UB RAS)
Cyril Thomas - One of the best experts on this subject based on the ideXlab platform.
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Insights into the WOx Coverage-Dependent Location and Oxidation State of Noble Metals Supported on Tungstated Oxides: The Case of Rh/WOx−Ce0.62Zr0.38O2
Journal of Physical Chemistry C, 2014Co-Authors: Thomas Bonnotte, Rachel P. Doherty, Christophe Méthivier, Céline Sayag, Jean-marc Krafft, Mickaël Sicard, Frédéric Ser, Cyril ThomasAbstract:Noble metals-promoted Tungstated oxides have been shown to be profitable in a wide variety of catalytic reactions of environmental interest but to be detrimental in the hydrogenation of aromatics. The origin of the deleterious effect of Tungstates on the hydrogenation performance of noble metals is still being debated. To provide further insights into this, the location and the oxidation state of Rh were investigated as a function of the W surface density (0−10 W/nm2) of Rh/WOx− Ce0.62Zr0.38O2 (Rh/W−CZ) catalysts after high-temperature reduction. For that purpose, a thorough characterization of the oxide phases was performed through N2- sorption, X-ray diffraction, Raman spectroscopy, NOx temperature-programmed desorption, and X-ray photoelectron spectroscopy (XPS), whereas the metallic phases were characterized by low-temperature H2 chemisorption, XPS, N2 Fourier transform infrared spectroscopy and benzene hydrogenation. It was found that Rh deposited on both Tungstates and CZ, and did not sinter with increasing W surface densities. The observed linear decrease in the Rh hydrogenation performance of the WOx-promoted Ce0.62Zr0.38O2 below pseudo monolayer coverage of CZ (4.8 W/nm2 CZ) was assigned to a strong metal support interaction effect between the Rh particles and the nonreducible underlying WOx phase, resulting in the formation of electron-deficient Rh species (Rhδ+).
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On the detrimental effect of Tungstates on the n-C10-SCR of NOx on Ag/g-Al2O3
Top. Catal., 2013Co-Authors: Juliette Blanchard, Rachel P. Doherty, Hiu Ying Law, Christophe Méthivier, Cyril ThomasAbstract:The influence of the addition of W to Al2O3, promoted or not by Ag, on the n-C10 SCR of NOx was investigated. It was shown that the addition of W was detrimental to the n-C10 SCR reaction. Based on the NOx- TPD, the XPS and the n-C10 SCR measurements, it was concluded that the loss of activity observed at temperatures lower than 400 C on the Ag/W(5)–Al2O3 catalyst compared with the Ag/Al2O3 sample is likely due to the preferential deposition of Ag on the Tungstate phase, making it inactive for the n-C10 SCR reaction which requires the active silver species to be in close contact with the Al2O3. At higher temperatures, the occupation, by the Tungstates, of the Al2O3 sites responsible for the n-C10-SCR reaction is proposed to be an additional drawback accounting for the detrimental effect of W on Al2O3-supported catalysts promoted or not by Ag.
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On the Detrimental Effect of Tungstates on the n-C10-SCR of NOx on Ag/γ-Al2O3
Topics in Catalysis, 2013Co-Authors: Juliette Blanchard, Rachel P. Doherty, Hiu Ying Law, Christophe Méthivier, Cyril ThomasAbstract:The influence of the addition of W to Al2O3, promoted or not by Ag, on the n-C10 SCR of NOx was investigated. It was shown that the addition of W was detrimental to the n-C10 SCR reaction. Based on the NOx- TPD, the XPS and the n-C10 SCR measurements, it was concluded that the loss of activity observed at temperatures lower than 400 C on the Ag/W(5)–Al2O3 catalyst compared with the Ag/Al2O3 sample is likely due to the preferential deposition of Ag on the Tungstate phase, making it inactive for the n-C10 SCR reaction which requires the active silver species to be in close contact with the Al2O3. At higher temperatures, the occupation, by the Tungstates, of the Al2O3 sites responsible for the n-C10-SCR reaction is proposed to be an additional drawback accounting for the detrimental effect of W on Al2O3-supported catalysts promoted or not by Ag.
